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Document and Entity Information - shares	3 Months Ended
Document and Entity Information - shares	Mar. 31, 2015	Apr. 30, 2015
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, 2015
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		21,703,173
Document Fiscal Year Focus	2015
Document Fiscal Period Focus	Q1

Condensed Consolidated Balance Sheets - USD ($)	Mar. 31, 2015	Dec. 31, 2014
Current assets:
Cash and cash equivalents	$ 33,698,000	$ 43,582,000
Prepaid expenses and other current assets	2,605,000	3,198,000
Restricted cash	50,000	125,000
Total current assets	36,353,000	46,905,000
Property and equipment, net	348,000	420,000
Other non-current assets	12,000	12,000
Total assets	36,713,000	47,337,000
Current liabilities:
Accounts payable	3,857,000	4,027,000
Accrued expenses and other current liabilities	6,452,000	5,777,000
Deferred revenue	455,000	455,000
Total current liabilities	10,764,000	10,259,000
Deferred revenue, non-current	13,341,000	13,455,000
Other		1,000
Total liabilities	24,105,000	23,715,000
Commitments and contingencies
Stockholders' equity:
Preferred stock, $0.01 par value, 5,000,000 authorized at March 31, 2015 and December 31, 2014 none issued and outstanding at March 31, 2015 and December 31, 2014
Common stock, $0.01 par value, 75,000,000 authorized at March 31, 2015 and December 31, 2014, 21,703,173 shares issued and outstanding at March 31, 2015 and December 31, 2014	217,000	217,000
Additional paid in capital	318,505,000	317,122,000
Accumulated other comprehensive income	(43,000)	(13,000)
Accumulated deficit	(306,921,000)	(294,578,000)
Total Onconova Therapeutics, Inc. stockholders' equity	11,758,000	22,748,000
Non-controlling interest	850,000	874,000
Total stockholders' equity	12,608,000	23,622,000
Total liabilities and stockholders' equity	$ 36,713,000	$ 47,337,000

Condensed Consolidated Balance Sheets (Parenthetical) - $ / shares	Mar. 31, 2015	Dec. 31, 2014
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	21,703,173	21,703,173
Common stock, shares outstanding	21,703,173	21,703,173

Condensed Consolidated Statements of Operations - USD ($)	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Condensed Consolidated Statements of Operations
Revenue	$ 114,000	$ 447,000
Operating expenses:
General and administrative	2,965,000	4,932,000
Research and development	9,498,000	14,248,000
Total operating expenses	12,463,000	19,180,000
Loss from operations	(12,349,000)	(18,733,000)
Change in fair value of warrant liability		16,000
Other income (expense), net	(18,000)	1,000
Net loss	(12,367,000)	(18,716,000)
Net loss attributable to non-controlling interest	24,000	37,000
Net loss attributable to Onconova Therapeutics, Inc	$ (12,343,000)	$ (18,679,000)
Net loss per share, basic and diluted (in dollars per shares)	$ (0.57)	$ (0.87)
Basic and diluted weighted average shares outstanding (in shares)	21,703,173	21,568,302

Consolidated Statements of Comprehensive Loss - USD ($)	3 Months Ended
Consolidated Statements of Comprehensive Loss - USD ($)	Mar. 31, 2015	Mar. 31, 2014
Consolidated Statements of Comprehensive Loss
Net loss	$ (12,367,000)	$ (18,716,000)
Other comprehensive income, before tax:
Foreign currency translation adjustments, net	(30,000)	(1,000)
Other comprehensive (loss) income, net of tax	(30,000)	(1,000)
Comprehensive loss	(12,397,000)	(18,717,000)
Comprehensive loss attributable to non-controlling interest	24,000	37,000
Comprehensive loss attributable to Onconova Therapeutics, Inc	$ (12,373,000)	$ (18,680,000)

Consolidated Statement of Stockholders' Equity - 3 months ended Mar. 31, 2015 - USD ($)	Common Stock	Additional Paid in Capital	Accumulated deficit	Accumulated other comprehensive income	Non-controlling interest	Total
Balance at Dec. 31, 2014	$ 217,000	$ 317,122,000	$ (294,578,000)	$ (13,000)	$ 874,000	$ 23,622,000
Balance (in shares) at Dec. 31, 2014	21,703,173
Increase (Decrease) in Stockholders' Equity
Net loss			(12,343,000)		(24,000)	(12,367,000)
Other comprehensive income				(30,000)		(30,000)
Stock-based compensation		1,383,000				1,383,000
Balance at Mar. 31, 2015	$ 217,000	$ 318,505,000	$ (306,921,000)	$ (43,000)	$ 850,000	$ 12,608,000
Balance (in shares) at Mar. 31, 2015	21,703,173

Condensed Consolidated Statements of Cash Flows - USD ($)	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Operating activities:
Net loss	$ (12,367,000)	$ (18,716,000)
Adjustment to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	72,000	141,000
Change in fair value of warrant liabilities		(16,000)
Treasury note discount amortization		(5,000)
Stock compensation expense	1,383,000	1,328,000
Changes in assets and liabilities:
Prepaid expenses and other current assets	593,000	(14,000)
Restricted cash	75,000
Accounts payable	(170,000)	(408,000)
Accrued expenses	675,000	1,975,000
Other liabilities	(1,000)	(3,000)
Deferred revenue	(114,000)	(447,000)
Net cash used in operating activities	(9,854,000)	(16,165,000)
Investing activities:
Payments for purchase of property and equipment		(72,000)
Maturities of marketable securities		10,000,000
Net cash provided by (used in) investing activities		9,928,000
Financing activities:
Proceeds from the exercise of stock options		853,000
Net cash provided by financing activities		853,000
Effect of foreign currency translation on cash	(30,000)	(1,000)
Net decrease in cash and cash equivalents	(9,884,000)	(5,385,000)
Cash and cash equivalents at beginning of period	43,582,000	60,009,000
Cash and cash equivalents at end of period	$ 33,698,000	$ 54,624,000

