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Document and Entity Information - shares	6 Months Ended
Jun. 30, 2013	Aug. 30, 2013
Document and Entity Information
Entity Registrant Name	Onconova Therapeutics, Inc.
Entity Central Index Key	0001130598
Document Type	10-Q
Document Period End Date	Jun. 30, 2013
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Entity Current Reporting Status	No
Entity Filer Category	Non-accelerated Filer
Entity Common Stock, Shares Outstanding		21,403,655
Document Fiscal Year Focus	2013
Document Fiscal Period Focus	Q2

Condensed Consolidated Balance Sheets - USD ($)	Jun. 30, 2013	Dec. 31, 2012
Current assets:
Cash and cash equivalents	$ 51,181,000	$ 81,527,000
Prepaid expenses and other current assets	5,867,000	1,725,000
Total current assets	57,048,000	83,252,000
Property and equipment, net	729,000	463,000
Restricted cash	125,000	125,000
Other non-current assets	12,000	12,000
Total assets	57,914,000	83,852,000
Current liabilities:
Accounts payable	4,410,000	5,517,000
Accrued expenses and other current liabilities	5,338,000	3,925,000
Warrant liability	50,000	62,000
Option liability		11,967,000
Deferred revenue	3,509,000	3,907,000
Total current liabilities	13,307,000	25,378,000
Deferred revenue, non-current	14,136,000	15,421,000
Other	47,000	44,000
Total liabilities	27,490,000	40,843,000
Commitments and contingencies
Redeemable convertible preferred stock, $0.01 par value per share, 18,548,253 shares authorized at June 30, 2013 and December 31, 2012, 16,912,199 issued and outstanding at June 30, 2013 and December 31, 2012, liquidation preference of $205,760,000 at June 30, 2013	203,366,000	201,315,000
Stockholders' deficit:
Common stock, $0.01 par value, 30,145,155 authorized at June 30, 2013 and December 31, 2012, 2,609,484 and 2,606,484 shares issued and outstanding at June 30, 2013 and December 31, 2012	26,000	26,000
Additional paid in capital	22,787,000	10,021,000
Accumulated other comprehensive income	5,000
Accumulated deficit	(195,760,000)	(168,353,000)
Total stockholders' deficit	(172,942,000)	(158,306,000)
Total liabilities, redeemable convertible preferred stock and stockholders' deficit	$ 57,914,000	$ 83,852,000

Condensed Consolidated Balance Sheets (Parenthetical)	Jun. 30, 2013 USD ($) $ / shares shares
Condensed Consolidated Balance Sheets
Redeemable convertible preferred stock, par value per share (in dollars per share) \| $ / shares	$ 0.01
Redeemable convertible preferred stock, shares authorized	18,548,253
Redeemable convertible preferred stock, shares issued	16,912,199
Redeemable convertible preferred stock, shares outstanding	16,912,199
Redeemable convertible preferred stock, liquidation preference (in dollars) \| $	$ 205,760,000
Common stock, par value (in dollars per share) \| $ / shares	$ 0.01
Common stock, shares authorized	30,145,155
Common stock, shares issued	2,609,484
Common stock, shares outstanding	2,609,484

Condensed Consolidated Statements of Operations - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Condensed Consolidated Statements of Operations
Revenue	$ 591,000	$ 220,000	$ 1,707,000	$ 418,000
Operating expenses:
General and administrative	3,117,000	1,627,000	6,463,000	4,087,000
Research and development	10,047,000	6,776,000	22,803,000	15,224,000
Total operating expenses	13,164,000	8,403,000	29,266,000	19,311,000
Loss from operations	(12,573,000)	(8,183,000)	(27,559,000)	(18,893,000)
Change in fair value of warrant liability	(2,000)	999,000	12,000	390,000
Interest expense	(2,000)	(230,000)	(2,000)	(251,000)
Other income (expense), net	15,000	(2,000)	142,000	539,000
Net loss before income taxes	(12,562,000)	(7,416,000)	(27,407,000)	(18,215,000)
Net loss	(12,562,000)	(7,416,000)	(27,407,000)	(18,215,000)
Accretion of redeemable convertible preferred stock	(1,032,000)	(927,000)	(2,051,000)	(2,158,000)
Net loss applicable to common stockholders	$ (13,594,000)	$ (8,343,000)	$ (29,458,000)	$ (20,373,000)
Net loss per share of common stock, basic and diluted (in dollars per share)	$ (5.21)	$ (3.84)	$ (11.29)	$ (9.37)
Basic and diluted weighted average shares outstanding (in shares)	2,609,495	2,173,549	2,608,450	2,173,549

Consolidated Statements of Redeemable Convertible Preferred Stock and Stockholders' Deficit - USD ($)	Total	Redeemable Convertible Preferred Stock	Common Stock	Additional Paid in Capital	Accumulated deficit	Accumulated other comprehensive income (loss)
Balance at Dec. 31, 2011	$ (138,419,000)	$ 119,997,000	$ 22,000		$ (138,441,000)
Balance (in shares) at Dec. 31, 2011		11,227,169	2,167,928
Increase (Decrease) in Stockholders' Equity
Net loss	(18,215,000)				(18,215,000)
Exercise of stock options	9,000			$ 9,000
Exercise of stock options (in shares)			5,700
Settlement of stock option liabilities	34,000			34,000
Issuance of preferred stock upon exercise of warrants		$ 2,802,000
Issuance of preferred stock upon exercise of warrants (in shares)		221,399
Accretion of preferred stock to redemption value	(2,158,000)	$ 2,158,000		(43,000)	(2,115,000)
Balance at Jun. 30, 2012	(158,749,000)	$ 124,957,000	$ 22,000		(158,771,000)
Balance (in shares) at Jun. 30, 2012		11,448,568	2,173,628
Balance at Dec. 31, 2012	$ (158,306,000)	$ 201,315,000	$ 26,000	10,021,000	(168,353,000)
Balance (in shares) at Dec. 31, 2012	2,606,484	16,912,199	2,606,484
Increase (Decrease) in Stockholders' Equity
Net loss	$ (27,407,000)				(27,407,000)
Other comprehensive income	5,000					$ 5,000
Exercise of stock options	44,000			44,000
Exercise of stock options (in shares)			3,000
Stock based compensation	291,000			291,000
Accretion of preferred stock to redemption value	(2,051,000)	$ 2,051,000		(2,051,000)
Modification of stock option awards	14,482,000			14,482,000
Balance at Jun. 30, 2013	$ (172,942,000)	$ 203,366,000	$ 26,000	$ 22,787,000	$ (195,760,000)	$ 5,000
Balance (in shares) at Jun. 30, 2013	2,609,484	16,912,199	2,609,484

Condensed Consolidated Statements of Cash Flows - USD ($)	6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012
Operating activities:
Net loss	$ (27,407,000)	$ (18,215,000)
Adjustment to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	207,000	157,000
Change in fair value of warrant liabilities	(12,000)	(390,000)
Stock compensation expense	2,844,000	2,540,000
Changes in assets and liabilities:
Grants receivable		19,000
Prepaid expenses and other current assets	(4,142,000)	177,000
Accounts payable	(1,107,000)	(2,532,000)
Accrued expenses	1,413,000	2,644,000
Other liabilities	3,000	(20,000)
Deferred revenue	(1,683,000)	3,373,000
Net cash used in operating activities	(29,884,000)	(12,247,000)
Investing activities:
Payments for purchase of property and equipment	(473,000)	(6,000)
Net cash used in investing activities	(473,000)	(6,000)
Financing activities:
Proceeds from the exercise of stock options	6,000	9,000
Proceeds from the exercise of warrants		2,167,000
Proceeds from the sale of Series H preferred stock		400,000
Proceeds from stockholder loan and convertible debt		9,486,000
Net cash provided by financing activities	6,000	12,062,000
Effect of foreign currency translation on cash	5,000
Net decrease in cash and cash equivalents	(30,346,000)	(191,000)
Cash and cash equivalents at beginning of period	81,527,000	2,713,000
Cash and cash equivalents at end of period	$ 51,181,000	$ 2,522,000

Summary of Significant Accounting Policies	6 Months Ended
Summary of Significant Accounting Policies	Jun. 30, 2013
Summary of Significant Accounting Policies
Summary of Significant Accounting Policies	2. Summary of Significant Accounting Policies Basis of Presentation The condensed consolidated financial statements are prepared in conformity with accounting principles generally accepted in the United States (“GAAP”) for interim financial information. Certain information and footnotes normally included in financial statements prepared in accordance with GAAP have been condensed or omitted pursuant to the rules and regulations of the Securities and Exchange Commission. The financial statements include the consolidated accounts of the Company and its wholly-owned subsidiary, Onconova Europe GmbH. All significant intercompany transactions have been eliminated. Unaudited Interim Financial Information The accompanying condensed consolidated balance sheet as of June 30, 2013, the condensed consolidated statements of operations and comprehensive loss for the three and six months ended June 30, 2013 and 2012, the condensed consolidated statements of redeemable convertible preferred stock and stockholders’ deficit and the condensed consolidated statements of cash flows for the six months ended June 30, 2013 and 2012 are unaudited. The interim unaudited condensed consolidated financial statements have been prepared on the same basis as the annual audited consolidated financial statements and, in the opinion of management, reflect all adjustments, which include only normal recurring adjustments, necessary for the fair statement of the Company’s financial position as of June 30, 2013 and the results of its operations, its comprehensive loss and its cash flows for the six months ended June 30, 2013 and 2012. The financial data and other information disclosed in these notes related to the six months ended June 30, 2013 and 2012 are unaudited. The results for the six months ended June 30, 2013 are not necessarily indicative of results to be expected for the year ending December 31, 2013, any other interim periods, or any future year or period. These unaudited condensed consolidated financial statements should be read in conjunction with the audited consolidated financial statements and the notes thereto for the year ended December 31, 2012 included in the Company’s final prospectus filed on July 25, 2013 with the Securities and Exchange Commission (the “SEC”) pursuant to Rule 424(b)(4) of the Securities Act of 1933, as amended (the “Securities Act”). Segment Information Operating segments are defined as components of an enterprise about which separate discrete information is available for evaluation by the chief operating decision maker, or decision-making group, in deciding how to allocate resources and in assessing performance. The Company views its operations and manages its business in one segment, which is the identification and development of oncology therapeutics. Significant Accounting Policies The Company’s significant accounting policies are disclosed in the audited consolidated financial statements for the year ended December 31, 2012 included in the Company’s final prospectus filed on July 25, 2013 with the SEC pursuant to Rule 424(b)(4) of the Securities Act. Since the date of such financial statements, there have been no changes to the Company’s significant accounting policies. Foreign Currency Translation The reporting currency of the Company and its U.S. subsidiary is the U.S. dollar. The functional currency of the Company’s non-U.S. subsidiary is the local currency. Assets and liabilities of the foreign subsidiary are translated into U.S. dollars based on exchange rates at the end of the period. Revenues and expenses are translated at average exchange rates during the reporting period. Gains and losses arising from the translation of assets and liabilities are included as a component of accumulated other comprehensive income. Gains and losses resulting from foreign currency transactions are reflected within the Company’s results of operations. The Company has not utilized any foreign currency hedging strategies to mitigate the effect of its foreign currency exposure. Deferred Initial Public Offering Costs Deferred IPO costs as of June 30, 2013, consisting of legal, accounting, printing and filing fees incurred in the preparation of the Company’s Registration Statement on Form S-1 were capitalized. The deferred costs are included in prepaid expenses and other current assets on the consolidated balance sheets. See Note 5. The deferred offering costs were offset against the IPO proceeds upon the completion of the offering in July 2013. Recent Accounting Pronouncements In February 2013, the Financial Accounting Standards Board (the “FASB”) amended its guidance to require an entity to present the effect of certain significant reclassifications out of accumulated other comprehensive income on the respective line items in net income. The new accounting guidance does not change the items that must be reported in other comprehensive income or when an item of other comprehensive income must be reclassified to net income. The guidance is effective prospectively for fiscal years beginning after December 15, 2012. The Company adopted these new provisions for the quarter beginning January 1, 2013. As the guidance requires additional presentation only, there was no impact to the Company’s consolidated financial position, results of operations or cash flows. In July 2013, the FASB issued guidance clarifying that an unrecognized tax benefit, or a portion of an unrecognized tax benefit, should be presented in the financial statements as a reduction to a deferred tax asset for a net operating loss carryforward, a similar tax loss, or a tax credit carryforward if such settlement is required or expected in the event the uncertain tax benefit is disallowed. In situations where a net operating loss carryforward, a similar tax loss, or a tax credit carryforward is not available at the reporting date under the tax law of the applicable jurisdiction or the tax law of the jurisdiction does not require, and the entity does not intend to use, the deferred tax asset for such purpose, the unrecognized tax benefit should be presented in the financial statements as a liability and should not be netted with the deferred tax asset. The guidance is effective for fiscal years, and interim periods within those years, beginning after December 15, 2013. Early adoption is permitted. The amendments should be applied prospectively to all unrecognized tax benefits that exist at the effective date. Retrospective application is permitted. The Company is currently evaluating the impact that adoption will have on the determination or reporting of its financial results.

