Traws Pharma (TRAW) 10-K 1 Apr 19 2018 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Mar. 01, 2019	Jun. 30, 2018
Document and Entity Information
Entity Registrant Name	Onconova Therapeutics, Inc.
Entity Central Index Key	0001130598
Document Type	10-K
Document Period End Date	Dec. 31, 2018
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Public Float			$ 32.7
Entity Common Stock, Shares Outstanding		5,895,004
Document Fiscal Year Focus	2018
Document Fiscal Period Focus	FY

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Current assets:
Cash and cash equivalents	$ 16,970	$ 4,024
Receivables	35	59
Prepaid expenses and other current assets	760	820
Total current assets	17,765	4,903
Property and equipment, net	9	64
Other non-current assets	149	12
Total assets	17,923	4,979
Current liabilities:
Accounts payable	4,039	6,186
Accrued expenses and other current liabilities	4,173	3,335
Deferred revenue	226	455
Total current liabilities	8,438	9,976
Warrant liability	176	1,773
Deferred revenue, non-current	3,922	4,091
Total liabilities	12,536	15,840
Commitments and contingencies
Stockholders' equity (deficit):
Preferred stock, $0.01 par value, 5,000,000 authorized at December 31, 2018 and 2017, none issued and outstanding at December 31, 2018 and 2017
Common stock, $0.01 par value, 250,000,000 and 25,000,000 authorized at December 31, 2018 and 2017, 5,674,220 and 718,078 shares issued and outstanding at December 31, 2018 and 2017	57	8
Additional paid in capital	387,238	350,614
Accumulated other comprehensive (loss) income	(12)	3
Accumulated deficit	(381,896)	(362,316)
Total Onconova Therapeutics, Inc. stockholders' equity (deficit)	5,387	(11,691)
Non-controlling interest		830
Total stockholders' equity (deficit)	5,387	(10,861)
Total liabilities and stockholders' equity (deficit)	$ 17,923	$ 4,979

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2018	Dec. 31, 2017
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	250,000,000	25,000,000
Common stock, shares issued	5,674,220	718,078
Common stock, shares outstanding	5,674,220	718,078

Consolidated Statements of Oper

Consolidated Statements of Operations - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Consolidated Statements of Operations
Revenue	$ 1,228	$ 787
Operating expenses:
General and administrative	7,586	7,405
Research and development	16,924	19,119
Total operating expenses	24,510	26,524
Loss from operations	(23,282)	(25,737)
Change in fair value of warrant liability	(1,597)	(1,628)
Other income, net	1,151	30
Net (loss) before income taxes	(20,534)	(24,079)
Income tax (benefit) expense	(124)	13
Net loss	(20,410)	(24,092)
Net gain attributable to non-controlling interest	(163)
Net loss attributable to Onconova Therapeutics, Inc.	$ (20,573)	$ (24,092)
Net loss per share of common stock, basic and diluted (in dollars per share)	$ (4.99)	$ (40.15)
Basic and diluted weighted average shares outstanding (in shares)	4,124,073	600,022

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Loss - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Consolidated Statements of Comprehensive Loss
Net loss	$ (20,410)	$ (24,092)
Other comprehensive income (loss), before tax
Foreign currency translation adjustments, net	(15)	34
Other comprehensive (loss) income , net of tax	(15)	34
Comprehensive loss	(20,425)	(24,058)
Comprehensive income attributable to non-controlling interest	(163)
Comprehensive loss attributable to Onconova Therapeutics, Inc	$ (20,588)	$ (24,058)

Consolidated Statements of Stoc

Consolidated Statements of Stockholders' Equity (Deficit) - USD ($) $ in Thousands	Common Stock	Additional Paid in Capital	Accumulated deficit	Accumulated other comprehensive income (loss)	Non-controlling interest	Total
Balance at Dec. 31, 2016	$ 5	$ 342,547	$ (338,224)	$ (31)	$ 830	$ 5,127
Balance (in shares) at Dec. 31, 2016	450,660
Increase (Decrease) in Stockholders' Equity (Deficit)
Net loss			(24,092)			(24,092)
Other comprehensive income (loss)				34		34
Stock-based compensation		1,710				1,710
Issuance of common stock, net	$ 3	6,357				6,360
Issuance of common stock, net (in shares)	267,418
Balance at Dec. 31, 2017	$ 8	350,614	(362,316)	3	830	$ (10,861)
Balance (in shares) at Dec. 31, 2017	718,078					718,078
Increase (Decrease) in Stockholders' Equity (Deficit)
Net loss			(20,573)		163	$ (20,410)
Other comprehensive income (loss)				(15)		(15)
Stock-based compensation		1,147				1,147
Dissolution of GBO			993		$ (993)
Shares issued in connection with reverse stock split (in shares)	101
Issuance of common stock and pre-funded warrants, net	$ 42	34,895				34,937
Issuance of common stock and pre-funded warrants, net (in shares)	4,215,581
Issuance of common stock upon exercise of warrants	$ 7	582				589
Issuance of common stock upon exercise of warrants (in shares)	740,460
Balance at Dec. 31, 2018	$ 57	$ 387,238	$ (381,896)	$ (12)		$ 5,387
Balance (in shares) at Dec. 31, 2018	5,674,220					5,674,220

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Operating activities:
Net loss	$ (20,410)	$ (24,092)
Adjustment to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	55	88
Change in fair value of warrant liabilities	(1,597)	(1,628)
Stock compensation expense	1,147	1,710
Gain on dissolution of GBO and other	(824)
Changes in assets and liabilities:
Receivables	24	(28)
Prepaid expenses and other current assets	60	768
Other assets	(137)
Accounts payable	(1,454)	863
Accrued expenses and other current liabilities	838	(1,047)
Deferred revenue	(398)	(454)
Net cash used in operating activities	(22,696)	(23,820)
Financing activities:
Proceeds from the sale of common stock and warrants, net of costs	35,068	6,360
Proceeds from the exercise of stock options	589
Net cash provided by financing activities	35,657	6,360
Effect of foreign currency translation on cash	(15)	34
Net increase (decrease) in cash and cash equivalents	12,946	(17,426)
Cash and cash equivalents at beginning of period	4,024	21,450
Cash and cash equivalents at end of period	$ 16,970	$ 4,024

Nature of Business

Nature of Business	12 Months Ended
	Dec. 31, 2018
Nature of Business
Nature of Business	1. Nature of Business Reverse Stock Split All common stock, equity, share and per share amounts in the financial statements and notes have been retroactively adjusted to reflect a one-for-fifteen reverse stock split which was effective September 25, 2018. 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 product candidates primarily 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 product 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. 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. On March 2, 2018, the Company entered into a License, Development and Commercialization Agreement with Pint International SA (which, together with its affiliate Pint Pharma GmbH, are collectively referred to as “Pint”). Under the terms of the agreement, the Company granted Pint an exclusive, royalty-bearing license, with the right to sublicense, under certain Company patent rights and know-how to develop and commercialize any pharmaceutical product containing rigosertib in all uses of rigosertib in certain Latin America countries. In 2012, the Company entered into a development and license agreement with Baxter Healthcare SA, the predecessor in interest to Baxalta GmbH (together with its affiliates, “Baxalta”), pursuant to which the Company granted 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 agreement terminated effective August 30, 2016, at which time the rights the Company licensed to Baxalta reverted to the Company at no cost. 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 December 2017, the Company entered into a license and collaboration agreement with HanX Biopharmaceuticals, Inc. (“HanX”), a company focused on development of novel oncology products, for the further development, registration and commercialization of ON 123300 in Greater China. ON 123300 is a preclinical compound which the Company believes has the potential to overcome the limitations of current generation CDK 4/6 inhibitors. The key feature of the collaboration is that HanX will provide all funding required for future Chinese IND enabling studies necessary for filing an IND with the Chinese Food and Drug Administration. The studies would be conducted to meet the Good Laboratory Practice (“GLP”) requirements of the FDA such that the Company could simultaneously file an IND with the US FDA. The Company and HanX will oversee the IND enabling studies. The Company will maintain global rights to ON 123300 outside of China. In April 2013, GBO, LLC, a Delaware limited liability company, (“GBO”) was formed pursuant to an agreement with GVK Biosciences Private Limited, a private limited company located in India, (“GVK”) to collaborate and develop two programs using the Company’s technology platform. The two preclinical programs sublicensed to GBO were not developed to clinical stage as initially hoped, and GBO was dissolved in June 2018. On March 21, 2018, the Company amended its certificate of incorporation to increase the number of authorized shares of common stock par value $0.01 per share from 25,000,000 to 100,000,000. On June 7, 2018, the Company amended its certificate of incorporation again to increase the number of authorized shares of common stock, par value $0.01 per share, from 100,000,000 to 250,000,000. On September 25, 2018, the Company amended its certificate of incorporation to effect a one-for-fifteen reverse stock split of its common stock. Liquidity The Company has incurred recurring operating losses since inception. For the year ended December 31, 2018, the Company incurred a net loss of $20,410,000 and as of December 31, 2018 the Company had generated an accumulated deficit of $381,896,000. 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. At December 31, 2018, the Company had cash and cash equivalents of $16,970,000. The Company will require substantial additional financing to fund its ongoing clinical trials and operations, and to continue to execute its strategy. These conditions raise substantial doubt about the Company’s ability to continue as a going concern within one year after the date that the financial statements are issued. From its inception through July 2013, the Company raised capital through the private issuance of preferred stock. On July 30, 2013, the Company completed its initial public offering (the “IPO”) of 39,611 shares of Common Stock, at a price of $2,250.00 per share. 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. From the IPO through December 31, 2016, the Company closed on several offerings which included Common Stock and warrants. Total net proceeds from these offerings was approximately $24.9 million. On April 26, 2017 the Company closed on an underwritten public offering of 165,079 shares of Common Stock. On May 17, 2017, the Company sold an additional 24,239 shares as a result of the underwriter’s exercise of its over-allotment option. Net proceeds from these transactions were approximately $5.3 million. (See Note 17) On November 14, 2017 the Company closed on a registered direct offering to select accredited investors of 61,333 shares of common stock. Net proceeds were approximately $1.1 million. (See Note 17) On February 12, 2018 the Company closed on an offering of units of common stock and warrants. The Company issued 467,000 shares of common stock, pre-funded warrants to purchase 196,167 shares of common stock, and preferred stock warrants to purchase shares of Series A convertible preferred stock convertible into 696,325 shares of common stock. Net proceeds were approximately $8.7 million. (See Note 17) On May 1, 2018 the Company closed on an offering of units of common stock and warrants. The Company issued 3,694,118 shares of common stock, pre-funded warrants to purchase 815,686 shares of common stock, and preferred stock warrants to purchase shares of Series B convertible preferred stock convertible into 4,509,804 shares of common stock. Net proceeds were approximately $25.6 million. (See Note 17) The Company has and may continue to delay, scale-back, or eliminate certain of its research and development activities and other aspects of its operations until such time as the Company is successful in securing additional funding. The Company is exploring various dilutive and non-dilutive sources of funding, including equity financings, strategic alliances, business development and other sources. The future success of the Company is dependent upon its ability to obtain additional funding. There can be no assurance, however, that the Company will be successful in obtaining such funding in sufficient amounts, on terms acceptable to the Company, or at all. The Company currently anticipates that current cash and cash equivalents will be sufficient to meet its anticipated cash requirements into the fourth quarter of 2019. Accordingly, management has concluded that substantial doubt exists with respect to the Company’s ability to continue as a going concern within one year after the date that these financial statements are issued.