Nature of Business	3 Months Ended
Nature of Business	Mar. 31, 2015
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 variety of cancers. The Company has three clinical-stage product candidates and several preclinical programs. To accelerate and broaden the development of rigosertib, the Company’s most advanced product candidate, the Company entered into a development and license agreement in 2012 with Baxter Healthcare SA (“BHSA”). In April 2015, Baxter International Inc.(“Baxter”) notified the Company of the assignment of the development and license agreement from Baxter Healthcare SA (“BHSA”) to Baxalta GmbH (“Baxalta”), in preparation for the anticipated spin-off by Baxter International Inc. of Baxalta Incorporated. The Company understands that both BHSA and Baxalta are indirectly wholly-owned subsidiaries of Baxter International Inc.(“Baxter”) and, in connection with the anticipated spin-off and related transactions, Baxalta will become an indirect wholly-owned subsidiary of Baxalta Incorporated. The development and license agreement grants Baxalta an exclusive, royalty-bearing license for the research, development, commercialization and manufacture (in specified instances) of rigosertib in all therapeutic indications in Europe (the “Baxalta Territory”). In 2011, the Company entered into a license agreement, as subsequently amended, with SymBio Pharmaceuticals Limited (“SymBio”), which grants SymBio certain rights 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 new programs using the Company’s technology platform through filing of an investigational new drug application (“IND”) and /or conducting proof of concept studies using the Company’s technology platform. Liquidity The Company has incurred recurring operating losses since inception. For the three months ended March 31, 2015, the Company incurred a net loss of $12,367,000 and as of March 31, 2015, the Company had generated an accumulated deficit of $306,921,000. The Company anticipates operating losses to continue for the foreseeable future due to, among other things, costs related to research, development of its product candidates and its preclinical programs, strategic alliances and its administrative organization. The Company will require substantial additional financing to fund its operations and to continue to execute its strategy. From its inception through July 2013, 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. During 2015, the Company implemented cost-reduction programs to reduce its operating losses. These programs may delay, scale-back, or eliminate certain of the Company’s research and development activities and other aspects of its operations until such time as the Company is successful in securing adequate additional funding. As a result of the cost reduction programs, the Company estimates that its cash and cash equivalents at December 31, 2014 of $43.6 million will be sufficient to fund operations through 2015 and for the first quarter of 2016. The Company is also exploring various dilutive and non-dilutive sources of funding, including equity and debt financings, strategic alliances, business development and other sources. Such financings would be used to fund future research and development programs, including clinical trials for which the Company does not currently have the resources to fund. There can be no assurance, however, that the Company will be successful in obtaining such financing at the level needed to complete its research and development programs, on terms acceptable to the Company, or at all, 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, 2015
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, 2015, the condensed consolidated statements of operations and comprehensive loss for the three months ended March 31, 2015 and 2014, the consolidated statement of stockholders’ equity for the three months ended March 31, 2015 and the condensed consolidated statements of cash flows for the three months ended March 31, 2015 and 2014 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, 2015 and the results of its operations, and its cash flows for the three months ended March 31, 2015 and 2014. The financial data and other information disclosed in these notes related to the three months ended March 31, 2015 and 2014 are unaudited. The results for the three months ended March 31, 2015 are not necessarily indicative of results to be expected for the year ending December 31, 2015, 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, 2014 included in the Company’s annual report on Form 10-K filed with the SEC on March 30, 2015. 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, 2014 included in the Company’s annual report on Form 10-K filed with the SEC on March 30, 2015. Since the date of such financial statements, there have been no changes to the Company’s significant accounting policies. Fair Value Measurements The carrying amounts reported in the accompanying consolidated financial statements for cash and cash equivalents, marketable securities, accounts payable, and accrued liabilities approximate their respective fair values because of the short-term nature of these accounts. There were no significant assets or liabilities requiring adjustment to fair value at March 31, 2015 or December 31, 2014. Recent Accounting Pronouncements In May 2014, the FASB issued guidance on revenue from contracts with customers that will supersede most current revenue recognition guidance. The underlying principle is that an entity will recognize revenue to depict the transfer of goods or services to customers at an amount that the entity expects to be entitled to in exchange for those goods or services. The guidance is effective for the interim and annual periods beginning on or after December 15, 2016, and early adoption is not permitted. The guidance permits the use of either a retrospective or cumulative effect transition method. The Company has not yet selected a transition method and is currently evaluating the impact of the amended guidance on the Company’s consolidated financial position, results of operations and related disclosures. In August 2014, the FASB issued guidance on determining when and how to disclose going-concern uncertainties in the financial statements. The new standard requires management to perform interim and annual assessments of an entity’s ability to continue as a going concern within one year of the date the financial statements are issued. An entity must provide certain disclosures if conditions or events raise substantial doubt about the entity’s ability to continue as a going concern. The guidance applies to all entities and is effective for annual periods ending after December 15, 2016, and interim periods thereafter, with early adoption permitted. The Company is evaluating the potential impact of the new guidance on its quarterly reporting process and its consolidated financial position, results of operations and related disclosures.