Fair Value Measurements

6 Months Ended

Jun. 30, 2013

Fair Value Measurements

Fair Value Measurements

3. Fair Value Measurements

The Company applies various valuation approaches in determining the fair value of its financial assets and liabilities within a hierarchy that maximizes the use of observable inputs and minimizes the use of unobservable inputs by requiring that observable inputs be used when available. Observable inputs are inputs that market participants would use in pricing the asset or liability based on market data obtained from sources independent of the Company. Unobservable inputs are inputs that reflect the Company’s assumptions about the inputs that market participants would use in pricing the asset or liability and are developed based on the best information available under the circumstances. The fair value hierarchy is broken down into three levels based on the source of inputs as follows:

Level 1—Valuations based on unadjusted quoted prices in active markets for identical assets or liabilities that the Company has the ability to access.

Level 2—Valuations based on quoted prices for similar assets or liabilities in active markets, quoted prices for identical or similar assets or liabilities in markets that are not active and models for which all significant inputs are observable, either directly or indirectly.

Level 3—Valuations based on inputs that are unobservable and significant to the overall fair value measurement.

The availability of observable inputs can vary among the various types of financial assets and liabilities. To the extent that the valuation is based on models or inputs that are less observable or unobservable in the market, the determination of fair value requires more judgment. In certain cases, the inputs used to measure fair value may fall into different levels of the fair value hierarchy. In such cases, for financial statement disclosure purposes, the level in the fair value hierarchy within which the fair value measurement is classified is based on the lowest level input that is significant to the overall fair value measurement.

The Company had no assets or liabilities classified as Level 1 or Level 2. The Series G Preferred Stock warrants (see Note 6) are classified as Level 3. The fair values of these instruments are determined using models based on market observable inputs and management judgment. There were no material re-measurements of fair value during the six months ended June 30, 2013 and the year ended December 31, 2012 with respect to financial assets and liabilities, other than those assets and liabilities that are measured at fair value on a recurring basis.

The Company has classified the Series G Preferred Stock warrants as a liability and has re-measured the liability to estimated fair value at June 30, 2013 and December 31, 2012, using the Black-Scholes option pricing model with the following assumptions: contractual life according to the remaining terms of the warrants, no dividend yield, weighted average risk-free interest rates of 0.33% and 0.31% at June 30, 2013 and December 31, 2012, respectively, and weighted average volatility of 72.07% and 64.87% at June 30, 2013 and December 31, 2012, respectively. The volatility was based on average historical share price trading data for a group of 11 comparable companies.

The following fair value hierarchy table presents information about the Company’s financial assets and liabilities measured at fair value on a recurring basis as of June 30, 2013 and December 31, 2012:

	Fair Value Measurement as of June 30, 2013								Fair Value Measurement as of December 31, 2012
	Level 1		Level 2		Level 3		Balance		Level 1		Level 2		Level 3		Balance

Warrant liability	$	—	$	—	$	50,000	$	50,000	$	—	$	—	$	62,000	$	62,000
Total	$	—	$	—	$	50,000	$	50,000	$	—	$	—	$	62,000	$	62,000

The following table presents a reconciliation of the Company’s liabilities measured at fair value on a recurring basis using significant unobservable inputs (Level 3) for the six months ended June 30, 2013:

	Warrant Liability
Balance at December 31, 2012	$	62,000
Change in fair value upon re-measurement	(12,000		)
Balance at June 30, 2013	$	50,000

There were no transfers between Level 1 and Level 2 in any of the periods reported.

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References + Details

Preferred Stock and Stockholders' Deficit

6 Months Ended

Jun. 30, 2013

Preferred Stock and Stockholders' Deficit

Preferred Stock and Stockholders' Deficit

6. Preferred Stock and Stockholders’ Deficit

Capitalization

The following is the composition of share capital as of the dates indicated:

	Authorized		Issued and Outstanding
	June 30,	December 31,	June 30,	December 31,
	2013	2012	2013	2012
Shares of $0.01 par value per share:
Common stock	30,145,155	30,145,155	2,609,484	2,606,484

Series A Preferred Stock	400,000	400,000	107,000	107,000
Series B Preferred Stock	1,200,000	1,200,000	1,107,189	1,107,189
Series C Preferred Stock	1,200,000	1,200,000	1,069,946	1,069,946
Series D Preferred Stock	1,625,000	1,625,000	1,583,568	1,583,568
Series E Preferred Stock	1,650,000	1,650,000	1,633,082	1,633,082
Series F Preferred Stock	2,000,000	2,000,000	2,000,000	2,000,000
Series G Preferred Stock	2,700,000	2,700,000	1,934,359	1,934,359
Series H Preferred Stock	2,042,950	2,042,950	2,013,424	2,013,424
Series I Preferred Stock	2,700,000	2,700,000	2,433,328	2,433,328
Series J Preferred Stock	3,030,303	3,030,303	3,030,303	3,030,303
Total Preferred Stock	18,548,253	18,548,253	16,912,199	16,912,199

In preparation for the IPO, the Company’s board of directors and stockholders approved a one-for-1.333 reverse stock split of the Company’s Common Stock. The reverse stock split became effective on July 17, 2013. All Common Stock share and per share amounts in the condensed consolidated financial statements and notes thereto have been retroactively adjusted for all periods presented to give effect to this reverse stock split, including reclassifying an amount equal to the reduction in par value of common stock to additional paid-in capital. The reverse stock split did not result in a retroactive adjustment of share amounts for the Preferred Stock.

In July 2012, the Company issued 2,433,328 shares of Series I Preferred Stock in exchange for the conversion of the convertible promissory notes and accrued interest in the amount of $26,444,000 and $323,000, respectively. The effective conversion price was $11.00 per share. Additionally, in July 2012, the Company issued 3,030,303 shares of Series J Preferred Stock at $16.50 per share for gross proceeds of $50,000,000. Issuance costs associated with this offering were $2,204,000.

Series A Preferred Stock was originally issued at $5.00 per share; Series B Preferred Stock was issued at $5.75 per share; Series C Preferred Stock was issued at $3.56 per share; Series D Preferred Stock was issued at $4.67 per share; Series E Preferred Stock was issued at $9.76 per share; Series F Preferred Stock was issued at $11.00 per share; Series G and Series H Preferred Stock were issued at $9.79 per share; Series I Preferred Stock was issued at $11.00 per share; and Series J Preferred Stock was issued at $16.50 per share.

The following is the activity of the Preferred Stock for the six months ended June 30, 2013:

	December 31, 2012		Issuance of Preferred Stock		Exercise of warrants		Accretion of redemption premium and issuance costs on Preferred Stock		June 30, 2013
Series A
Shares	107,000		—		—		—		107,000
Amount	$	535,000	$	—	$	—	$	—	$	535,000
Series B
Shares	1,107,189		—		—		—		1,107,189
Amount	$	12,733,000	$	—	$	—	$	—	$	12,733,000
Series C
Shares	1,069,946		—		—		—		1,069,946
Amount	$	7,618,000	$	—	$	—	$	—	$	7,618,000
Series D
Shares	1,583,568		—		—		—		1,583,568
Amount	$	18,211,000	$	—	$	—	$	—	$	18,211,000
Series E
Shares	1,633,082		—		—		—		1,633,082
Amount	$	18,780,000	$	—	$	—	$	—	$	18,780,000
Series F
Shares	2,000,000		—		—		—		2,000,000
Amount	$	23,000,000	$	—	$	—	$	—	$	23,000,000
Series G
Shares	1,934,359		—		—		—		1,934,359
Amount	$	22,819,000	$	—	$	—	$	—	$	22,819,000
Series H
Shares	2,013,424		—		—		—		2,013,424
Amount	$	22,005,000	$	—	$	—	$	767,000	$	22,772,000
Series I
Shares	2,433,328		—		—		—		2,433,328
Amount	$	26,933,000	$	—	$	—	$	200,000	$	27,133,000
Series J
Shares	3,030,303		—		—		—		3,030,303
Amount	$	48,681,000	$	—	$	—	$	1,084,000	$	49,765,000
Total
Shares	16,912,199		—		—		—		16,912,199
Amount	$	201,315,000	$	—	$	—	$	2,051,000	$	203,366,000

Voting

As of June 30, 2013, each holder of outstanding shares of Preferred Stock had the right to one vote for each share of Common Stock into which such Preferred Stock could then be converted. The holders of shares of Preferred Stock had full voting rights and powers equal to the voting rights and powers of shares of Common Stock and were entitled to notice of any stockholders’ meeting and voted together with the holders of Common Stock, with respect to any question upon which holders of shares of Common Stock have the right to vote, as a single class, including without limitation, actions to increase or decrease the aggregate number of authorized shares of Common Stock and/or Preferred Stock.

Dividends

As of June 30, 2013, the holders of each share of Series A, Series B, Series C, Series D, Series E, Series F, Series G, Series H, Series I and Series J Preferred Stock were entitled to receive dividends when, as, and if declared by the Company’s board of directors in the following order of preference: (i) the Series D, Series E, Series F, Series G, Series H, Series I and Series J Preferred Stock, which ranked pari passu; (ii) the Series B and Series C Preferred Stock, which ranked pari passu; (iii) the Series A Preferred Stock; and then (iv) Common Stock.

Liquidation

As of June 30, 2013, the assets of the Company legally available for distribution to stockholders were distributable in the following order of priority: (i) the holders of the shares of Series D, Series E, Series F, Series G, Series H, Series I and Series J Preferred Stock, which ranked pari passu; (ii) the holders of the shares of Series B and Series C Preferred Stock, which ranked pari passu; (iii) the holders of the shares of Series A Preferred Stock; and (iv) the holders of the shares of Common Stock. Each series of Preferred Stock was entitled to receive an amount per share equal to the greater of (1) the original issuance price for such series, plus all declared but unpaid dividends thereon, or (2) the amount that the holders of such series would receive per share of Common Stock if all shares of such series of Preferred Stock were converted to Common Stock immediately prior to such liquidation. If, upon a deemed liquidation event, the assets of the Company were insufficient to make payment in full to all holders of a series of Preferred Stock, then such assets would be distributed among the holders of such series of Preferred Stock at the time outstanding ratably in proportion to the full amount to which they would otherwise be respectively entitled. The holders of Common Stock were entitled to receive, after the payment of the liquidation preference of all Preferred Stock outstanding, the remaining assets of the Company on a pro rata basis.

Conversion

As of June 30, 2013, each issued and outstanding share of Preferred Stock was convertible into Common Stock at the holder’s option at any time after the date of issuance or automatically upon the occurrence of certain events as defined in the Company’s ninth amended and restated certificate of incorporation, at a defined conversion rate. At June 30, 2013, the number of shares of Common Stock into which one share of each series of Preferred Stock was convertible was as follows, after giving effect to the reverse stock split discussed in Note 11: the Series A Preferred Stock, 0.80; the Series B Preferred Stock, 0.85; the Series C Preferred Stock, 0.75; the Series D Preferred Stock, 0.75; the Series E Preferred Stock, 0.75; the Series F Preferred Stock, 0.77; the Series G Preferred Stock, 0.75; the Series H Preferred Stock, 0.75; the Series I Preferred Stock, 0.75; and the Series J Preferred Stock, 0.75.

The conversion price for each share of Preferred Stock was subject to adjustment upon the occurrence of certain events. The conversion price of each share of a series of Preferred Stock was adjusted if the Company issued additional shares, subject to specified exceptions, at a price lower than the then current conversion price for such series, which is measured and recognized if the contingency occurs.

On July 30, 2013, immediately prior to the consummation of the IPO, all outstanding shares of Preferred Stock automatically converted in shares of Common Stock at the applicable conversion ratio then in effect. See Note 11.

Redemption

To the extent it was then lawfully able to do so, the Company was required at any time, upon written request of the holders of at least 66.67% of the then outstanding Series A, Series B and Series C Preferred Stock collectively, or upon written request of the holders of at least a majority of the then outstanding shares of Series D, Series E and Series F Preferred Stock collectively, in each case as determined on an as-converted to Common Stock basis, to redeem the requested number of outstanding shares of Series A Preferred Stock at $5.00 per share, Series B Preferred Stock at $11.50 per share, and Series C Preferred Stock at $7.12 per share, and/or Series D, E and F Preferred Stock at $11.50 per share, as the case may be.