Summary of Significant Accounti

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2018
Summary of Significant Accounting Policies
Summary of Significant Accounting Policies	2. Summary of Significant Accounting Policies Basis of Presentation The consolidated financial statements are prepared in conformity with accounting principles generally accepted in the United States (“GAAP”). The financial statements include the consolidated accounts of the Company, its wholly‑owned subsidiary, Onconova Europe GmbH, and GBO, which was dissolved in June 2018. All significant intercompany transactions have been eliminated. Certain prior year amounts have been reclassified to conform to current period presentation. All common stock, equity, share and per share amounts in the financial statements and notes have been retroactively adjusted to reflect a one-for-fifteen reverse stock split which was effective September 25, 2018. 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. Use of Estimates The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets, liabilities, revenues, expenses, other comprehensive income and related disclosures. On an ongoing basis, management evaluates its estimates, including estimates related to clinical trial accruals, warrant liability, and allocation of consideration for revenue recognition. The Company bases its estimates on historical experience and other market‑specific or other relevant assumptions that it believes to be reasonable under the circumstances. Actual results may differ from those estimates or assumptions. Concentrations of Credit Risk and Off‑Balance Sheet Risk Financial instruments that potentially subject the Company to concentrations of credit risk are primarily cash and cash equivalents. The Company maintains a portion of its cash and cash equivalent balances in the form of money market accounts with financial institutions that management believes are creditworthy. The Company has no financial instruments with off‑balance sheet risk of loss. Cash and Cash Equivalents The Company considers all highly liquid investments with original or remaining maturity from the date of purchase of three months or less to be cash equivalents. Cash and cash equivalents include bank demand deposits, marketable securities with maturities of three months or less at purchase, and money market funds that invest primarily in certificates of deposit, commercial paper and U.S. government and U.S. government agency obligations. Cash equivalents are reported at fair value. Fair Value of Financial Instruments The carrying amounts reported in the accompanying consolidated financial statements for cash and cash equivalents, accounts payable, and accrued liabilities approximate their respective fair values because of the short‑term nature of these accounts. The fair value of the warrant liability is discussed in Note 8, "Fair Value Measurements." Property and Equipment Property and equipment are stated at cost, less accumulated depreciation. Property and equipment are depreciated using the straight-line method over the estimated useful lives of the assets. Leasehold improvements are amortized over the useful life of the asset or the lease term, whichever is shorter. Maintenance and repairs are expensed as incurred. The following estimated useful lives were used to depreciate the Company's assets: Estimated Useful Life Lab equipment 5 - 6 years Software 3 years Computer and office equipment 5 - 6 years Leasehold improvements Shorter of the lease term or estimated useful life Upon retirement or sale, the cost of the disposed asset and the related accumulated depreciation are removed from the accounts and any resulting gain or loss is recognized. The Company reviews long‑lived assets for impairment when events or changes in circumstances indicate that the carrying value of the assets may not be recoverable. Recoverability is measured by comparison of the assets’ book value to future net undiscounted cash flows that the assets are expected to generate. If such assets are considered to be impaired, the impairment to be recognized is measured by the amount by which the book value of the assets exceeds their fair value, which is measured based on the projected discounted future net cash flows generated from the assets. No impairment losses have been recorded through December 31, 2018. Warrant Accounting Common stock warrants are accounted for in accordance with applicable accounting guidance provided in ASC Topic 815, Derivatives and Hedging—Contracts in Entity's Own Equity (ASC Topic 815), as either derivative liabilities or as equity instruments depending on the specific terms of the warrant agreement. (See Note 4). The Company's warrants that are classified as liabilities are recorded at fair value. The warrants are subject to remeasurement at each balance sheet date and any change in fair value is recognized as a component of change in fair value of warrant liability in the consolidated statements of operations. The Company has both tradable and non-tradable warrants. At December 31, 2018, the tradable warrants are classified as level 1 liabilities and the Company uses the Nasdaq quoted market price to estimate the fair value of the related derivative warrant liability. The non-tradable warrants are classified as level 3 liabilities and the Company uses the Black-Scholes pricing model to estimate the fair value of the related derivative warrant liability. (See Note 8 for a discussion of the fair value hierarchy). Foreign Currency Translation The reporting currency of the Company and its U.S. subsidiaries 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. Revenue Recognition The Company recognizes revenue in accordance with Accounting Standards Codification Topic 606, Revenue from Contracts with Customers (ASC 606), which the Company adopted effective January 1, 2018 using the modified retrospective method. There was no material impact to our financial position and results of operations as a result of the adoption. The Company applies ASC 606 to all contracts with customers, except for contracts that are within the scope of other standards, such as leases, insurance, collaboration arrangements and financial instruments. In accordance with ASC 606, the Company recognizes revenue when its customer obtains control of promised goods or services, in an amount that reflects the consideration which the Company expects to receive in exchange for those goods or services. To determine revenue recognition for arrangements that the Company determines are within the scope of ASC 606, the Company performs the following five steps: (i) identify the contract(s) with a customer; (ii) identify the performance obligations in the contract; (iii) determine the transaction price; (iv) allocate the transaction price to the performance obligations in the contract; and (v) recognize revenue when (or as) the Company satisfies a performance obligation. The Company only applies the five-step model to contracts when it is probable that it will collect the consideration it is entitled to in exchange for the goods and services it transfers to the customer. At contract inception, the Company assesses the goods or services promised within each contract that falls under the scope of ASC 606, determines those that are performance obligations and assesses whether each promised good or service is distinct. The Company then recognizes as revenue the amount of the transaction price that is allocated to the respective performance obligation when (or as) the performance obligation is satisfied. The Company derives revenue from collaboration and licensing agreements and from the sale of products associated with material transfer, collaboration and supply agreements. License, Collaboration and Other Revenues The Company enters into licensing and collaboration agreements, under which it licenses certain of its product candidates’ rights to third parties. The Company recognizes revenue related to these agreements in accordance with ASC 606. The terms of these arrangements typically include payment from third parties of one or more of the following: non-refundable, up-front license fees; development, regulatory and commercial milestone payments; and royalties on net sales of the licensed product. In determining the appropriate amount of revenue to be recognized as it fulfills its obligation under each of its agreements, the Company performs the five steps described above. As part of the accounting for these arrangements, the Company must develop assumptions that require judgment to determine the stand-alone selling price, which may include forecasted revenues, development timelines, reimbursement of personnel costs, discount rates and probabilities of technical and regulatory success. Licensing of Intellectual Property : If the license to the Company’s intellectual property is determined to be distinct from the other performance obligations identified in the arrangement, the Company recognizes revenue from non-refundable, up-front fees allocated to the license when the license is transferred to the licensee and the licensee is able to use and benefit from the license. For licenses that are bundled with other performance obligations, the Company utilizes judgment to assess the nature of the combined performance obligation to determine whether the combined performance obligation is satisfied over time or at a point in time and, if over time, the appropriate method of measuring progress for purposes of recognizing revenue from non-refundable, up-front-fees. The Company evaluates the measure of progress each reporting period, and, if necessary, adjusts the measure of performance and related revenue recognition. Milestone Payments : At the inception of each arrangement that includes development milestone payments, the Company evaluates whether the milestones are considered probable of being reached and estimates the amount to be included in the transaction price using the most likely amount method. If it is probable that a significant revenue reversal will not occur, the associated milestone value is included in the transaction price. Milestone payments that are not within the control of the Company or the licensees, such as regulatory approvals, are not considered probable of being achieved until those approvals are received. The transaction price is then allocated to each performance obligation on a relative stand-alone selling price basis, for which the Company recognizes revenue as or when the performance obligations under the contract are satisfied. At the end of each subsequent reporting period, the Company re-evaluates the probability of achievement of such development milestones and any related constraint and, if necessary, adjusts its estimate of the overall transaction price. Any such adjustments are recorded on a cumulative catch-up basis, which would affect revenues and earnings in their period of adjustment. Manufacturing supply services . Arrangements that include a promise for future supply of drug substance or drug product for either clinical development or commercial supply at the customer’s discretion are generally considered as options. The Company assesses if these options provide material rights to the licensee and if so, they are accounted for as separate performance obligations. If the Company is entitled to additional payments when the customer exercises these options, any additional payments are recorded when the customer obtains control of the goods, which is upon shipment. Royalties: For arrangements that include sales-based royalties, including milestone payments based on the level of sales, and for which the license is deemed to be the predominant item to which royalties relate, the Company recognizes revenue at the later of (i) when the related sales occur, or (ii) when the performance obligation to which some of all of the royalty has been allocated has been satisfied (or partially satisfied). To date, the Company has not recognized any royalty revenue from its license agreements. Research and Development Expenses Research and development costs are charged to expense as incurred. These costs include, but are not limited to, license fees related to the acquisition of in-licensed products; employee-related expenses, including salaries, benefits and travel; expenses incurred under agreements with contract research organizations and investigative sites that conduct clinical trials and preclinical studies; the cost of acquiring, developing and manufacturing clinical trial materials; facilities, depreciation and other expenses, which include direct and allocated expenses for rent and maintenance of facilities, insurance and other supplies; and costs associated with preclinical activities and regulatory operations. Costs for certain development activities, such as clinical trials, are recognized based on an evaluation of the progress to completion of specific tasks using data such as patient enrollment, clinical site activations, or information provided to the Company by its vendors with respect to their actual costs incurred. Payments for these activities are based on the terms of the individual arrangements, which may differ from the pattern of costs incurred, and are reflected in the consolidated financial statements as prepaid or accrued research and development expense, as the case may be. Comprehensive Loss Comprehensive loss is defined as the change in equity of a business enterprise during a period from transactions and other events and circumstances from non-owner sources. Income Taxes The Company accounts for income taxes under the asset and liability method. Deferred tax assets and liabilities are recognized for the future tax consequences attributable to differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax bases using enacted tax rates in effect for the year in which the differences are expected to affect taxable income. The deferred tax asset primarily includes net operating loss and tax credit carry forwards, accrued expenses not currently deductible and the cumulative temporary differences related to certain research and patent costs, which have been charged to expense in the accompanying statements of operations but have been recorded as assets for income tax purposes. The portion of any deferred tax asset for which it is more likely than not that a tax benefit will not be realized must then be offset by recording a valuation allowance. A full valuation allowance has been established against all of the deferred tax assets (see Note 9, “Income Taxes”), as it is more likely than not that these assets will not be realized given the Company’s history of operating losses. The Company recognizes the tax benefit from an uncertain tax position only if it is more likely than not to be sustained upon examination based on the technical merits of the position. The amount for which an exposure exists is measured as the largest amount of benefit determined on a cumulative probability basis that the Company believes is more likely than not to be realized upon ultimate settlement of the position. Stock‑Based Compensation Expense The Company applies the provisions of FASB Accounting Standards Codification (“ASC”) Topic 718, Compensation—Stock Compensation (“ASC 718”), which requires the measurement and recognition of compensation expense for all stock-based awards made to employees and non-employees, including employee stock options. Share‑based payment transactions with employees, including grants of employee stock options, are recognized as compensation expense over the requisite service period based on their estimated fair values. ASC 718 also requires significant judgment and the use of estimates, particularly surrounding Black‑Scholes assumptions such as stock price volatility over the option term and expected option lives, as well as expected option forfeiture rates, to estimate the grant date fair value of equity‑based compensation and requires the recognition of the fair value of stock compensation in the statement of operations. Clinical Trial Expense Accruals As part of the process of preparing its financial statements, the Company is required to estimate its expenses resulting from its obligations under contracts with vendors, clinical research organizations and consultants and under clinical site agreements in connection with conducting clinical trials. The financial terms of these contracts are subject to negotiations, which vary from contract to contract and may result in payment flows that do not match the periods over which materials or services are provided under such contracts. The Company’s objective is to reflect the appropriate trial expenses in its financial statements by matching those expenses with the period in which services are performed and efforts are expended. The Company accounts for these expenses according to the progress of the trial as measured by patient progression and the timing of various aspects of the trial. The Company determines accrual estimates through financial models taking into account discussion with applicable personnel and outside service providers as to the progress or state of consummation of trials, or the services completed. During the course of a clinical trial, the Company adjusts its clinical expense recognition if actual results differ from its estimates. The Company makes estimates of its accrued expenses as of each balance sheet date based on the facts and circumstances known to it at that time. The Company’s clinical trial accruals are dependent upon the timely and accurate reporting of contract research organizations and other third-party vendors. Although the Company does not expect its estimates to be materially different from amounts actually incurred, its understanding of the status and timing of services performed relative to the actual status and timing of services performed may vary and may result in it reporting amounts that are too high or too low for any particular period. For the years ended December 31, 2018 and 2017, there were no material adjustments to the Company’s prior period estimates of accrued expenses for clinical trials. Basic and Diluted Net Loss Per Share of Common Stock Basic net loss per share of common stock is computed by dividing net loss applicable to common stockholders by the weighted-average number of shares of Common Stock outstanding during the period, excluding the dilutive effects of stock options and warrants. Diluted net loss per share of common stock is computed by dividing the net loss applicable to common stockholders by the sum of the weighted-average number of shares of Common Stock outstanding during the period plus the potential dilutive effects of stock options and warrants outstanding during the period calculated in accordance with the treasury stock method, but are excluded if their effect is anti-dilutive. Because the impact of these items is anti-dilutive during periods of net loss, there was no difference between basic and diluted net loss per share of Common Stock for the years ended December 31, 2018 and 2017. Recent Accounting Pronouncements In November 2018, the FASB issued guidance, which clarifies the interaction between ASC Topic 808, Collaborative Arrangements , and ASC Topic 606, Revenue from Contracts with Customers . The guidance, among other items, clarifies that certain transactions between collaborative participants should be accounted for as revenue under Topic 606 when the collaborative arrangement participant is a customer in the context of a unit of account. The guidance is effective for fiscal years beginning after December 15, 2019. The Company believes that the adoption of this guidance will not have a material impact on the Company’s consolidated financial statements. In August 2018, the FASB issued guidance which changes the disclosure requirements for fair value measurement. The guidance amends the disclosure requirements in ASC Topic 820 by adding, changing, or removing certain disclosures. The guidance is effective for fiscal years beginning after December 15, 2019. The Company believes that the adoption of this guidance will not have a material impact on the Company’s consolidated financial statements. The Company is evaluating the impact of the adoption of the standard on its financial statement disclosures. In February 2016, the FASB issued guidance which supersedes much of the current guidance for leases. The new guidance requires lessees to recognize a right‑of‑use asset and a lease liability on their balance sheets for all the leases with terms greater than twelve months. Based on certain criteria, leases will be classified as either financing or operating, with classification affecting the pattern of expense recognition in the income statement. For leases with a term of twelve months or less, a lessee is permitted to make an accounting policy election by class of underlying asset not to recognize lease assets and lease liabilities. If a lessee makes this election, it should recognize lease expense for such leases generally on a straight‑line basis over the lease term. The guidance is effective for fiscal years beginning after December 15, 2018, and interim periods within those years, with early adoption permitted. In transition, lessees and lessors are required to recognize and measure leases at the beginning of the earliest period presented using a modified retrospective approach. The modified retrospective approach includes a number of optional practical expedients primarily focused on leases that commenced before the effective date of the new guidance, including continuing to account for leases that commence before the effective date in accordance with previous guidance, unless the lease is modified. The Company has evaluated the impact of the adoption of the guidance on its consolidated financial statements and expects to record a right-of-use asset and lease liability for certain of its leases as of the adoption date. The adoption of the guidance will not have a material effect on the Company’s financial statements.

Property and Equipment

Property and Equipment	12 Months Ended
	Dec. 31, 2018
Property and Equipment
Property and Equipment	3. Property and Equipment Property and equipment and related accumulated depreciation are as follows: December 31, 2018 2017 Laboratory equipment $ 1,037,000 $ 1,037,000 Software 92,000 92,000 Computer and office equipment 354,000 354,000 Leasehold improvements 745,000 745,000 2,228,000 2,228,000 Less accumulated depreciation (2,219,000) (2,164,000) $ 9,000 $ 64,000 Depreciation and amortization expense was $55,000 and $88,000 for the years ended December 31, 2018 and 2017, respectively.

Warrants

Warrants	12 Months Ended
	Dec. 31, 2018
Warrants
Warrants	4. Warrants Common stock warrants are accounted for in accordance with applicable accounting guidance provided in ASC Topic 815, Derivatives and Hedging-Contracts in Entity’s Own Equity (ASC Topic 815), as either derivative liabilities or as equity instruments depending on the specific terms of the warrant agreement. Some of the Company’s warrants are classified as liabilities because in certain circumstances they could require cash settlement. Warrants outstanding at December 31, 2017 and 2018, and warrant activity for the year ended December 31, 2018 is as follows (reflects the number of common shares as if the warrants were converted to common stock): Balance Balance Exercise Expiration December 31, Warrants Warrants Warrants December 31, Description Classification Price Date 2017 Issued Exercised Expired 2018 Non-tradable warrants Liability $ 172.50 July 2021 6,456 — — — 6,456 Tradable warrants Liability $ 73.80 July 2021 212,801 — — — 212,801 Non-tradable pre-funded warrants Equity $ 0.15 July 2023 394 — — — 394 Non-tradable warrants Equity $ 6.69375 * — 663,167 — — 663,167 Non-tradable warrants Equity $ 7.96875 * — 33,158 — — 33,158 Non-tradable warrants Equity $ 14.10 March 2021 — 5,000 — — 5,000 Non-tradable warrants Equity $ 21.15 March 2021 — 8,333 — — 8,333 Non-tradable warrants Equity $ 7.7895 June 2021 — 15,000 — — 15,000 Non-tradable pre-funded warrants Equity $ 0.15 none — 196,167 (110,000) — 86,167 Non-tradable warrants Equity $ 6.375 ** — 4,509,804 (76,842) — 4,432,962 Non-tradable pre-funded warrants Equity $ 0.15 none — 815,686 (553,618) — 262,068 219,651 6,246,315 (740,460) — 5,725,506 * These preferred stock warrants expire on the earlier of (A) the one-month anniversary of the date on which the Company publically releases topline results of the INSPIRE Pivotal phase 3 that compare the overall survival (OS) of patients in the rigosertib group vs the Physician’s Choice group, in all patients and in a subgroup of patients with IPSS-R very high risk and (B) December 31, 2019. These preferred stock warrants may be exercised on a cashless basis in certain circumstances specified therein. ** These preferred stock warrants expire on the 18-month anniversary of June 8, 2018, the date on which the Company publicly announced through the filing of a Current Report on Form 8-K that a Certificate of Amendment to the Company’s Tenth Amended and Restated Certificate of Incorporation, as amended, to increase the number of authorized shares of common stock from 100,000,000 to 250,000,000, was filed with the Secretary of State of the State of Delaware. These preferred stock warrants may be exercised on a cashless basis in certain circumstances specified therein.

Net Loss Per Share of Common St

Net Loss Per Share of Common Stock	12 Months Ended
	Dec. 31, 2018
Net Loss Per Share of Common Stock
Net Loss Per Share of Common Stock	5. Net Loss Per Share of Common Stock The following table sets forth the computation of basic and diluted earnings per share for the years ended December 31, 2018 and 2017: Year ended December 31, 2018 2017 Basic and diluted net loss per share of common stock: Net loss attributable to Onconova Therapeutics, Inc $ (20,573,000) $ (24,092,000) Weighted average shares of common stock outstanding 4,124,073 600,022 Net loss per share of common stock—basic and diluted $ (4.99) $ (40.15) The following potentially dilutive securities outstanding at December 31, 2018 and 2017 have been excluded from the computation of diluted weighted average shares outstanding, as they would be antidilutive (reflects the number of common shares as if the dilutive securities had been converted to common stock): December 31, 2018 2017 Warrants 5,725,506 3,294,771 Stock options 379,328 894,996 6,104,834 4,189,767

Revenue

Revenue	12 Months Ended
	Dec. 31, 2018
Revenue
Revenue	6. Revenue The Company recognized revenue under its license and collaboration agreements with SymBio, HanX and Pint as follows (See Note 14): Year ended December 31, 2018 2017 Symbio Upfront license fee recognition over time $ 398,000 $ 455,000 Supplies 61,000 332,000 Hanx Upfront license payment recognized at a point in time 450,000 — Pint Upfront license payment recognized at a point it time 319,000 — $ 1,228,000 $ 787,000 Deferred revenue is as follows: Symbio Upfront Payment Deferred balance at December 31, 2017 $ 4,546,000 Recognition to revenue 398,000 Deferred balance at December 31, 2018 $ 4,148,000 See Note 14, “License and Collaboration Agreements,” for a further discussion of the agreements with SymBio and HanX.