Balance Sheet Detail

3 Months Ended

Mar. 31, 2015

Balance Sheet Detail

Balance Sheet Detail

4. Balance Sheet Detail

Prepaid expenses and other current assets:

	March 31,		December 31,
	2015		2014

Research and development	$	1,541,000	$	1,782,000
Manufacturing	416,000		451,000
Insurance	361,000		578,000
Other	287,000		387,000
	$	2,605,000	$	3,198,000

Property and equipment:

	March 31,			December 31,
	2015			2014

Property and equipment	$	2,623,000		$	2,625,000
Accumulated depreciation	(2,275,000		)	(2,205,000		)
	$	348,000		$	420,000

Accrued expenses and other current liabilities:

	March 31,		December 31,
	2015		2014

Research and development	$	4,897,000	$	4,482,000
Employee compensation	1,265,000		854,000
Professional fees	290,000		418,000
Taxes	—		18,000
Other	—		5,000
	$	6,452,000	$	5,777,000

Stock-Based Compensation

3 Months Ended

Mar. 31, 2015

Stock-Based Compensation

Stock-Based Compensation

5. Stock-Based Compensation

In January 2008, the board of directors approved the 2007 Equity Compensation Plan (the “2007 Plan”), which amended, restated and renamed the Company’s 1999 Stock Based Compensation Plan (the “1999 Plan”), which provided for the granting of incentive and nonqualified stock options and restricted stock to its employees, directors and consultants at the discretion of the board of directors.

Further, in July 2013, the Company’s board of directors and stockholders approved, effective immediately prior to the listing of the Common Stock on the NASDAQ Global Select Market, the 2013 Equity Compensation Plan (the “2013 Plan”), which amended, restated and renamed the 2007 Plan . Under the 2013 Plan, the Company may grant incentive stock options, non-statutory stock options, stock appreciation rights, restricted stock, restricted stock units, deferred share awards, performance awards and other equity-based awards to employees, directors and consultants. The Company initially reserved 6,107,831 shares of Common Stock for issuance, subject to adjustment as set forth in the 2013 Plan. At March 31, 2015, there were 1,941,349 shares available for future issuance.

Stock-based compensation expense includes stock options granted to employees and non-employees and has been reported in the Company’s statements of operations and comprehensive loss in either research and development expenses or general and administrative expenses depending on the function performed by the optionee. No net tax benefits related to the stock-based compensation costs have been recognized since the Company’s inception. The Company recognized stock-based compensation expense as follows for the three months ended March 31, 2015and 2014:

	Three months ended March 31,
	2015		2014
General and Administrative	$	760,000	$	647,000
Research and development	623,000		681,000
	$	1,383,000	$	1,328,000

A summary of stock option activity for the three months ended March 31, 2015 is as follows:

	Options Outstanding
	Shares Available for Grant		Number of Shares		Weighted- Average Exercise Price	Weighted- Average Remaining Contractual Term (in years)	Aggregate Intrinsic Value
Balance, December 31, 2014	1,012,310		4,631,299		10.04	7.89	42,923
Authorized	868,126		—
Granted	(121,500	)	121,500		4.52
Exercised	—		—
Forfeited	182,413		(182,413	)	10.41

Balance, March 31, 2015	1,941,349		4,570,386		9.88	7.70	1,000
Vested or expected to vest, March 31, 2015			4,498,624		9.88	7.70	1,000
Exercisable, March 31, 2015			2,837,006		10.33	6.93	1,000

The intrinsic value of options exercised during the three months ended March 31, 2015 and 2014 was $0 and $1,614,000, respectively. The aggregate intrinsic value is calculated as the difference between the exercise price of the underlying awards and the quoted price of the Company’s common stock for those awards that have an exercise price currently below the closing price.

Information with respect to stock options outstanding and exercisable at March 31, 2015 is as follows:

Exercise Price	Shares	Exercisable
$1.33 - $4.52	988,165	208,742
$5.76 - $6.00	574,891	574,891
$6.13 - $7.53	620,188	528,931
$13.28 - $13.48	1,620,176	926,840
$14.68 - $15.12	703,466	555,943
$21.79 - $29.14	63,500	41,659
	4,570,386	2,837,006

Options granted after April 23, 2013

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

The Company uses the Black-Scholes option-pricing model to estimate the fair value of stock options at the grant date. The Black-Scholes model requires the Company to make certain estimates and assumptions, including estimating the fair value of the Company’s common stock, assumptions related to the expected price volatility of the Company’s stock, the period during which the options will be outstanding, the rate of return on risk-free investments and the expected dividend yield for the Company’s stock.

As of March 31, 2015, there was $7,486,000 of unrecognized compensation expense related to the unvested stock options issued from April 24, 2013 through March 31, 2015, which is expected to be recognized over a weighted-average period of approximately 3.14 years.

The weighted-average assumptions underlying the Black-Scholes calculation of grant date fair value include the following:

		Three months ended March 31, 2015
Risk-free interest rate		1.54%
Expected volatility		78.52%
Expected term		6.24 years
Expected dividend yield		0%
Weighted average grant date fair value		$3.11

The weighted-average valuation assumptions were determined as follows:

Risk-free interest rate: The Company based the risk-free interest rate on the interest rate payable on U.S. Treasury securities in effect at the time of grant for a period that is commensurate with the assumed expected option term.

Expected term of options: Due to its lack of sufficient historical data, the Company estimates the expected life of its employee stock options using the “simplified” method, as prescribed in Staff Accounting Bulletin (SAB) No. 107, whereby the expected life equals the arithmetic average of the vesting term and the original contractual term of the option.

Expected stock price volatility: Due to the Company’s limited operating history and a lack of company specific historical and implied volatility data, the Company has based its estimate of expected volatility on the historical volatility of a group of similar companies that are publicly traded. When selecting these public companies on which it has based its expected stock price volatility, the Company selected companies with comparable characteristics to it, including enterprise value, risk profiles, position within the industry, and with historical share price information sufficient to meet the expected life of the stock-based awards. The historical volatility data was computed using the daily closing prices for the selected companies’ shares during the equivalent period of the calculated expected term of the stock-based awards. Due to its lack of sufficient historical data, the Company will continue to apply this process until a sufficient amount of historical information regarding the volatility of its own stock price becomes available.