In addition, to the extent it was lawfully able to do so, the Company was required at any time, upon written request of the holders of at least a majority of the then outstanding shares of Series G Preferred Stock, to redeem, from the holders requesting such redemption, the requested number of outstanding shares of Series G Preferred Stock at $11.50 per share.

To the extent it would have been lawfully able to do so, the Company would have been required at any time on or after September 21, 2013, upon written request of the holders of at least a majority of the then outstanding shares of Series H Preferred Stock, to redeem, from the holders requesting such redemption, the requested number of outstanding shares of Series H Preferred Stock at $11.50 per share.

To the extent it would have been lawfully able to do so, the Company would have been required at any time on or after July 25, 2015, upon written request of the holders of at least a majority of the then outstanding shares of Series I Preferred Stock, to redeem, from the holders requesting such redemption, the requested number of outstanding shares of Series I Preferred Stock at $11.50 per share.

To the extent it would have been lawfully able to do so, the Company would have been required at any time on or after July 27, 2015, upon written request of the holders of at least a majority of the then outstanding shares of Series J Preferred Stock, to redeem, from the holders requesting such redemption, the requested number of outstanding shares of Series J Preferred Stock at $18.00 per share.

If, upon any applicable redemption date, defined as sixty days after the Company receives the written request for redemption, the funds of the Company legally available for redemption of Preferred Stock would have been insufficient to redeem the total number of shares to be redeemed on that date, those funds that were legally available would have been used to redeem the maximum possible number of shares, ratably among the holders of such shares to be redeemed. All remaining shares not redeemed would have remained outstanding until such time as additional funds become legally available for redemption.

If more than one series of Preferred Stock had been contemporaneously subject to redemption, the redemption rights of the Preferred Stock would have followed the liquidation order of priority.

As of June 30, 2013, Preferred Stock with an aggregate redemption value of $103,122,000 was redeemable. During 2013 and 2015, additional shares of Preferred Stock with an aggregate redemption value of $23,154,000 and $82,529,000, respectively, would have become redeemable at the option of the holders of Preferred Stock.

Series G Preferred Stock Warrant Transactions

The Company issued 6,128 Series G Preferred Stock warrants in connection with a Loan and Security Agreement. Additionally, the Company issued one Series G Preferred Stock warrant for every two shares of Series G Preferred Stock purchased in 2009 and 2010. The warrants were initially recorded at their fair value calculated using the Black-Scholes model, with the following weighted average assumptions: exercise price of $9.79, share price of $9.79, expected term of three years, risk-free rate of 1.52% and volatility of 85.46%. The warrants are classified as liabilities because they are exercisable for Preferred Stock, and the value of the warrants is adjusted to current fair value at each reporting period end. For the three and six months ended June 30, 2013, the Company recorded $(2,000) and $12,000, respectively, in the consolidated statements of operations and comprehensive loss related to the change in the fair value of the outstanding warrants.

There were no Series G Preferred Stock warrant transactions during the six months ended June 30, 2013.

Stock-Based Compensation

6 Months Ended

Jun. 30, 2013

Stock-Based Compensation

Stock-Based Compensation

7. Stock-Based Compensation

In January 2008, the board of directors approved the 2007 Equity Compensation Plan (the “2007 Plan”), which amended and restated the Company’s 1999 Stock Based Compensation Plan, which provides for the granting of incentive and nonqualified stock options and restricted stock to its employees, directors and consultants at the discretion of the board of directors. Under the 2007 Plan, the Company increased the number of shares reserved for issuance under the 2007 Plan such that the number of reserved shares is equal to 17% of the fully diluted shares calculated annually on December 10th.

	June 30,		December 31,
	2013	2012	2012	2011
Shares of Common Stock reserved for issuance under the 2007 Plan	3,081,644	2,285,803	3,081,644	2,285,803

Stock options may be granted with exercise prices of not less than the estimated fair value of the Company’s common stock on the date of grant and generally vest over a period of up to four years. Stock options granted under the 2007 Plan generally expire no later than ten years from the date of grant. A summary of stock option activity for the six months ended June 30, 2013 is as follows:

					Weighted-
					Average
			Weighted-		Remaining
			Average		Contractual
	Number of		Exercise		Term
	Options		Price		(in years)
Outstanding at December 31, 2012	2,564,147		$	8.10	7.52
Granted	314,890		13.30
Exercised	(3,000	)	2.00
Forfeited	(79,518	)	13.28
Outstanding at June 30, 2013	2,796,519		$	8.56	7.27

Vested or expected to vest at June 30, 2013	2,796,519		$	8.56	7.27
Exercisable at June 30, 2013	1,790,647		$	6.48	6.16

At June 30, 2013 and December 31, 2012, the aggregate intrinsic value of the option liability recorded was $0 and $11,967,000, respectively. During the six months ended June 30, 2013, the Company granted 314,890 options at an intrinsic value of $0 at the grant date. At certain times throughout the Company’s history, the chairman of the Company’s board of directors, who is also a significant stockholder of the Company (the “Significant Holder”), has afforded option holders the opportunity for liquidity in transactions in which options were exercised and the shares of Common Stock issued in connection therewith were simultaneously purchased by the Significant Holder (each, a “Purchase Transaction”). Because the Company has established a pattern of providing cash settlement alternatives for option holders, the Company has accounted for its stock-based compensation awards as liability awards, the fair value of which is then re-measured at each balance sheet date. Upon the exercise of stock options from January 1, 2013 through April 23, 2013, stock option liabilities of $38,000 were reclassified to stockholders’ deficit.

On April 23, 2013, the Company distributed a notification letter to all equity award holders under the 2007 Plan advising them that Purchase Transactions will no longer occur, unless, at the time of a Purchase Transaction, the option holder has held the Common Stock issued upon exercise of options for a period of greater than six months prior to selling such Common Stock to the Significant Holder and that any such sale to the Significant Holder would be at the fair value of the Common Stock on the date of such sale. Based on these new criteria for Purchase Transactions, the Company remeasured options outstanding under the 2007 Plan as of April 23, 2013 to their intrinsic value and reclassified such options from liabilities to stockholders’ deficit within the Company’s consolidated balance sheets, which amounted to $14,482,000.

A roll forward of the stock option liability balance for the six months ended June 30, 2013 is as follows:

Balance at December 31, 2012	$	11,967,000
Change in fair value upon remeasurement	2,553,000
Settlements of option liability awards	(38,000		)
Stock option award modification	(14,482,000		)
Balance at June 30, 2013	$	—

The Company accounts for all stock-based payments made after April 23, 2013 to employees and directors using an option pricing model for estimating fair value. Accordingly, stock-based compensation expense is measured based on the estimated fair value of the awards on the date of grant, net of forfeitures. Compensation expense is recognized for the portion that is ultimately expected to vest over the period during which the recipient renders the required services to the Company using the straight-line single option method. In accordance with authoritative guidance, the fair value of non-employee stock based awards is re-measured as the awards vest, and the resulting increase in fair value, if any, is recognized as expense in the period the related services are rendered.

The Company estimates the fair value of its share-based awards to employees and directors using the Black-Scholes option pricing model. The Black-Scholes model requires the input of highly complex and subjective assumptions, including (a) the expected stock price volatility, (b) the calculation of the expected term of the award, (c) the risk free interest rate and (d) expected dividends. Due to the Company’s limited operating history and a lack of company specific historical and implied volatility data, the Company has based its estimate of expected volatility on the historical volatility of a group of similar companies that are publicly traded. When selecting these public companies on which it has based its expected stock price volatility, the Company selected companies with comparable characteristics to it, including enterprise value, risk profiles, position within the industry, and with historical share price information sufficient to meet the expected life of the stock-based awards. The historical volatility data was computed using the daily closing prices for the selected companies’ shares during the equivalent period of the calculated expected term of the stock-based awards. Due to its lack of sufficient historical data, the Company will continue to apply this process until a sufficient amount of historical information regarding the volatility of its own stock price becomes available. The Company has estimated the expected life of its employee stock options using the “simplified” method, whereby, the expected life equals the arithmetic average of the vesting term and the original contractual term of the option. The risk-free interest rates for periods within the expected life of the option are based on the U.S. Treasury yield curve in effect during the period the options were granted. The Company has never paid, and does not expect to pay dividends in the foreseeable future.

Stock-based compensation expense includes stock options granted to employees and non-employees and has been reported in the Company’s statements of operations and comprehensive loss in either research and development expenses or general and administrative expenses depending on the function performed by the optionee. No net tax benefits related to the stock-based compensation costs have been recognized since the Company’s inception.

During the period from April 23, 2013 through June 30, 2013, the Company granted options to purchase 3,450 shares of its common stock at an exercise price of $14.74 per share. The Company recorded $33,000 of compensation expense related to these options. The fair value of these nonemployee options was estimated using the Black-Scholes option pricing model with the following weighted-average assumptions: no dividend yield, volatility of 81.32%, maximum contractual life of 5.0 years, and a risk-free interest rate of 0.98%.

The Company recognized stock-based compensation expense as follows for the three and six months ended June 30, 2013 and 2012:

	Quarter Ended June 30,				Six Months Ended June 30,
	2013		2012		2013		2012

General and administrative	$	220,000	$	54,000	$	1,526,000	$	1,321,000
Research and development	159,000		49,000		1,317,000		1,219,000
	$	379,000	$	103,000	$	2,843,000	$	2,540,000

As of June 30, 2013, there was $2,351,000 of unrecognized compensation expense related to unvested stock options, which is expected to be recognized over a weighted-average period of approximately 2.08 years. The Company accounts for stock options issued to nonemployees using a fair value approach. The compensation costs of these arrangements are subject to re-measurement over the vesting terms as earned.

Information with respect to stock options outstanding and exercisable at June 30, 2013 is as follows:

			Weighted
			Average
			Remaining
Exercise			Contractual
Price		Shares	Life (years)	Exercisable
$	1.33	161,614	1.04	161,614
2.67		65,207	2.57	65,207
5.76		396,941	6.69	367,664
6.00		420,267	4.18	420,267
6.13		607,653	6.72	498,326
7.53		35,235	8.91	28,586
13.28		1,105,252	9.59	244,633
14.74		4,350	9.90	4,350
		2,796,519	7.27	1,790,647

