Document and Entity Information	3 Months Ended
Document and Entity Information	Mar. 31, 2014	Apr. 30, 2014
Document and Entity Information
Entity Registrant Name	Onconova Therapeutics, Inc.
Entity Central Index Key	0001130598
Document Type	10-Q
Document Period End Date	Mar. 31, 2014
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Entity Current Reporting Status	Yes
Entity Filer Category	Non-accelerated Filer
Entity Common Stock, Shares Outstanding		21,640,387
Document Fiscal Year Focus	2014
Document Fiscal Period Focus	Q1

Condensed Consolidated Balance Sheets (USD $)	Mar. 31, 2014	Dec. 31, 2013
Current assets:
Cash and cash equivalents	$ 54,624,000	$ 60,009,000
Marketable securities	29,999,000	39,994,000
Prepaid expenses and other current assets	4,401,000	4,387,000
Total current assets	89,024,000	104,390,000
Property and equipment, net	557,000	626,000
Restricted cash	125,000	125,000
Other non-current assets	12,000	12,000
Total assets	89,718,000	105,153,000
Current liabilities :
Accounts payable	3,302,000	3,710,000
Accrued expenses and other current liabilities	7,795,000	5,820,000
Warrant liability	4,000	20,000
Deferred revenue	455,000	788,000
Total current liabilities	11,556,000	10,338,000
Deferred revenue, non-current	13,795,000	13,909,000
Other	3,000	6,000
Total liabilities	25,354,000	24,253,000
Commitments and contingencies
Stockholders' equity:
Preferred stock, $0.01 par value, 5,000,000 authorized at March 31, 2014 and December 31, 2013, none issued and outstanding at March 31, 2014 and December 31, 2013
Common stock, $0.01 par value, 75,000,000 authorized at March 31, 2014 and December 31, 2013, 21,638,887 and 21,467,482 shares issued and outstanding at March 31, 2014 and December 31 2013	217,000	215,000
Additional paid in capital	313,272,000	311,093,000
Accumulated other comprehensive income		1,000
Accumulated deficit	(249,575,000)	(230,896,000)
Total Onconova Therapeutics, Inc. stockholders' equity	63,914,000	80,413,000
Non-controlling interest	450,000	487,000
Total stockholders' equity	64,364,000	80,900,000
Total liabilities and stockholders' equity	$ 89,718,000	$ 105,153,000

Condensed Consolidated Balance Sheets (Parenthetical) (USD $)	Mar. 31, 2014	Dec. 31, 2013
Condensed Consolidated Balance Sheets
Preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01
Preferred stock, shares authorized	5,000,000	5,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized	75,000,000	75,000,000
Common stock, shares issued	21,638,887	21,467,482
Common stock, shares outstanding	21,638,887	21,467,482

Condensed Consolidated Statements of Operations (USD $)	3 Months Ended
Condensed Consolidated Statements of Operations (USD $)	Mar. 31, 2014	Mar. 31, 2013
Condensed Consolidated Statements of Operations
Revenue	$ 447,000	$ 1,116,000
Operating expenses:
General and administrative	4,932,000	3,346,000
Research and development	14,248,000	12,756,000
Total operating expenses	19,180,000	16,102,000
Loss from operations	(18,733,000)	(14,986,000)
Change in fair value of warrant liability	16,000	14,000
Other income, net	1,000	127,000
Net loss	(18,716,000)	(14,845,000)
Net loss attributable to non-controlling interest	37,000
Net loss attributable to Onconova Therapeutics, Inc	(18,679,000)	(14,845,000)
Accretion of redeemable convertible preferred stock		(1,019,000)
Net loss applicable to common stockholders	$ (18,679,000)	$ (15,864,000)
Net loss per share of common stock, basic and diluted (in dollars per share)	$ (0.87)	$ (6.08)
Basic and diluted weighted average shares outstanding (in shares)	21,568,302	2,607,406

Condensed Consolidated Statements of Comprehensive Loss (USD $)	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Condensed Consolidated Statements of Comprehensive Loss
Net loss	$ (18,716,000)	$ (14,845,000)
Other comprehensive income, before tax:
Foreign currency translation adjustments, net	(1,000)	7,000
Other comprehensive income, net of tax	(1,000)	7,000
Comprehensive loss	(18,717,000)	(14,838,000)
Comprehensive loss attributable to non-controlling interest	37,000
Comprehensive loss attributable to Onconova Therapeutics, Inc	$ (18,680,000)	$ (14,838,000)

Consolidated Statement of Stockholders' Equity (USD $)	Total	Common Stock	Additional Paid in Capital	Accumulated deficit	Accumulated other comprehensive income	Non-controlling interest
Balance at Dec. 31, 2013	$ 80,900,000	$ 215,000	$ 311,093,000	$ (230,896,000)	$ 1,000	$ 487,000
Balance (in shares) at Dec. 31, 2013		21,467,482
Increase (Decrease) in Stockholders' Equity
Net loss	(18,716,000)			(18,679,000)		(37,000)
Other comprehensive income	(1,000)				(1,000)
Exercise of stock options	853,000	2,000	851,000
Exercise of stock options (in shares)		171,405
Stock-based compensation	1,328,000		1,328,000
Balance at Mar. 31, 2014	$ 64,364,000	$ 217,000	$ 313,272,000	$ (249,575,000)		$ 450,000
Balance (in shares) at Mar. 31, 2014		21,638,887

- Definition

This element represents the amount of recognized equity-based compensation during the period, that is, the amount recognized as expense in the income statement (or as asset if compensation is capitalized). Alternate captions include the words "stock-based compensation".

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- Definition

Number of share options (or share units) exercised during the current period.

+ References+ Details

Condensed Consolidated Statements of Cash Flows (USD $)	3 Months Ended
Condensed Consolidated Statements of Cash Flows (USD $)	Mar. 31, 2014	Mar. 31, 2013
Operating activities:
Net loss	$ (18,716,000)	$ (14,845,000)
Adjustment to reconcile net loss to net cash (used in) provided by operating activities :
Depreciation and amortization	141,000	98,000
Change in fair value of warrant liabilities	(16,000)	(14,000)
Treasury note discount amortization	(5,000)
Stock compensation expense	1,328,000	2,465,000
Changes in assets and liabilities :
Prepaid expenses and other current assets	(14,000)	(941,000)
Accounts payable	(408,000)	(1,274,000)
Accrued expenses	1,975,000	1,634,000
Other liabilities	(3,000)	20,000
Deferred revenue	(447,000)	(1,092,000)
Net cash used in operating activities	(16,165,000)	(13,949,000)
Investing activities:
Payments for purchase of property and equipment	(72,000)	(284,000)
Maturities of marketable securities	10,000,000
Net cash provided by (used in) investing activities	9,928,000	(284,000)
Financing activities:
Proceeds from the exercise of stock options	853,000	6,000
Net cash provided by financing activities	853,000	6,000
Effect of foreign currency translation on cash	(1,000)	7,000
Net decrease in cash and cash equivalents	(5,385,000)	(14,220,000)
Cash and cash equivalents at beginning of period	60,009,000	81,527,000
Cash and cash equivalents at end of period	$ 54,624,000	$ 67,307,000