Expected annual dividend yield: The Company has never paid, and does not expect to pay in the foreseeable future, dividends. Accordingly, the Company assumed an expected dividend yield of 0.0%.

Estimated forfeiture rate: The Company’s estimated annual forfeiture rate on stock option grants was 4.14% in 2015 and 2014 and 1.69% in 2013, based on the historical forfeiture experience.

Options granted through April 23, 2013

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.

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. As of March 31, 2015, there was $570,000 of unrecognized compensation expense related to these unvested awards, which is expected to be recognized over a weighted-average period of approximately 1.61 years.

License and Collaboration Agreements	3 Months Ended
License and Collaboration Agreements	Mar. 31, 2015
License and Collaboration Agreements
License and Collaboration Agreements	7. License and Collaboration Agreements Baxalta Agreement In September 2012, the Company entered into a development and license agreement with Baxter Healthcare SA. In April 2015, Baxter International Inc. notified the Company of the assignment of the development and license agreement from Baxter Healthcare SA (“BHSA”) to Baxalta GmbH (“Baxalta”), in preparation for the anticipated spin-off by Baxter International Inc. of Baxalta Incorporated. The Company understands that both BHSA and Baxalta are indirectly wholly-owned subsidiaries of Baxter International Inc.(“Baxter”) and, in connection with the anticipated spin-off and related transactions, Baxalta will become an indirect wholly-owned subsidiary of Baxalta Incorporated, which will itself become a standalone, publicly traded company traded on the New York Stock Exchange once the spin-off is complete. The development and license agreement grants Baxalta an exclusive, royalty-bearing license for the research, development, commercialization and manufacture (in specified instances) of rigosertib in all therapeutic indications in Europe (the “Baxalta Territory”). In accordance with this agreement, BHSA made a $50,000,000 upfront payment to the Company. In July 2012, BHSA 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. BHSA also invested $4,950,000 in the Company’s IPO. The securities of the Company owned by BHSA have also been transferred to Baxalta as part of the spin-off of Baxalta Incorporated. 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. As a result, at this time the Company is not pursuing a pancreatic cancer indication. 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 in survival of 2.3 months was not sufficient to establish the required level of statistical significance and, therefore did not achieve the primary endpoint of the trial. An additional Phase 3 clinical trial for rigosertib IV in higher-risk MDS patients is required to obtain marketing approval in the Baxalta Territory. The Company could elect to have Baxalta fund fifty percent of the costs of the next phase 3 trial of rigosertib IV in higher-risk MDS, up to $15.0 million. If the Company chooses to do so then the approval milestone for higher-risk MDS will be reduced by $15.0 million. On January 27, 2015, Onconova was notified that BHSA has elected not to pursue additional clinical trials, or the submission of a drug approval application, for rigosertib oral in lower-risk MDS patients. Onconova would have received a milestone payment under its agreement with BHSA if the parties had mutually agreed to progress the development of oral rigosertib in lower-risk MDS patients. The decision by BHSA does not alter the collaboration agreement between the parties. Onconova has the right to continue the development of oral rigosertib in this indication on its own, and Baxalta has the right to commercialize oral rigosertib for lower-risk MDS in its territory, subject to its ongoing compliance with the agreement, including payment of applicable milestones. The Company and Baxalta may work together for potential future rigosertib indications, beyond the initial indications noted above. Generally, if Baxalta chooses to participate in the development of additional indications, Baxalta will be responsible for a percentage of all research and development costs and expenses and the Company could earn additional milestone payments. Baxalta has full responsibility for all commercialization activities for the product in the Baxalta Territory, at Baxalta’s sole cost and expense. The development and license agreement contemplates that the Company and Baxalta may negotiate a supply agreement under terms satisfactory to both parties whereby the Company will supply Baxalta with Baxalta’s required levels of product to support commercialization efforts in the Baxalta Territory. Baxalta also has the right to engage third parties for the manufacture and supply of its requirements for the licensed product. The Company is eligible to receive pre-commercial milestone payments if specified development and regulatory milestones are achieved. The potential pre-commercial development milestone payments to the Company include $25,000,000 for each drug approval application filed for indications specified in the agreement, and up to $100,000,000 for marketing approval for each of the specified MDS indications. 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 Baxalta’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 Baxalta in the Baxalta Territory. The agreement with Baxalta 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 in accordance with the terms of the agreement. Either party may terminate due to the uncured material breach or bankruptcy of the other party, force majeure, or in the event of a specified commercial failure. The Company may terminate the agreement in the event that Baxalta brings a challenge against it in relation to the licensed patents. Baxalta may terminate the agreement without cause upon 180 days’ prior written notice. 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 (the “Symbio Territory”). 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, and $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 the Company is 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. The Company recognized revenues under this agreement of $113,000 and $113,000, for the three months ended March 31, 2015 and 2014, respectively. The Company did not recognize any revenues related to the supply agreement with Symbio during the three months ended March 31, 2015 and 2014.