License and Collaboration Agreements	6 Months Ended
License and Collaboration Agreements	Jun. 30, 2013
License and Collaboration Agreements
License and Collaboration Agreements	8. License and Collaboration Agreements Baxter Agreement In September 2012, the Company entered into a development and license agreement with Baxter granting Baxter an exclusive, royalty-bearing license for the research, development, commercialization and manufacture (in specified instances) of rigosertib in all therapeutic indications in Europe (the “Baxter Territory”). Baxter is a stockholder in the Company and invested in Series J Preferred Stock issued in July 2012. Under the terms of the agreement, the Company is initially required to perform research and development to advance three initial rigosertib indications, rigosertib intravenous (“rigosertib IV”) in higher risk myelodysplastic syndrome (“MDS”) patients, rigosertib IV in pancreatic cancer patients and rigosertib oral (“rigosertib Oral”) in lower risk MDS patients, through phase 3, phase 3 and phase 2 clinical trials, respectively. If an additional phase 3 clinical trial beyond the current phase 3 clinical trial in process for rigosertib IV in higher risk MDS patients is required to obtain marketing approval in the Baxter Territory, the Company could require Baxter to fund a percentage of the costs of such additional trial up to a specified maximum. At the completion of the current phase 3 trial for rigosertib IV in pancreatic cancer and the current phase 2 trial for rigosertib Oral in lower risk MDS patients and the review of the resulting data and findings, the Company and Baxter will decide whether or not to pursue further development of rigosertib for these indications. If the Company and Baxter mutually agree to progress the development of rigosertib IV in pancreatic cancer patients and rigosertib Oral in lower risk MDS patients, then certain milestone payments will be payable to the Company, and the Company will be required to use its commercially reasonable efforts to progress the development of rigosertib for these indications to a drug approval application in the Baxter Territory. The Company and Baxter will work together for potential future rigosertib indications, beyond the initial indications noted above. Generally, if Baxter chooses to participate in the development of additional indications, Baxter will be responsible for a percentage of all research and development costs and expenses and the Company could earn additional milestone payments. Baxter has full responsibility for all commercialization activities for the product in the Baxter Territory, at Baxter’s sole cost and expense. The Company and Baxter have agreed to negotiate a supply agreement under terms satisfactory to both parties whereby the Company will supply Baxter with Baxter’s required levels of product to support commercialization efforts in the Baxter Territory. Baxter also has the right to engage third parties for the manufacture and supply of its requirements for the licensed product. Under the terms of the agreement, Baxter made an upfront payment of $50,000,000. The Company is eligible to receive pre-commercial milestone payments of up to an aggregate of $512,500,000 if specified development and regulatory milestones are achieved. The potential pre-commercial development milestone payments to us include the following: · $50,000,000 for successful completion of a phase 3 clinical trial for rigosertib IV in higher risk MDS patients; · $25,000,000 for each of the two joint decisions to proceed with the development of rigosertib for certain indications specified in the arrangement with Baxter; and · $25,000,000 for each drug approval application filed for indications specified in the arrangement with Baxter. The Company may also receive up to $337,500,000 in milestone payments for regulatory approvals of the three rigosertib indications specified in the arrangement with Baxter, each of which may be up to and in excess of $100,000,000. The Company is also potentially eligible to receive an additional $20,000,000 pre-commercial milestone payment related to the timing of regulatory approval for rigosertib IV in higher risk MDS patients in Europe. In addition to these pre-commercial milestones, the Company is eligible to receive up to an aggregate of $250,000,000 in milestone payments based on Baxter’s achievement of pre-specified threshold levels of annual net sales of rigosertib. The Company will also be entitled to receive royalties at percentage rates ranging from the low-teens to the low-twenties on net sales of rigosertib by Baxter in the Baxter Territory. The agreement with Baxter will remain in effect until the expiration of all applicable royalty terms and satisfaction of all payment obligations in each licensed country, unless terminated earlier due to the uncured material breach or bankruptcy of a party, force majeure, or in the event of a specified commercial failure. The Company may terminate the agreement in the event that Baxter brings a challenge against it in relation to the licensed patents. Baxter may terminate the agreement without cause commencing after a specified period of time from the execution of the agreement. The Company has determined that the deliverables under the Baxter agreement include the exclusive, royalty-bearing, sublicensable license to rigosertib and the research and development services to be performed by the Company. The Company concluded that the license had standalone value to Baxter and was separable from the research and development services because the license is sublicensable, there are no restrictions as to Baxter’s use of the license and Baxter has significant research capabilities in this field. In determining the separate units of accounting, the Company considered applicable accounting guidance and noted that in an arrangement with multiple deliverables, the delivered item or items shall be considered a separate unit of accounting if the delivered item or items have value to the customer on a stand-alone basis. The item or items have value on a stand-alone basis if they are sold separately by any vendor or the customer could resell the delivered item(s) on a stand-alone basis. In the context of a customer’s ability to resell the delivered item(s), this criterion does not require the existence of an observable market for the deliverable(s). The Baxter agreement allows Baxter to sublicense rigosertib and its ability to sublicense is not contingent on the approval or right of first refusal by the Company. The Company determined that Baxter’s ability to sublicense the intellectual property to others demonstrates that the license has stand-alone value. In addition, at the time of entering into the Baxter agreement in September 2012, the rigosertib program was in a phase 3 clinical trial for higher risk MDS, a phase 3 clinical trial for pancreatic cancer and a phase 2 trial for lower risk MDS. The protocols for the clinical trials had been written and provided to Baxter and a Special Protocol Assessment (“SPA”) had already been granted to the Company by the U.S. Food and Drug Administration (“FDA”) for higher risk MDS. These later stage clinical trials, where protocols have been prepared and trials are in process, can be completed more easily by entities other than the Company, as compared to earlier stage clinical trials. The remaining services to be performed by the Company are not proprietary and could be performed by other qualified parties. For example, the Company relies on clinical research organizations (“CROs”) to complete the clinical trials, and Baxter could engage the same or similar CROs to complete the trials on its behalf. Although Baxter is not performing development activities related to rigosertib, Baxter possesses the internal expertise (or a vendor could be hired) to complete the efforts under the rigosertib programs without further assistance from the Company. Baxter develops, manufactures and markets products that save and sustain the lives of people with hemophilia, immune disorders, infectious diseases, kidney disease, trauma, and other chronic and acute medical conditions. As a global, diversified healthcare company, Baxter applies a unique combination of expertise in medical devices, pharmaceuticals and biotechnology to create products that advance patient care worldwide. Baxter employs over 50,000 people, with significant revenues and expenditures for research and development. Baxter has expertise in completing clinical trials, assessing clinical trial results and preparing regulatory filings and has also developed and obtained regulatory and marketing approval in Europe for numerous products used to treat hematologic conditions. Baxter has expertise in rare hematologic conditions, and the Company believes that rigosertib is a natural complement to Baxter’s existing treatments for patients with these conditions. Baxter has the rights and full access to past and future intellectual information in order to obtain regulatory approval of rigosertib in Europe. In connection with the Baxter agreement, the Company licensed to Baxter all information and all patents controlled by the Company necessary for the development, manufacture, use and sale of rigosertib and all present and future formulations and dosages in all present and future therapeutic indications in the licensed territory. Accordingly, given Baxter’s ability to sublicense under the agreement and its ability internally or with outside help to conduct the ongoing development efforts, the Company concluded that the license has stand-alone value. In order to determine if the license can be treated as a separate unit of accounting, the Company also considered whether there is a general right of return associated with the license. The $50,000,000 upfront payment received by the Company is non-refundable; therefore, there is no right of return for the license. As a result, the Company concluded that the license is a separate unit of accounting. The Company was not able to establish vendor-specific objective evidence of selling price or third-party evidence for either the license or the research and development services and instead allocated the arrangement consideration between the license and research and development services based on their relative selling prices using best estimate of selling price (“BESP”). Management developed the BESP of the license using a discounted cash flow model, taking into consideration assumptions including the development and commercialization timeline, discount rate and probability of success. Management utilized a third party valuation specialist to assist with the determination of BESP of the license. Management estimated the selling price of the research and development services using third party costs and a discounted cash flow model. The estimated selling prices utilized assumptions including internal estimates of research and development personnel needed to perform the research and development services; and estimates of expected cash outflows to third parties for services and supplies over the expected period that the services will be performed. The key assumptions in these models included the following market conditions and entity-specific factors: (a) the specific rights provided under the license, (b) the stage of development of rigosertib and estimated remaining development and commercialization timelines, (c) the probability of successfully developing and commercializing rigosertib, (d) the market size including the associated sales figures which generate royalty revenue, (e) cost of goods sold, which was assumed to be a specified percentage of revenues based on estimated cost of goods sold of a typical oncology product, (f) sales and marketing costs, which were based on the costs required to field an oncology sales force and marketing group, including external costs required to promote an oncology product, (g) the expected product life of rigosertib assuming commercialization and (h) the competitive environment. The Company utilized a discount rate of 16%, representing the cost of capital derived from returns on equity for comparable companies. Based on management’s analyses, it was determined that the BESP of the license was $120,000,000 and the BESP of the research and development services was $20,600,000. As noted above, the Company received an up-front payment of $50,000,000 under the Baxter agreement, which represents the allocable agreement consideration. Based on the respective BESPs, this payment was allocated $42,400,000 to the license and $7,600,000 to the research and development services. Since the delivery of the license occurred upon the execution of the Baxter agreement and there was no general right of return, $42,400,000 of the $50,000,000 upfront payment was recognized upon the execution of the Baxter agreement. The portion allocated to research and development services is being recognized over the period of performance on a proportional performance basis through March 31, 2014. Management estimated the period of performance to be the period necessary for completion of the non-contingent obligations to perform research and development services required to advance the three formulations of rigosertib described above. For the three and six months ended June 30, 2013, the Company recognized $990,000 and $1,456,000, respectively, of research and development revenue under the Baxter agreement. The Company and Baxter have agreed to establish a joint committee to facilitate the governance and oversight of the parties’ activities under the agreements. Management considered whether participation on the joint committee may be a deliverable and determined that it was not a deliverable. Had management considered participation on the joint committee as a deliverable, it would not have had a material impact on the accounting for the arrangement based on the analysis of the estimated selling price of such participation. As noted above, in July 2012, Baxter purchased Series J Preferred Stock. Because the Series J Preferred Stock was acquired within several months of the Baxter development and license agreement, management considered whether the Preferred Stock was issued at fair value and if not, whether the consideration received for the Preferred Stock ($50,000,000) or for the collaboration and license agreement ($50,000,000) should be allocated in the financial statements in a manner differently than the prices stated in the agreements. Management, with the assistance of an outside valuation specialist, determined that the price paid by Baxter for the Series J Preferred Stock approximated its fair value, and therefore the consideration received under the agreements was allocated in accordance with terms of the individual agreements. SymBio Agreement In July 2011, the Company entered into a license agreement with SymBio, as subsequently amended, granting SymBio an exclusive, royalty-bearing license for the development and commercialization of rigosertib in Japan and Korea. Under the SymBio license agreement, SymBio is obligated to use commercially reasonable efforts to develop and obtain market approval for rigosertib inside the licensed territory and the Company has similar obligations outside of the licensed territory. The Company has also entered into an agreement with SymBio providing for it to supply SymBio with development-stage product. Under the SymBio license agreement, the Company also agreed to supply commercial product to SymBio under specified terms that will be included in a commercial supply agreement to be negotiated prior to the first commercial sale of rigosertib. The supply of development-stage product and the supply of commercial product will be at the Company’s cost plus a defined profit margin. Sales of development-stage product have been de minimis. The Company has additionally granted SymBio a right of first negotiation to license or obtain the rights to develop and commercialize compounds having a chemical structure similar to rigosertib in the licensed territory. Under the terms of the SymBio license agreement, the Company received an upfront payment of $7,500,000. The Company is eligible to receive milestone payments of up to an aggregate of $33,000,000 from SymBio upon the achievement of specified development and regulatory milestones for specified indications. Of the development milestones, $3,000,000 is due after enrollment of the first patient in the event a decision is made, after the Company’s interim analysis, to start a phase 3 clinical trial of rigosertib IV in combination with gemcitabine for pancreatic cancer patients in the United States. Of the regulatory milestones, $5,000,000 is due upon receipt of marketing approval in the United States for rigosertib IV in higher risk MDS patients, $3,000,000 is due upon receipt of marketing approval in Japan for rigosertib IV in higher risk MDS patients, $5,000,000 is due upon receipt of marketing approval in the United States for rigosertib Oral in lower risk MDS patients, $5,000,000 is due upon receipt of marketing approval in Japan for rigosertib Oral in lower risk MDS patients, $5,000,000 is due upon receipt of marketing approval in the United States for rigosertib IV in combination with gemcitabine in pancreatic cancer patients, and $3,000,000 is due upon receipt of marketing approval in Japan for rigosertib IV in combination with gemcitabine for pancreatic cancer patients. Furthermore, upon receipt of marketing approval in the United States and Japan for an additional indication of rigosertib, which we are currently not pursuing, an aggregate of $4,000,000 would be due. In addition to these pre-commercial milestones, the Company is eligible to receive tiered milestone payments based upon annual net sales of rigosertib by SymBio of up to an aggregate of $30,000,000. Further, under the terms of the SymBio license agreement, SymBio will make royalty payments to the Company at percentage rates ranging from the mid-teens to 20% based on net sales of rigosertib by SymBio. Royalties will be payable under the SymBio agreement on a country-by-country basis in the licensed territory, until the later of the expiration of marketing exclusivity in those countries, a specified period of time after first commercial sale of rigosertib in such country, or the expiration of all valid claims of the licensed patents covering rigosertib or the manufacture or use of rigosertib in such country. If no valid claim exists covering the composition of matter of rigosertib or the use of or treatment with rigosertib in a particular country before the expiration of the royalty term, and specified competing products achieve a specified market share percentage in such country, SymBio’s obligation to pay the Company royalties will continue at a reduced royalty rate until the end of the royalty term. In addition, the applicable royalties payable to the Company may be reduced if SymBio is required to pay royalties to third-parties for licenses to intellectual property rights necessary to develop, use, manufacture or commercialize rigosertib in the licensed territory. The license agreement with SymBio will remain in effect until the expiration of the royalty term. However, the SymBio license agreement may be terminated earlier due to the uncured material breach or bankruptcy of a party, or force majeure. If SymBio terminates the license agreement in these circumstances, its licenses to rigosertib will survive, subject to SymBio’s milestone and royalty obligations, which SymBio may elect to defer and offset against any damages that may be determined to be due from the Company. In addition, the Company may terminate the license agreement in the event that SymBio brings a challenge against it in relation to the licensed patents, and SymBio may terminate the license agreement without cause by providing the Company with written notice within a specified period of time in advance of termination. The Company determined that the deliverables under the SymBio agreement include the exclusive, royalty-bearing, sublicensable license to rigosertib, the research and development services to be provided by the Company and its obligation to serve on a joint committee. The Company concluded that the license did not have standalone value to SymBio and was not separable from the research and development services, because of the uncertainty of SymBio’s ability to develop rigosertib in the SymBio territory on its own and the uncertainty of SymBio’s ability to sublicense rigosertib and recover a substantial portion of the original upfront payment of $7,500,000 paid by SymBio to the Company. The supply of rigosertib for SymBio’s commercial requirements is contingent upon the receipt of regulatory approvals to commercialize rigosertib in Japan and Korea. Because the Company’s commercial supply obligation was contingent upon the receipt of future regulatory approvals, and there were no binding commitments or firm purchase orders pending for commercial supply at or near the execution of the agreement, the commercial supply obligation is deemed to be contingent and is not valued as a deliverable under the SymBio agreement. If SymBio orders the supplies from the Company, the Company expects the pricing for this supply to equal its third-party manufacturing cost plus a pre-negotiated percentage, which will not result in a significant incremental discount to market rates. Due to the lack of standalone value for the license, research and development services, and joint committee obligation, the upfront payment is being recognized ratably using the straight line method through December 2027, the expected term of the agreement. For each of the three and six months ended June 30, 2013 and 2012, the Company recognized revenues of $113,000 and $227,000, respectively, under this agreement. In addition, the Company recognized revenues related to the supply agreement with SymBio in the amounts of $0 and $10,000 for the three months ended June 30, 2013 and 2012, respectively, and $24,000 and $10,000 for the six months ended June 30, 2013 and 2012, respectively.