Nature of Business	3 Months Ended
Nature of Business	Mar. 31, 2014
Nature of Business
Nature of Business	1. Nature of Business The Company Onconova Therapeutics, Inc. (the “Company”) was incorporated in the State of Delaware on December 22, 1998 and commenced operations on January 1, 1999. The Company’s headquarters are located in Newtown, Pennsylvania. The Company is a clinical-stage biopharmaceutical company focused on discovering and developing novel small molecule drug candidates to treat cancer. Using its proprietary chemistry platform, the Company has created an extensive library of targeted anti-cancer agents designed to work against specific cellular pathways that are important to cancer cells. The Company believes that the drug candidates in its pipeline have the potential to be efficacious in a wide variety of cancers without causing harm to normal cells. The Company has three clinical-stage product candidates and six preclinical programs. To accelerate and broaden the development of rigosertib, the Company’s most advanced product candidate, the Company entered into a collaboration and license agreement in 2012 with Baxter Healthcare SA (“Baxter”), a subsidiary of Baxter International Inc., to commercialize rigosertib in Europe. In 2011, the Company entered into a collaboration and license agreement with SymBio Pharmaceuticals Limited (“SymBio”) to commercialize rigosertib in Japan and Korea. The Company has retained development and commercialization rights to rigosertib in the rest of the world, including the United States. During 2012, Onconova Europe GmbH was established as a wholly owned subsidiary of the Company for the purpose of further developing business in Europe. In April 2013, GBO, LLC, a Delaware limited liability company, (“GBO”) was formed pursuant to a collaboration agreement with GVK Biosciences Private Limited, a private limited company located in India, (“GVK BIO”) to collaborate and develop two new clinical programs using the Company’s technology platform. Liquidity The Company has incurred recurring operating losses since inception. For the three months ended March 31, 2014, the Company incurred a net loss of $18,716,000 and as of March 31, 2014, the Company had generated an accumulated deficit of $249,575,000. The Company anticipates operating losses to continue for the foreseeable future due to, among other things, costs related to research funding, development of its product candidates and its preclinical programs, strategic alliances and the development of its administrative organization. The Company will require substantial additional financing to continue to fund its operations and execute its strategy. Since its inception, the Company raised significant capital through the issuance of redeemable convertible preferred stock, par value $0.01 per share, in ten series denominated as Series A through Series J (“Series A Preferred Stock” through “Series J Preferred Stock,” respectively, and collectively the “Preferred Stock”). On July 30, 2013, the Company completed its initial public offering (the “IPO”) of 5,941,667 shares of the Company’s common stock, par value $0.01 per share (“Common Stock”), at a price of $15.00 per share, including 775,000 shares of Common Stock issued upon the exercise in full by the underwriters of their option to purchase additional shares at the same price to cover over-allotments. The Company received net proceeds of $79,811,000 from the sale, net of underwriting discounts and commissions and other estimated offering expenses. 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. The accompanying condensed consolidated financial statements have been prepared assuming that the Company will continue as a going concern, which contemplates the realization of assets and satisfaction of liabilities in the normal course of business. The Company’s ability to continue as a going concern is dependent on its ability to raise additional capital to fund its research and development and commercial programs and meet its obligations. Management intends to fund future operations through additional equity offerings, licensing revenue, grants, government contracts and, if any of the Company’s product candidates receive marketing approval, future sales of its products. There can be no assurance, however, that the Company will be successful in obtaining financing at the level needed to sustain operations or on terms acceptable to the Company, or that the Company will obtain approvals necessary to market its products or achieve profitability or sustainable, positive cash flow.

Summary of Significant Accounting Policies	3 Months Ended
Summary of Significant Accounting Policies	Mar. 31, 2014
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 “SEC”). The financial statements include the consolidated accounts of the Company, its wholly-owned subsidiary, Onconova Europe GmbH and GBO. All significant intercompany transactions have been eliminated. Unaudited Interim Financial Information The accompanying condensed consolidated balance sheet as of March 31, 2014, the condensed consolidated statements of operations, the condensed consolidated statements of comprehensive loss, the condensed consolidated statement of stockholders’ equity and the condensed consolidated statements of cash flows for the three months ended March 31, 2014 and 2013 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 March 31, 2014 and the results of its operations, and its cash flows for the three months ended March 31, 2014 and 2013. The financial data and other information disclosed in these notes related to the three months ended March 31, 2014 and 2013 are unaudited. The results for the three months ended March 31, 2014 are not necessarily indicative of results to be expected for the year ending December 31, 2014, 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, 2013 included in the Company’s annual report on Form 10-K filed with the SEC on March 20, 2014. 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, 2013 included in the Company’s annual report on Form 10-K filed with the SEC on March 20, 2014. 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. Recent Accounting Pronouncements In July 2013, the Financial Accounting Standards Board (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 was effective for fiscal years, and interim periods within those years, beginning after December 15, 2013. The Company adopted these new provisions during the quarter beginning January 1, 2014. The guidance did not have an impact on the Company’s consolidated financial position, results of operations or cash flows.

- Definition

The entire disclosure for the organization, consolidation and basis of presentation of financial statements disclosure, and significant accounting policies of the reporting entity. May be provided in more than one note to the financial statements, as long as users are provided with an understanding of (1) the significant judgments and assumptions made by an enterprise in determining whether it must consolidate a VIE and/or disclose information about its involvement with a VIE, (2) the nature of restrictions on a consolidated VIE's assets reported by an enterprise in its statement of financial position, including the carrying amounts of such assets, (3) the nature of, and changes in, the risks associated with an enterprise's involvement with the VIE, and (4) how an enterprise's involvement with the VIE affects the enterprise's financial position, financial performance, and cash flows. Describes procedure if disclosures are provided in more than one note to the financial statements.

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Fair Value Measurements

3 Months Ended

Mar. 31, 2014

Fair Value Measurements

Fair Value Measurements

3. Fair Value Measurements

Fair value is defined as the exchange price that would be received for an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date.