Balance Sheet Detail

Balance Sheet Detail	12 Months Ended
	Dec. 31, 2018
Balance Sheet Detail
Balance Sheet Detail	7. Balance Sheet Detail Prepaid expenses and other current assets are as follows: December 31, 2018 2017 Research and development $ 415,000 $ 514,000 Manufacturing 111,000 48,000 Insurance 166,000 181,000 Other 68,000 77,000 $ 760,000 $ 820,000 Accrued expenses and other current liabilities are as follows: December 31, 2018 2017 Research and development $ 2,285,000 $ 1,912,000 Employee compensation 1,650,000 1,258,000 Professional fees 225,000 165,000 Other 13,000 — $ 4,173,000 $ 3,335,000

Fair Value Measurements

Fair Value Measurements	12 Months Ended
	Dec. 31, 2018
Fair Value Measurements
Fair Value Measurements	8. 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. On January 5, 2016, the Company entered into a securities purchase agreement (the “Securities Purchase Agreement”) with an institutional investor providing for the issuance and sale by the Company of 12,912 shares of Common Stock, at a purchase price of $142.50 per share and warrants to purchase up to 6,456 shares of Common Stock (the “Warrants”) for aggregate gross proceeds of $1,840,000 (see Note 17). The Company has classified the warrants as a liability (see Note 4). The fair value was estimated using the Black-Scholes pricing model. On July 29, 2016 the Company closed on a Rights Offering, issuing 239,986 shares of Common Stock, 212,801 Tradable Warrants and 43,760 Pre-Funded Warrants. The Tradable Warrants are exercisable for a period of five years for one share of Common Stock at an exercise price of $73.80 per share. After the one-year anniversary of issuance, the Company may redeem the Tradable Warrants for $0.001 per Tradable Warrant if the volume weighted average price of its Common Stock is above $184.50 for each of 10 consecutive trading days (see Note 13). The Company has classified the Tradable Warrants as a liability (see Note 5). The Tradable Warrants have been listed on the Nasdaq Capital Market since issuance and the Company regularly monitors the trading activity. During the period from issuance on July 29, 2016 through March 31, 2017 the Company determined that trading volume was insufficient to use the Nasdaq Capital Market value to determine the fair value of the warrant liability. The fair value was estimated using the Black-Scholes pricing model. During the quarter ended June 30, 2017, the Company determined that an active and orderly market for the Tradable Warrants had developed and that the Nasdaq Capital Market price was the best indicator of fair value of the warrant liability. Consequently, the Company changed its valuation technique from the Black-Scholes pricing model to the quoted market price, effective April 1, 2017. The change in valuation technique resulted in a reclassification of the liability within the valuation hierarchy from Level 3 to Level 1. The quoted market price was used to determine the fair value at December 31, 2018 and 2017. The Company estimated the fair value of the non-tradable warrant liability at December 31, 2018 using the Black-Scholes option pricing model with the following weighted-average assumptions: Risk-free interest rate 2.46 % Expected volatility 82.18 % Expected term 2.53 years Expected dividend yield 0 % Expected volatility is based on the historical volatility of the Company’s common stock since its IPO in July 2013. 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 December 31, 2018 and 2017: Fair Value Measurement as of: December 31, 2018 December 31, 2017 Level 1 Level 2 Level 3 Balance Level 1 Level 2 Level 3 Balance Tradable warrants liability $ 176,000 $ — $ — $ 176,000 $ 1,755,000 $ — $ — $ 1,755,000 Non-tradable warrants liability — — — — — — 18,000 18,000 Total $ 176,000 $ — $ — $ 176,000 $ 1,755,000 $ — $ 18,000 $ 1,773,000 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 years ended December 31, 2018 and 2017: Warrant Liability Balance at December 31, 2016 $ 3,401,000 Reclassification of tradable warrants to Level 1 (4,857,000) Change in fair value upon re-measurement 1,474,000 Balance at December 31, 2017 18,000 Change in fair value upon re-measurement (18,000) Balance at December 31, 2018 $ — There were no transfers between Level 1 and Level 2 in any of the periods reported.

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2018
Income Taxes
Income Taxes	9. Income Taxes The Company accounts for income taxes under FASB ASC 740 (“ASC 740”). Deferred income tax assets and liabilities are determined based upon differences between financial reporting and tax bases of assets and liabilities, which are measured using the enacted tax rates and laws that will be in effect when the differences are expected to reverse. Income taxes have been based on the following income (loss) before income tax expense: December 31, 2018 2017 Domestic $ (20,579,000) $ (24,131,000) Foreign 45,000 52,000 $ (20,534,000) $ (24,079,000) The provision for income taxes consists of the following: December 31, 2018 2017 Current US Federal $ — $ — State and Local — — Foreign 13,000 13,000 Total Current $ 13,000 $ 13,000 Deferred US Federal $ (137,000) $ — State and Local — — Foreign — — Total Deferred $ — $ — Total (Benefit) Expense $ (124,000) $ 13,000 As of December 31, 2018, the Company had federal net operating loss (“NOL”) carry forwards of $231,950,000, state NOL carry forwards of $187,950,000 and research and development tax credit carry forwards of $82,335,000, which may be available to reduce future taxable income. There are $210,490,000 of federal NOLs that were generated in tax periods prior to 2018 that will begin to expire at various dates starting in 2022 and ending in 2044. The NOL that was generated in 2018 of $21,460,000 will carry forward indefinitely and not expire pursuant to changes in tax laws but will be limited in a single tax year to 80 percent of federal taxable income. The state NOL carry forwards will begin to expire at various dates starting in 2025. The NOL carry forwards are subject to review and possible adjustment by the Internal Revenue Service and state tax authorities. NOL and tax credit carry forwards may become subject to an annual limitation in the event of certain cumulative changes in the ownership interest of significant stockholders over a three-year period in excess of 50%, as defined under Sections 382 and 383 of the Internal Revenue Code of 1986, as amended, as well as similar state tax provisions. This will likely limit the amount of US NOLs, tax credit and tax attribute carryforwards that the Company can utilize to offset future taxable income or tax liabilities. The Company will complete a full Section 382 and 383 analysis prior to any utilization of any NOL and tax credit carry forwards. The amount of the annual limitation, if any, will be determined based on the value of the Company immediately prior to the ownership change. Subsequent ownership changes may further affect the limitation in future years. The Company’s reserves related to taxes are based on a determination of whether and how much of a tax benefit taken by the Company in its tax filings or positions is more likely than not to be realized. The Company recognized no material adjustment for unrecognized income tax benefits. Through December 31, 2018, the Company had no unrecognized tax benefits or related interest and penalties accrued. The principal components of the Company’s deferred tax assets are as follows: December 31, 2018 2017 Deferred tax assets: Net operating loss carryovers $ 63,494,000 $ 57,557,000 R&D tax credits 82,246,000 79,725,000 Non-qualified stock options 4,611,000 5,355,000 Deferred revenue 1,175,000 1,242,000 Charitable contributions 4,000 4,000 Accrued expenses 454,000 407,000 Fixed assets 92,000 85,000 Deferred tax assets 152,076,000 144,375,000 Less valuation allowance (151,939,000) (144,375,000) Net deferred tax assets $ 137,000 $ — ASC 740 requires a valuation allowance to reduce the deferred tax assets reported if, based on the weight of available evidence, it is more likely than not that some portion or all of the deferred tax assets will not be realized. After consideration of all the evidence, both positive and negative, the Company has recorded a full valuation allowance against its deferred tax assets at December 31, 2018 and 2017, respectively, except for the refundable AMT credit. The Company experienced a net change in valuation allowance of $7,564,000 and $(13,434,000) for the years ended December 31, 2018 and 2017, respectively. A reconciliation of income tax (expense) benefit at the statutory federal income tax rate and income taxes as reflected in the financial statements is as follows: December 31, 2018 2017 Federal income tax expense at statutory rate 21.0 % 34.0 % Permanent items 1.4 (8.1) Effect of Tax Act — (116.9) State income tax, net of federal benefit 6.9 5.8 Tax credits 12.2 29.3 Provision to return — — Change in valuation allowance (36.6) 55.8 Other (4.3) — Effective income tax rate 0.6 % (0.1) %

Stock-Based Compensation

Stock-Based Compensation	12 Months Ended
	Dec. 31, 2018
Stock-Based Compensation
Stock-Based Compensation	10. Stock‑Based Compensation The 2007 Equity Compensation Plan as amended (the “2007 Plan”), 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. The 2013 Equity Compensation Plan (the “2013 Plan”), 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 40,718 shares of Common Stock for issuance, subject to adjustment as set forth in the 2013 Plan. The 2013 Plan included an evergreen provision, pursuant to which the maximum aggregate number of shares that may be issued under the 2013 Plan is increased on the first day of each fiscal year by the lesser of (a) a number of shares equal to four percent (4%) of the issued and outstanding Common Stock of the Company, without duplication, (b) 13,333 shares and (c) such lesser number as determined by the Company’s board of directors, subject to specified limitations. The 2018 Omnibus Incentive Compensation Plan (the “2018 Plan”) was unanimously approved by the Company’s Board of Directors on May 24, 2018 and was approved by the Company’s stockholders on June 27, 2018. The 2018 Plan replaces the 2013 Plan. Upon stockholders’ approval of the 2018 Plan, no further awards will be made under the 2013 Plan. Awards granted under the 2013 Plan will continue in effect in accordance with the terms of the applicable award agreement and the terms of the 2013 Plan in effect when the awards were granted. Under the 2018 Plan, the Company may grant incentive stock options, non-qualified stock options, stock awards, stock units, stock appreciation rights and other stock-based awards to employees, non-employee directors and consultants, and advisors. The maximum aggregate number of shares of the Company’s common stock that may be issued under the 2018 Plan is 402,354, which is equal to the sum of (i) 400,000 shares of the Company’s common stock, plus (ii) 2,354 shares, which is the number of shares of the Company common stock reserved for issuance under the 2013 Plan that remained available as of the effective date of the 2018 Plan. In addition, the number of shares of common stock subject to outstanding awards under the 2013 Plan that terminate, expire, or are cancelled, forfeited, exchanged, or surrendered without having been exercised, vested, or paid in shares under the 2013 Plan after the effective date of the 2018 Plan will be available for issuance under the 2018 Plan. At December 31, 2018, there were 95,264 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 years ended December 31, 2018 and 2017: Year ended December 31, 2018 2017 General and administrative $ 589,000 $ 975,000 Research and development 507,000 735,000 $ 1,096,000 $ 1,710,000 A summary of stock option activity for the six months ended December 31, 2018 is as follows: Options Outstanding Weighted Weighted- Average Shares Average Remaining Aggregate Available Number Exercise Contractual Intrinsic for Grant of Shares Price Term (in years) Value Balance, December 31, 2017 3,842 59,666 $ 855.30 6.72 $ 0 Authorized 413,333 — Granted (335,405) 335,405 $ 7.50 Exercised — — $ — Forfeitures 15,743 (15,743) $ 615.72 Cancelled (2,249) Balance, December 31, 2018 95,264 379,328 $ 76.33 9.19 $ 0 Vested or expected to vest, December 31, 2018 365,790 $ 76.33 9.19 $ 0 Exercisable at December 31, 2018 51,973 $ 76.33 9.19 $ 0 Information with respect to stock options outstanding and exercisable at December 31, 2018 is as follows: Exercise Price Shares Exercisable $3.41 – $7.05 308,339 — $16.35 – $97.50 50,555 32,060 $222.00 - $225.00 1,931 1,594 $348.00 – $597.00 4,931 4,777 $651.00 – $1,129.50 5,636 5,606 $1,992.00 - $2,268.00 7,585 7,585 $4,156.50 - $4,371.00 351 351 379,328 51,973 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 Common 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 December 31, 2018, there was $1,429,000 of unrecognized compensation expense related to the unvested stock options issued from April 24, 2013 through December 31, 2018, which is expected to be recognized over a weighted-average period of approximately 2.31 years. The weighted-average assumptions underlying the Black-Scholes calculation of grant date fair value include the following: Year ended December 31, 2018 2017 Risk-free interest rate 2.84 % 2.09 % Expected volatility 79.42 % 79.02 % Expected term 5.94 years 5.98 years Expected dividend yield 0 % 0 % Weighted average grant date fair value $ 1.18 $ 1.76 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: Expected volatility is based on the historical volatility of the Company’s Common Stock since its IPO in July 2013. · Expected annual dividend yield: The Company has never paid, and does not expect to pay, dividends in the foreseeable future. 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 2018 and 2017, based on the historical forfeiture experience.

Employee Benefit Plan

Employee Benefit Plan	12 Months Ended
	Dec. 31, 2018
Employee Benefit Plan
Employee Benefit Plan	11. Employee Benefit Plan In October 2007, the Company established a 401(k) Retirement Savings Plan. Employees are eligible to participate in the plan as soon as they join the Company if they are at least 21 years of age and work a minimum of 1,000 hours per year. The Company matches $0.75 for every dollar of the first 6% of payroll that employees invest, up to the legal limit. Employer contributions vest immediately. For the years ended December 31, 2018 and 2017, the Company contributed $224,000 and $124,000, respectively.

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2018
Commitments and Contingencies
Commitments and Contingencies	12. Commitments and Contingencies Operating leases In January 2007, the Company entered into a lease for 8,100 square feet of office and lab space in Newtown, Pennsylvania, and in October 2009, the Company and the landlord amended the lease to add three additional one-year options to extend the lease term. In November 2013 the Company renewed the lease for the period April 1, 2014 to March 31, 2015, for rent of $11,000 per month. In December 2014 the Company renewed the lease for the period April 1, 2015 to March 31, 2016, for rent of $11,500 per month. In November 2015 the Company renewed the lease for the period April 1, 2016 to March 31, 2017, for rent of $11,900 per month. In September 2012, the Company sub-leased an additional 1,356 square feet of office space. The lease was renewed through February 28, 2017 for rent of $1,600 per month. In February 2017, the Company combined the leases and renewed the lease for the combined space for the period March 1, 2017 to February 28, 2018, for rent of $13,800 per month. The Company renewed the lease for the combined space for the period March 1, 2018 to February 28, 2019, for rent of $14,200 per month. The Company renewed the lease for the combined space for the period March 1, 2019 to February 28, 2020, for rent of $14,700 per month. Future minimum lease payments under these non-cancellable leases having terms in excess of one year as of December 31, 2018 are as follows: December 31, 2018 2019 $ 175,000 2020 29,000 Total minimum lease payments $ 204,000 Net rent expense was $165,000 and $152,000 for the years ended December 31, 2018 and 2017, respectively. Employment agreements The Company has entered into employment agreements with certain of its executives. The agreements provide for, among other things, salary, bonus and severance payments.

Research Agreements

Research Agreements	12 Months Ended
	Dec. 31, 2018
Research Agreements
Research Agreements	13. 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 December 31, 2018 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 a percentage of any sublicensing fees received by the Company.

License and Collaboration Agree

License and Collaboration Agreements	12 Months Ended
	Dec. 31, 2018
License and Collaboration Agreements
License and Collaboration Agreements	14. License and Collaboration Agreements SymBio Agreement In July 2011, the Company entered into a license agreement with SymBio, which has been 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 in 2011. 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 assessed the SymBio arrangement in accordance with ASC 606 and determined that its performance obligations 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 was not distinct since it was of no benefit to SymBio without the ongoing research and development services and that, as such, the license and the research and development services should be bundled as a single performance obligation. Since the provision of the license and research and development services are considered a single performance obligation, the $7,500,000 upfront payment is being recognized as revenue ratably through December 2037, the expected period over which the Company expects the research and development services to be performed as the services are performed. SymBio’s purchases of rigosertib as development-stage product or for commercial requirements represent options under the agreement and revenues are therefore recognized when control of the product is transferred, which is typically when shipped. 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. In January 2018, the agreement was amended to provide SymBio a discount of 35% on future purchases, limited to a cumulative total amount of $300,000. HanX Agreement In December 2017, the Company entered into a license and collaboration agreement with HanX Biopharmaceuticals, Inc. (“HanX”), a company focused on development of novel oncology products, for the further development, registration and commercialization of ON 123300 in Greater China. ON 123300 is a preclinical compound which the Company believes has the potential to overcome the limitations of current generation CDK 4/6 inhibitors. The key feature of the collaboration is that HanX will provide all funding required for future Chinese IND enabling studies necessary for filing an IND with the Chinese Food and Drug Administration. The studies would be conducted to meet the Good Laboratory Practice (“GLP”) requirements of the FDA such that the Company could simultaneously file an IND with the US FDA. The Company and HanX will oversee the IND enabling studies. The Company will maintain global rights to ON 12330 outside of China. Pursuant to the agreement, the Company received a $450,000 upfront payment on April 11, 2018. If the compound receives regulatory approval and is commercialized, the Company would receive regulatory and commercial milestone payments, as well as royalties on sales in the Greater China territory. The Company assessed the HanX arrangement for revenue recognition in accordance with ASC 606 and determined that the license was distinct and that control of the license had been transferred during the first quarter of 2018. As such, the Company recognized the $450,000 allocated to the license in the quarter ended March 31, 2018. Pint Agreement On March 2, 2018, the Company entered into a License, Development and Commercialization Agreement (the “License Agreement”) and a Securities Purchase Agreement (the “Securities Purchase Agreement”) with Pint. Under the terms of the License Agreement, the Company granted Pint an exclusive, royalty-bearing license, with the right to sublicense, under certain Company patent rights and know-how to develop and commercialize any pharmaceutical product (the “Product”) containing rigosertib in all uses of rigosertib in humans in Latin American countries (the “Territory,” including Argentina, Belize, Bolivia, Brazil, Chile, Colombia, Costa Rica, Cuba, Dominican Republic, Ecuador, El Salvador, French Guiana, British Guiana, Suriname, Guatemala, Haiti, Honduras, Mexico, Nicaragua, Panama, Paraguay, Peru, Uruguay and Venezuela). Pint agreed to make an upfront equity investment in the Company’s common stock. In addition, the Company could receive up to $41.5 million in additional regulatory, development and sales-based milestone payments, an additional equity investment, as well as tiered, double digit royalties based on net aggregate net sales in the Territory. Pint and the Company have also agreed to enter into a supply agreement providing for Pint purchasing rigosertib and the Product from the Company within 90 days of the FDA approval of an a New Drug Application (“NDA”) for the Product. Pint may terminate the License Agreement in whole (but not in part) at any time upon 45 days’ prior written notice. The License Agreement also contains certain provisions for termination by either party in the event of breach of the License Agreement by the other party, subject to a cure period, or bankruptcy of the other party. Under the terms of the Securities Purchase Agreement, Pint agreed to make an upfront equity investment in the Company at a specified premium to the Company’s share price. Pursuant to the Securities Purchase Agreement, closing of the upfront equity investment occurred on April 4, 2018 and Pint purchased 54,463 shares of common stock for $1,250,000. The total amount of the premium was $319,000 and this amount was allocated to the license. In addition, under the Securities Purchase Agreement, if the FDA approves the NDA for the Product, Pint will reimburse the Company for certain research and development expenses. Half of the reimbursement amount will be paid in cash, the other half of the amount will be by an equity investment at a premium to the average of the volume weighted average price of common stock for the ten consecutive trading days ended on the day the FDA approves the NDA. Pursuant to the Securities Purchase Agreement, the common stock purchased by Pint is subject to certain lock-up restrictions and Pint is entitled to certain registration and participation rights. The Company assessed the Pint arrangement for revenue recognition in accordance with ASC 606 and determined that the license was distinct and that control of the license had been transferred during the second quarter of 2018. As such, the Company recognized the $319,000 allocated to the license in the quarter ended June 30, 2018.