Summary of Significant Accounting Policies (Policies)	6 Months Ended
Summary of Significant Accounting Policies (Policies)	Jun. 30, 2013
Summary of Significant Accounting Policies
Basis of Presentation	Basis of Presentation The condensed consolidated financial statements are prepared in conformity with accounting principles generally accepted in the United States (“GAAP”) for interim financial information. Certain information and footnotes normally included in financial statements prepared in accordance with GAAP have been condensed or omitted pursuant to the rules and regulations of the Securities and Exchange Commission. The financial statements include the consolidated accounts of the Company and its wholly-owned subsidiary, Onconova Europe GmbH. All significant intercompany transactions have been eliminated.
Unaudited Interim Financial Information	Unaudited Interim Financial Information The accompanying condensed consolidated balance sheet as of June 30, 2013, the condensed consolidated statements of operations and comprehensive loss for the three and six months ended June 30, 2013 and 2012, the condensed consolidated statements of redeemable convertible preferred stock and stockholders’ deficit and the condensed consolidated statements of cash flows for the six months ended June 30, 2013 and 2012 are unaudited. The interim unaudited condensed consolidated financial statements have been prepared on the same basis as the annual audited consolidated financial statements and, in the opinion of management, reflect all adjustments, which include only normal recurring adjustments, necessary for the fair statement of the Company’s financial position as of June 30, 2013 and the results of its operations, its comprehensive loss and its cash flows for the six months ended June 30, 2013 and 2012. The financial data and other information disclosed in these notes related to the six months ended June 30, 2013 and 2012 are unaudited. The results for the six months ended June 30, 2013 are not necessarily indicative of results to be expected for the year ending December 31, 2013, any other interim periods, or any future year or period. These unaudited condensed consolidated financial statements should be read in conjunction with the audited consolidated financial statements and the notes thereto for the year ended December 31, 2012 included in the Company’s final prospectus filed on July 25, 2013 with the Securities and Exchange Commission (the “SEC”) pursuant to Rule 424(b)(4) of the Securities Act of 1933, as amended (the “Securities Act”).
Segment Information	Segment Information Operating segments are defined as components of an enterprise about which separate discrete information is available for evaluation by the chief operating decision maker, or decision-making group, in deciding how to allocate resources and in assessing performance. The Company views its operations and manages its business in one segment, which is the identification and development of oncology therapeutics.
Significant Accounting Policies	Significant Accounting Policies The Company’s significant accounting policies are disclosed in the audited consolidated financial statements for the year ended December 31, 2012 included in the Company’s final prospectus filed on July 25, 2013 with the SEC pursuant to Rule 424(b)(4) of the Securities Act. Since the date of such financial statements, there have been no changes to the Company’s significant accounting policies.
Foreign Currency Translation	Foreign Currency Translation The reporting currency of the Company and its U.S. subsidiary is the U.S. dollar. The functional currency of the Company’s non-U.S. subsidiary is the local currency. Assets and liabilities of the foreign subsidiary are translated into U.S. dollars based on exchange rates at the end of the period. Revenues and expenses are translated at average exchange rates during the reporting period. Gains and losses arising from the translation of assets and liabilities are included as a component of accumulated other comprehensive income. Gains and losses resulting from foreign currency transactions are reflected within the Company’s results of operations. The Company has not utilized any foreign currency hedging strategies to mitigate the effect of its foreign currency exposure.
Deferred Initial Public Offering Costs	Deferred Initial Public Offering Costs Deferred IPO costs as of June 30, 2013, consisting of legal, accounting, printing and filing fees incurred in the preparation of the Company’s Registration Statement on Form S-1 were capitalized. The deferred costs are included in prepaid expenses and other current assets on the consolidated balance sheets. See Note 5. The deferred offering costs were offset against the IPO proceeds upon the completion of the offering in July 2013.
Recent Accounting Pronouncements	Recent Accounting Pronouncements In February 2013, the Financial Accounting Standards Board (the “FASB”) amended its guidance to require an entity to present the effect of certain significant reclassifications out of accumulated other comprehensive income on the respective line items in net income. The new accounting guidance does not change the items that must be reported in other comprehensive income or when an item of other comprehensive income must be reclassified to net income. The guidance is effective prospectively for fiscal years beginning after December 15, 2012. The Company adopted these new provisions for the quarter beginning January 1, 2013. As the guidance requires additional presentation only, there was no impact to the Company’s consolidated financial position, results of operations or cash flows. In July 2013, the FASB issued guidance clarifying that an unrecognized tax benefit, or a portion of an unrecognized tax benefit, should be presented in the financial statements as a reduction to a deferred tax asset for a net operating loss carryforward, a similar tax loss, or a tax credit carryforward if such settlement is required or expected in the event the uncertain tax benefit is disallowed. In situations where a net operating loss carryforward, a similar tax loss, or a tax credit carryforward is not available at the reporting date under the tax law of the applicable jurisdiction or the tax law of the jurisdiction does not require, and the entity does not intend to use, the deferred tax asset for such purpose, the unrecognized tax benefit should be presented in the financial statements as a liability and should not be netted with the deferred tax asset. The guidance is effective for fiscal years, and interim periods within those years, beginning after December 15, 2013. Early adoption is permitted. The amendments should be applied prospectively to all unrecognized tax benefits that exist at the effective date. Retrospective application is permitted. The Company is currently evaluating the impact that adoption will have on the determination or reporting of its financial results.

Fair Value Measurements (Tables)

6 Months Ended

Jun. 30, 2013

Fair Value Measurements

Schedule of financial assets and liabilities measured at fair value on a recurring basis

	Fair Value Measurement as of June 30, 2013								Fair Value Measurement as of December 31, 2012
	Level 1		Level 2		Level 3		Balance		Level 1		Level 2		Level 3		Balance

Warrant liability	$	—	$	—	$	50,000	$	50,000	$	—	$	—	$	62,000	$	62,000
Total	$	—	$	—	$	50,000	$	50,000	$	—	$	—	$	62,000	$	62,000

Schedule of reconciliation of liabilities measured at fair value on a recurring basis using significant unobservable inputs (Level 3)

	Warrant Liability
Balance at December 31, 2012	$	62,000
Change in fair value upon re-measurement	(12,000		)
Balance at June 30, 2013	$	50,000

Balance Sheet Detail (Tables)

6 Months Ended

Jun. 30, 2013

Balance Sheet Detail

Schedule of prepaid expenses and other current assets

	June 30,		December 31,
	2013		2012

Research and development	$	2,399,000	$	1,429,000
Deferred initial public offering costs	2,285,000		—
Other	1,183,000		296,000
	$	5,867,000	$	1,725,000

Schedule of property and equipment

	June 30,			December 31,
	2013			2012

Property and equipment	$	2,284,000		$	1,811,000
Accumulated depreciation	(1,555,000		)	(1,348,000		)
	$	729,000		$	463,000

Schedule of accrued expenses and other current liabilities

	June 30,		December 31,
	2013		2012

Research and development	$	3,972,000	$	3,521,000
Payroll	818,000		247,000
Other	548,000		157,000
	$	5,338,000	$	3,925,000

Preferred Stock and Stockholders' Deficit (Tables)

6 Months Ended

Jun. 30, 2013

Preferred Stock and Stockholders' Deficit

Schedule of composition of share capital

	Authorized		Issued and Outstanding
	June 30,	December 31,	June 30,	December 31,
	2013	2012	2013	2012
Shares of $0.01 par value per share:
Common stock	30,145,155	30,145,155	2,609,484	2,606,484

Series A Preferred Stock	400,000	400,000	107,000	107,000
Series B Preferred Stock	1,200,000	1,200,000	1,107,189	1,107,189
Series C Preferred Stock	1,200,000	1,200,000	1,069,946	1,069,946
Series D Preferred Stock	1,625,000	1,625,000	1,583,568	1,583,568
Series E Preferred Stock	1,650,000	1,650,000	1,633,082	1,633,082
Series F Preferred Stock	2,000,000	2,000,000	2,000,000	2,000,000
Series G Preferred Stock	2,700,000	2,700,000	1,934,359	1,934,359
Series H Preferred Stock	2,042,950	2,042,950	2,013,424	2,013,424
Series I Preferred Stock	2,700,000	2,700,000	2,433,328	2,433,328
Series J Preferred Stock	3,030,303	3,030,303	3,030,303	3,030,303
Total Preferred Stock	18,548,253	18,548,253	16,912,199	16,912,199

Schedule of activity of the Preferred Stock

The following is the activity of the Preferred Stock for the six months ended June 30, 2013:

	December 31, 2012		Issuance of Preferred Stock		Exercise of warrants		Accretion of redemption premium and issuance costs on Preferred Stock		June 30, 2013
Series A
Shares	107,000		—		—		—		107,000
Amount	$	535,000	$	—	$	—	$	—	$	535,000
Series B
Shares	1,107,189		—		—		—		1,107,189
Amount	$	12,733,000	$	—	$	—	$	—	$	12,733,000
Series C
Shares	1,069,946		—		—		—		1,069,946
Amount	$	7,618,000	$	—	$	—	$	—	$	7,618,000
Series D
Shares	1,583,568		—		—		—		1,583,568
Amount	$	18,211,000	$	—	$	—	$	—	$	18,211,000
Series E
Shares	1,633,082		—		—		—		1,633,082
Amount	$	18,780,000	$	—	$	—	$	—	$	18,780,000
Series F
Shares	2,000,000		—		—		—		2,000,000
Amount	$	23,000,000	$	—	$	—	$	—	$	23,000,000
Series G
Shares	1,934,359		—		—		—		1,934,359
Amount	$	22,819,000	$	—	$	—	$	—	$	22,819,000
Series H
Shares	2,013,424		—		—		—		2,013,424
Amount	$	22,005,000	$	—	$	—	$	767,000	$	22,772,000
Series I
Shares	2,433,328		—		—		—		2,433,328
Amount	$	26,933,000	$	—	$	—	$	200,000	$	27,133,000
Series J
Shares	3,030,303		—		—		—		3,030,303
Amount	$	48,681,000	$	—	$	—	$	1,084,000	$	49,765,000
Total
Shares	16,912,199		—		—		—		16,912,199
Amount	$	201,315,000	$	—	$	—	$	2,051,000	$	203,366,000

Stock-Based Compensation (Tables)

6 Months Ended

Jun. 30, 2013

Stock-Based Compensation

Schedule of shares reserved for issuance under the 2007 Plan

	June 30,		December 31,
	2013	2012	2012	2011
Shares of Common Stock reserved for issuance under the 2007 Plan	3,081,644	2,285,803	3,081,644	2,285,803

Schedule of stock option activity

A summary of stock option activity for the six months ended June 30, 2013 is as follows:

					Weighted-
					Average
			Weighted-		Remaining
			Average		Contractual
	Number of		Exercise		Term
	Options		Price		(in years)
Outstanding at December 31, 2012	2,564,147		$	8.10	7.52
Granted	314,890		13.30
Exercised	(3,000	)	2.00
Forfeited	(79,518	)	13.28
Outstanding at June 30, 2013	2,796,519		$	8.56	7.27

Vested or expected to vest at June 30, 2013	2,796,519		$	8.56	7.27
Exercisable at June 30, 2013	1,790,647		$	6.48	6.16