The Company utilizes a valuation hierarchy for disclosure of the inputs to the valuations used to measure fair value. This hierarchy prioritizes the inputs into three broad levels as follows. Level 1 inputs are quoted prices (unadjusted) in active markets for identical assets or liabilities. Level 2 inputs are quoted prices for similar assets and liabilities in active markets or inputs that are observable for the asset or liability, either directly or indirectly through market corroboration, for substantially the full term of the financial instrument. Level 3 inputs are unobservable inputs based on the Company’s own assumptions used to measure assets and liabilities at fair value. A financial asset or liability’s classification within the hierarchy is determined based on the lowest level input that is significant to the fair value measurement.

The Company had no assets or liabilities classified as Level 1 or Level 2. The warrants (see Note 7) are classified as Level 3.

The Company has classified the warrants as a liability and has re-measured the liability to estimated fair value at March 31, 2014 and December 31, 2013, 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 0.13% and 0.34% at March 31, 2014 and December 31, 2013, respectively, and weighted average volatility of 72.11% and 74.40% at March 31, 2014 and December 31, 2013, 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 March 31, 2014 and December 31, 2013:

	Fair Value Measurement as of March 31, 2014								Fair Value Measurement as of December 31, 2013
	Level 1		Level 2		Level 3		Balance		Level 1		Level 2		Level 3		Balance

Warrant liability	$	—	$	—	$	4,000	$	4,000	$	—	$	—	$	20,000	$	20,000
Total	$	—	$	—	$	4,000	$	4,000	$	—	$	—	$	20,000	$	20,000

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 three months ended March 31, 2014:

	Warrant Liability
Balance at December 31, 2013	$	20,000
Change in fair value upon re-measurement	(16,000		)
Balance at March 31, 2014	$	4,000

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.

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Marketable Securities

3 Months Ended

Mar. 31, 2014

Marketable Securities

Marketable Securities

4. Marketable Securities

Marketable securities with initial maturities longer than three months but that mature within one year from the balance sheet date are classified as current assets and are summarized as follows:

	March 31, 2014		December 31, 2013

U.S. Treasury obligations	$	29,999,000	$	39,994,000

As of March 31, 2014 and December 31, 2013, all of the Company’s investments were classified as held-to-maturity.

- Definition

The entire disclosure for investments in certain debt and equity securities.

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+ Details

Net Loss Per Share of Common Stock

3 Months Ended

Mar. 31, 2014

Net Loss Per Share of Common Stock

Net Loss Per Share of Common Stock

5. Net Loss Per Share of Common Stock

The following potentially dilutive securities outstanding at March 31, 2014 and 2013 have been excluded from the computation of diluted weighted average shares outstanding, as they would be antidilutive:

	March 31,
	2014	2013
Preferred Stock	—	12,838,127
Warrants	4,597	4,597
Stock options	4,252,171	2,792,169
	4,256,768	15,634,893

- Definition

The entire disclosure for earnings per share.

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Balance Sheet Detail

3 Months Ended

Mar. 31, 2014

Balance Sheet Detail

Balance Sheet Detail

6. Balance Sheet Detail

Prepaid expenses and other current assets:

	March 31,		December 31,
	2014		2013

Research and development	$	2,435,000	$	2,242,000
Manufacturing	1,025,000		1,051,000
Insurance	421,000		645,000
Other	520,000		449,000
	$	4,401,000	$	4,387,000

Property and equipment:

	March 31,			December 31,
	2014			2013

Property and equipment	$	2,471,000		$	2,402,000
Accumulated depreciation	(1,914,000		)	(1,776,000		)
	$	557,000		$	626,000

Accrued expenses and other current liabilities:

	March 31,		December 31,
	2014		2013

Research and development	$	5,808,000	$	4,625,000
Employee compensation	1,383,000		509,000
Professional fees	329,000		310,000
Taxes	208,000		302,000
Other	67,000		74,000
	$	7,795,000	$	5,820,000

Warrants	3 Months Ended
Warrants	Mar. 31, 2014
Warrants
Warrants	7. Warrants In June 2009, 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. The warrants are classified as liabilities due to certain anti-dilution provisions, and the value of the warrants is adjusted to current fair value at each reporting period end. For the three months ended March 31, 2014 and 2013, the Company recorded $16,000 and $14,000, respectively, in the consolidated statements of operations related to the change in the fair value of the outstanding warrants. Immediately prior to the consummation of the IPO, the 6,128 Series G Preferred Stock warrants outstanding were automatically converted into 4,597 Common Stock warrants (after giving effect to the one-for-1.333 reverse stock split that became effective on July 17, 2013 in connection with the IPO).

Stock-Based Compensation

3 Months Ended

Mar. 31, 2014

Stock-Based Compensation

Stock-Based Compensation

8. Stock-Based Compensation

The Company recognized stock-based compensation expense as follows for the three months ended March 31, 2014 and 2013:

	Three Months Ended March 31,
	2014		2013
General and administrative	$	647,000	$	1,307,000
Research and development	681,000		1,158,000
	$	1,328,000	$	2,465,000

Stock options may be granted with exercise prices of not less than the estimated fair value of the Common Stock on the date of grant and generally vest over a period of up to four years. Stock options granted under the 2013 Plan generally expire no later than ten years from the date of grant. A summary of stock option activity for the three months ended March 31, 2014 is as follows:

	Number of Options		Weighted- Average Exercise Price		Weighted- Average Remaining Contractual Term (in years)
Outstanding at December 31, 2013	4,344,365		$	11.05	7.91
Granted	132,500		7.63
Exercised	(171,405	)	4.95
Forfeited	(53,289	)	11.47

Outstanding at March 31, 2014	4,252,171		$	11.19	8.02
Vested or expected to vest at March 31, 2014	4,180,309		$	11.19	8.02
Exercisable at March 31, 2014	2,352,446		$	9.39	7.00

We utilized the Black-Scholes valuation model for estimating the fair value of the stock compensation granted, with the following weighted-average assumptions:

	Employee Stock Options For the Three Months Ended
	March 31,
	2014

Average risk-free interest rates	1.98		%
Average expected life (in years)	6.25
Volatility	78.48		%
Weighted-average fair value (in dollars)	$	5.28

Due to the Company’s limited operating history as a public company 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.

Based on our historical experience, we have assumed an annualized forfeiture rate of 1.69% for our options. Under the true-up provisions of the stock based compensation guidance, we will record additional expense if the actual forfeiture rate is lower than we estimated, and will record a recovery of prior expense if the actual forfeiture is higher than we estimated.

As of March 31, 2014, there was $1,559,000 of unrecognized compensation expense related to the unvested liability awards, which is expected to be recognized over a weighted-average period of approximately 2.28 years.