Preclinical Collaboration

Preclinical Collaboration	12 Months Ended
	Dec. 31, 2018
Preclinical Collaboration
Preclinical Collaboration	15. Preclinical Collaboration In December 2012, the Company agreed to form GBO, an entity owned by the Company and GVK. The purpose of GBO was to collaborate on and develop two programs through filing of an investigational new drug application and/or conducting proof of concept studies using the Company’s technology platform. During 2013, GVK 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 sublicense 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 made additional capital contributions. The GVK percentage interest in GBO could have changed from the initial 10% to up to 50%, depending on the amount of its total capital contributions. During November 2014, GVK made an additional capital contribution of $500,000 which increased its interest in GBO to 17.5%. The Company evaluated its variable interests in GBO on a quarterly basis and determined that it was the primary beneficiary. GVK had operational control of GBO and the Company had strategic and scientific control. The two preclinical programs sublicensed to GBO were not developed to clinical stage as initially hoped, and GBO was dissolved in June 2018. The dissolution resulted in a gain of $693,000 to the Company, primarily as a result of forgiveness of GBO payables to GVK. Upon consolidation of GBO, the $693,000 gain and $(163,000) non-controlling interest portion were recorded by the Company in the quarter ended June 30, 2018.

Related-Party Transactions

Related-Party Transactions	12 Months Ended
	Dec. 31, 2018
Related-Party Transactions
Related-Party Transactions	16. 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 years ended December 31, 2018 and 2017 were $351,000 and $351,000, respectively. At December 31, 2018 and 2017, the Company had $88,000 and $526,000 payable to Mount Sinai under this agreement. 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 under this agreement for the years ended December 31, 2018 and 2017 were $132,000 and $132,000, respectively. At December 31, 2018 and December 31, 2017, the Company had $33,000 and $33,000, respectively, payable under this agreement.

Securities Registrations and Sa

Securities Registrations and Sales Agreements	12 Months Ended
	Dec. 31, 2018
Securities Registrations and Sales Agreements
Securities Registrations and Sales Agreements	17. Securities Registrations and Sales Agreements On October 8, 2015, the Company entered into a purchase agreement, and a registration rights agreement (the “Registration Rights Agreement”) with Lincoln Park. A registration statement (Form S-1 No. 333-207533), relating to the shares, which was filed with the SEC became effective on November 3, 2015. Subject to the terms and conditions of the purchase agreement, including the effectiveness of a registration statement covering the resale of the shares, the Company was permitted to sell additional shares of its Common Stock, having an aggregate offering price of up to $15,000,000 to Lincoln Park from time to time until December 1, 2018. Upon execution of the Lincoln Park purchase agreement, Lincoln Park made an initial purchase of 5,645 shares of the Company’s Common Stock for $1,500,000. Subject to the terms and conditions of the purchase agreement, including the effectiveness of a registration statement covering the resale of the shares, the Company had the right to sell to and Lincoln Park was obligated to purchase up to an additional $15,000,000 of shares of Common Stock, subject to certain limitations, from time to time until December 1, 2018. The Company could direct Lincoln Park, at its sole discretion and subject to certain conditions, to purchase up to 666 shares of Common Stock on any business day, increasing to up to 1,666 shares depending upon the closing sale price of the Common Stock (such purchases, “Regular Purchases”). However, in no event was a Regular Purchase be more than $1,000,000. The purchase price of shares of Common Stock related to the future funding was based on the prevailing market prices of such shares at the time of sales. In addition, the Company could direct Lincoln Park to purchase additional amounts as accelerated purchases if on the date of a Regular Purchase the closing sale price of the Common Stock was not below the threshold price as set forth in the Purchase Agreement. The Company’s sales of shares of Common Stock to Lincoln Park under the Purchase Agreement were limited to no more than the number of shares that would result in the beneficial ownership by Lincoln Park and its affiliates, at any single point in time, of more than 4.99% of the then-outstanding shares of the Common Stock, which limit increased to 9.99% on May 1, 2016. Pursuant to the terms of the Lincoln Park purchase agreement and to comply with the listing rules of the Nasdaq Stock Market, the number of shares issued to Lincoln Park thereunder was not exceed 19.99% of the Company’s shares outstanding on October 8, 2015 unless the approval of the Company’s stockholders was obtained. This limitation did not apply if the average price paid for all shares issued and sold under the purchase agreement was equal to or greater than $233.40. The Company was not required or permitted to issue any shares of Common Stock under the Lincoln Park purchase agreement if such issuance would breach the Company’s obligations under the listing rules of the Nasdaq Stock Market. As consideration for entering into the purchase agreement, the Company issued to Lincoln Park 1,333 shares of Common Stock. Lincoln Park represented to the Company, among other things, that it was an “accredited investor” (as such term is defined in Rule 501(a) of Regulation D under the Securities Act of 1933, as amended (the “Securities Act”), and the Company sold the securities in reliance upon an exemption from registration contained in Section 4(2) under the Securities Act. The securities sold may not be offered or sold in the United States absent registration or an applicable exemption from registration requirements. Proceeds received from sales to Lincoln Park were used to fund the development of the Company’s clinical and preclinical programs, for other research and development activities and for general corporate purposes. In December 2016, the Company entered into a sales agreement with FBR Capital Markets & Co. (“FBR”) 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 through FBR. The Shares to be sold under the Sales Agreement, if any, will be issued and sold pursuant to the Company’s shelf registration statement on Form S-3 (File No 333-199219), previously filed with the SEC on October 8, 2014 and declared effective by the SEC on November 20, 2014. A prospectus supplement related to the Company’s at-the-market equity program was filed with the SEC on December 5, 2016. Sales under the Sales Agreement were 1,367 shares for net proceeds of approximately $64,000. The Sales Agreement was terminated effective April 19, 2017. On November 9, 2017, the Company entered into a placement agency agreement with Laidlaw relating to the Company’s registered direct offering, issuance and sale to select accredited investors of 61,333 shares of the Company’s common stock at a price of $22.50 per share on a best efforts basis. These shares are registered under the Securities Act on the Company’s Registration Statement on Form S-3 (File No. 333-199219). The offering closed on November 14, 2017. The net proceeds to the Company from the offering, after deducting placement agent fees and other expenses, were approximately $1,082,000. The Company intends to use the net proceeds from this offering to fund the development of its clinical and preclinical programs, for other research and development activities and for general corporate purposes, which may include capital expenditures and funding its working capital needs. On February 8, 2018, the Company entered into an underwriting agreement (the “February 2018 Underwriting Agreement”) with H.C. Wainwright & Co., LLC (“HCW”), relating to the public offering (the “February 2018 Offering”) of 380,500 shares of the Company’s common stock and pre-funded warrants (the “February 2018 Pre-Funded Warrants”) to purchase an aggregate of 196,167 shares of common stock. Each share of common stock or February 2018 Pre-Funded Warrant, as applicable, was sold as a unit with a warrant to purchase Series A Preferred Stock which is convertible to common stock (the “February 2018 Preferred Stock Warrants”). Each February 2018 Preferred Stock Warrant is for one-fifteenth of a share of common stock, on an as converted basis. The combined public offering price was $15.15 per common stock unit or $15.00 per February 2018 Pre-Funded Warrant unit. The Company also granted HCW a 30-day option to purchase up to 86,500 additional shares of common stock at a purchase price of $15.00 per share and February 2018 Preferred Stock Warrants to purchase shares of Series A Preferred Stock convertible into 86,500 shares of common stock at a purchase price of $0.15 per February 2018 Preferred Stock Warrant, less the underwriting discounts and commissions. Prior to closing, HCW exercised this option in full. The offering closed on February 12, 2018. Net proceeds from the offering were approximately $8.7 million after deducting underwriting discounts and commissions and other estimated offering expenses payable by the Company. The Company intends to use the net proceeds from the offering to fund the development of its clinical and preclinical programs, for other research and development activities and for general corporate purposes, which may include capital expenditures and funding its working capital needs. The shares of common stock or February 2018 Pre-Funded Warrants, as applicable, and the accompanying February 2018 Preferred Stock Warrants could only be purchased together as a unit in the offering but were issued as separate securities. The February 2018 Pre-Funded Warrants are exercisable immediately at an exercise price of $0.15 per share, may be exercised until they are exercised in full, and may be exercised on a cashless basis in certain circumstances specified therein. The February 2018 Preferred Stock Warrants are exercisable immediately for Series A Preferred Stock at an exercise price of $15.15 per common share, on an as converted basis and will expire on the earlier of (A) the one-month anniversary of the date on which the Company publically releases topline results of the INSPIRE Pivotal phase 3 that compare the overall survival (OS) of patients in the rigosertib group vs the Physician’s Choice group, in all patients and in a subgroup of patients with IPSS-R very high risk and (B) December 31, 2019. The February 2018 Preferred Stock Warrants may be exercised on a cashless basis in certain circumstances specified therein. HCW acted as sole book-running manager for the offering, which was a firm commitment underwritten public offering pursuant to a registration statement on Form S-1 (Registration No. 333-222374) that was declared effective by the SEC on February 7, 2018. The offering was made only by means of a prospectus forming a part of the effective registration statement. The Company paid HCW a commission equal to 7.0% of the gross proceeds of the offering, a management fee equal to 1.0% of the gross proceeds of the offering and other expenses. As additional compensation, the Company issued warrants to HCW exercisable for shares of Series A Preferred Stock, which are convertible into 33,158 shares of common stock subject to the terms of the Series A Preferred Stock. These warrants have substantially the same terms as the February 2018 Preferred Stock Warrants except that the exercise price per share is equal to $18.9375 per share of common stock, on an as converted basis. On September 24, 2018, in exchange for HCW agreement to provide shareholder advisory services to the Company for a period of three months starting on September 24, 2018, the Company repriced these warrants to an exercise price per share equal to $7.96875 per share of common stock, on an as converted basis. On April 27, 2018, the Company entered into an underwriting agreement with HCW relating to the public offering (the “April 2018 Offering”) of 3,105,882 shares of the Company’s common stock and pre-funded warrants (the “May 2018 Pre-Funded Warrants”) to purchase an aggregate of 815,686 shares of common stock. Each share of common stock or May 2018 Pre-Funded Warrant, as applicable, was sold as a unit with a warrant to purchase Series B Preferred Stock which is convertible to common stock (the “May 2018 Preferred Stock Warrants”). Each May 2018 Preferred Stock Warrant is for one-fifteenth of a share of common stock, on an as converted basis. The combined public offering price was $6.375 per common stock unit or $6.225 per May 2018 Pre-Funded Warrant unit. The Company also granted HCW a 30-day option to purchase up to 588,235 additional shares of common stock at a purchase price of $6.225 per share and May 2018 Preferred Stock Warrants to purchase shares of Series B Preferred Stock convertible into 588,235 shares of common stock at a purchase price of $0.15 per May 2018 Preferred Stock Warrant, less the underwriting discounts and commissions. Prior to closing, HCW exercised this option in full. The offering closed on May 1, 2018. Net proceeds from the offering were approximately $25.6 million after deducting underwriting discounts and commissions and other estimated offering expenses payable by the Company. The Company intends to use the net proceeds from the offering to fund the development of its clinical and preclinical programs, for other research and development activities and for general corporate purposes, which may include capital expenditures and funding its working capital needs. The shares of common stock or May 2018 Pre-Funded Warrants, as applicable, and the accompanying May 2018 Preferred Stock Warrants could only be purchased together as a unit in the offering but were issued as separate securities. The May 2018 Pre-Funded Warrants are exercisable immediately at an exercise price of $0.15 per share, may be exercised until they are exercised in full, and may be exercised on a cashless basis in certain circumstances. The May 2018 Preferred Stock Warrants are exercisable immediately for Series B Preferred Stock at an exercise price of $6.375 per common share, on an as converted basis and will expire on the 18-month anniversary of June 8, 2018, the date on which the Company publicly announced through the filing of a Current Report on Form 8-K that a Certificate of Amendment to the Company’s Tenth Amended and Restated Certificate of Incorporation, as amended, to increase the number of authorized shares of common stock from 100,000,000 to 250,000,000, was filed with the Secretary of State of the State of Delaware. The May 2018 Preferred Stock Warrants may be exercised on a cashless basis in certain circumstances. HCW acted as sole book-running manager for the offering, which was a firm commitment underwritten public offering pursuant to a registration statement on Form S-1 (Registration No. 333-224315) that was declared effective by the SEC on April 26, 2018. The offering was made only by means of a prospectus forming a part of the effective registration statement. The Company paid HCW a commission equal to 8.0% of the gross proceeds of the offering, a management fee equal to 1.0% of the gross proceeds of the offering and other expenses. In connection with the February 2018 Offering, the Company agreed to certain restrictions (the “Company Lock-Up”) set forth in Section 5(j) of the February 2018 Underwriting Agreement. The Company Lock-Up, among other items, prohibited the Company, during a period of one hundred and thirty-five (135) days from February 8, 2018, without the prior written consent of HCW, from offering or selling any Common Stock or any securities convertible into or exercisable or exchangeable for Common Stock. In order to receive HCW’s waiver of the Company Lock-Up, in connection with the April 2018 Offering, on April 16, 2018, the Company entered into a Lock-Up Waiver Agreement (the “Lock-Up Waiver Agreement”) with HCW and certain holders of the February 2018 Preferred Stock Warrants, pursuant to which (i) HCW waived the Company Lock-Up solely with respect to the April 2018 Offering, and (ii) the Company agreed to reduce the exercise price of the February 2018 Preferred Stock Warrants such that the exercise price of the February 2018 Preferred Stock Warrants shall be equal to 105% of the public offering price of common stock sold in the April 2018 Offering (but only to the extent that such public offering price is lower than the current exercise price of the February 2018 Preferred Stock Warrants) and that such repricing shall be effective concurrently with the closing of the April 2018 Offering. This modification of the February 2018 Preferred Stock Warrants was accounted for as an equity issuance cost. In accordance with the Lock-Up Waiver Agreements, the exercise price of the February 2018 Preferred Stock Warrants was repriced from $15.15 per share of common stock, on as converted basis to $6.69375 per share of common stock, on as converted basis, when the April 2018 Offering closed on May 1, 2018.