Schedule of roll forward of the stock option liability

A roll forward of the stock option liability balance for the six months ended June 30, 2013 is as follows:

Balance at December 31, 2012	$	11,967,000
Change in fair value upon remeasurement	2,553,000
Settlements of option liability awards	(38,000		)
Stock option award modification	(14,482,000		)
Balance at June 30, 2013	$	—

Schedule of stock-based compensation expense

The Company recognized stock-based compensation expense as follows for the three and six months ended June 30, 2013 and 2012:

	Quarter Ended June 30,				Six Months Ended June 30,
	2013		2012		2013		2012

General and administrative	$	220,000	$	54,000	$	1,526,000	$	1,321,000
Research and development	159,000		49,000		1,317,000		1,219,000
	$	379,000	$	103,000	$	2,843,000	$	2,540,000

Schedule of information with respect to stock options outstanding and exercisable

Information with respect to stock options outstanding and exercisable at June 30, 2013 is as follows:

			Weighted
			Average
			Remaining
Exercise			Contractual
Price		Shares	Life (years)	Exercisable
$	1.33	161,614	1.04	161,614
2.67		65,207	2.57	65,207
5.76		396,941	6.69	367,664
6.00		420,267	4.18	420,267
6.13		607,653	6.72	498,326
7.53		35,235	8.91	28,586
13.28		1,105,252	9.59	244,633
14.74		4,350	9.90	4,350
		2,796,519	7.27	1,790,647

Nature of Business (Details)		3 Months Ended		6 Months Ended
Nature of Business (Details)	Jul. 30, 2013 USD ($) $ / shares shares	Jun. 30, 2013 USD ($) item $ / shares	Jun. 30, 2012 USD ($)	Jun. 30, 2013 USD ($) item $ / shares	Jun. 30, 2012 USD ($)	Dec. 31, 2012 USD ($) $ / shares
Nature of Business
Number of clinical-stage product candidates \| item		3		3
Number of preclinical programs \| item		6		6
Net loss \| $		$ (12,562,000)	$ (7,416,000)	$ (27,407,000)	$ (18,215,000)
Accumulated deficit \| $		$ (195,760,000)		$ (195,760,000)		$ (168,353,000)
Preferred stock, par value per share (in dollars per share)		$ 0.01		$ 0.01		$ 0.01
Number of series denominated as Series A through Series J preferred stock \| item				10
Subsequent events
Common stock, par value (in dollars per share)		$ 0.01		$ 0.01		$ 0.01
Subsequent event \| IPO
Subsequent events
Number of shares issued in initial public offering \| shares	5,941,667
Common stock, par value (in dollars per share)	$ 0.01
Price per share (in dollars per share)	$ 15.00
Number of shares issued pursuant to an option granted to the underwriters to cover over-allotments \| shares	775,000
Net proceeds received from the sale, net of underwriting discounts and commissions and other estimated offering expenses \| $	$ 79,600,000

Balance Sheet Detail (Details) - USD ($)	Jun. 30, 2013	Dec. 31, 2012
Prepaid expenses and other current assets:
Research and development	$ 2,399,000	$ 1,429,000
Deferred initial public offering costs	2,285,000
Other	1,183,000	296,000
Total	5,867,000	1,725,000
Property and equipment:
Property and equipment	2,284,000	1,811,000
Accumulated depreciation	(1,555,000)	(1,348,000)
Total	729,000	463,000
Accrued expenses and other current liabilities:
Research and development	3,972,000	3,521,000
Payroll	818,000	247,000
Other	548,000	157,000
Accrued expenses and other current liabilities	$ 5,338,000	$ 3,925,000

Preferred Stock and Stockholders' Deficit (Details)		1 Months Ended	3 Months Ended		6 Months Ended
Preferred Stock and Stockholders' Deficit (Details)	Jul. 17, 2013	Jul. 31, 2012 USD ($) $ / shares shares	Jun. 30, 2013 USD ($) shares	Jun. 30, 2012 USD ($)	Jun. 30, 2013 USD ($) item shares	Jun. 30, 2012 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2013 USD ($)	Jul. 30, 2013 shares	Jun. 30, 2013 USD ($) $ / shares shares	Dec. 31, 2012 $ / shares shares
Preferred stock and stockholders' deficit
Shares of preferred stock issued										16,912,199	16,912,199
Composition of share capital
Common stock, par value per share (in dollars per share) \| $ / shares										$ 0.01	$ 0.01
Common stock authorized (in shares)										30,145,155	30,145,155
Common stock issued (in shares)										2,609,484	2,606,484
Common stock outstanding (in shares)										2,609,484	2,606,484
Preferred stock authorized (in shares)										18,548,253	18,548,253
Preferred stock issued (in shares)										16,912,199	16,912,199
Preferred stock outstanding (in shares)			16,912,199		16,912,199					16,912,199	16,912,199
Activity of the preferred stock
Balance at the beginning of the period (in shares)					16,912,199
Accretion of redemption premium and issuance costs on Preferred Stock \| $					$ (2,051,000)	$ (2,158,000)
Balance at the end of the period (in shares)			16,912,199		16,912,199
Number of voting rights per share of common stock for each holder of preferred stock \| item					1
Weighted average assumptions
Change in fair value of warrant liability \| $			$ (2,000)	$ 999,000	$ 12,000	$ 390,000
Subsequent event
Preferred stock and stockholders' deficit
Reverse stock split of common stock	0.75
Composition of share capital
Preferred stock outstanding (in shares)									0
Activity of the preferred stock
Balance at the end of the period (in shares)
Series G Preferred Stock Warrant
Activity of the preferred stock
Number of warrants issued (in shares)										6,128
Ratio of the number of warrants issued for each share of preferred stock purchased										.50
Weighted average assumptions
Exercise price (in dollars per share) \| $ / shares										$ 9.79
Share price (in dollars per share) \| $ / shares										$ 9.79
Expected term					3 years
Risk-free rate (as a percent)					1.52%
Volatility (as a percent)					85.46%
Change in fair value of warrant liability \| $			$ (2,000)		$ 12,000
Convertible promissory notes
Preferred stock and stockholders' deficit
Principal amount of the notes converted \| $		$ 26,444,000
Accrued interest \| $		$ 323,000
Preferred stock
Preferred stock and stockholders' deficit
Shares of preferred stock issued										16,912,199	16,912,199
Composition of share capital
Preferred stock authorized (in shares)										18,548,253	18,548,253
Preferred stock issued (in shares)										16,912,199	16,912,199
Preferred stock outstanding (in shares)			16,912,199		16,912,199					16,912,199	16,912,199
Activity of the preferred stock
Balance at the beginning of the period (in shares)					16,912,199
Balance at the beginning of the period \| $					$ 201,315,000
Accretion of redemption premium and issuance costs on Preferred Stock \| $					$ 2,051,000
Balance at the end of the period (in shares)			16,912,199		16,912,199
Balance at the end of the period \| $			$ 203,366,000		$ 203,366,000
Number of days after receipt of the written request for redemption considered for determining redemption date					60 days
Aggregate redemption value of preferred stock \| $										$ 103,122,000
Preferred stock \| Expected
Activity of the preferred stock
Aggregate redemption value of preferred stock \| $							$ 82,529,000	$ 23,154,000
Preferred stock \| Minimum
Activity of the preferred stock
Percentage of holding of outstanding Series A, Series B and Series C Preferred Stock holders from whom the written request required for redemption at specified price					66.67%
Number of series of preferred stock contemporaneously subject to redemption considered for following liquidation order of priority \| item					1
Series A Preferred Stock
Preferred stock and stockholders' deficit
Shares of preferred stock issued										107,000	107,000
Issue price (in dollars per share) \| $ / shares										$ 5.00
Composition of share capital
Preferred stock authorized (in shares)										400,000	400,000
Preferred stock issued (in shares)										107,000	107,000
Preferred stock outstanding (in shares)			107,000		107,000					107,000	107,000
Activity of the preferred stock
Balance at the beginning of the period (in shares)					107,000
Balance at the beginning of the period \| $					$ 535,000
Balance at the end of the period (in shares)			107,000		107,000
Balance at the end of the period \| $			$ 535,000		$ 535,000
Number of shares of common stock issued for each share of preferred stock										0.80
Redemption price (in dollars per share) \| $ / shares										$ 5.00
Series B Preferred Stock
Preferred stock and stockholders' deficit
Shares of preferred stock issued										1,107,189	1,107,189
Issue price (in dollars per share) \| $ / shares										$ 5.75
Composition of share capital
Preferred stock authorized (in shares)										1,200,000	1,200,000
Preferred stock issued (in shares)										1,107,189	1,107,189
Preferred stock outstanding (in shares)			1,107,189		1,107,189					1,107,189	1,107,189
Activity of the preferred stock
Balance at the beginning of the period (in shares)					1,107,189
Balance at the beginning of the period \| $					$ 12,733,000
Balance at the end of the period (in shares)			1,107,189		1,107,189
Balance at the end of the period \| $			$ 12,733,000		$ 12,733,000
Number of shares of common stock issued for each share of preferred stock										0.85
Redemption price (in dollars per share) \| $ / shares										$ 11.50
Series C Preferred Stock
Preferred stock and stockholders' deficit
Shares of preferred stock issued										1,069,946	1,069,946
Issue price (in dollars per share) \| $ / shares										$ 3.56
Composition of share capital
Preferred stock authorized (in shares)										1,200,000	1,200,000
Preferred stock issued (in shares)										1,069,946	1,069,946
Preferred stock outstanding (in shares)			1,069,946		1,069,946					1,069,946	1,069,946
Activity of the preferred stock
Balance at the beginning of the period (in shares)					1,069,946
Balance at the beginning of the period \| $					$ 7,618,000
Balance at the end of the period (in shares)			1,069,946		1,069,946
Balance at the end of the period \| $			$ 7,618,000		$ 7,618,000
Number of shares of common stock issued for each share of preferred stock										0.75
Redemption price (in dollars per share) \| $ / shares										$ 7.12
Series D Preferred Stock
Preferred stock and stockholders' deficit
Shares of preferred stock issued										1,583,568	1,583,568
Issue price (in dollars per share) \| $ / shares										$ 4.67
Composition of share capital
Preferred stock authorized (in shares)										1,625,000	1,625,000
Preferred stock issued (in shares)										1,583,568	1,583,568
Preferred stock outstanding (in shares)			1,583,568		1,583,568					1,583,568	1,583,568
Activity of the preferred stock
Balance at the beginning of the period (in shares)					1,583,568
Balance at the beginning of the period \| $					$ 18,211,000
Balance at the end of the period (in shares)			1,583,568		1,583,568
Balance at the end of the period \| $			$ 18,211,000		$ 18,211,000
Number of shares of common stock issued for each share of preferred stock										0.75
Redemption price (in dollars per share) \| $ / shares										$ 11.50
Series E Preferred Stock
Preferred stock and stockholders' deficit
Shares of preferred stock issued										1,633,082	1,633,082
Issue price (in dollars per share) \| $ / shares										$ 9.76
Composition of share capital
Preferred stock authorized (in shares)										1,650,000	1,650,000
Preferred stock issued (in shares)										1,633,082	1,633,082
Preferred stock outstanding (in shares)			1,633,082		1,633,082					1,633,082	1,633,082
Activity of the preferred stock
Balance at the beginning of the period (in shares)					1,633,082
Balance at the beginning of the period \| $					$ 18,780,000
Balance at the end of the period (in shares)			1,633,082		1,633,082
Balance at the end of the period \| $			$ 18,780,000		$ 18,780,000
Number of shares of common stock issued for each share of preferred stock										0.75
Redemption price (in dollars per share) \| $ / shares										$ 11.50
Series F Preferred Stock
Preferred stock and stockholders' deficit
Shares of preferred stock issued										2,000,000	2,000,000
Issue price (in dollars per share) \| $ / shares										$ 11.00
Composition of share capital
Preferred stock authorized (in shares)										2,000,000	2,000,000
Preferred stock issued (in shares)										2,000,000	2,000,000
Preferred stock outstanding (in shares)			2,000,000		2,000,000					2,000,000	2,000,000
Activity of the preferred stock
Balance at the beginning of the period (in shares)					2,000,000
Balance at the beginning of the period \| $					$ 23,000,000
Balance at the end of the period (in shares)			2,000,000		2,000,000
Balance at the end of the period \| $			$ 23,000,000		$ 23,000,000
Number of shares of common stock issued for each share of preferred stock										0.77
Redemption price (in dollars per share) \| $ / shares										$ 11.50
Series G Preferred Stock
Preferred stock and stockholders' deficit
Shares of preferred stock issued										1,934,359	1,934,359
Issue price (in dollars per share) \| $ / shares										$ 9.79
Composition of share capital
Preferred stock authorized (in shares)										2,700,000	2,700,000
Preferred stock issued (in shares)										1,934,359	1,934,359
Preferred stock outstanding (in shares)			1,934,359		1,934,359					1,934,359	1,934,359
Activity of the preferred stock
Balance at the beginning of the period (in shares)					1,934,359
Balance at the beginning of the period \| $					$ 22,819,000
Balance at the end of the period (in shares)			1,934,359		1,934,359
Balance at the end of the period \| $			$ 22,819,000		$ 22,819,000
Number of shares of common stock issued for each share of preferred stock										0.75
Redemption price (in dollars per share) \| $ / shares										$ 11.50
Series H Preferred Stock
Preferred stock and stockholders' deficit
Shares of preferred stock issued										2,013,424	2,013,424
Issue price (in dollars per share) \| $ / shares										$ 9.79
Composition of share capital
Preferred stock authorized (in shares)										2,042,950	2,042,950
Preferred stock issued (in shares)										2,013,424	2,013,424
Preferred stock outstanding (in shares)			2,013,424		2,013,424					2,013,424	2,013,424
Activity of the preferred stock
Balance at the beginning of the period (in shares)					2,013,424
Balance at the beginning of the period \| $					$ 22,005,000
Accretion of redemption premium and issuance costs on Preferred Stock \| $					$ 767,000
Balance at the end of the period (in shares)			2,013,424		2,013,424
Balance at the end of the period \| $			$ 22,772,000		$ 22,772,000
Number of shares of common stock issued for each share of preferred stock										0.75
Redemption price (in dollars per share) \| $ / shares										$ 11.50
Series I Preferred Stock
Preferred stock and stockholders' deficit
Shares of preferred stock issued										2,433,328	2,433,328
Issue price (in dollars per share) \| $ / shares										$ 11.00
Composition of share capital
Preferred stock authorized (in shares)										2,700,000	2,700,000
Preferred stock issued (in shares)										2,433,328	2,433,328
Preferred stock outstanding (in shares)			2,433,328		2,433,328					2,433,328	2,433,328
Activity of the preferred stock
Balance at the beginning of the period (in shares)					2,433,328
Balance at the beginning of the period \| $					$ 26,933,000
Accretion of redemption premium and issuance costs on Preferred Stock \| $					$ 200,000
Balance at the end of the period (in shares)			2,433,328		2,433,328
Balance at the end of the period \| $			$ 27,133,000		$ 27,133,000
Number of shares of common stock issued for each share of preferred stock										0.75
Redemption price (in dollars per share) \| $ / shares										$ 11.50
Series I Preferred Stock \| Convertible promissory notes
Preferred stock and stockholders' deficit
Number of shares of preferred stock issued upon conversion of note		2,433,328
Issue price (in dollars per share) \| $ / shares		$ 11.00
Series J Preferred Stock
Preferred stock and stockholders' deficit
Gross proceeds from issuance of shares of preferred stock \| $		$ 50,000,000
Shares of preferred stock issued										3,030,303	3,030,303
Issue price (in dollars per share) \| $ / shares		$ 16.50								$ 16.50
Number of shares of preferred stock issued		3,030,303
Issuance costs associated with offering \| $		$ 2,204,000
Composition of share capital
Preferred stock authorized (in shares)										3,030,303	3,030,303
Preferred stock issued (in shares)										3,030,303	3,030,303
Preferred stock outstanding (in shares)			3,030,303		3,030,303					3,030,303	3,030,303
Activity of the preferred stock
Balance at the beginning of the period (in shares)					3,030,303
Balance at the beginning of the period \| $					$ 48,681,000
Accretion of redemption premium and issuance costs on Preferred Stock \| $					$ 1,084,000
Balance at the end of the period (in shares)			3,030,303		3,030,303
Balance at the end of the period \| $			$ 49,765,000		$ 49,765,000
Number of shares of common stock issued for each share of preferred stock										0.75
Redemption price (in dollars per share) \| $ / shares										$ 18.00