As of March 31, 2014, there was $11,043,000 of unrecognized compensation expense related to the unvested stock options issued from April 23, 2013 through March 31, 2014, which is expected to be recognized over a weighted-average period of approximately 3.52 years. The Company accounts for stock options issued to nonemployees using a fair value approach.

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 had 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 March 31, 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 Company’s 2007 Equity Compensation Plan (the “2007 Plan”) advising them that Purchase Transactions would 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.

At March 31, 2014 and 2013, the aggregate intrinsic value of the option liability recorded was $0 and $14,394,000, respectively.

A roll forward of the stock option liability balance for the three months ended March 31, 2013 is as follows:

Balance at December 31, 2012	11,967,000
Change in intrinsic value upon re-measurement	2,465,000
Settlements of option liability awards	(38,000	)
Balance at March 31, 2013	14,394,000

- Definition

The entire disclosure for compensation-related costs for equity-based compensation, which may include disclosure of policies, compensation plan details, allocation of equity compensation, incentive distributions, equity-based arrangements to obtain goods and services, deferred compensation arrangements, employee stock ownership plan details and employee stock purchase plan details.

+ References+ Details

Research Agreements	3 Months Ended
Research Agreements	Mar. 31, 2014
Research Agreements
Research Agreements	9. Research Agreements The Company has entered into various licensing and right-to-sublicense agreements with educational institutions for the exclusive use of patents and patent applications, as well as any patents that may develop from research being conducted by such educational institutions in the field of anticancer therapy, genes and proteins. Results from this research have been licensed to the Company pursuant to these agreements. Under one of these agreements with Temple University (“Temple”), the Company is required to make annual maintenance payments to Temple and royalty payments based upon a percentage of sales generated from any products covered by the licensed patents, with minimum specified royalty payments. As no sales had been generated through March 31, 2014 under the licensed patents, the Company has not incurred any royalty expenses related to this agreement. In addition, the Company is required to pay Temple 25% of any sublicensing fees received by the Company. In 2011, the Company recorded $1,875,000 of expense related to the Temple agreement in connection with the collaboration agreement the Company executed with SymBio. In 2012, the company recorded $12,500,000 of expense related to the Temple agreement in connection with the collaboration agreement the Company executed with Baxter. These expenses were recorded in the consolidated statement of operations as research and development expenses. In May 2010, the Company signed a funding agreement with the Leukemia and Lymphoma Society (“LLS”) to fund the development of rigosertib. Under this agreement, the Company was entitled to receive milestone payments of up to $10,000,000 through 2013 in connection with clinical trials to be conducted. The aggregate milestone payment amount was subsequently reduced to $8,000,000 pursuant to an amendment signed in January 2013, after which LLS was not obligated to fund any further amounts. In the event that the research is successful, the Company must proceed with commercialization of the licensed product or repay the amount funded. In addition, LLS is entitled to receive regulatory and commercial milestone payments and royalties from the Company based on the Company’s net sales of the licensed product, with the amount of such milestone payments and royalties not to exceed three times the amount funded ($24,000,000). During the year ended December 31, 2012, in connection with the execution of the Baxter agreement (Note 10), the Company paid $1,000,000 to LLS and recorded this amount in research and development expenses. This payment reduced the maximum milestone and royalty payment obligation under this agreement to $23,000,000 at March 31, 2014 and December 31, 2013. As a result of the potential obligation to repay the funds under this arrangement, the $8,000,000 of milestone payments received, have been recorded as deferred revenue at March 31, 2014 and December 31, 2013 and will be recognized as revenue commencing with the resolution of the repayment contingency.

License and Collaboration Agreements	3 Months Ended
License and Collaboration Agreements	Mar. 31, 2014
License and Collaboration Agreements
License and Collaboration Agreements	10. 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”). In July 2012, Baxter purchased $50,000,000 of the Company’s Series J Preferred Stock, which automatically converted to shares of Common Stock immediately prior to the consummation of the IPO. Baxter also invested $5,000,000 in the Company’s IPO. Under the terms of the agreement, the Company was initially required to perform research and development to advance three initial rigosertib indications, rigosertib intravenous (“IV”) in higher risk myelodysplastic syndrome (“MDS”) patients, rigosertib IV in pancreatic cancer patients and rigosertib oral in lower risk MDS patients, through Phase 3, Phase 3 and Phase 2 clinical trials, respectively. In December 2013, a pre-planned interim futility and safety analysis of the pancreatic cancer trial was performed and the trial was discontinued. In February 2014, the Company announced top-line analysis of a Phase 3 trial of rigosertib IV in higher risk MDS patients. Although the results of this study showed numerical improvement in median overall survival in the rigosertib treated patients, the observed improvement of 2.4 months did not meet the required level of statistical significance. However, an encouraging improvement in median overall survival was evident in the subset of patients who had progressed on or failed to respond to previous treatment with hypomethylating agents (“HMAs”). The Company is performing additional analyses of the data from this trial, and is aiming to meet with regulatory authorities to discuss next steps for rigosertib IV development and/or registration in this patient population. If an additional Phase 3 clinical trial 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 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 this indication. If the Company and Baxter mutually agree to progress the development of 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 this indication 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 $337,500,000 if specified development and regulatory milestones are achieved. The potential pre-commercial development milestone payments to the Company include the following: · $50,000,000 for achievement of the primary endpoint of a Phase 3 clinical trial for rigosertib IV in higher risk MDS patients (the “MDS IV indication”) or mutual agreement of the parties to file for any marketing approval in either the European Union as a whole or in all of the Big Five EU Countries (specified in the agreement as:Germany, United Kingdom, France, Italy and Spain); · $25,000,000 for the joint decision to proceed with the development of rigosertib for lower risk MDS; 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 $212,500,000 in milestone payments for regulatory approvals of the rigosertib MDS 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 of the MDS IV indication 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 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 had already been granted to the Company by the U.S. Food and Drug Administration (the “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 was 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. As of March 31, 2014, all of the deferred revenue related to such research and development services has been recognized. For the three months ended March 31, 2014 and 2013, the Company recognized $333,000 and $978,000, 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 Series J 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 $22,000,000 from SymBio upon the achievement of specified development and regulatory milestones for specified indications. 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. Furthermore, upon receipt of marketing approval in the United States and Japan for an additional specified 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 the three months ended March 31, 2014 and 2013, the Company recognized revenues of $113,000, and $113,000, respectively, under this agreement. In addition, the Company recognized revenues of $0 and $25,000 for the three months ended March 31, 2014 and 2013, respectively, related to the supply agreement with SymBio.