Subsequent Events

Subsequent Events	12 Months Ended
	Dec. 31, 2018
Subsequent Events
Subsequent Events	18. Subsequent Events On January 15, 2019, Stephen Fruchtman, M.D. was appointed as a director and the Chief Executive Officer of the Company and successor to Ramesh Kumar, Ph.D. On the same date, Ramesh Kumar, Ph.D., resigned as the Chief Executive Officer and as a director of the Company. Dr. Kumar is serving as a consultant to the Company pursuant to a Consulting Agreement (the “Consulting Agreement”). In connection with Dr. Kumar’s resignation, the Company entered into a Separation and Release Agreement (the “Separation Agreement”) with Dr. Kumar, dated as of January 15, 2019. Under the Separation Agreement Dr. Kumar is entitled to the severance payments and benefits as set forth in the Separation Agreement. The severance payments and benefits under the Separation Agreement include, without limitation, the following: Severance Payments. Under severance payments provisions, which remain the same as those in the Employment Agreement, the Company will pay Dr. Kumar a severance amount equal to $933,774, which is the sum of (x) $602,435, 12 months of base salary at the rate in effect immediately prior to January 15, 2019 and (y) $331,339, 55% of the base salary amount referred to in the preceding sentence. The severance amount will be paid in installments in accordance with the Company’s normal payroll practices over the 12-month period following the Termination Date. Stock Option Acceleration and Extension. The stock option acceleration provision remains the same as that under the Employment Agreement, and under this provision, all stock options (the “Outstanding Options”) held by Dr. Kumar will vest on the Termination Date. Dr. Kumar is also entitled to a stock option extension provision, under which the Company will amend the post-termination exercise periods set forth in the agreements reflecting the Outstanding Options such that Dr. Kumar will have until the earlier of (i) January 15, 2022 and (ii) the last day of the applicable ten-year term of the applicable Outstanding Option to exercise the Outstanding Options. Other Benefits. Dr. Kumar will also receive accrued benefits and certain health benefits; and the enhanced benefits include, among other things, a COBRA (Consolidated Omnibus Budget Reconciliation Act) reimbursement extension, under which if Dr. Kumar remains on COBRA coverage for the entire 12-month period following the Termination Date, the Company will continue to pay Dr. Kumar COBRA reimbursements for an additional six-month period following the expiration of the 12-month period, subject to certain terms and conditions. Under the Consulting Agreement, during the five-month period starting on February 18, 2019, at the request of the Company, Dr. Kumar will provide consulting service to the Company, and will be paid $10,000 per month for up to 20 hours of services (pro-rated for each partial calendar month during the term), and $500 per hour for each additional hour Dr. Kumar performs services in excess of 20 hours in any month (pro-rated for each partial calendar month during the term), subject to terms and conditions of the Consulting Agreement. The Company and Dr. Kumar may each terminate the Consulting Agreement by giving the other 90 days’ written notice. The Company has no obligation to request any consulting service during the term. In March 2019, the Company communicated to certain employees a plan of termination to reduce a number of positions as part of its ongoing commitment to reduce costs and conserve cash. The plan affects six employees, who have been offered severance pay in accordance with Company policy or, if applicable, their employment agreements. As a result of the workforce reduction, the Company estimates that it will record in the first quarter of 2019, a one-time severance-related charge totaling approximately $0.7 million. Annual estimated savings from the workforce reduction are expected to be approximately $1.5 million and should be fully realized during 2020. The severance-related charge and savings are subject to a number of assumptions, and actual results may differ materially. The Company may also incur other charges or cash expenditures not currently contemplated due to events that may occur as a result of, or associated with, the workforce reduction.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2018
Summary of Significant Accounting Policies
Basis of Presentation	Basis of Presentation The consolidated financial statements are prepared in conformity with accounting principles generally accepted in the United States (“GAAP”). The financial statements include the consolidated accounts of the Company, its wholly‑owned subsidiary, Onconova Europe GmbH, and GBO, which was dissolved in June 2018. All significant intercompany transactions have been eliminated. Certain prior year amounts have been reclassified to conform to current period presentation. All common stock, equity, share and per share amounts in the financial statements and notes have been retroactively adjusted to reflect a one-for-fifteen reverse stock split which was effective September 25, 2018.
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.
Use of Estimates	Use of Estimates The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets, liabilities, revenues, expenses, other comprehensive income and related disclosures. On an ongoing basis, management evaluates its estimates, including estimates related to clinical trial accruals, warrant liability, and allocation of consideration for revenue recognition. The Company bases its estimates on historical experience and other market‑specific or other relevant assumptions that it believes to be reasonable under the circumstances. Actual results may differ from those estimates or assumptions.
Concentrations of Credit Risk and Off-Balance Sheet Risk	Concentrations of Credit Risk and Off‑Balance Sheet Risk Financial instruments that potentially subject the Company to concentrations of credit risk are primarily cash and cash equivalents. The Company maintains a portion of its cash and cash equivalent balances in the form of money market accounts with financial institutions that management believes are creditworthy. The Company has no financial instruments with off‑balance sheet risk of loss.
Cash and Cash Equivalents	Cash and Cash Equivalents The Company considers all highly liquid investments with original or remaining maturity from the date of purchase of three months or less to be cash equivalents. Cash and cash equivalents include bank demand deposits, marketable securities with maturities of three months or less at purchase, and money market funds that invest primarily in certificates of deposit, commercial paper and U.S. government and U.S. government agency obligations. Cash equivalents are reported at fair value.
Fair Value of Financial Instruments	Fair Value of Financial Instruments The carrying amounts reported in the accompanying consolidated financial statements for cash and cash equivalents, accounts payable, and accrued liabilities approximate their respective fair values because of the short‑term nature of these accounts. The fair value of the warrant liability is discussed in Note 8, "Fair Value Measurements."
Property and Equipment	Property and Equipment Property and equipment are stated at cost, less accumulated depreciation. Property and equipment are depreciated using the straight-line method over the estimated useful lives of the assets. Leasehold improvements are amortized over the useful life of the asset or the lease term, whichever is shorter. Maintenance and repairs are expensed as incurred. The following estimated useful lives were used to depreciate the Company's assets: Estimated Useful Life Lab equipment 5 - 6 years Software 3 years Computer and office equipment 5 - 6 years Leasehold improvements Shorter of the lease term or estimated useful life Upon retirement or sale, the cost of the disposed asset and the related accumulated depreciation are removed from the accounts and any resulting gain or loss is recognized. The Company reviews long‑lived assets for impairment when events or changes in circumstances indicate that the carrying value of the assets may not be recoverable. Recoverability is measured by comparison of the assets’ book value to future net undiscounted cash flows that the assets are expected to generate. If such assets are considered to be impaired, the impairment to be recognized is measured by the amount by which the book value of the assets exceeds their fair value, which is measured based on the projected discounted future net cash flows generated from the assets. No impairment losses have been recorded through December 31, 2018.
Warrant Accounting	Warrant Accounting Common stock warrants are accounted for in accordance with applicable accounting guidance provided in ASC Topic 815, Derivatives and Hedging—Contracts in Entity's Own Equity (ASC Topic 815), as either derivative liabilities or as equity instruments depending on the specific terms of the warrant agreement. (See Note 4). The Company's warrants that are classified as liabilities are recorded at fair value. The warrants are subject to remeasurement at each balance sheet date and any change in fair value is recognized as a component of change in fair value of warrant liability in the consolidated statements of operations. The Company has both tradable and non-tradable warrants. At December 31, 2018, the tradable warrants are classified as level 1 liabilities and the Company uses the Nasdaq quoted market price to estimate the fair value of the related derivative warrant liability. The non-tradable warrants are classified as level 3 liabilities and the Company uses the Black-Scholes pricing model to estimate the fair value of the related derivative warrant liability. (See Note 8 for a discussion of the fair value hierarchy).
Foreign Currency Translation	Foreign Currency Translation The reporting currency of the Company and its U.S. subsidiaries 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.
Revenue Recognition	Revenue Recognition The Company recognizes revenue in accordance with Accounting Standards Codification Topic 606, Revenue from Contracts with Customers (ASC 606), which the Company adopted effective January 1, 2018 using the modified retrospective method. There was no material impact to our financial position and results of operations as a result of the adoption. The Company applies ASC 606 to all contracts with customers, except for contracts that are within the scope of other standards, such as leases, insurance, collaboration arrangements and financial instruments. In accordance with ASC 606, the Company recognizes revenue when its customer obtains control of promised goods or services, in an amount that reflects the consideration which the Company expects to receive in exchange for those goods or services. To determine revenue recognition for arrangements that the Company determines are within the scope of ASC 606, the Company performs the following five steps: (i) identify the contract(s) with a customer; (ii) identify the performance obligations in the contract; (iii) determine the transaction price; (iv) allocate the transaction price to the performance obligations in the contract; and (v) recognize revenue when (or as) the Company satisfies a performance obligation. The Company only applies the five-step model to contracts when it is probable that it will collect the consideration it is entitled to in exchange for the goods and services it transfers to the customer. At contract inception, the Company assesses the goods or services promised within each contract that falls under the scope of ASC 606, determines those that are performance obligations and assesses whether each promised good or service is distinct. The Company then recognizes as revenue the amount of the transaction price that is allocated to the respective performance obligation when (or as) the performance obligation is satisfied. The Company derives revenue from collaboration and licensing agreements and from the sale of products associated with material transfer, collaboration and supply agreements. License, Collaboration and Other Revenues The Company enters into licensing and collaboration agreements, under which it licenses certain of its product candidates’ rights to third parties. The Company recognizes revenue related to these agreements in accordance with ASC 606. The terms of these arrangements typically include payment from third parties of one or more of the following: non-refundable, up-front license fees; development, regulatory and commercial milestone payments; and royalties on net sales of the licensed product. In determining the appropriate amount of revenue to be recognized as it fulfills its obligation under each of its agreements, the Company performs the five steps described above. As part of the accounting for these arrangements, the Company must develop assumptions that require judgment to determine the stand-alone selling price, which may include forecasted revenues, development timelines, reimbursement of personnel costs, discount rates and probabilities of technical and regulatory success. Licensing of Intellectual Property : If the license to the Company’s intellectual property is determined to be distinct from the other performance obligations identified in the arrangement, the Company recognizes revenue from non-refundable, up-front fees allocated to the license when the license is transferred to the licensee and the licensee is able to use and benefit from the license. For licenses that are bundled with other performance obligations, the Company utilizes judgment to assess the nature of the combined performance obligation to determine whether the combined performance obligation is satisfied over time or at a point in time and, if over time, the appropriate method of measuring progress for purposes of recognizing revenue from non-refundable, up-front-fees. The Company evaluates the measure of progress each reporting period, and, if necessary, adjusts the measure of performance and related revenue recognition. Milestone Payments : At the inception of each arrangement that includes development milestone payments, the Company evaluates whether the milestones are considered probable of being reached and estimates the amount to be included in the transaction price using the most likely amount method. If it is probable that a significant revenue reversal will not occur, the associated milestone value is included in the transaction price. Milestone payments that are not within the control of the Company or the licensees, such as regulatory approvals, are not considered probable of being achieved until those approvals are received. The transaction price is then allocated to each performance obligation on a relative stand-alone selling price basis, for which the Company recognizes revenue as or when the performance obligations under the contract are satisfied. At the end of each subsequent reporting period, the Company re-evaluates the probability of achievement of such development milestones and any related constraint and, if necessary, adjusts its estimate of the overall transaction price. Any such adjustments are recorded on a cumulative catch-up basis, which would affect revenues and earnings in their period of adjustment. Manufacturing supply services . Arrangements that include a promise for future supply of drug substance or drug product for either clinical development or commercial supply at the customer’s discretion are generally considered as options. The Company assesses if these options provide material rights to the licensee and if so, they are accounted for as separate performance obligations. If the Company is entitled to additional payments when the customer exercises these options, any additional payments are recorded when the customer obtains control of the goods, which is upon shipment. Royalties: For arrangements that include sales-based royalties, including milestone payments based on the level of sales, and for which the license is deemed to be the predominant item to which royalties relate, the Company recognizes revenue at the later of (i) when the related sales occur, or (ii) when the performance obligation to which some of all of the royalty has been allocated has been satisfied (or partially satisfied). To date, the Company has not recognized any royalty revenue from its license agreements.
Research and Development Expenses	Research and Development Expenses Research and development costs are charged to expense as incurred. These costs include, but are not limited to, license fees related to the acquisition of in-licensed products; employee-related expenses, including salaries, benefits and travel; expenses incurred under agreements with contract research organizations and investigative sites that conduct clinical trials and preclinical studies; the cost of acquiring, developing and manufacturing clinical trial materials; facilities, depreciation and other expenses, which include direct and allocated expenses for rent and maintenance of facilities, insurance and other supplies; and costs associated with preclinical activities and regulatory operations. Costs for certain development activities, such as clinical trials, are recognized based on an evaluation of the progress to completion of specific tasks using data such as patient enrollment, clinical site activations, or information provided to the Company by its vendors with respect to their actual costs incurred. Payments for these activities are based on the terms of the individual arrangements, which may differ from the pattern of costs incurred, and are reflected in the consolidated financial statements as prepaid or accrued research and development expense, as the case may be.
Comprehensive Loss	Comprehensive Loss Comprehensive loss is defined as the change in equity of a business enterprise during a period from transactions and other events and circumstances from non-owner sources.
Income Taxes	Income Taxes The Company accounts for income taxes under the asset and liability method. Deferred tax assets and liabilities are recognized for the future tax consequences attributable to differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax bases using enacted tax rates in effect for the year in which the differences are expected to affect taxable income. The deferred tax asset primarily includes net operating loss and tax credit carry forwards, accrued expenses not currently deductible and the cumulative temporary differences related to certain research and patent costs, which have been charged to expense in the accompanying statements of operations but have been recorded as assets for income tax purposes. The portion of any deferred tax asset for which it is more likely than not that a tax benefit will not be realized must then be offset by recording a valuation allowance. A full valuation allowance has been established against all of the deferred tax assets (see Note 9, “Income Taxes”), as it is more likely than not that these assets will not be realized given the Company’s history of operating losses. The Company recognizes the tax benefit from an uncertain tax position only if it is more likely than not to be sustained upon examination based on the technical merits of the position. The amount for which an exposure exists is measured as the largest amount of benefit determined on a cumulative probability basis that the Company believes is more likely than not to be realized upon ultimate settlement of the position.
Stock-Based Compensation Expense	Stock‑Based Compensation Expense The Company applies the provisions of FASB Accounting Standards Codification (“ASC”) Topic 718, Compensation—Stock Compensation (“ASC 718”), which requires the measurement and recognition of compensation expense for all stock-based awards made to employees and non-employees, including employee stock options. Share‑based payment transactions with employees, including grants of employee stock options, are recognized as compensation expense over the requisite service period based on their estimated fair values. ASC 718 also requires significant judgment and the use of estimates, particularly surrounding Black‑Scholes assumptions such as stock price volatility over the option term and expected option lives, as well as expected option forfeiture rates, to estimate the grant date fair value of equity‑based compensation and requires the recognition of the fair value of stock compensation in the statement of operations.
Clinical Trial Expense Accruals	Clinical Trial Expense Accruals As part of the process of preparing its financial statements, the Company is required to estimate its expenses resulting from its obligations under contracts with vendors, clinical research organizations and consultants and under clinical site agreements in connection with conducting clinical trials. The financial terms of these contracts are subject to negotiations, which vary from contract to contract and may result in payment flows that do not match the periods over which materials or services are provided under such contracts. The Company’s objective is to reflect the appropriate trial expenses in its financial statements by matching those expenses with the period in which services are performed and efforts are expended. The Company accounts for these expenses according to the progress of the trial as measured by patient progression and the timing of various aspects of the trial. The Company determines accrual estimates through financial models taking into account discussion with applicable personnel and outside service providers as to the progress or state of consummation of trials, or the services completed. During the course of a clinical trial, the Company adjusts its clinical expense recognition if actual results differ from its estimates. The Company makes estimates of its accrued expenses as of each balance sheet date based on the facts and circumstances known to it at that time. The Company’s clinical trial accruals are dependent upon the timely and accurate reporting of contract research organizations and other third-party vendors. Although the Company does not expect its estimates to be materially different from amounts actually incurred, its understanding of the status and timing of services performed relative to the actual status and timing of services performed may vary and may result in it reporting amounts that are too high or too low for any particular period. For the years ended December 31, 2018 and 2017, there were no material adjustments to the Company’s prior period estimates of accrued expenses for clinical trials.
Basic and Diluted Net Loss Per Share of Common Stock	Basic and Diluted Net Loss Per Share of Common Stock Basic net loss per share of common stock is computed by dividing net loss applicable to common stockholders by the weighted-average number of shares of Common Stock outstanding during the period, excluding the dilutive effects of stock options and warrants. Diluted net loss per share of common stock is computed by dividing the net loss applicable to common stockholders by the sum of the weighted-average number of shares of Common Stock outstanding during the period plus the potential dilutive effects of stock options and warrants outstanding during the period calculated in accordance with the treasury stock method, but are excluded if their effect is anti-dilutive. Because the impact of these items is anti-dilutive during periods of net loss, there was no difference between basic and diluted net loss per share of Common Stock for the years ended December 31, 2018 and 2017.
Recent Accounting Pronouncements	Recent Accounting Pronouncements In November 2018, the FASB issued guidance, which clarifies the interaction between ASC Topic 808, Collaborative Arrangements , and ASC Topic 606, Revenue from Contracts with Customers . The guidance, among other items, clarifies that certain transactions between collaborative participants should be accounted for as revenue under Topic 606 when the collaborative arrangement participant is a customer in the context of a unit of account. The guidance is effective for fiscal years beginning after December 15, 2019. The Company believes that the adoption of this guidance will not have a material impact on the Company’s consolidated financial statements. In August 2018, the FASB issued guidance which changes the disclosure requirements for fair value measurement. The guidance amends the disclosure requirements in ASC Topic 820 by adding, changing, or removing certain disclosures. The guidance is effective for fiscal years beginning after December 15, 2019. The Company believes that the adoption of this guidance will not have a material impact on the Company’s consolidated financial statements. The Company is evaluating the impact of the adoption of the standard on its financial statement disclosures. In February 2016, the FASB issued guidance which supersedes much of the current guidance for leases. The new guidance requires lessees to recognize a right‑of‑use asset and a lease liability on their balance sheets for all the leases with terms greater than twelve months. Based on certain criteria, leases will be classified as either financing or operating, with classification affecting the pattern of expense recognition in the income statement. For leases with a term of twelve months or less, a lessee is permitted to make an accounting policy election by class of underlying asset not to recognize lease assets and lease liabilities. If a lessee makes this election, it should recognize lease expense for such leases generally on a straight‑line basis over the lease term. The guidance is effective for fiscal years beginning after December 15, 2018, and interim periods within those years, with early adoption permitted. In transition, lessees and lessors are required to recognize and measure leases at the beginning of the earliest period presented using a modified retrospective approach. The modified retrospective approach includes a number of optional practical expedients primarily focused on leases that commenced before the effective date of the new guidance, including continuing to account for leases that commence before the effective date in accordance with previous guidance, unless the lease is modified. The Company has evaluated the impact of the adoption of the guidance on its consolidated financial statements and expects to record a right-of-use asset and lease liability for certain of its leases as of the adoption date. The adoption of the guidance will not have a material effect on the Company’s financial statements.