Stock-Based Compensation (Details) - USD ($)		2 Months Ended	3 Months Ended		6 Months Ended		12 Months Ended	174 Months Ended
Stock-Based Compensation (Details) - USD ($)	Apr. 23, 2013	Jun. 30, 2013	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012	Dec. 31, 2012	Jun. 30, 2013	Dec. 31, 2011
Stock-Based Compensation
Percentage of increase in number of shares reserved for issuance under the 2007 Plan equal to fully diluted shares calculated annually					17.00%
Shares of Common Stock reserved for issuance under the 2007 Plan		3,081,644	3,081,644	2,285,803	3,081,644	2,285,803	3,081,644	3,081,644	2,285,803
Additional disclosures
Net tax benefits related to the stock-based compensation costs								$ 0
Compensation expense			$ 379,000	$ 103,000	$ 2,843,000	$ 2,540,000
Stock option liability
Balance at the beginning of the period					11,967,000
Stock option award modification					$ (14,482,000)
Balance at the end of the period							$ 11,967,000
Stock options
Number of Options
Balance at the beginning of the period (in shares)					2,564,147
Granted (in shares)					314,890
Exercised (in shares)					(3,000)
Forfeited (in shares)					(79,518)
Balance at the end of the period (in shares)		2,796,519	2,796,519		2,796,519		2,564,147	2,796,519
Vested or expected to vest at the end of the period (in shares)		2,796,519	2,796,519		2,796,519			2,796,519
Exercisable at the end of the period (in shares)		1,790,647	1,790,647		1,790,647			1,790,647
Weighted-Average Exercise Price
Balance at the beginning of the period (in dollars per share)					$ 8.10
Granted (in dollars per share)					13.30
Exercised (in dollars per share)					2.00
Forfeited (in dollars per share)					13.28
Balance at the end of the period (in dollars per share)		$ 8.56	$ 8.56		8.56		$ 8.10	$ 8.56
Vested or expected to vest at the end of the period (in dollars per share)		8.56	8.56		8.56			8.56
Exercisable at the end of the period (in dollars per share)		$ 6.48	$ 6.48		$ 6.48			$ 6.48
Weighted-Average Remaining Contractual Term
Outstanding at the end of the period					7 years 3 months 7 days		7 years 6 months 7 days
Vested or expected to vest at the end of the period					7 years 3 months 7 days
Exercisable at the end of the period					6 years 1 month 28 days
Additional disclosures
Grant date intrinsic value of awards granted (in dollars per share)					$ 0.00
Minimum period for which common stock to be held by option holder prior to selling to the significant holder	6 months
Stock option liability
Balance at the beginning of the period					$ 11,967,000
Change in fair value upon remeasurement					2,553,000
Settlements of option liability awards					(38,000)
Stock option award modification					(14,482,000)
Balance at the end of the period		$ 0	$ 0		$ 0		$ 11,967,000	$ 0
Stock options \| Nonemployee
Number of Options
Granted (in shares)		3,450
Weighted-Average Exercise Price
Granted (in dollars per share)		$ 14.74
Additional disclosures
Compensation expense		$ 33,000
Assumptions used to determine fair values for nonemployee options
Dividend yield (as a percent)		0.00%
Volatility (as a percent)		81.32%
Risk-free interest rate (as a percent)		0.98%
Stock options \| Maximum
Stock-based compensation
Vesting period					4 years
Expiration period					10 years
Stock options \| Maximum \| Nonemployee
Assumptions used to determine fair values for nonemployee options
Contractual life		5 years

License and Collaboration Agreements (Details)	1 Months Ended		3 Months Ended		6 Months Ended
License and Collaboration Agreements (Details)	Sep. 30, 2012 USD ($) item	Jul. 31, 2011 USD ($)	Jun. 30, 2013 USD ($)	Jun. 30, 2012 USD ($)	Jun. 30, 2013 USD ($)	Jun. 30, 2012 USD ($)
License and collaboration agreements
Recognized revenues			$ 591,000	$ 220,000	$ 1,707,000	$ 418,000
Baxter \| Maximum
License and collaboration agreements
Number of employees \| item	50,000
Collaboration arrangement \| Baxter
License and collaboration agreements
Discount rate (as a percent)	16.00%
BESP of the license	$ 120,000,000
BESP of the research and development services	20,600,000
Up-front payment allocated to license	42,400,000
Up-front payment allocated to research and development services	7,600,000
Allocated up-front payment of license recognized upon execution of agreement	42,400,000
Research and development revenue			990,000		1,456,000
Consideration received for the Preferred Stock	$ 50,000,000
Collaboration arrangement \| Rigosertib \| Baxter
License and collaboration agreements
Number of initial rigosertib indications \| item	3
Upfront payment	$ 50,000,000
Number of joint decisions to proceed with the development of rigosertib for specified indications \| item	2
Aggregate potential milestone payments based on annual net sales of rigosertib	$ 250,000,000
Collaboration arrangement \| Rigosertib \| Baxter \| Minimum
License and collaboration agreements
Percentage of royalty payments based on net sales of rigosertib	10.00%
Collaboration arrangement \| Rigosertib \| Baxter \| Maximum
License and collaboration agreements
Aggregate milestone payments	$ 512,500,000
Potential milestone payments for regulatory approvals of specified indications	$ 337,500,000
Percentage of royalty payments based on net sales of rigosertib	20.00%
Collaboration arrangement \| Rigosertib \| Baxter \| Rigosertib intravenous ("IV") in higher risk myelodysplastic syndrome ("MDS") patients
License and collaboration agreements
Potential pre-commercial milestone payments for successful completion of a Phase 3 clinical trial for indication	$ 50,000,000
Potential pre-commercial milestone payments for drug approval application filed for specified indications	25,000,000
Additional potential pre-commercial milestone payments related to the timing of regulatory approval of indication	20,000,000
Collaboration arrangement \| Rigosertib \| Baxter \| Rigosertib intravenous ("IV") in higher risk myelodysplastic syndrome ("MDS") patients \| Minimum
License and collaboration agreements
Potential milestone payments for regulatory approvals of specified indications	100,000,000
Collaboration arrangement \| Rigosertib \| Baxter \| Rigosertib IV in pancreatic cancer patients
License and collaboration agreements
Potential pre-commercial milestone payments for joint decisions to proceed with the development of rigosertib for certain indications	25,000,000
Potential pre-commercial milestone payments for drug approval application filed for specified indications	25,000,000
Collaboration arrangement \| Rigosertib \| Baxter \| Rigosertib IV in pancreatic cancer patients \| Minimum
License and collaboration agreements
Potential milestone payments for regulatory approvals of specified indications	100,000,000
Collaboration arrangement \| Rigosertib \| Baxter \| Rigosertib oral in lower risk MDS patients
License and collaboration agreements
Potential pre-commercial milestone payments for joint decisions to proceed with the development of rigosertib for certain indications	25,000,000
Potential pre-commercial milestone payments for drug approval application filed for specified indications	25,000,000
Collaboration arrangement \| Rigosertib \| Baxter \| Rigosertib oral in lower risk MDS patients \| Minimum
License and collaboration agreements
Potential milestone payments for regulatory approvals of specified indications	$ 100,000,000
Collaboration arrangement \| Rigosertib \| SymBio
License and collaboration agreements
Upfront payment		$ 7,500,000
Aggregate potential milestone payments based on annual net sales of rigosertib		$ 30,000,000
Percentage of royalty payments based on net sales of rigosertib		20.00%
Recognized revenues			113,000	113,000	227,000	227,000
Collaboration arrangement \| Rigosertib \| SymBio \| Supply agreement
License and collaboration agreements
Binding commitments		$ 0
Recognized revenues			$ 0	$ 10,000	$ 24,000	$ 10,000
Collaboration arrangement \| Rigosertib \| SymBio \| United States and Japan
License and collaboration agreements
Aggregate milestone payments due upon receipt of marketing approval for an additional indication		4,000,000
Collaboration arrangement \| Rigosertib \| SymBio \| Maximum
License and collaboration agreements
Aggregate milestone payments		33,000,000
Collaboration arrangement \| Rigosertib \| SymBio \| Rigosertib intravenous ("IV") in higher risk myelodysplastic syndrome ("MDS") patients \| United States
License and collaboration agreements
Regulatory milestones payments due upon receipt of marketing approval for indication		5,000,000
Collaboration arrangement \| Rigosertib \| SymBio \| Rigosertib intravenous ("IV") in higher risk myelodysplastic syndrome ("MDS") patients \| Japan
License and collaboration agreements
Regulatory milestones payments due upon receipt of marketing approval for indication		3,000,000
Collaboration arrangement \| Rigosertib \| SymBio \| Rigosertib oral in lower risk MDS patients \| United States
License and collaboration agreements
Regulatory milestones payments due upon receipt of marketing approval for indication		5,000,000
Collaboration arrangement \| Rigosertib \| SymBio \| Rigosertib oral in lower risk MDS patients \| Japan
License and collaboration agreements
Regulatory milestones payments due upon receipt of marketing approval for indication		5,000,000
Collaboration arrangement \| Rigosertib \| SymBio \| Rigosertib IV in combination with gemcitabine for pancreatic cancer patients \| United States
License and collaboration agreements
Potential development milestones payments due after enrollment of the first patient in event of decision made to start phase 3 clinical trial of indication		3,000,000
Regulatory milestones payments due upon receipt of marketing approval for indication		5,000,000
Collaboration arrangement \| Rigosertib \| SymBio \| Rigosertib IV in combination with gemcitabine for pancreatic cancer patients \| Japan
License and collaboration agreements
Regulatory milestones payments due upon receipt of marketing approval for indication		$ 3,000,000

Joint Venture	6 Months Ended
Joint Venture	Jun. 30, 2013
Joint Venture
Joint Venture	9. Joint Venture In December 2012, the Company agreed to create a joint venture with GVK Biosciences Private Limited (‘‘GVK BIO’’), a private limited company located in India. The resulting joint venture, GBO, LLC, a Delaware limited liability company (‘‘GBO’’), was formed on April 1, 2013. The purpose of GBO is to collaborate on and develop two new programs through filing of an investigational new drug application and/or conducting proof of concept studies using the Company’s technology platform. GBO has not commenced operations as of June 30, 2013.