Preclinical Collaboration	3 Months Ended
Preclinical Collaboration	Mar. 31, 2014
Preclinical Collaboration
Preclinical Collaboration	11. Preclinical Collaboration In December 2012, we formed GBO, an entity jointly-owned by both us and GVK BIO. The purpose of GBO is to collaborate on and develop two programs through filing of an investigational new drug application (“IND”) and/or conducting proof of concept studies using the Company’s technology platform. During 2013, GVK BIO made an initial capital contribution of $500,000 in exchange for a 10% interest in GBO, and the Company made an initial capital contribution of a sub-license to all the intellectual property controlled by the Company related to the two specified programs in exchange for a 90% interest. Under the terms of the agreement, GVK BIO may make additional capital contributions. The GVK BIO percentage interest in GBO may change from the initial 10% to up to 50%, depending on the amount of its total capital contributions. The Company evaluates its variable interests in GBO on a quarterly basis and has determined that it is the primary beneficiary. For thirty days following the 15-month anniversary of the commencement of either of the two programs, the Company will have an option to (i) cancel the license and (ii) purchase all rights in and to that program. There are three of these buy-back scenarios depending on the stage of development of the underlying assets. GVK BIO will have operational control of GBO and the Company will have strategic and scientific control.

- Definition

The entire disclosure for equity method investments and joint ventures. Equity method investments are investments that give the investor the ability to exercise significant influence over the operating and financial policies of an investee. Joint ventures are entities owned and operated by a small group of businesses as a separate and specific business or project for the mutual benefit of the members of the group.

+ References+ Details

Initial Public Offering	3 Months Ended
Initial Public Offering	Mar. 31, 2014
Initial Public Offering
Initial Public Offering	12. Initial Public Offering 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 September 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 $79,811,000 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.

Related-Party Transactions	3 Months Ended
Related-Party Transactions	Mar. 31, 2014
Related-Party Transactions
Related-Party Transactions	13. 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 under this research agreement for the three months ended March 31, 2014 and 2013 were $295,000 and $27,000, respectively. At March 31, 2014 and December 31, 2013, the Company owed Mount Sinai $173,000 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 March 31, 2014 and 2013 were $0 and $107,000, respectively. At March 31, 2014 and December 31, 2013, the Company had no outstanding amounts payable to this supplier. The Company purchases chemical compounds and sources development services 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 March 31, 2014 and 2013 were $32,000 and $35,000, respectively. At March 31, 2014 and December 31, 2013, the Company owed this supplier $127,000 and $157,000 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. The Company has entered into a consulting agreement with a member of its board of directors, who is also a significant stockholder. The board member provides consulting services to the Company on the terms set forth in the agreement. Payments to this board member for the three months ended March 31, 2014, and 2013 were $47,000 and $45,000, respectively. At March 31, 2014 and December 31, 2013, the Company had no outstanding amounts payable under this agreement.

- Definition

The entire disclosure for related party transactions. Examples of related party transactions include transactions between (a) a parent company and its subsidiary; (b) subsidiaries of a common parent; (c) and entity and its principal owners; and (d) affiliates.

+ References+ Details

Summary of Significant Accounting Policies (Policies)	3 Months Ended
Summary of Significant Accounting Policies (Policies)	Mar. 31, 2014
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 “SEC”). The financial statements include the consolidated accounts of the Company, its wholly-owned subsidiary, Onconova Europe GmbH and GBO. All significant intercompany transactions have been eliminated.
Unaudited Interim Financial Information	Unaudited Interim Financial Information The accompanying condensed consolidated balance sheet as of March 31, 2014, the condensed consolidated statements of operations, the condensed consolidated statements of comprehensive loss, the condensed consolidated statement of stockholders’ equity and the condensed consolidated statements of cash flows for the three months ended March 31, 2014 and 2013 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 March 31, 2014 and the results of its operations, and its cash flows for the three months ended March 31, 2014 and 2013. The financial data and other information disclosed in these notes related to the three months ended March 31, 2014 and 2013 are unaudited. The results for the three months ended March 31, 2014 are not necessarily indicative of results to be expected for the year ending December 31, 2014, 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, 2013 included in the Company’s annual report on Form 10-K filed with the SEC on March 20, 2014.
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, 2013 included in the Company’s annual report on Form 10-K filed with the SEC on March 20, 2014. 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.
Recent Accounting Pronouncements	Recent Accounting Pronouncements In July 2013, the Financial Accounting Standards Board (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 was effective for fiscal years, and interim periods within those years, beginning after December 15, 2013. The Company adopted these new provisions during the quarter beginning January 1, 2014. The guidance did not have an impact on the Company’s consolidated financial position, results of operations or cash flows.

- Definition

Disclosure of accounting policy for (1) transactions denominated in a currency other than the reporting enterprise's functional currency, (2) translating foreign currency financial statements that are incorporated into the financial statements of the reporting enterprise by consolidation, combination, or the equity method of accounting, and (3) remeasurement of the financial statements of a foreign reporting enterprise in a hyperinflationary economy.

+ References+ Details

Fair Value Measurements (Tables)

3 Months Ended

Mar. 31, 2014

Fair Value Measurements

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

	Fair Value Measurement as of March 31, 2014								Fair Value Measurement as of December 31, 2013
	Level 1		Level 2		Level 3		Balance		Level 1		Level 2		Level 3		Balance

Warrant liability	$	—	$	—	$	4,000	$	4,000	$	—	$	—	$	20,000	$	20,000
Total	$	—	$	—	$	4,000	$	4,000	$	—	$	—	$	20,000	$	20,000

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, 2013	$	20,000
Change in fair value upon re-measurement	(16,000		)
Balance at March 31, 2014	$	4,000

- Definition

Tabular disclosure of the fair value measurement of liabilities using significant unobservable inputs (Level 3), a reconciliation of the beginning and ending balances, separately presenting changes attributable to the following: (1) total gains or losses for the period (realized and unrealized), segregating those gains or losses included in earnings (or changes in net assets), and gains or losses recognized in other comprehensive income (loss) and a description of where those gains or losses included in earnings (or changes in net assets) are reported in the statement of income (or activities); (2) purchases, sales, issues, and settlements (each type disclosed separately); and (3) transfers in and transfers out of Level 3 (for example, transfers due to changes in the observability of significant inputs) by class of liability.

+ References+ Details

Marketable Securities (Tables)

3 Months Ended

Mar. 31, 2014

Marketable Securities

Summary of marketable securities

	March 31, 2014		December 31, 2013

U.S. Treasury obligations	$	29,999,000	$	39,994,000

- Definition

Tabular disclosure of all investments in certain debt and equity securities for which the entity has the positive intent and ability to hold until maturity.