Summary of Significant Accounting Policies (Policies)	3 Months Ended
Summary of Significant Accounting Policies (Policies)	Mar. 31, 2015
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, 2015, the condensed consolidated statements of operations and comprehensive loss for the three months ended March 31, 2015 and 2014, the consolidated statement of stockholders’ equity for the three months ended March 31, 2015 and the condensed consolidated statements of cash flows for the three months ended March 31, 2015 and 2014 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, 2015 and the results of its operations, and its cash flows for the three months ended March 31, 2015 and 2014. The financial data and other information disclosed in these notes related to the three months ended March 31, 2015 and 2014 are unaudited. The results for the three months ended March 31, 2015 are not necessarily indicative of results to be expected for the year ending December 31, 2015, 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, 2014 included in the Company’s annual report on Form 10-K filed with the SEC on March 30, 2015.
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, 2014 included in the Company’s annual report on Form 10-K filed with the SEC on March 30, 2015. Since the date of such financial statements, there have been no changes to the Company’s significant accounting policies.
Fair Value Measurements	Fair Value Measurements The carrying amounts reported in the accompanying consolidated financial statements for cash and cash equivalents, marketable securities, accounts payable, and accrued liabilities approximate their respective fair values because of the short-term nature of these accounts. There were no significant assets or liabilities requiring adjustment to fair value at March 31, 2015 or December 31, 2014.
Recent Accounting Pronouncements	Recent Accounting Pronouncements In May 2014, the FASB issued guidance on revenue from contracts with customers that will supersede most current revenue recognition guidance. The underlying principle is that an entity will recognize revenue to depict the transfer of goods or services to customers at an amount that the entity expects to be entitled to in exchange for those goods or services. The guidance is effective for the interim and annual periods beginning on or after December 15, 2016, and early adoption is not permitted. The guidance permits the use of either a retrospective or cumulative effect transition method. The Company has not yet selected a transition method and is currently evaluating the impact of the amended guidance on the Company’s consolidated financial position, results of operations and related disclosures. In August 2014, the FASB issued guidance on determining when and how to disclose going-concern uncertainties in the financial statements. The new standard requires management to perform interim and annual assessments of an entity’s ability to continue as a going concern within one year of the date the financial statements are issued. An entity must provide certain disclosures if conditions or events raise substantial doubt about the entity’s ability to continue as a going concern. The guidance applies to all entities and is effective for annual periods ending after December 15, 2016, and interim periods thereafter, with early adoption permitted. The Company is evaluating the potential impact of the new guidance on its quarterly reporting process and its consolidated financial position, results of operations and related disclosures.

Balance Sheet Detail (Tables)

3 Months Ended

Mar. 31, 2015

Balance Sheet Detail

Schedule of prepaid expenses and other current assets

	March 31,		December 31,
	2015		2014

Research and development	$	1,541,000	$	1,782,000
Manufacturing	416,000		451,000
Insurance	361,000		578,000
Other	287,000		387,000
	$	2,605,000	$	3,198,000

Schedule of property and equipment

	March 31,			December 31,
	2015			2014

Property and equipment	$	2,623,000		$	2,625,000
Accumulated depreciation	(2,275,000		)	(2,205,000		)
	$	348,000		$	420,000

Schedule of accrued expenses and other current liabilities

	March 31,		December 31,
	2015		2014

Research and development	$	4,897,000	$	4,482,000
Employee compensation	1,265,000		854,000
Professional fees	290,000		418,000
Taxes	—		18,000
Other	—		5,000
	$	6,452,000	$	5,777,000

Stock-Based Compensation (Tables)

3 Months Ended

Mar. 31, 2015

Stock-Based Compensation

Schedule of stock-based compensation expense

	Three months ended March 31,
	2015		2014
General and Administrative	$	760,000	$	647,000
Research and development	623,000		681,000
	$	1,383,000	$	1,328,000

Schedule of stock option activity

	Options Outstanding
	Shares Available for Grant		Number of Shares		Weighted- Average Exercise Price	Weighted- Average Remaining Contractual Term (in years)	Aggregate Intrinsic Value
Balance, December 31, 2014	1,012,310		4,631,299		10.04	7.89	42,923
Authorized	868,126		—
Granted	(121,500	)	121,500		4.52
Exercised	—		—
Forfeited	182,413		(182,413	)	10.41

Balance, March 31, 2015	1,941,349		4,570,386		9.88	7.70	1,000
Vested or expected to vest, March 31, 2015			4,498,624		9.88	7.70	1,000
Exercisable, March 31, 2015			2,837,006		10.33	6.93	1,000

Schedule of information with respect to stock options outstanding and exercisable

Information with respect to stock options outstanding and exercisable at March 31, 2015 is as follows:

Exercise Price	Shares	Exercisable
$1.33 - $4.52	988,165	208,742
$5.76 - $6.00	574,891	574,891
$6.13 - $7.53	620,188	528,931
$13.28 - $13.48	1,620,176	926,840
$14.68 - $15.12	703,466	555,943
$21.79 - $29.14	63,500	41,659
	4,570,386	2,837,006

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

		Three months ended March 31, 2015
Risk-free interest rate		1.54%
Expected volatility		78.52%
Expected term		6.24 years
Expected dividend yield		0%
Weighted average grant date fair value		$3.11

Nature of Business (Details 2) - USD ($)	Jul. 30, 2013	Mar. 31, 2015	Dec. 31, 2014
Initial Public Offering
Common stock, par value (in dollars per share)		$ 0.01	$ 0.01
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
Proceeds from initial public offering of common stock, net of issuance costs	$ 79,811,000
Over-allotment option
Initial Public Offering
Number of shares issued in initial public offering	775,000

Balance Sheet Detail (Details) - USD ($)	Mar. 31, 2015	Dec. 31, 2014
Prepaid expenses and other current assets:
Research and development	$ 1,541,000	$ 1,782,000
Manufacturing	416,000	451,000
Insurance	361,000	578,000
Other	287,000	387,000
Total	2,605,000	3,198,000
Property and equipment:
Property and equipment	2,623,000	2,625,000
Accumulated depreciation	(2,275,000)	(2,205,000)
Property and equipment, net	348,000	420,000
Accrued expenses
Research and development	4,897,000	4,482,000
Employee compensation	1,265,000	854,000
Professional fees	290,000	418,000
Taxes		18,000
Other		5,000
Total	$ 6,452,000	$ 5,777,000