Related-Party Transactions	6 Months Ended
Related-Party Transactions	Jun. 30, 2013
Related-Party Transactions
Related-Party Transactions	10. Related-Party Transactions The Company has entered into a research agreement, as subsequently amended, with the Mount Sinai School of Medicine (“Mount Sinai”), with which a member of its board of directors and a significant stockholder is affiliated. Mount Sinai is undertaking research on behalf of the Company on the terms set forth in the agreements. Mount Sinai, in connection with the Company, will prepare applications for patents generated from the research. Results from all projects will belong exclusively to Mount Sinai, but the Company will have an exclusive option to license any inventions. Payments to Mount Sinai for the three months ended June 30, 2013 and 2012 were $198,000 and $285,000, respectively and for the six months ended June 30, 2013 and 2012 were $225,000 and $469,000, respectively. At June 30, 2013 and 2012, the Company owed Mount Sinai $295,000 and $0, respectively, which is included in accounts payable on the consolidated balance sheets. The Company outsources the synthesis of some of its chemical compounds to vendors in the United States and in foreign countries. A supplier, of which a member of the Company’s board of directors and a significant stockholder is an owner, produces one of these compounds under contract. The Company’s aggregate payments for these services for the three months ended June 30, 2013 and 2012 were $0 and $0, respectively and for the six months ended June 30, 2013 and 2012 were $107,000 and $52,500, respectively. At June 30, 2013 and 2012, the Company owed this supplier $0 and $9,000, respectively, which is included in accounts payable on the consolidated balance sheets. The Company purchases chemical compounds from corporations owned by a former member of its board of directors. The Company’s aggregate payments to these suppliers for the three months ended June 30, 2013 and 2012 were $212,000 and $173,000, respectively and for the six months ended June 30, 2013 and 2012 were $240,000 and $452,000, respectively. At June 30, 2013 and 2012, the Company owed this supplier $31,000 and $0, respectively, which is included in accounts payable on the consolidated balance sheets. The Company also rents office space in Pennington, New Jersey from a corporation related to these suppliers and affiliated with the former member of our board of directors.

Subsequent Event	6 Months Ended
Subsequent Event	Jun. 30, 2013
Subsequent Event
Subsequent Event	11. Subsequent Event On July 24, 2013, the Company’s Registration Statement was declared effective by the SEC, and on July 25, 2013, the Company’s Common Stock began trading on the NASDAQ Global Market under the symbol ONTX. On July 30, 2013, immediately prior to the consummation of the IPO, all outstanding shares of Preferred Stock automatically converted into shares of Common Stock at the applicable conversion ratio then in effect. As a result of the conversion, as of July 30, 2013, the Company had no shares of Preferred Stock outstanding. On July 30, 2013, the Company completed the IPO. The Company received net proceeds of $79,600,000 from the IPO, net of underwriting discounts and commissions and other estimated offering expenses. In preparation for the IPO, the Company’s board of directors and stockholders approved a one-for-1.333 reverse stock split of the Company’s Common Stock. The reverse stock split became effective on July 17, 2013. All Common Stock share and per share amounts in the condensed consolidated financial statements and notes thereto have been retroactively adjusted for all periods presented to give effect to this reverse stock split, including reclassifying an amount equal to the reduction in par value of common stock to additional paid-in capital. The reverse stock split did not result in a retroactive adjustment of share amounts for the Preferred Stock. In addition, in July 2013, the Company’s board of directors and stockholders approved an amendment of the Company’s certificate of incorporation to, among other things, change the definition of a designated public offering to remove the per share price requirement and to set the threshold at gross proceeds to the Company of at least $25.0 million. Further, in July 2013, the Company’s board of directors and stockholders approved, effective immediately prior to the listing of its Common Stock on the NASDAQ Global Market, the 2013 Equity Compensation Plan (the ‘‘2013 Plan’’). Under the 2013 Plan, the Company may grant incentive stock options, non-statutory stock options, stock appreciation rights, restricted stock, restricted stock units, deferred share awards, performance awards and other equity-based awards to employees, directors and consultants. The Company initially reserved 6,107,831 shares of common stock for issuance, subject to adjustment as set forth in the 2013 Plan, of which 3,315,662 shares of common stock will be available for future issuance. On July 25, 2013, in conjunction with the IPO, the Company issued 485,500 stock options.

Summary of Significant Accounting Policies (Details)	6 Months Ended
Summary of Significant Accounting Policies (Details)	Jun. 30, 2013 item
Segment Information
Number of operating segments	1

Net Loss Per Share of Common Stock (Details) - shares	6 Months Ended
Net Loss Per Share of Common Stock (Details) - shares	Jun. 30, 2013	Jun. 30, 2012
Potentially dilutive securities outstanding excluded from the computation of diluted weighted average shares as they would be antidilutive
Potentially dilutive securities outstanding excluded from the computation of diluted weighted average shares	15,639,243	10,857,939
Preferred Stock
Potentially dilutive securities outstanding excluded from the computation of diluted weighted average shares as they would be antidilutive
Potentially dilutive securities outstanding excluded from the computation of diluted weighted average shares	12,838,127	8,742,006
Warrants
Potentially dilutive securities outstanding excluded from the computation of diluted weighted average shares as they would be antidilutive
Potentially dilutive securities outstanding excluded from the computation of diluted weighted average shares	4,597	4,597
Stock options
Potentially dilutive securities outstanding excluded from the computation of diluted weighted average shares as they would be antidilutive
Potentially dilutive securities outstanding excluded from the computation of diluted weighted average shares	2,796,519	2,111,336

Fair Value Measurements (Details)	6 Months Ended	12 Months Ended
Fair Value Measurements (Details)	Jun. 30, 2013 USD ($) item	Dec. 31, 2012 USD ($)
Fair Value Measurements
Fair value material re-measurements	$ 0	$ 0
Assumption used to estimate the fair value of warrant liability by utilizing the Black-Scholes option pricing model
Number of group companies of which average historical share price trading data used for estimation of volatility \| item	11
Series G Preferred Stock \| Warrants
Assumption used to estimate the fair value of warrant liability by utilizing the Black-Scholes option pricing model
Dividend yield (as a percent)	0.00%	0.00%
Weighted average volatility (as a percent)	72.07%	64.87%
Series G Preferred Stock \| Warrants \| Weighted average
Assumption used to estimate the fair value of warrant liability by utilizing the Black-Scholes option pricing model
Weighted average risk-free interest rate (as a percent)	0.33%	0.31%
Recurring basis
Financial assets and liabilities measured at fair value
Warrant liability	$ 50,000	$ 62,000
Total	50,000	62,000
Recurring basis \| Level 3
Financial assets and liabilities measured at fair value
Warrant liability	50,000	62,000
Total	$ 50,000	$ 62,000

Fair Value Measurements (Details 2) - Warrants	6 Months Ended
Fair Value Measurements (Details 2) - Warrants	Jun. 30, 2013 USD ($)
Reconciliation of the warrant liability measured at fair value
Balance at the beginning of the period	$ 62,000
Change in fair value upon re-measurement	(12,000)
Balance at the end of the period	50,000
Additional disclosures
Transfer of assets from level 1 to level 2	0
Transfer of assets from level 2 to level 1	0
Transfer of liabilities from level 1 to level 2	0
Transfer of liabilities from level 2 to level 1	$ 0

Stock-Based Compensation (Details 2) - USD ($)	3 Months Ended		6 Months Ended
Stock-Based Compensation (Details 2) - USD ($)	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Stock-based compensation
Total stock-based compensation	$ 379,000	$ 103,000	$ 2,843,000	$ 2,540,000
Unrecognized compensation expense	2,351,000		$ 2,351,000
Weighted-average period for recognizing unrecognized compensation expense			2 years 29 days
General and administrative
Stock-based compensation
Total stock-based compensation	220,000	54,000	$ 1,526,000	1,321,000
Research and development
Stock-based compensation
Total stock-based compensation	$ 159,000	$ 49,000	$ 1,317,000	$ 1,219,000

Stock-Based Compensation (Details 3)	6 Months Ended
Stock-Based Compensation (Details 3)	Jun. 30, 2013 $ / shares shares
Options Outstanding
Shares	2,796,519
Weighted Average Remaining Contractual Life	7 years 3 months 7 days
Exercisable
Number (in shares)	1,790,647
Exercise Price $1.33
Stock-based compensation
Exercise Price (in dollars per share) \| $ / shares	$ 1.33
Options Outstanding
Shares	161,614
Weighted Average Remaining Contractual Life	1 year 14 days
Exercisable
Number (in shares)	161,614
Exercise Price $2.67
Stock-based compensation
Exercise Price (in dollars per share) \| $ / shares	$ 2.67
Options Outstanding
Shares	65,207
Weighted Average Remaining Contractual Life	2 years 6 months 25 days
Exercisable
Number (in shares)	65,207
Exercise Price $5.76
Stock-based compensation
Exercise Price (in dollars per share) \| $ / shares	$ 5.76
Options Outstanding
Shares	396,641
Weighted Average Remaining Contractual Life	6 years 8 months 8 days
Exercisable
Number (in shares)	367,664
Exercise Price $6.00
Stock-based compensation
Exercise Price (in dollars per share) \| $ / shares	$ 6.00
Options Outstanding
Shares	420,267
Weighted Average Remaining Contractual Life	4 years 2 months 5 days
Exercisable
Number (in shares)	420,267
Exercise Price $6.13
Stock-based compensation
Exercise Price (in dollars per share) \| $ / shares	$ 6.13
Options Outstanding
Shares	607,653
Weighted Average Remaining Contractual Life	6 years 8 months 19 days
Exercisable
Number (in shares)	498,326
Exercise Price $7.53
Stock-based compensation
Exercise Price (in dollars per share) \| $ / shares	$ 7.53
Options Outstanding
Shares	35,235
Weighted Average Remaining Contractual Life	8 years 10 months 28 days
Exercisable
Number (in shares)	28,586
Exercise Price $13.28
Stock-based compensation
Exercise Price (in dollars per share) \| $ / shares	$ 13.28
Options Outstanding
Shares	1,105,252
Weighted Average Remaining Contractual Life	9 years 7 months 2 days
Exercisable
Number (in shares)	244,633
Exercise Price $14.74
Stock-based compensation
Exercise Price (in dollars per share) \| $ / shares	$ 14.74
Options Outstanding
Shares	4,350
Weighted Average Remaining Contractual Life	9 years 10 months 24 days
Exercisable
Number (in shares)	4,350

Joint Venture (Details)	Dec. 31, 2012 item
Joint Venture
Number of new programs to be collaborated and developed	2

Related-Party Transactions (Details) - USD ($)	3 Months Ended		6 Months Ended
Related-Party Transactions (Details) - USD ($)	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Mount Sinai
Related-party transactions
Payments to related party	$ 198,000	$ 285,000	$ 225,000	$ 469,000
Amounts due to related party	295,000	0	295,000	0
Supplier business owned by board members
Related-party transactions
Payments to related party	0	0	107,000	52,500
Amounts due to related party	0	9,000	0	9,000
Corporations owned by former board members
Related-party transactions
Payments to related party	212,000	173,000	240,000	452,000
Amounts due to related party	$ 31,000	$ 0	$ 31,000	$ 0