+ References+ Details

Net Loss Per Share of Common Stock (Tables)

3 Months Ended

Mar. 31, 2014

Net Loss Per Share of Common Stock

Schedule of antidilutive securities which have been excluded from the computation of diluted weighted average shares outstanding

	March 31,
	2014	2013
Preferred Stock	—	12,838,127
Warrants	4,597	4,597
Stock options	4,252,171	2,792,169
	4,256,768	15,634,893

Balance Sheet Detail (Tables)

3 Months Ended

Mar. 31, 2014

Balance Sheet Detail

Schedule of prepaid expenses and other current assets

	March 31,		December 31,
	2014		2013

Research and development	$	2,435,000	$	2,242,000
Manufacturing	1,025,000		1,051,000
Insurance	421,000		645,000
Other	520,000		449,000
	$	4,401,000	$	4,387,000

Schedule of property and equipment

	March 31,			December 31,
	2014			2013

Property and equipment	$	2,471,000		$	2,402,000
Accumulated depreciation	(1,914,000		)	(1,776,000		)
	$	557,000		$	626,000

Schedule of accrued expenses and other current liabilities

	March 31,		December 31,
	2014		2013

Research and development	$	5,808,000	$	4,625,000
Employee compensation	1,383,000		509,000
Professional fees	329,000		310,000
Taxes	208,000		302,000
Other	67,000		74,000
	$	7,795,000	$	5,820,000

Stock-Based Compensation (Tables)

3 Months Ended

Mar. 31, 2014

Stock-Based Compensation

Schedule of stock-based compensation expense

	Three Months Ended March 31,
	2014		2013
General and administrative	$	647,000	$	1,307,000
Research and development	681,000		1,158,000
	$	1,328,000	$	2,465,000

Schedule of stock option activity

	Number of Options		Weighted- Average Exercise Price		Weighted- Average Remaining Contractual Term (in years)
Outstanding at December 31, 2013	4,344,365		$	11.05	7.91
Granted	132,500		7.63
Exercised	(171,405	)	4.95
Forfeited	(53,289	)	11.47

Outstanding at March 31, 2014	4,252,171		$	11.19	8.02
Vested or expected to vest at March 31, 2014	4,180,309		$	11.19	8.02
Exercisable at March 31, 2014	2,352,446		$	9.39	7.00

Schedule of weighted-average assumptions used for estimating the fair value of the stock compensation granted

	Employee Stock Options For the Three Months Ended
	March 31,
	2014

Average risk-free interest rates	1.98		%
Average expected life (in years)	6.25
Volatility	78.48		%
Weighted-average fair value (in dollars)	$	5.28

Schedule of roll forward of the stock option liability

Balance at December 31, 2012	11,967,000
Change in intrinsic value upon re-measurement	2,465,000
Settlements of option liability awards	(38,000	)
Balance at March 31, 2013	14,394,000

Nature of Business (Details) (USD $)	0 Months Ended	3 Months Ended
Nature of Business (Details) (USD $)	Jul. 30, 2013	Mar. 31, 2014 item	Mar. 31, 2013	Dec. 31, 2013	Apr. 30, 2013 item
Nature of Business
Number of clinical-stage product candidates		3
Number of preclinical programs		6
Number of clinical programs developed by GBO, LLC					2
Net loss		$ (18,716,000)	$ (14,845,000)
Accumulated deficit		(249,575,000)		(230,896,000)
Preferred stock, par value per share (in dollars per share)		$ 0.01
Number of series denominated as Series A through Series J preferred stock		10
Initial Public Offering
Common stock, par value (in dollars per share)		$ 0.01		$ 0.01
Net proceeds received from the sale, net of underwriting discounts and commissions and other estimated offering expenses	79,811,000
Preferred stock outstanding (in shares)	0
IPO
Initial Public Offering
Number of shares issued in initial public offering	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	775,000
Net proceeds received from the sale, net of underwriting discounts and commissions and other estimated offering expenses	$ 79,811,000

Fair Value Measurements (Details) (USD $)	3 Months Ended	12 Months Ended
Fair Value Measurements (Details) (USD $)	Mar. 31, 2014	Dec. 31, 2013
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	11
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)	72.11%	74.40%
Warrants \| Weighted average
Assumption used to estimate the fair value of warrant liability by utilizing the Black-Scholes option pricing model
Risk-free interest rate (as a percent)	0.13%	0.34%
Recurring basis
Financial assets and liabilities measured at fair value
Warrant liability	$ 4,000	$ 20,000
Total	4,000	20,000
Recurring basis \| Level 3
Financial assets and liabilities measured at fair value
Warrant liability	4,000	20,000
Total	$ 4,000	$ 20,000

Fair Value Measurements (Details 2) (USD $)			3 Months Ended
Fair Value Measurements (Details 2) (USD $)	Mar. 31, 2014	Dec. 31, 2013	Mar. 31, 2014 Warrants
Reconciliation of the warrant liability measured at fair value
Balance at the beginning of the period			$ 20,000
Change in fair value upon re-measurement			(16,000)
Balance at the end of the period			4,000
Additional disclosures
Amount of transfers of assets out of Level 1 into Level 2	0	0
Amount of transfers of assets out of Level 2 into Level 1	0	0
Amount of transfers of liabilities out of Level 1 into Level 2	0	0
Amount of transfers of liabilities out of Level 2 into Level 1	$ 0	$ 0

Marketable Securities (Details) (USD $)	Mar. 31, 2014	Dec. 31, 2013
Marketable securities, current
Marketable securities	$ 29,999,000	$ 39,994,000
U.S. Treasury obligations
Marketable securities, current
Marketable securities	$ 29,999,000	$ 39,994,000

Net Loss Per Share of Common Stock (Details)	3 Months Ended
Net Loss Per Share of Common Stock (Details)	Mar. 31, 2014	Mar. 31, 2013
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	4,256,768	15,634,893
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
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	4,252,171	2,792,169

- Definition

Securities (including those issuable pursuant to contingent stock agreements) that could potentially dilute basic earnings per share (EPS) or earnings per unit (EPU) in the future that were not included in the computation of diluted EPS or EPU because to do so would increase EPS or EPU amounts or decrease loss per share or unit amounts for the period presented.

