Stemline Therapeutics (STML) 10-Q 9 Nov 17 2017 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2017	Nov. 09, 2017
Document and Entity Information
Entity Registrant Name	STEMLINE THERAPEUTICS INC
Entity Central Index Key	1,264,587
Document Type	10-Q
Document Period End Date	Sep. 30, 2017
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Entity Current Reporting Status	Yes
Entity Filer Category	Accelerated Filer
Entity Common Stock, Shares Outstanding		25,286,907
Document Fiscal Year Focus	2,017
Document Fiscal Period Focus	Q3

Balance Sheets

Balance Sheets - USD ($)	Sep. 30, 2017	Dec. 31, 2016
Current assets:
Cash and cash equivalents	$ 10,265,356	$ 10,316,064
Short-term investments	55,259,923	36,562,900
Prepaid expenses and other current assets	598,356	290,747
Total current assets	66,123,635	47,169,711
Property and equipment, net	145,968	22,531
Long-term investments	14,348,432	20,714,551
Other assets	212,305	212,305
Total assets	80,830,340	68,119,098
Current liabilities:
Accounts payable and accrued expenses	14,368,329	9,284,514
Current portion of deferred grant revenue		898,199
Other current liabilities	96,827	71,100
Total current liabilities	14,465,156	10,253,813
Other liabilities	121,033	142,200
Total liabilities	14,586,189	10,396,013
Stockholders' equity:
Preferred stock $0.0001 par value, 5,000,000 shares authorized, none issued and outstanding at September 30, 2017 and December 31, 2016
Common stock $0.0001 par value, 53,750,000 shares authorized at September 30, 2017 and 33,750,000 shares authorized at December 31, 2016. 25,271,907 shares issued and outstanding at September 30, 2017 and 19,219,223 shares issued and outstanding at December 31, 2016	2,527	1,922
Additional paid-in capital	248,855,696	193,563,572
Accumulated other comprehensive loss	(87,683)	(99,802)
Accumulated deficit	(182,526,389)	(135,742,607)
Total stockholders' equity	66,244,151	57,723,085
Total liabilities and stockholders' equity	$ 80,830,340	$ 68,119,098

Balance Sheets (Parenthetical)

Balance Sheets (Parenthetical) - $ / shares	Sep. 30, 2017	Dec. 31, 2016
Balance Sheets
Preferred stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
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)	$ 0.0001	$ 0.0001
Common stock, shares authorized	53,750,000	33,750,000
Common stock, shares issued	25,271,907	19,219,223
Common stock, shares outstanding	25,271,907	19,219,223

Statements of Operations

Statements of Operations - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Revenues:
Grant revenue	$ 299,397	$ 299,401	$ 898,199	$ 741,953
Operating expenses:
Research and development	12,417,652	7,176,960	33,517,006	20,585,659
General and administrative	4,152,449	3,187,869	14,000,854	8,914,630
Total operating expenses	16,570,101	10,364,829	47,517,860	29,500,289
Loss from operations	(16,270,704)	(10,065,428)	(46,619,661)	(28,758,336)
Other income	381	1,378	381	11,736
Other expense	(3,566)		(3,566)
Interest income	217,742	132,006	543,753	417,113
Net loss before income taxes	(16,056,147)	(9,932,044)	(46,079,093)	(28,329,487)
Income tax benefit		8,822		35,578
Net loss	$ (16,056,147)	$ (9,923,222)	$ (46,079,093)	$ (28,293,909)
Net loss per common share:
Basic and Diluted (in dollars per share)	$ (0.68)	$ (0.56)	$ (2.01)	$ (1.59)
Weighted-average shares outstanding:
Basic and Diluted (in shares)	23,464,505	17,831,022	22,901,883	17,777,675

Statements of Comprehensive Los

Statements of Comprehensive Loss - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Statements of Comprehensive Loss
Net loss	$ (16,056,147)	$ (9,923,222)	$ (46,079,093)	$ (28,293,909)
Other comprehensive gain (loss):
Unrealized gain (loss) on investments, net of tax	30,207	(10,975)	9,112	117,914
Reclassification adjustment for (gain) loss on investments included in net loss	3,007	(1,378)	3,007	(11,736)
Other comprehensive gain (loss)	33,214	(12,353)	12,119	106,178
Comprehensive loss	$ (16,022,933)	$ (9,935,575)	$ (46,066,974)	$ (28,187,731)