Summary of Significant Accoun_3

Summary of Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2018
Summary of Significant Accounting Policies
Schedule of estimated useful lives used to depreciate the Company's assets	Estimated Useful Life Lab equipment 5 - 6 years Software 3 years Computer and office equipment 5 - 6 years Leasehold improvements Shorter of the lease term or estimated useful life

Property and Equipment (Tables)

Property and Equipment (Tables)	12 Months Ended
	Dec. 31, 2018
Property and Equipment
Schedule of property and equipment and related accumulated depreciation	December 31, 2018 2017 Laboratory equipment $ 1,037,000 $ 1,037,000 Software 92,000 92,000 Computer and office equipment 354,000 354,000 Leasehold improvements 745,000 745,000 2,228,000 2,228,000 Less accumulated depreciation (2,219,000) (2,164,000) $ 9,000 $ 64,000

Warrants (Tables)

Warrants (Tables)	12 Months Ended
	Dec. 31, 2018
Warrants
Schedule of warrants outstanding and warrant activity	Balance Balance Exercise Expiration December 31, Warrants Warrants Warrants December 31, Description Classification Price Date 2017 Issued Exercised Expired 2018 Non-tradable warrants Liability $ 172.50 July 2021 6,456 — — — 6,456 Tradable warrants Liability $ 73.80 July 2021 212,801 — — — 212,801 Non-tradable pre-funded warrants Equity $ 0.15 July 2023 394 — — — 394 Non-tradable warrants Equity $ 6.69375 * — 663,167 — — 663,167 Non-tradable warrants Equity $ 7.96875 * — 33,158 — — 33,158 Non-tradable warrants Equity $ 14.10 March 2021 — 5,000 — — 5,000 Non-tradable warrants Equity $ 21.15 March 2021 — 8,333 — — 8,333 Non-tradable warrants Equity $ 7.7895 June 2021 — 15,000 — — 15,000 Non-tradable pre-funded warrants Equity $ 0.15 none — 196,167 (110,000) — 86,167 Non-tradable warrants Equity $ 6.375 ** — 4,509,804 (76,842) — 4,432,962 Non-tradable pre-funded warrants Equity $ 0.15 none — 815,686 (553,618) — 262,068 219,651 6,246,315 (740,460) — 5,725,506 * These preferred stock warrants expire on the earlier of (A) the one-month anniversary of the date on which the Company publically releases topline results of the INSPIRE Pivotal phase 3 that compare the overall survival (OS) of patients in the rigosertib group vs the Physician’s Choice group, in all patients and in a subgroup of patients with IPSS-R very high risk and (B) December 31, 2019. These preferred stock warrants may be exercised on a cashless basis in certain circumstances specified therein. ** These preferred stock warrants expire on the 18-month anniversary of June 8, 2018, the date on which the Company publicly announced through the filing of a Current Report on Form 8-K that a Certificate of Amendment to the Company’s Tenth Amended and Restated Certificate of Incorporation, as amended, to increase the number of authorized shares of common stock from 100,000,000 to 250,000,000, was filed with the Secretary of State of the State of Delaware. These preferred stock warrants may be exercised on a cashless basis in certain circumstances specified therein.

Net Loss Per Share of Common _2

Net Loss Per Share of Common Stock (Tables)	12 Months Ended
	Dec. 31, 2018
Net Loss Per Share of Common Stock
Schedule of computation of basic and diluted earnings per share	Year ended December 31, 2018 2017 Basic and diluted net loss per share of common stock: Net loss attributable to Onconova Therapeutics, Inc $ (20,573,000) $ (24,092,000) Weighted average shares of common stock outstanding 4,124,073 600,022 Net loss per share of common stock—basic and diluted $ (4.99) $ (40.15)
Schedule of antidilutive securities which have been excluded from the computation of diluted weighted average shares outstanding	December 31, 2018 2017 Warrants 5,725,506 3,294,771 Stock options 379,328 894,996 6,104,834 4,189,767

Revenue (Tables)

Revenue (Tables)	12 Months Ended
	Dec. 31, 2018
Revenue
Schedule of recognized revenue under funding, license and collaboration agreements	Year ended December 31, 2018 2017 Symbio Upfront license fee recognition over time $ 398,000 $ 455,000 Supplies 61,000 332,000 Hanx Upfront license payment recognized at a point in time 450,000 — Pint Upfront license payment recognized at a point it time 319,000 — $ 1,228,000 $ 787,000
Schedule of deferred revenue	Symbio Upfront Payment Deferred balance at December 31, 2017 $ 4,546,000 Recognition to revenue 398,000 Deferred balance at December 31, 2018 $ 4,148,000

Balance Sheet Detail (Tables)

Balance Sheet Detail (Tables)	12 Months Ended
	Dec. 31, 2018
Balance Sheet Detail
Schedule of prepaid expenses and other current assets	December 31, 2018 2017 Research and development $ 415,000 $ 514,000 Manufacturing 111,000 48,000 Insurance 166,000 181,000 Other 68,000 77,000 $ 760,000 $ 820,000
Schedule of accrued expenses and other current liabilities	December 31, 2018 2017 Research and development $ 2,285,000 $ 1,912,000 Employee compensation 1,650,000 1,258,000 Professional fees 225,000 165,000 Other 13,000 — $ 4,173,000 $ 3,335,000

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	12 Months Ended
	Dec. 31, 2018
Fair Value Measurements
Schedule of Black-Scholes option pricing model assumptions	The Company estimated the fair value of the non-tradable warrant liability at December 31, 2018 using the Black-Scholes option pricing model with the following weighted-average assumptions: Risk-free interest rate 2.46 % Expected volatility 82.18 % Expected term 2.53 years Expected dividend yield 0 %
Schedule of financial assets and liabilities measured at fair value on a recurring basis	Fair Value Measurement as of: December 31, 2018 December 31, 2017 Level 1 Level 2 Level 3 Balance Level 1 Level 2 Level 3 Balance Tradable warrants liability $ 176,000 $ — $ — $ 176,000 $ 1,755,000 $ — $ — $ 1,755,000 Non-tradable warrants liability — — — — — — 18,000 18,000 Total $ 176,000 $ — $ — $ 176,000 $ 1,755,000 $ — $ 18,000 $ 1,773,000
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, 2016 $ 3,401,000 Reclassification of tradable warrants to Level 1 (4,857,000) Change in fair value upon re-measurement 1,474,000 Balance at December 31, 2017 18,000 Change in fair value upon re-measurement (18,000) Balance at December 31, 2018 $ —

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2018
Income Taxes
Schedule of income taxes based on income (loss) before income tax expense	December 31, 2018 2017 Domestic $ (20,579,000) $ (24,131,000) Foreign 45,000 52,000 $ (20,534,000) $ (24,079,000)
Schedule of provision for income taxes	December 31, 2018 2017 Current US Federal $ — $ — State and Local — — Foreign 13,000 13,000 Total Current $ 13,000 $ 13,000 Deferred US Federal $ (137,000) $ — State and Local — — Foreign — — Total Deferred $ — $ — Total (Benefit) Expense $ (124,000) $ 13,000
Schedule of principal components of the Company's deferred tax assets	December 31, 2018 2017 Deferred tax assets: Net operating loss carryovers $ 63,494,000 $ 57,557,000 R&D tax credits 82,246,000 79,725,000 Non-qualified stock options 4,611,000 5,355,000 Deferred revenue 1,175,000 1,242,000 Charitable contributions 4,000 4,000 Accrued expenses 454,000 407,000 Fixed assets 92,000 85,000 Deferred tax assets 152,076,000 144,375,000 Less valuation allowance (151,939,000) (144,375,000) Net deferred tax assets $ 137,000 $ —
Schedule of reconciliation of income tax (expense) benefit at the statutory federal income tax rate and income taxes as reflected in the financial statements	December 31, 2018 2017 Federal income tax expense at statutory rate 21.0 % 34.0 % Permanent items 1.4 (8.1) Effect of Tax Act — (116.9) State income tax, net of federal benefit 6.9 5.8 Tax credits 12.2 29.3 Provision to return — — Change in valuation allowance (36.6) 55.8 Other (4.3) — Effective income tax rate 0.6 % (0.1) %

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	12 Months Ended
	Dec. 31, 2018
Stock-Based Compensation
Schedule of stock-based compensation expense	Year ended December 31, 2018 2017 General and administrative $ 589,000 $ 975,000 Research and development 507,000 735,000 $ 1,096,000 $ 1,710,000
Schedule of stock option activity	Options Outstanding Weighted Weighted- Average Shares Average Remaining Aggregate Available Number Exercise Contractual Intrinsic for Grant of Shares Price Term (in years) Value Balance, December 31, 2017 3,842 59,666 $ 855.30 6.72 $ 0 Authorized 413,333 — Granted (335,405) 335,405 $ 7.50 Exercised — — $ — Forfeitures 15,743 (15,743) $ 615.72 Cancelled (2,249) Balance, December 31, 2018 95,264 379,328 $ 76.33 9.19 $ 0 Vested or expected to vest, December 31, 2018 365,790 $ 76.33 9.19 $ 0 Exercisable at December 31, 2018 51,973 $ 76.33 9.19 $ 0
Schedule of information with respect to stock options outstanding and exercisable	Information with respect to stock options outstanding and exercisable at December 31, 2018 is as follows: Exercise Price Shares Exercisable $3.41 – $7.05 308,339 — $16.35 – $97.50 50,555 32,060 $222.00 - $225.00 1,931 1,594 $348.00 – $597.00 4,931 4,777 $651.00 – $1,129.50 5,636 5,606 $1,992.00 - $2,268.00 7,585 7,585 $4,156.50 - $4,371.00 351 351 379,328 51,973
Schedule of weighted-average assumptions used for estimating the fair value of the stock compensation granted	Year ended December 31, 2018 2017 Risk-free interest rate 2.84 % 2.09 % Expected volatility 79.42 % 79.02 % Expected term 5.94 years 5.98 years Expected dividend yield 0 % 0 % Weighted average grant date fair value $ 1.18 $ 1.76

Commitments and Contingencies (

Commitments and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2018
Commitments and Contingencies
Schedule of future minimum lease payments under non-cancellable leases	December 31, 2018 2019 $ 175,000 2020 29,000 Total minimum lease payments $ 204,000

Nature of Business - Reverse St

Nature of Business - Reverse Stock Split (Details)	Sep. 25, 2018
Nature of Business
Reverse stock split ratio	0.067

Nature of Business - The Compan

Nature of Business - The Company - Clinical-stage Product Candidates (Details)	Dec. 31, 2018item
Nature of Business
Number of clinical-stage product candidates	3

Nature of Business - The Comp_2

Nature of Business - The Company - Preclinical Collaboration (Details) - Program	Jun. 30, 2018	Dec. 31, 2012
GBO
Preclinical Collaboration
Number of new programs to be collaborated and developed	2	2

Nature of Business - The Comp_3

Nature of Business - The Company (Details)	Sep. 25, 2018	Dec. 31, 2018$ / sharesshares	Jun. 07, 2018$ / sharesshares	Jun. 06, 2018shares	Mar. 21, 2018$ / sharesshares	Mar. 20, 2018shares	Dec. 31, 2017$ / sharesshares
Nature of Business
Common Stock authorized (in shares) | shares		250,000,000	250,000,000	100,000,000	100,000,000	25,000,000	25,000,000
Common stock, par value (in dollars per share) | $ / shares		$ 0.01	$ 0.01		$ 0.01		$ 0.01
Reverse stock split ratio	0.067

Nature of Business - Liquidity

Nature of Business - Liquidity - Financial Statement Items (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Nature of Business
Net loss	$ (20,410)	$ (24,092)
Accumulated deficit	381,896	362,316
Cash and cash equivalents	$ 16,970	$ 4,024	$ 21,450

Nature of Business - Liquidit_2

Nature of Business - Liquidity - Sale of Stock (Details) - USD ($) $ / shares in Units, $ in Thousands	Jul. 30, 2013	Dec. 31, 2016
Sale of Securities
Aggregate offering price		$ 24,900
IPO
Sale of Securities
Issuance of stock (in shares)	39,611
Price per share (in dollars per share)	$ 2,250
Proceeds from initial public offering of common stock, net of issuance costs	$ 79,811

Nature of Business - Liquidit_3

Nature of Business - Liquidity - Underwritten Public Offering (Details) - USD ($) $ in Millions	Nov. 14, 2017	May 17, 2017	Apr. 26, 2017
The Offering
Subsidiary, Sale of Stock [Line Items]
Issuance of stock (in shares)	61,333		165,079
Net proceeds from sales of common stock	$ 1.1	$ 5.3
Underwriter's option | Laidlaw | Maximum
Subsidiary, Sale of Stock [Line Items]
Issuance of stock (in shares)		24,239

Nature of Business - Liquidit_4

Nature of Business - Liquidity - Rights Offering (Details) - USD ($) $ in Millions	May 01, 2018	Feb. 12, 2018	Jul. 29, 2016
Sale of Securities
Proceeds from Issuance or Sale of Equity	$ 25.6	$ 8.7
Dealer-Manager Agreement, rights offering
Sale of Securities
Issuance of stock (in shares)	3,694,118	467,000	239,986
Aggregate net proceeds	$ 25.6	$ 8.7
Pre-funded warrants | Series A Convertible Preferred Stock
Sale of Securities
Shares of common stock warrants will purchase (in shares)		696,325
Pre-funded warrants | Series B Convertible Preferred Stock
Sale of Securities
Shares of common stock warrants will purchase (in shares)	4,509,804
Pre-funded warrants | Securities Offering
Sale of Securities
Shares of common stock warrants will purchase (in shares)	815,686	196,167