Stock-Based Compensation (Details) - USD ($)	3 Months Ended		12 Months Ended
Stock-Based Compensation (Details) - USD ($)	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2014	Jul. 31, 2013
Stock-based compensation
Total stock-based compensation	$ 1,383,000	$ 1,328,000
Additional disclosures
Net tax benefits related to the stock-based compensation costs	$ 0
Stock options
Shares available for grant
Balance at the beginning of period (in shares)	1,012,310
Authorized (in shares)	868,126
Granted (in shares)	(121,500)
Forfeited (in shares)	182,413
Balance at the end of the period (in shares)	1,941,349		1,012,310
Number of Shares
Balance at the beginning of the period (in shares)	4,631,299
Granted (in shares)	121,500
Forfeited (in shares)	(182,413)
Balance at the end of the period (in shares)	4,570,386		4,631,299
Vested or expected to vest at the end of the period (in shares)	4,498,624
Exercisable at the end of the period (in shares)	2,837,006
Weighted-Average Exercise Price
Balance at the beginning of the period (in dollars per share)	$ 10.04
Granted (in dollars per share)	4.52
Forfeited (in dollars per share)	10.41
Balance at the end of the period (in dollars per share)	9.88		$ 10.04
Vested or expected to vest at the end of the period (in dollars per share)	9.88
Exercisable at the end of the period (in dollars per share)	$ 10.33
Weighted-Average Remaining Contractual Term
SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2	7 years 8 months 12 days		7 years 10 months 21 days
SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2	7 years 8 months 12 days		7 years 10 months 21 days
Vested or expected to vest at the end of the period	7 years 8 months 12 days
Exercisable at the end of the period	6 years 11 months 5 days
Additional disclosures
Aggregate intrinsic value of options outstanding	$ 1,000		$ 42,923
Aggregate intrinsic value of vested options	1,000
Aggregate intrinsic value of options Exercisable	1,000
Intrinsic value of options exercised	$ 0	1,614,000
Stock options \| 2013 Plan
Shares available for grant
Authorized (in shares)				6,107,831
Balance at the end of the period (in shares)	1,941,349
General and administrative
Stock-based compensation
Total stock-based compensation	$ 760,000	647,000
Research and development
Stock-based compensation
Total stock-based compensation	$ 623,000	$ 681,000

Stock-Based Compensation (Details 2) - Stock options	3 Months Ended
Stock-Based Compensation (Details 2) - Stock options	Mar. 31, 2015 $ / shares shares
Stock-Based Compensation
Shares	4,570,386
Number (in shares)	2,837,006
Exercise Price Range $1.33 - $4.52
Stock-Based Compensation
Exercise price, lower range limit (in dollars per share) \| $ / shares	$ 1.33
Exercise price, upper range limit (in dollars per share) \| $ / shares	$ 4.52
Shares	988,165
Number (in shares)	208,742
Exercise Price Range $5.76 - $6.00
Stock-Based Compensation
Exercise price, lower range limit (in dollars per share) \| $ / shares	$ 5.76
Exercise price, upper range limit (in dollars per share) \| $ / shares	$ 6.00
Shares	574,891
Number (in shares)	574,891
Exercise Price Range $6.13 - $7.53
Stock-Based Compensation
Exercise price, lower range limit (in dollars per share) \| $ / shares	$ 6.13
Exercise price, upper range limit (in dollars per share) \| $ / shares	$ 7.53
Shares	620,188
Number (in shares)	528,931
Exercise Price Range $13.28 - $13.48
Stock-Based Compensation
Exercise price, lower range limit (in dollars per share) \| $ / shares	$ 13.28
Exercise price, upper range limit (in dollars per share) \| $ / shares	$ 13.48
Shares	1,620,176
Number (in shares)	926,840
Exercise Price Range $14.86 - $15.12
Stock-Based Compensation
Exercise price, lower range limit (in dollars per share) \| $ / shares	$ 14.68
Exercise price, upper range limit (in dollars per share) \| $ / shares	$ 15.12
Shares	703,466
Number (in shares)	555,943
Exercise Price Range $21.79 - $29.14
Stock-Based Compensation
Exercise price, lower range limit (in dollars per share) \| $ / shares	$ 21.79
Exercise price, upper range limit (in dollars per share) \| $ / shares	$ 29.14
Shares	63,500
Number (in shares)	41,659

Stock-Based Compensation (Details 3) - USD ($)		3 Months Ended	12 Months Ended
Stock-Based Compensation (Details 3) - USD ($)	Apr. 23, 2013	Mar. 31, 2015	Dec. 31, 2014
Additional disclosures
Share Based Compensation Arrangement by Share Based Payment Award Reclassification to Stockholders Deficit	$ 14,482,000
Unrecognized compensation expense of unvested liability awards		$ 570,000
Unrecognized compensation cost of options granted but not yet vested		$ 7,486,000
Weighted-average period for recognizing unrecognized compensation expense of unvested liability awards		1 year 7 months 10 days
Weighted-average period for recognizing unrecognized compensation expense related to unvested stock options		3 years 1 month 21 days
Stock options
Assumptions used to determine fair values for nonemployee options
Risk-free interest rates (as a percent)		1.54%
Expected volatility (as a percent)		78.52%
Expected term		6 years 2 months 27 days
Expected dividend yield (as a percent)		0.00%
Weighted-average grant fair value (in dollars per share)		$ 3.11
Additional disclosures
Annualized forfeiture rate (as a percent)		4.14%	1.69%