+ References+ Details

Balance Sheet Detail (Details) (USD $)	Mar. 31, 2014	Dec. 31, 2013
Prepaid expenses and other current assets:
Research and development	$ 2,435,000	$ 2,242,000
Manufacturing	1,025,000	1,051,000
Insurance	421,000	645,000
Other	520,000	449,000
Total	4,401,000	4,387,000
Property and equipment:
Property and equipment, gross	2,471,000	2,402,000
Accumulated depreciation	(1,914,000)	(1,776,000)
Property and equipment, net	557,000	626,000
Accrued expenses and other current liabilities:
Research and development	5,808,000	4,625,000
Employee compensation	1,383,000	509,000
Professional fees	329,000	310,000
Taxes	208,000	302,000
Other	67,000	74,000
Total	$ 7,795,000	$ 5,820,000

Warrants (Details) (USD $)	3 Months Ended
Warrants (Details) (USD $)	Mar. 31, 2014	Mar. 31, 2013	Jun. 30, 2009
Warrants
Change in fair value of warrant liability	$ (16,000)	$ (14,000)
Series G Preferred Stock Warrant
Warrants
Number of warrants issued (in shares)			6,128
Ratio of the number of warrants issued for each share of preferred stock purchased			0.50
Change in fair value of warrant liability	$ 16,000	$ 14,000
Warrants outstanding immediately prior to IPO	6,128
Preferred Stock warrants converted into common stock warrants (in shares)	4,597
Common stock warrants, reverse stock split	0.750

Stock-Based Compensation (Details) (USD $)	3 Months Ended
Stock-Based Compensation (Details) (USD $)	Mar. 31, 2014	Mar. 31, 2013
Stock-based compensation
Total stock-based compensation	$ 1,328,000	$ 2,465,000
General and administrative
Stock-based compensation
Total stock-based compensation	647,000	1,307,000
Research and development
Stock-based compensation
Total stock-based compensation	$ 681,000	$ 1,158,000

Stock-Based Compensation (Details 2) (USD $)	3 Months Ended			12 Months Ended	0 Months Ended	3 Months Ended
Stock-Based Compensation (Details 2) (USD $)	Mar. 31, 2014	Mar. 31, 2014 Stock options	Mar. 31, 2013 Stock options	Dec. 31, 2013 Stock options	Apr. 23, 2013 Stock options 2007 Plan	Mar. 31, 2014 Stock options Maximum
Stock-based compensation
Vesting period						4 years
Expiration period						10 years
Number of Options
Balance at the beginning of the period (in shares)		4,344,365
Granted (in shares)		132,500	310,540
Exercised (in shares)		(171,405)
Forfeited (in shares)		(53,289)
Balance at the end of the period (in shares)		4,252,171		4,344,365
Vested or expected to vest at the end of the period (in shares)		4,180,309
Exercisable at the end of the period (in shares)		2,352,446
Weighted-Average Exercise Price
Balance at the beginning of the period (in dollars per share)		$ 11.05
Granted (in dollars per share)		$ 7.63
Exercised (in dollars per share)		$ 4.95
Forfeited (in dollars per share)		$ 11.47
Balance at the end of the period (in dollars per share)		$ 11.19		$ 11.05
Vested or expected to vest at the end of the period (in dollars per share)		$ 11.19
Exercisable at the end of the period (in dollars per share)		$ 9.39
Weighted-Average Remaining Contractual Term
Outstanding		8 years 7 days		7 years 10 months 28 days
Vested or expected to vest at the end of the period		8 years 7 days
Exercisable at the end of the period		7 years
Weighted-average assumptions
Average risk-free interest rates (as a percent)		1.98%
Average expected life (in years)		6 years 3 months
Volatility (as a percent)		78.48%
Weighted-average fair value (in dollars per share)		$ 5.28
Additional disclosures
Annualized forfeiture rate (as a percent)		1.69%
Grant date intrinsic value of awards granted (in dollars per share)		$ 0.00
Unrecognized compensation expense of unvested liability awards	$ 1,559,000
Weighted-average period for recognizing unrecognized compensation expense of unvested liability awards	2 years 3 months 11 days
Unrecognized compensation cost of options granted but not yet vested	11,043,000
Period for recognizing unrecognized compensation cost of options granted but not yet vested	3 years 6 months 7 days
Stock option liability
Balance at the beginning of the period			11,967,000	11,967,000
Change in intrinsic value upon re-measurement			2,465,000
Settlements of option liability awards			(38,000)
Balance at the end of the period		0	14,394,000
Reclassification to stockholders' deficit					$ (14,482,000)

Research Agreements (Details) (USD $)			3 Months Ended	12 Months Ended		3 Months Ended	12 Months Ended
Research Agreements (Details) (USD $)	Mar. 31, 2014	Dec. 31, 2013	Mar. 31, 2014 Temple	Dec. 31, 2012 Temple	Dec. 31, 2011 Temple	Mar. 31, 2014 LLS Rigosertib item	Dec. 31, 2012 LLS Rigosertib	Dec. 31, 2013 LLS Rigosertib	Mar. 31, 2014 LLS Rigosertib Maximum	Dec. 31, 2013 LLS Rigosertib Maximum	Jan. 31, 2013 LLS Rigosertib Maximum	May 31, 2010 LLS Rigosertib Maximum
Research Agreements
Sales generated from products covered by the licensed patents			$ 0
Percentage of sublicensing fees received to be paid by the entity			25.00%
Payments made in connection with the collaboration agreement					1,875,000		1,000,000
Expense in connection with the collaboration agreement				12,500,000
Potential milestone payments											8,000,000	10,000,000
Potential royalties payment as multiplier of amount funded						3
Potential milestone and royalty payment obligation									23,000,000	23,000,000		24,000,000
Deferred revenue, non-current	$ 13,795,000	$ 13,909,000				$ 8,000,000		$ 8,000,000