Summary of Significant Accoun_4

Summary of Significant Accounting Policies - Unaudited Interim Financial Information (Details)	Sep. 25, 2018
Summary of Significant Accounting Policies
Reverse stock split ratio	0.067

Summary of Significant Accoun_5

Summary of Significant Accounting Policies - Segment Information (Details)	12 Months Ended
	Dec. 31, 2018segment
Segment Information
Number of operating segments	1

Summary of Significant Accoun_6

Summary of Significant Accounting Policies - Concentrations of Credit Risk and Off-Balance Sheet Risk (Details) $ in Thousands	Dec. 31, 2018USD ($)
Concentrations of Credit Risk and Off-Balance Sheet Risk
Off-balance sheet risk, asset	$ 0
Off-balance sheet risk, liability	$ 0

Summary of Significant Accoun_7

Summary of Significant Accounting Policies - Property and Equipment (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2018USD ($)
Property and Equipment
Impairment losses	$ 0
Laboratory equipment | Minimum
Property and Equipment
Estimated useful lives	P5Y
Laboratory equipment | Maximum
Property and Equipment
Estimated useful lives	P6Y
Software
Property and Equipment
Estimated useful lives	P3Y
Computer and office equipment | Minimum
Property and Equipment
Estimated useful lives	P5Y
Computer and office equipment | Maximum
Property and Equipment
Estimated useful lives	P6Y

Property and Equipment - Proper

Property and Equipment - Property and Equipment and Related Accumulated Depreciation (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Property and Equipment
Property and equipment, gross	$ 2,228	$ 2,228
Less accumulated depreciation	(2,219)	(2,164)
Property and equipment, net	9	64
Laboratory equipment
Property and Equipment
Property and equipment, gross	1,037	1,037
Software
Property and Equipment
Property and equipment, gross	92	92
Computer and office equipment
Property and Equipment
Property and equipment, gross	354	354
Leasehold improvements
Property and Equipment
Property and equipment, gross	$ 745	$ 745

Property and Equipment - Deprec

Property and Equipment - Depreciation and Amortization Expense (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Property and Equipment
Depreciation and amortization expense	$ 55,000	$ 88,000

Warrants (Details)

Warrants (Details) - $ / shares	12 Months Ended
	Dec. 31, 2018	Jun. 07, 2018	Jun. 06, 2018	Mar. 21, 2018	Mar. 20, 2018	Dec. 31, 2017
Warrants outstanding and warrant activity
Balance at beginning of the period (in shares)	219,651
Warrants Issued (in shares)	6,246,315
Warrants Exercised (in shares)	(740,460)
Balance at end of the period (in shares)	5,725,506
Common Stock authorized (in shares)	250,000,000	250,000,000	100,000,000	100,000,000	25,000,000	25,000,000
Non-tradable warrants expiring July 2021, Liability
Warrants
Warrant exercise price (in dollars per share)	$ 172.50
Warrants outstanding and warrant activity
Balance at beginning of the period (in shares)	6,456
Balance at end of the period (in shares)	6,456
Tradable warrants expiring July 2021, Liability
Warrants
Warrant exercise price (in dollars per share)	$ 73.80
Warrants outstanding and warrant activity
Balance at beginning of the period (in shares)	212,801
Balance at end of the period (in shares)	212,801
Non-tradable pre-funded warrants expiring July 2023, Equity
Warrants
Warrant exercise price (in dollars per share)	$ 0.15
Warrants outstanding and warrant activity
Balance at beginning of the period (in shares)	394
Balance at end of the period (in shares)	394
Non-tradable warrants with exercise price 6.69375 Equity
Warrants
Warrant exercise price (in dollars per share)	$ 6.69375
Warrants outstanding and warrant activity
Warrants Issued (in shares)	663,167
Balance at end of the period (in shares)	663,167
Non-tradable warrants with exercise price 7.96875 Equity
Warrants
Warrant exercise price (in dollars per share)	$ 7.96875
Warrants outstanding and warrant activity
Warrants Issued (in shares)	33,158
Balance at end of the period (in shares)	33,158
Non-tradable warrants with exercise price 14.10 Equity
Warrants
Warrant exercise price (in dollars per share)	$ 14.10
Warrants outstanding and warrant activity
Warrants Issued (in shares)	5,000
Balance at end of the period (in shares)	5,000
Non-tradable warrants with exercise price 21.15 Equity
Warrants
Warrant exercise price (in dollars per share)	$ 21.15
Warrants outstanding and warrant activity
Warrants Issued (in shares)	8,333
Balance at end of the period (in shares)	8,333
Non-tradable warrants with exercise price 7.7895 Equity
Warrants
Warrant exercise price (in dollars per share)	$ 7.7895
Warrants outstanding and warrant activity
Warrants Issued (in shares)	15,000
Balance at end of the period (in shares)	15,000
Non-tradable pre-funded warrants with exercise Price 0.15 Equity
Warrants
Warrant exercise price (in dollars per share)	$ 0.15
Warrants outstanding and warrant activity
Warrants Issued (in shares)	196,167
Warrants Exercised (in shares)	(110,000)
Balance at end of the period (in shares)	86,167
Non-tradable warrants with exercise price 6.375 Equity
Warrants
Warrant exercise price (in dollars per share)	$ 6.375
Warrants outstanding and warrant activity
Warrants Issued (in shares)	4,509,804
Warrants Exercised (in shares)	(76,842)
Balance at end of the period (in shares)	4,432,962
Non-tradable warrants with exercise price 0.15 Equity1
Warrants
Warrant exercise price (in dollars per share)	$ 0.15
Warrants outstanding and warrant activity
Warrants Issued (in shares)	815,686
Warrants Exercised (in shares)	(553,618)
Balance at end of the period (in shares)	262,068

Net Loss Per Share of Common _3

Net Loss Per Share of Common Stock - Computation of Basic and Diluted Earnings per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Basic and diluted net loss per share of common stock:
Net loss attributable to Onconova Therapeutics, Inc.	$ (20,573)	$ (24,092)
Weighted average shares of common stock outstanding (in shares)	4,124,073	600,022
Net loss per share of common stock-basic and diluted	$ (4.99)	$ (40.15)

Net Loss Per Share of Common _4

Net Loss Per Share of Common Stock (Details) - shares	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
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	6,104,834	4,189,767
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	5,725,506	3,294,771
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	379,328	894,996

Revenue (Details)

Revenue (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Revenue
Revenue	$ 1,228	$ 787
Deferred revenue
Balance at the beginning of the period	455
Balance at the end of the period	226	455
Symbio Upfront Payment
Deferred revenue
Balance at the beginning of the period	4,546
Recognition to revenue	398
Balance at the end of the period	4,148	4,546
SymBio | Symbio Upfront Payment
Revenue
Revenue	398	455
SymBio | Supplies
Revenue
Revenue	61	$ 332
HanX | Hanx upfront licence payment
Revenue
Revenue	450
Pint | Pint upfront licence payment
Revenue
Revenue	$ 319

Balance Sheet Detail - Prepaid

Balance Sheet Detail - Prepaid Expenses and Other Current Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Prepaid expenses and other current assets:
Research and development	$ 415	$ 514
Manufacturing	111	48
Insurance	166	181
Other	68	77
Total	$ 760	$ 820

Balance Sheet Detail - Accrued

Balance Sheet Detail - Accrued Expenses and Other Current Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Accrued expenses and other current liabilities:
Research and development	$ 2,285	$ 1,912
Employee compensation	1,650	1,258
Professional fees	225	165
Other	13
Total	$ 4,173	$ 3,335

Fair Value Measurements - Secur

Fair Value Measurements - Securities Purchase Agreement (Details) - Securities Purchase Agreement $ / shares in Units, $ in Thousands	Jan. 05, 2016USD ($)$ / sharesshares
Sale of Securities
Issuance of stock (in shares)	12,912
Share price (in dollars per share) | $ / shares	$ 142.50
Aggregate gross proceeds | $	$ 1,840
Common Stock Warrants
Sale of Securities
Shares of common stock warrants will purchase (in shares)	6,456

Fair Value Measurements - Right

Fair Value Measurements - Rights Offering (Details) - Dealer-Manager Agreement, rights offering - $ / shares	May 01, 2018	Feb. 12, 2018	Jul. 29, 2016
Sale of Securities
Issuance of stock (in shares)	3,694,118	467,000	239,986
Tradable warrants
Sale of Securities
Rights or warrants issued (in shares)			212,801
Exercisable, term (in years)			5 years
Shares into which each warrant can be converted (in shares)			1
Exercise price (in dollars per share)			$ 73.80
Redemption period (in years)			1 year
Redemption price (in dollars per share)			$ 0.001
Volume weighted average price per share of common stock (in dollars per share)			$ 184.50
Threshold consecutive trading days (in days)			10 days
Pre-funded warrants
Sale of Securities
Rights or warrants issued (in shares)			43,760

Fair Value Measurements - Fair

Fair Value Measurements - Fair Value Assumptions (Details)	Dec. 31, 2018Y
Risk-free interest rate
Assumption used to estimate the fair value of warrant liability by utilizing the Black-Scholes option pricing model
Non-tradable warrant liability	2.46
Expected volatility
Assumption used to estimate the fair value of warrant liability by utilizing the Black-Scholes option pricing model
Non-tradable warrant liability	82.18
Expected term
Assumption used to estimate the fair value of warrant liability by utilizing the Black-Scholes option pricing model
Non-tradable warrant liability	2.53
Expected dividend yield
Assumption used to estimate the fair value of warrant liability by utilizing the Black-Scholes option pricing model
Non-tradable warrant liability	0

Fair Value Measurements - Fai_2

Fair Value Measurements - Fair Value Hierarchy Table (Details) - Recurring basis - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Liabilities measured at fair value
Total	$ 176	$ 1,773
Tradable warrants
Liabilities measured at fair value
Warrant liability	176	1,755
Non-tradable warrants
Liabilities measured at fair value
Warrant liability		18
Level 1
Liabilities measured at fair value
Total	176	1,755
Level 1 | Tradable warrants
Liabilities measured at fair value
Warrant liability	$ 176	1,755
Level 3
Liabilities measured at fair value
Total		18
Level 3 | Non-tradable warrants
Liabilities measured at fair value
Warrant liability		$ 18

Fair Value Measurements - Recon

Fair Value Measurements - Reconciliation of Level 3 Liabilities (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Reconciliation of the warrant liability measured at fair value
Balance at the beginning of the period	$ 18	$ 3,401
Change in fair value upon re-measurement	$ (18)	1,474
Balance at the end of the period		18
Tradable warrants
Reconciliation of the warrant liability measured at fair value
Reclassification of tradable warrants to Level 1		$ (4,857)

Fair Value Measurements - Trans

Fair Value Measurements - Transfers (Details)	Dec. 31, 2018USD ($)
Fair Value Measurements
Amount of transfers of assets out of Level 1 into Level 2	$ 0
Amount of transfers of assets out of Level 2 into Level 1	0
Amount of transfers of liabilities out of Level 1 into Level 2	0
Amount of transfers of liabilities out of Level 2 into Level 1	$ 0

Income Taxes - Income (Loss) be

Income Taxes - Income (Loss) before Income Tax Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Income taxes based on income (loss) before income tax expense
Domestic	$ (20,579)	$ (24,131)
Foreign	45	52
Net (loss) before income taxes	$ (20,534)	$ (24,079)

Income Taxes - Provision for In

Income Taxes - Provision for Income Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Current
Foreign	$ 13	$ 13
Total Current	13	13
Deferred
US Federal	(137)
Total (Benefit) Expense	$ (124)	$ 13

Income Taxes - Net Operating Lo

Income Taxes - Net Operating Loss Carryforwards (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2018USD ($)
Income Taxes
Net operating loss with indefinite life	$ 21,460
Federal
Income Taxes
Net operating loss (NOL) carry forwards	231,950
Net operating loss with expiration from 2022 to 2044	$ 210,490
NOL indefinite life percentage of limitation	80.00%
State
Income Taxes
Net operating loss (NOL) carry forwards	$ 187,950

Income Taxes - Tax Credit Carry

Income Taxes - Tax Credit Carry Forwards (Details) $ in Thousands	Dec. 31, 2018USD ($)
Research and Development Tax Credit Carry Forwards | IRS
Income Taxes
Tax credit carry forwards	$ 82,335

Income Taxes - Unrecognized Tax

Income Taxes - Unrecognized Tax Benefits (Details) $ in Thousands	Dec. 31, 2018USD ($)
Unrecognized tax benefits
Unrecognized income tax benefits	$ 0
Interest and penalties accrued	$ 0

Income Taxes - Deferred Tax Ass

Income Taxes - Deferred Tax Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Deferred tax assets:
Net operating loss carryovers	$ 63,494	$ 57,557
R&D tax credits	82,246	79,725
Non-qualified stock options	4,611	5,355
Deferred revenue	1,175	1,242
Charitable contributions	4	4
Accrued expenses	454	407
Fixed assets	92	85
Deferred tax assets	152,076	144,375
Less valuation allowance	(151,939)	(144,375)
Net deferred tax assets	$ 137	$ 0

Income Taxes - Valuation Allowa

Income Taxes - Valuation Allowance (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Income Taxes
Net change in valuation allowance	$ 7,564,000	$ (13,434,000)

Income Taxes - Reconciliation o

Income Taxes - Reconciliation of Income Tax (Expense) Benefit at the Statutory Federal Income Tax Rate and Income Taxes (Details)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Reconciliation of income tax (expense) benefit at the statutory federal income tax rate and income taxes
Federal income tax expense at statutory rate (as a percent)	21.00%	34.00%
Permanent items (as a percent)	1.40%	(8.10%)
Effect of Tax Act (as a percent)		(116.90%)
State income tax, net of federal benefit (as a percent)	6.90%	5.80%
Tax credits (as a percent)	12.20%	29.30%
Change in valuation allowance (as a percent)	(36.60%)	55.80%
Other (as a percent)	(4.30%)
Effective income tax rate (as a percent)	0.60%	(0.10%)

Stock-Based Compensation - Comm

Stock-Based Compensation - Common Stock Reserved for Issuance and Shares Available for Future Issuance (Details) - shares	Dec. 31, 2018	Dec. 31, 2017	Jul. 31, 2013
2018 Plan
Stock-Based Compensation
Common Stock reserved for issuance (in shares)	2,354
Maximum aggregate number of shares that may be issued under the plan	402,354
Common Stock available for future issuance (in shares)	95,264
2018 Plan | Common Stock
Stock-Based Compensation
Maximum aggregate number of shares that may be issued under the plan	400,000
Stock options
Stock-Based Compensation
Common Stock available for future issuance (in shares)	95,264	3,842
Stock options | 2013 Plan
Stock-Based Compensation
Common Stock reserved for issuance (in shares)			40,718
Evergreen provision, percentage of issued and outstanding common stock (as a percent)			4.00%
Evergreen provision, shares (in shares)			13,333

Stock-Based Compensation - Stoc

Stock-Based Compensation - Stock-Based Compensation Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Stock-Based Compensation
Net tax benefits related to the stock-based compensation costs	$ 0
Total stock-based compensation	1,096	$ 1,710
General and administrative
Stock-Based Compensation
Total stock-based compensation	589	975
Research and development
Stock-Based Compensation
Total stock-based compensation	$ 507	$ 735

Stock-Based Compensation - Summ

Stock-Based Compensation - Summary of Stock Option Activity (Details) - Stock options - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Shares Available for Grant
Balance at the beginning of the period (in shares)	3,842
Authorized (in shares)	413,333
Granted (in shares)	(335,405)
Forfeitures (in shares)	15,743
Cancelled (in shares)	(2,249)
Balance at the end of the period (in shares)	95,264	3,842
Number of Shares
Balance at the beginning of the period (in shares)	59,666
Granted (in shares)	(335,405)
Forfeitures (in shares)	(15,743)
Balance at the end of the period (in shares)	379,328	59,666
Vested or expected to vest at the end of the period (in shares)	365,790
Exercisable at the end of the period (in shares)	51,973
Weighted-Average Exercise Price
Balance at the beginning of the period (in dollars per share)	$ 855.30
Granted (in dollars per share)	7.50
Forfeitures (in dollars per share)	615.72
Balance at the end of the period (in dollars per share)	76.33	$ 855.30
Vested or expected to vest at the end of the period (in dollars per share)	76.33
Exercisable at the end of the period (in dollars per share)	$ 76.33
Additional Disclosures
Weighted average remaining contractual term	9 years 2 months 9 days	6 years 8 months 19 days
Weighted average remaining contractual term of options vested or expected to vest	9 years 2 months 9 days
Weighted average remaining contractual term of options exercisable	9 years 2 months 9 days
Aggregate intrinsic value of options outstanding	$ 0	$ 0
Aggregate intrinsic value of options vested or expected to vest	0
Aggregate intrinsic value of options exercisable	$ 0