License and Collaboration Agreements (Details)	1 Months Ended					3 Months Ended
License and Collaboration Agreements (Details)	Feb. 28, 2014 USD ($)	Jul. 31, 2013 USD ($)	Sep. 30, 2012 USD ($) item	Jul. 31, 2012 USD ($)	Jul. 31, 2011 USD ($)	Mar. 31, 2015 USD ($)	Mar. 31, 2014 USD ($)
License and collaboration agreements
Recognized revenues						$ 114,000	$ 447,000
Collaboration arrangement \| Baxalta
License and collaboration agreements
Net proceeds received from the sale, net of underwriting discounts and commissions and other estimated offering expenses		$ 4,950,000
Written notice period to terminate the agreement			180 days
Collaboration arrangement \| Rigosertib \| Rigosertib IV in higher risk MDS patients
License and collaboration agreements
Funding percentage to the entity	50.00%
Collaboration arrangement \| Rigosertib \| Baxalta
License and collaboration agreements
Number of initial rigosertib indications \| item			3
Upfront payment			$ 50,000,000
Potential pre-commercial payments that could be received for each drug approval application filed for indications specified in the agreement			25,000,000
Potential pre-commercial payments that could be received for marketing approval for each of the specified MDS indications			100,000,000
Aggregate potential milestone payments based on annual net sales of rigosertib			$ 250,000,000
Collaboration arrangement \| Rigosertib \| Baxalta \| Rigosertib IV in higher risk MDS patients
License and collaboration agreements
Term of improvement observed	2 years 3 months 18 days
Cost funded to the entity	$ 15,000,000
Reduction in milestone payment	$ 15,000,000
Collaboration arrangement \| Rigosertib \| SymBio
License and collaboration agreements
Upfront payment					$ 7,500,000
Aggregate milestone payments					22,000,000
Aggregate potential milestone payments based on annual net sales of rigosertib					$ 30,000,000
Percentage of royalty payments based on net sales of rigosertib					20.00%
Recognized revenues						113,000	113,000
Collaboration arrangement \| Rigosertib \| SymBio \| Supply agreement
License and collaboration agreements
Binding commitments					$ 0
Recognized revenues						$ 0	$ 0
Collaboration arrangement \| Rigosertib \| SymBio \| United States and Japan
License and collaboration agreements
Aggregate milestone payments due upon receipt of marketing approval for an additional indication					4,000,000
Collaboration arrangement \| Rigosertib \| SymBio \| MDS IV indication \| United States
License and collaboration agreements
Regulatory milestones payments due upon receipt of marketing approval for indication					5,000,000
Collaboration arrangement \| Rigosertib \| SymBio \| MDS IV indication \| Japan
License and collaboration agreements
Regulatory milestones payments due upon receipt of marketing approval for indication					3,000,000
Collaboration arrangement \| Rigosertib \| SymBio \| Rigosertib oral in lower risk MDS patients \| United States
License and collaboration agreements
Regulatory milestones payments due upon receipt of marketing approval for indication					5,000,000
Collaboration arrangement \| Rigosertib \| SymBio \| Rigosertib oral in lower risk MDS patients \| Japan
License and collaboration agreements
Regulatory milestones payments due upon receipt of marketing approval for indication					$ 5,000,000
Series J Preferred Stock \| Collaboration arrangement \| Baxalta
License and collaboration agreements
Consideration received for the Preferred Stock				$ 50,000,000

Research Agreements	3 Months Ended
Research Agreements	Mar. 31, 2015
Research Agreements
Research Agreements	6. 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, 2015 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 (the “LLS-funded Research Program”). Under the LLS-funded Research Program, 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. During the year ended December 31, 2012, in connection with the execution of the Baxter agreement, 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, 2015 and December 31, 2014. No further payments are due to LLS if the LLS-funded Research Program does not lead to regulatory approval of rigosertib. If the LLS-funded Research Program leads to approval of rigosertib by the regulatory authorities, the Company must proceed with commercialization of the licensed product or repay the amount funded. 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. 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, 2015 and December 31, 2014.

Preclinical Collaboration	3 Months Ended
Preclinical Collaboration	Mar. 31, 2015
Preclinical Collaboration
Preclinical Collaboration	8. Preclinical Collaboration In December 2012, the Company agreed to form GBO, an entity owned by the Company 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. During November 2014, GVK BIO made an additional capital contribution of $500,000 which increased its interest in GBO to 17.5%. 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. In addition, upon the occurrence of certain events, namely termination of the Company’s participation in the programs either with or without a change in control, GVK BIO will be entitled to purchase or obtain the Company’s interest in GBO. GVK BIO will have operational control of GBO and the Company will have strategic and scientific control.

Related-Party Transactions	3 Months Ended
Related-Party Transactions	Mar. 31, 2015
Related-Party Transactions
Related-Party Transactions	9. 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, 2015 and 2014 were $357,000 and $295,000, respectively. At March 31, 2015 and December 31, 2014, the Company owed Mount Sinai $1,000 and $0, respectively, which is included in accounts payable on the consolidated balance sheets. 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, 2015 and 2014 were $0 and $32,000, respectively. At March 31, 2015 and December 31, 2014, the Company owed this supplier $8,000 and $8,000, respectively, which is included in accounts payable on the consolidated balance sheets. While the Company has consolidated its operations to its Newtown, Pennsylvania headquarters, the Company previously occupied office space in Pennington, New Jersey pursuant to a lease which runs through May 2015, from a corporation related to these suppliers and affiliated with the former member of its 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, 2015 and 2014 were $49,000 and $47,000 respectively. At March 31, 2015 and December 31, 2014, the Company had no outstanding amounts payable under this agreement.