License and Collaboration Agreements (Details) (USD $)	0 Months Ended	3 Months Ended			1 Months Ended		3 Months Ended		1 Months Ended		0 Months Ended	1 Months Ended							3 Months Ended					1 Months Ended		1 Months Ended
License and Collaboration Agreements (Details) (USD $)	Jul. 30, 2013	Mar. 31, 2014	Mar. 31, 2013	Sep. 30, 2012 Baxter Minimum item	Jul. 31, 2013 Collaboration arrangement Baxter	Sep. 30, 2012 Collaboration arrangement Baxter item	Mar. 31, 2014 Collaboration arrangement Baxter	Mar. 31, 2013 Collaboration arrangement Baxter	Sep. 30, 2012 Collaboration arrangement Rigosertib Baxter item	Sep. 30, 2012 Collaboration arrangement Rigosertib Baxter Maximum	Feb. 01, 2014 Collaboration arrangement Rigosertib Baxter Rigosertib IV in higher risk MDS patients	Sep. 30, 2012 Collaboration arrangement Rigosertib Baxter MDS IV indication	Sep. 30, 2012 Collaboration arrangement Rigosertib Baxter MDS IV indication Minimum	Sep. 30, 2012 Collaboration arrangement Rigosertib Baxter Rigosertib IV in pancreatic cancer patients	Sep. 30, 2012 Collaboration arrangement Rigosertib Baxter Rigosertib IV in pancreatic cancer patients Minimum	Sep. 30, 2012 Collaboration arrangement Rigosertib Baxter Rigosertib oral in lower risk MDS patients	Sep. 30, 2012 Collaboration arrangement Rigosertib Baxter Rigosertib oral in lower risk MDS patients Minimum	Jul. 31, 2011 Collaboration arrangement Rigosertib SymBio	Mar. 31, 2014 Collaboration arrangement Rigosertib SymBio	Mar. 31, 2013 Collaboration arrangement Rigosertib SymBio	Mar. 31, 2014 Collaboration arrangement Rigosertib SymBio Supply agreement	Mar. 31, 2013 Collaboration arrangement Rigosertib SymBio Supply agreement	Jul. 31, 2011 Collaboration arrangement Rigosertib SymBio Supply agreement	Jul. 31, 2011 Collaboration arrangement Rigosertib SymBio United States and Japan	Jul. 31, 2011 Collaboration arrangement Rigosertib SymBio Maximum	Jul. 31, 2011 Collaboration arrangement Rigosertib SymBio MDS IV indication United States	Jul. 31, 2011 Collaboration arrangement Rigosertib SymBio MDS IV indication Japan	Jul. 31, 2011 Collaboration arrangement Rigosertib SymBio Rigosertib oral in lower risk MDS patients United States	Jul. 31, 2011 Collaboration arrangement Rigosertib SymBio Rigosertib oral in lower risk MDS patients Japan	Jul. 31, 2012 Series J Preferred Stock	Jul. 31, 2012 Series J Preferred Stock Collaboration arrangement Baxter
License and collaboration agreements
Consideration received for the Preferred Stock						$ 50,000,000																								$ 50,000,000	$ 50,000,000
Proceeds from IPO	79,811,000				5,000,000
Number of initial rigosertib indications									3
Term of improvement observed											2 years 4 months 24 days
Upfront payment									50,000,000									7,500,000
Aggregate milestone payments										337,500,000															22,000,000
Potential pre-commercial milestone payments for achievement of the primary endpoint of a Phase 3 clinical trial for indication												50,000,000
Potential pre-commercial milestone payments for joint decision to proceed with the development of rigosertib for certain indications														25,000,000		25,000,000
Potential pre-commercial milestone payments for number of EU Countries where marketing approval is to be filed						5
Potential pre-commercial milestone payments for drug approval application filed for specified indications												25,000,000		25,000,000		25,000,000
Potential milestone payments for regulatory approvals of specified indications										212,500,000			100,000,000		100,000,000		100,000,000
Additional potential pre-commercial milestone payments related to the timing of regulatory approval of indication												20,000,000
Aggregate potential milestone payments based on annual net sales of rigosertib									250,000,000									30,000,000
Percentage of royalty payments based on net sales of rigosertib																		20.00%
Number of employees				50,000
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							333,000	978,000
Regulatory milestones payments due upon receipt of marketing approval for indication																										5,000,000	3,000,000	5,000,000	5,000,000
Aggregate milestone payments due upon receipt of marketing approval for an additional indication																								4,000,000
Binding commitments																							0
Recognized revenues		$ 447,000	$ 1,116,000																$ 113,000	$ 113,000	$ 0	$ 25,000

Preclinical Collaboration (Details) (GBO, USD $)	3 Months Ended			12 Months Ended
Preclinical Collaboration (Details) (GBO, USD $)	Mar. 31, 2014 item	Dec. 31, 2013	Dec. 31, 2012 item	Dec. 31, 2013 GVK BIO item	Dec. 31, 2013 GVK BIO Minimum	Dec. 31, 2013 GVK BIO Maximum
Preclinical Collaboration
Number of new programs to be collaborated and developed			2
Initial capital contribution				$ 500,000
Ownership interest in the joint venture (as a percent)		90.00%		10.00%	10.00%	50.00%
Number of products for which additional capital contributions necessary for IND approval				1
Period for which option available to cancel the license and purchase all rights following 15-month anniversary of commencement of program	30 days
Period of anniversary following which option available to cancel the license and purchase all rights for thirty days	15 months
Number of buy-back scenarios	3

Initial Public Offering (Details) (USD $)	0 Months Ended
Initial Public Offering (Details) (USD $)	Jul. 30, 2013	Jul. 17, 2013	Jul. 31, 2013
Initial Public Offering
Preferred stock outstanding (in shares)	0
Net proceeds received from the sale, net of underwriting discounts and commissions and other estimated offering expenses	$ 79,811,000
Reverse stock split of common stock		0.75
Designated public offering amended threshold gross proceeds, minimum			$ 25,000,000

- Definition

The number of securities classified as temporary equity that have been issued and are held by the entity's shareholders. Securities outstanding equals securities issued minus securities held in treasury. Temporary equity is a security with redemption features that are outside the control of the issuer, is not classified as an asset or liability in conformity with GAAP, and is not mandatorily redeemable. Includes any type of security that is redeemable at a fixed or determinable price or on a fixed or determinable date or dates, is redeemable at the option of the holder, or has conditions for redemption which are not solely within the control of the issuer. If convertible, the issuer does not control the actions or events necessary to issue the maximum number of shares that could be required to be delivered under the conversion option if the holder exercises the option to convert the stock to another class of equity. If the security is a warrant or a rights issue, the warrant or rights issue is considered to be temporary equity if the issuer cannot demonstrate that it would be able to deliver upon the exercise of the option by the holder in all cases. Includes stock with put option held by ESOP and stock redeemable by holder only in the event of a change in control of the issuer.

+ References+ Details

Related-Party Transactions (Details) (USD $)	3 Months Ended
Related-Party Transactions (Details) (USD $)	Mar. 31, 2014	Mar. 31, 2013	Dec. 31, 2013	Dec. 31, 2012
Mount Sinai
Related-party transactions
Payments to related party	$ 295,000	$ 27,000
Amounts due to related party	173,000		0
Supplier business owned by board members
Related-party transactions
Payments to related party	0	107,000
Amounts due to related party	0		0
Corporations owned by former board members
Related-party transactions
Payments to related party	32,000	35,000
Amounts due to related party	127,000		157,000
Member of board of directors
Related-party transactions
Payments to related party	47,000	45,000
Amounts due to related party			$ 0	$ 0

- Definition

Amount for accounts payable to related parties.

+ References+ Details

Summary of Significant Accounting Policies (Details)	3 Months Ended
Summary of Significant Accounting Policies (Details)	Mar. 31, 2014 item
Segment Information
Number of operating segments	1