Stock-Based Compensation - St_2

Stock-Based Compensation - Stock Options Outstanding and Exercisable (Details)	12 Months Ended
	Dec. 31, 2018$ / sharesshares
Stock options
Share-Based Compensation
Shares (in shares)	379,328
Exercisable (in shares)	51,973
Exercise Price Range $3.41 - $7.05
Share-Based Compensation
Exercise price, lower range limit (in dollars per share) | $ / shares	$ 3.41
Exercise price, upper range limit (in dollars per share) | $ / shares	$ 7.05
Exercise Price Range $3.41 - $7.05 | Stock options
Share-Based Compensation
Shares (in shares)	308,339
Exercise Price Range $16.35 - $97.50
Share-Based Compensation
Exercise price, lower range limit (in dollars per share) | $ / shares	$ 16.35
Exercise price, upper range limit (in dollars per share) | $ / shares	$ 97.50
Exercise Price Range $16.35 - $97.50 | Stock options
Share-Based Compensation
Shares (in shares)	50,555
Exercisable (in shares)	32,060
Exercise Price Range $222.00 - $225.00
Share-Based Compensation
Exercise price, lower range limit (in dollars per share) | $ / shares	$ 222
Exercise price, upper range limit (in dollars per share) | $ / shares	$ 225
Exercise Price Range $222.00 - $225.00 | Stock options
Share-Based Compensation
Shares (in shares)	1,931
Exercisable (in shares)	1,594
Exercise Price Range $348.00 - $597.00
Share-Based Compensation
Exercise price, lower range limit (in dollars per share) | $ / shares	$ 348
Exercise price, upper range limit (in dollars per share) | $ / shares	$ 597
Exercise Price Range $348.00 - $597.00 | Stock options
Share-Based Compensation
Shares (in shares)	4,931
Exercisable (in shares)	4,777
Exercise Price Range $651.00 - $1,129.50
Share-Based Compensation
Exercise price, lower range limit (in dollars per share) | $ / shares	$ 651
Exercise price, upper range limit (in dollars per share) | $ / shares	$ 1,129.50
Exercise Price Range $651.00 - $1,129.50 | Stock options
Share-Based Compensation
Shares (in shares)	5,636
Exercisable (in shares)	5,606
Exercise Price Range $1,992.00 - $2,268.00
Share-Based Compensation
Exercise price, lower range limit (in dollars per share) | $ / shares	$ 1,992
Exercise price, upper range limit (in dollars per share) | $ / shares	$ 2,268
Exercise Price Range $1,992.00 - $2,268.00 | Stock options
Share-Based Compensation
Shares (in shares)	7,585
Exercisable (in shares)	7,585
Exercise Price Range $4,156.50 - $4,371.00
Share-Based Compensation
Exercise price, lower range limit (in dollars per share) | $ / shares	$ 4,156.50
Exercise price, upper range limit (in dollars per share) | $ / shares	$ 4,371
Exercise Price Range $4,156.50 - $4,371.00 | Stock options
Share-Based Compensation
Shares (in shares)	351
Exercisable (in shares)	351

Stock-Based Compensation - Opti

Stock-Based Compensation - Options Granted after April 23, 2013 - Unrecognized Compensation Expense (Details) - Options granted after April 23, 2013 - Stock options $ in Thousands	12 Months Ended
	Dec. 31, 2018USD ($)
Stock-Based Compensation
Unrecognized compensation expense related to unvested stock options	$ 1,429
Weighted-average period for recognizing unrecognized compensation expense related to unvested stock options (in years)	2 years 3 months 22 days

Stock-Based Compensation - Op_2

Stock-Based Compensation - Options Granted after April 23, 2013 - Fair Value Assumptions (Details) - $ / shares	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Assumptions used
Risk-free interest rate (as a percent)	2.84%	2.09%
Expected volatility (as a percent)	79.42%	79.02%
Expected term (in years)	5 years 11 months 9 days	5 years 11 months 23 days
Expected dividend yield (as a percent)	0.00%	0.00%
Weighted average grant fair value (in dollars per share)	$ 1.18	$ 1.76
Options granted after April 23, 2013 | Stock options
Assumptions used
Expected dividend yield (as a percent)	0.00%	0.00%
Annualized forfeiture rate (as a percent)	4.14%	4.14%

Employee Benefit Plan (Details)

Employee Benefit Plan (Details) - Retirement Savings Plan - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Minimum age of employees required to be eligible for participation	21 years
Minimum working hours per year required to be eligible for participation	1000 hours
Employer's match for every dollar of the first specified percentage of payroll that employees invest	$ 0.75
Employer's matching contribution percentage	6.00%
Contributions	$ 224,000	$ 124,000

Commitments and Contingencies -

Commitments and Contingencies - Office and Lab Space in Newton, Pennsylvania (Details)	1 Months Ended	12 Months Ended						19 Months Ended
	Oct. 31, 2009Option	Feb. 28, 2020USD ($)	Feb. 28, 2019USD ($)	Feb. 28, 2018USD ($)	Mar. 31, 2017USD ($)	Mar. 31, 2016USD ($)	Mar. 31, 2015USD ($)	Feb. 28, 2017USD ($)	Sep. 30, 2012ft²	Jan. 31, 2007ft²
Operating leases
Lease rent per month		$ 14,700	$ 14,200	$ 13,800
Office and lab space of 8,100 square feet area in Newtown, Pennsylvania
Operating leases
Area of space leased (in square feet) | ft²										8,100
Number of options available for lease extensions | Option	3
Additional lease term under option	1 year
Lease rent per month					$ 11,900	$ 11,500	$ 11,000
Additional office space of 1,356 square feet area in Newtown, Pennsylvania
Operating leases
Area of space leased (in square feet) | ft²									1,356
Sub-lease rent per month								$ 1,600

Commitments and Contingencies_2

Commitments and Contingencies - Office Space in Munich, Germany (Details) - USD ($)	12 Months Ended
	Feb. 28, 2020	Feb. 28, 2019	Feb. 28, 2018
Operating leases
Lease rent per month	$ 14,700	$ 14,200	$ 13,800

Commitments and Contingencies_3

Commitments and Contingencies - Future Minimum Lease Payments (Details) $ in Thousands	Dec. 31, 2018USD ($)
Future minimum lease payments under non-cancellable leases
2019	$ 175
2020	29
Total minimum lease payments	$ 204

Commitments and Contingencies_4

Commitments and Contingencies - Rent Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Commitments and Contingencies
Net rent expense	$ 165	$ 152

Research Agreements (Details)

Research Agreements (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2018USD ($)
Temple
Research Agreements
Sales generated from products covered by the licensed patents	$ 0

License and Collaboration Agr_2

License and Collaboration Agreements - SymBio Agreement (Details) - USD ($)	Apr. 11, 2018	Mar. 02, 2018	Jan. 31, 2018	Jul. 31, 2011	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2018	Dec. 31, 2017
License and collaboration agreements
Revenue							$ 1,228,000	$ 787,000
Value of stock issued								$ 6,360,000
Common Stock
License and collaboration agreements
Issuance of stock (in shares)								267,418
Value of stock issued								$ 3,000
License agreement | SymBio
License and collaboration agreements
Percentage of discount on future purchases			35.00%
License agreement | SymBio | Maximum
License and collaboration agreements
Cumulative amount of discount on purchases			$ 300,000
License agreement | HanX
License and collaboration agreements
Upfront payment received	$ 450,000
License agreement | Pint
License and collaboration agreements
Revenue					$ 319,000
License agreement | Rigosertib | SymBio
License and collaboration agreements
Upfront payment received				$ 7,500,000
Aggregate milestone payments				22,000,000
Aggregate potential milestone payments based on annual net sales				$ 30,000,000
Percentage of royalty payments based on net sales of rigosertib (as a percent)				20.00%
License agreement | Rigosertib | Pint
License and collaboration agreements
Aggregate potential milestone payments based on annual net sales		$ 41,500,000
Prior written notice period for termination (in days)		45 days
License and collaboration | HanX license payment | HanX
License and collaboration agreements
Revenue						$ 450,000
Securities Purchase Agreement | Common Stock | Pint
License and collaboration agreements
Issuance of stock (in shares)		54,463
Value of stock issued		$ 1,250,000
Amount of premium		$ 319,000,000
United States and Japan | License agreement | Rigosertib | SymBio
License and collaboration agreements
Aggregate milestone payments due upon receipt of marketing approval for an additional indication				$ 4,000,000
United States | License agreement | Rigosertib | SymBio | MDS IV indication
License and collaboration agreements
Regulatory milestones payments due upon receipt of marketing approval for indication				5,000,000
United States | License agreement | Rigosertib | SymBio | Rigosertib oral in lower risk MDS patients
License and collaboration agreements
Regulatory milestones payments due upon receipt of marketing approval for indication				5,000,000
Japan | License agreement | Rigosertib | SymBio | MDS IV indication
License and collaboration agreements
Regulatory milestones payments due upon receipt of marketing approval for indication				3,000,000
Japan | License agreement | Rigosertib | SymBio | Rigosertib oral in lower risk MDS patients
License and collaboration agreements
Regulatory milestones payments due upon receipt of marketing approval for indication				$ 5,000,000

Preclinical Collaboration (Deta

Preclinical Collaboration (Details) $ in Thousands	1 Months Ended	3 Months Ended	12 Months Ended
	Nov. 30, 2014USD ($)	Jun. 30, 2018USD ($)Program	Dec. 31, 2018USD ($)	Dec. 31, 2013USD ($)Program	Dec. 31, 2012Program
Preclinical Collaboration
Gain on dissolution of GBO		$ 693	$ 824
Non-controlling interest portion upon consolidation		$ (163)	$ (163)
GBO
Preclinical Collaboration
Number of new programs to be collaborated and developed | Program		2			2
Ownership interest in the joint venture (as a percent)				90.00%
GBO | GVK BIO
Preclinical Collaboration
Number of new programs to be collaborated and developed | Program				2
Initial capital contribution				$ 500
Ownership interest in the joint venture (as a percent)	17.50%			10.00%
Additional capital contributions	$ 500
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 (Det

Related-Party Transactions (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Mount Sinai
Related-Party Transactions
Payments to related party	$ 351	$ 351
Amounts due to related party	88	526
Member of board of directors
Related-Party Transactions
Payments to related party	132	132
Amounts due to related party	$ 33	$ 33

Securities Registrations and _2

Securities Registrations and Sales Agreements - Sales and Purchase Agreements (Details) - USD ($) $ / shares in Units, $ in Thousands	Oct. 08, 2015	Dec. 31, 2016
Securities Registrations and Sales Agreement
Aggregate offering price		$ 24,900
Lincoln Park | Purchase agreement
Securities Registrations and Sales Agreement
Issuance of stock (in shares)	5,645
Aggregate offering price	$ 15,000
Net proceeds from sales of common stock	$ 1,500
Business day limit (in shares)	666
Business day limit contingent upon the closing price of the stock (in shares)	1,666
Regular purchase, one day limit	$ 1,000
Beneficial ownership percentage (as a percent)	4.99%
Beneficial ownership percentage after 180 days (as a percent)	9.99%
Maximum shares issued as a percentage of shares outstanding (as a percent)	19.99%
Minimum average price per share (in dollars per share)	$ 233.40
Stock issued as consideration (in shares)	1,333

Securities Registrations and _3

Securities Registrations and Sales Agreements - FBR capital (Details) - ATM Program - FBR Capital Markets and Co. $ in Thousands	1 Months Ended
	Dec. 31, 2016USD ($)shares
Sale of Securities
Issuance of stock (in shares) | shares	1,367
Net proceeds from sales of common stock | $	$ 64

Securities Registrations and _4

Securities Registrations and Sales Agreements - Underwriting and Placement agency agreement (Details) - Laidlaw - Placement Agency Agreement - USD ($) $ / shares in Units, $ in Thousands	Nov. 14, 2017	Nov. 09, 2017
Issuance of stock (in shares)		61,333
Share price (in dollars per share)		$ 22.50
Net proceeds from sales of common stock	$ 1,082

Securities Registrations and _5

Securities Registrations and Sales Agreements - underwriting agreement with HCW (Details) - USD ($) $ / shares in Units, $ in Millions

May 01, 2018

Apr. 27, 2018

Apr. 16, 2018

Feb. 12, 2018

Feb. 08, 2018

Nov. 14, 2017

Apr. 26, 2017

Dec. 31, 2017

Dec. 31, 2018

Sep. 24, 2018

Jun. 07, 2018

Jun. 06, 2018

Mar. 21, 2018

Mar. 20, 2018

Subsidiary, Sale of Stock [Line Items]

Net proceeds from stock offering

$ 25.6

$ 8.7

Common Stock authorized (in shares)

25,000,000

250,000,000

250,000,000

100,000,000

100,000,000

25,000,000

Percentage of exercise price of warrants

105.00%

Common Stock

Subsidiary, Sale of Stock [Line Items]

Issuance of stock (in shares)

267,418

Pre-funded warrants

Subsidiary, Sale of Stock [Line Items]

Warrant exercise price (in dollars per share)

$ 0.15

$ 0.15

Preferred stock warrants | Series A Convertible Preferred Stock

Subsidiary, Sale of Stock [Line Items]

Warrant exercise price (in dollars per share)

$ 6.375

Preferred stock warrants | Common Stock

Subsidiary, Sale of Stock [Line Items]

Warrant exercise price (in dollars per share)

$ 6.69375

$ 15.15

HCW

Subsidiary, Sale of Stock [Line Items]

Underwriters commission (in percentage)

8.00%

7.00%

Management fee (in percentage)

1.00%

1.00%

HCW | Common Stock

Subsidiary, Sale of Stock [Line Items]

Number of common stock shares for conversion preferred stock received as compensation

33,158

HCW | Preferred stock warrants | Common Stock

Subsidiary, Sale of Stock [Line Items]

Warrants exercise price received as compensation (in dollars per share)

$ 18.9375

$ 7.96875

The Offering

Subsidiary, Sale of Stock [Line Items]

Issuance of stock (in shares)

61,333

165,079

The Offering | Common Stock

Subsidiary, Sale of Stock [Line Items]

Issuance of stock (in shares)

3,105,882

380,500

Share price (in dollars per share)

$ 6.375

$ 15.15

The Offering | Pre-funded warrants

Subsidiary, Sale of Stock [Line Items]

Warrant purchase price (in dollars per share)

$ 15

The Offering | Pre-funded warrants | Common Stock

Subsidiary, Sale of Stock [Line Items]

Number of securities to each class of warrant (in shares)

815,686

196,167

Underwriter's option | HCW

Subsidiary, Sale of Stock [Line Items]

Period available to underwriters to purchase additional shares under the offering

30 days

Underwriter's option | HCW | Common Stock

Subsidiary, Sale of Stock [Line Items]

Issuance of stock (in shares)

588,235

86,500

Share price (in dollars per share)

$ 6.225

$ 15

Lock-up period for purchased shares by counterparty (in days)

135 days

Underwriter's option | HCW | Preferred stock warrants | Common Stock

Subsidiary, Sale of Stock [Line Items]

Number of securities to each class of warrant (in shares)

588,235

86,500

Warrant purchase price (in dollars per share)

$ 0.15

$ 0.15

Subsequent Events (Details)

Subsequent Events (Details)	Feb. 18, 2019USD ($)	Jan. 15, 2019USD ($)	Mar. 31, 2019USD ($)	Dec. 31, 2018
Stock options
Subsequent Events
Applicable Outstanding Option to exercise the Outstanding Options (in years)				9 years 2 months 9 days
Subsequent Events | One-time severance-related charge
Subsequent Events
Number of employees terminated			700,000
Annual estimated savings			$ 1,500,000
Subsequent Events | Consulting Agreement
Subsequent Events
Period of service (in months)	5 months
Consulting fee	$ 10,000
Service hours	20
Consulting fee for additional hour	$ 500
Written notice period (in days)	90 days
Subsequent Events | Separation Agreement
Subsequent Events
COBRA coverage (in months)		12 months
COBRA additional coverage (in months)		6 months
Subsequent Events | Separation Agreement | Employee severance
Subsequent Events
Severance amount		$ 933,774
Base salary		602,435
55 % of base salary		$ 331,339
Subsequent Events | Separation Agreement | Stock options
Subsequent Events
Applicable Outstanding Option to exercise the Outstanding Options (in years)		10 years