Securities Registration and Sales Agreement)	3 Months Ended
Securities Registration and Sales Agreement)	Mar. 31, 2015
Securities registration and sales agreement
Securities Registration and Sales Agreement	10. Securities Registration and Sales Agreement In October 2014, the Company entered into a sales agreement (the “Sales Agreement”) with Cantor Fitzgerald & Co. (“Cantor”) to create an at-the-market equity program under which the Company from time to time may offer and sell shares of its Common Stock, having an aggregate offering price of up to $20,000,000 through Cantor. Upon delivery of a placement notice and subject to the terms and conditions of the sales agreement, Cantor will use its commercially reasonable efforts to sell the shares from time to time, based upon the Company’s instructions. The Company has provided Cantor with customary indemnification rights, and Cantor will be entitled to a commission of up to 3.0% of the gross proceeds per share sold. Sales of shares, if any, under the sales agreement may be made in transactions that are deemed to be “at the market offerings” as defined in Rule 415 under the Securities Act of 1933, as amended, including sales made by means of ordinary brokers’ transactions, including on The NASDAQ Global Select Market, at market prices or as otherwise agreed with Cantor. The Company has no obligation to sell any shares under the Sales Agreement, and may at any time suspend offers under the Sales Agreement or terminate the Sales Agreement. A registration statement (Form S-3 No. 333-199219), relating to the shares, which was filed with the SEC became effective on November 20, 2014. No shares had been sold under the Sales Agreement as of March 31, 2015. Based on the Company’s share price at March 31, 2015, the Company would have been limited to issuing shares having an aggregate offering price of up to $10,200,000, due to limitations based on the Company’s public float. This report shall not constitute an offer to sell or the solicitation of an offer to buy nor shall there be any sale of the shares in any state in which such offer, solicitation or sale would be unlawful prior to registration or qualification under the securities laws of any such state.

Summary of Significant Accounting Policies (Details)	3 Months Ended
Summary of Significant Accounting Policies (Details)	Mar. 31, 2015 segment
Segment Information
Number of operating segments	1

Nature of Business (Details)	3 Months Ended
Nature of Business (Details)	Mar. 31, 2015 USD ($) class item $ / shares	Mar. 31, 2014 USD ($)	Dec. 31, 2014 USD ($)
Nature of Business
Number of clinical-stage product candidates \| item	3
Net loss	$ (12,367,000)	$ (18,716,000)
Accumulated deficit	$ (306,921,000)		$ (294,578,000)
Preferred stock, par value per share (in dollars per share) \| $ / shares	$ 0.01
Number of series denominated as Series A through Series J preferred stock \| class	10

Net Loss Per Share of Common Stock (Details) - shares	3 Months Ended
Net Loss Per Share of Common Stock (Details) - shares	Mar. 31, 2015	Mar. 31, 2014
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	4,574,983	4,256,768
Warrant
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	4,570,386	4,252,171

Research Agreements (Details) - USD ($)	3 Months Ended	12 Months Ended
Research Agreements (Details) - USD ($)	Mar. 31, 2015	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2014	May 31, 2010	Jan. 31, 2003
Research Agreements
Deferred revenue, non-current	$ 13,341,000			$ 13,455,000
Temple
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
Expense in connection with the collaboration agreement		$ 12,500,000
LLS \| Rigosertib
Research Agreements
Payments made in connection with the collaboration agreement		$ 1,000,000
Potential milestone payments					$ 10,000,000	$ 8,000,000
Potential milestone and royalty payment obligation	$ 23,000,000			23,000,000
Deferred revenue, non-current				$ 8,000,000

Preclinical Collaboration (Details)	1 Months Ended	3 Months Ended	12 Months Ended
Preclinical Collaboration (Details)	Nov. 30, 2014 USD ($)	Mar. 31, 2015 item	Dec. 31, 2013 USD ($) Program
GVK BIO
Preclinical Collaboration
Ownership interest in the joint venture (as a percent)	17.50%
Additional capital contributions	$ 500,000
GBO
Preclinical Collaboration
Number of new programs to be collaborated and developed \| Program			2
Ownership interest in the joint venture (as a percent)			90.00%
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 \| item		3
GBO \| GVK BIO
Preclinical Collaboration
Initial capital contribution			$ 500,000
Ownership interest in the joint venture (as a percent)			10.00%
GBO \| GVK BIO \| Minimum
Preclinical Collaboration
Ownership interest in the joint venture (as a percent)			10.00%
GBO \| GVK BIO \| Maximum
Preclinical Collaboration
Ownership interest in the joint venture (as a percent)			50.00%

Related-Party Transactions (Details) - USD ($)	3 Months Ended
Related-Party Transactions (Details) - USD ($)	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2014
Mount Sinai
Related-party transactions
Payments to related party	$ 357,000	$ 295,000
Amounts due to related party	1,000		$ 0
Corporations owned by former board members
Related-party transactions
Payments to related party	0	32,000
Amounts due to related party	8,000		8,000
Member of board of directors
Related-party transactions
Payments to related party	49,000	$ 47,000
Amounts due to related party	$ 0		$ 0

Securities Registration and Sales Agreement (Details) - USD ($)	1 Months Ended	3 Months Ended
	Oct. 31, 2014	Mar. 31, 2015	Dec. 31, 2014
Securities Registration and Sales Agreement
Common stock issued (in shares)		21,703,173	21,703,173
Securities registration October 2014
Securities Registration and Sales Agreement
At-the-market equity program, aggregate offering price	$ 20,000,000	$ 10,200,000
At-the-market equity program, commission percentage	3.00%
Common stock issued (in shares)	0	0