Statement of Stockholders' Equi

Statement of Stockholders' Equity - 9 months ended Sep. 30, 2017 - USD ($)	Common Stock	Additional Paid-in Capital	Accumulated Other Comprehensive Loss	Accumulated Deficit	Total
Balance at Dec. 31, 2016	$ 1,922	$ 193,563,572	$ (99,802)	$ (135,742,607)	$ 57,723,085
Balance (in shares) at Dec. 31, 2016	19,219,223
Increase (Decrease) in Stockholders' Equity
Restricted stock grants	$ 89	(89)
Restricted stock grants (in shares)	899,950
Forfeiture of restricted stock grants	$ (4)	4
Forfeiture of restricted stock grants (in shares)	(42,048)
Stock-based compensation expense		6,178,079			6,178,079
Adoption of accounting standard update related to stock compensation accounting (ASU 2016-09)		704,689		(704,689)
Employee Stock Purchase Plan compensation expense		38,897			38,897
Issuance of common stock in connection with the ESPP	$ 2	121,669			121,671
Issuance of common stock in connection with the ESPP (in shares)	18,607
Issuance of common stock in connection with the exercise of stock options		7,179			$ 7,179
Issuance of common stock in connection with the exercise of stock options (in shares)	1,175				1,175
Issuance of common stock in connection with follow-on public offering	$ 518	48,241,696			$ 48,242,214
Issuance of common stock in connection with follow-on public offering (in shares)	5,175,000
Net loss				(46,079,093)	(46,079,093)
Other comprehensive income			12,119		12,119
Balance at Sep. 30, 2017	$ 2,527	$ 248,855,696	$ (87,683)	$ (182,526,389)	$ 66,244,151
Balance (in shares) at Sep. 30, 2017	25,271,907

Statements of Cash Flows

Statements of Cash Flows - USD ($)	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Cash flows from operating activities
Net loss	$ (46,079,093)	$ (28,293,909)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation	2,856	79,306
Stock-based compensation expense	6,178,079	5,666,813
Employee Stock Purchase Plan compensation expense	38,897	43,258
Amortization of premium paid on marketable securities	119,355	167,540
Net gain on sale of marketable securities	3,007	(11,736)
Income tax benefit from other comprehensive income		(35,578)
Changes in operating assets and liabilities:
Prepaid expenses and other current assets	(307,609)	128,277
Other assets		(212,305)
Accounts payable and accrued expenses	5,043,713	(734,024)
Deferred grant revenue	(898,199)	(241,953)
Other current liabilities	25,727
Other liabilities	(21,167)	128,734
Net cash used in operating activities	(35,894,434)	(23,315,577)
Cash flows from investing activities
Purchase of furniture and fixtures	(86,191)	(7,128)
Purchase of marketable securities	(55,396,963)	(22,194,580)
Sale and maturities of marketable securities	42,955,816	41,097,748
Net cash (used in) provided by investing activities	(12,527,338)	18,896,040
Cash flows from financing activities
Proceeds from issuance of common stock from follow-on public offering, net	48,242,214
Proceeds from issuance of common stock from ESPP	121,671	59,954
Proceeds from exercise of stock options	7,179	111,378
Net cash provided by financing activities	48,371,064	171,332
Net decrease in cash and cash equivalents	(50,708)	(4,248,205)
Cash and cash equivalents at beginning of period	10,316,064	13,376,196
Cash and cash equivalents at end of period	$ 10,265,356	$ 9,127,991

Organization and Basis of Prese

Organization and Basis of Presentation	9 Months Ended
	Sep. 30, 2017
Organization and Basis of Presentation
Organization and Basis of Presentation	1. Organization and Basis of Presentation Organization Stemline Therapeutics, Inc. (the “Company”) is a clinical stage biopharmaceutical company focused on discovering, acquiring, developing and potentially commercializing innovative oncology therapeutics that target difficult to treat cancers. The Company’s activities to date have primarily consisted of advancing its clinical stage programs, expanding and strengthening its intellectual property portfolio, identifying and acquiring additional product and technology rights and raising capital. The Company was incorporated in Delaware on August 8, 2003 and has its principal office in New York, New York. Stemline Therapeutics, Inc. has incurred losses from operations since inception of $194.0 million. Since its inception, most of its resources have been dedicated to the discovery, acquisition and preclinical and clinical development of its product candidates. The Company has expended, and will continue to expend, substantial resources for the foreseeable future developing and potentially commercializing its product pipeline, as well as acquiring additional assets. These expenditures include costs associated with general and administrative functions, facilities, research and development, acquiring new technologies, manufacturing product candidates, conducting preclinical experiments, clinical trials, obtaining regulatory approvals, preparing to commercialize, and commercializing any products that might be approved for marketing. The Company anticipates incurring additional losses until such time, if ever, that it can generate significant sales of its products currently in development. The Company expects its research and development expenses to increase significantly in connection with its ongoing and planned clinical trials and related manufacturing campaigns. The Company expects its general and administrative expenses to increase significantly as it begins its pre-commercial and commercial efforts. As a result, the Company expects to continue to incur significant and increasing operating losses for the foreseeable future. If adequate funds are not available to the Company on a timely basis, or at all, the Company may be required to terminate or delay clinical trials or other development activities for its product candidates for one or more indications, or delay its establishment of sales and marketing capabilities or other activities that may be necessary to commercialize its products, if the Company obtains marketing approval. Basis of Presentation The accompanying unaudited financial statements have been prepared in accordance with United States generally accepted accounting principles (“GAAP”) and with the instructions to Form 10-Q and Article 10 of Regulation S-X. Accordingly, they do not include all information and footnotes required by GAAP for complete financial statements. In the opinion of management, the accompanying financial statements include all adjustments (including normal recurring adjustments) considered necessary for fair presentation of the Company’s financial position, results of operations and cash flows for the periods presented. Operating results for the current interim period are not necessarily indicative of the results that may be expected for the fiscal year ending December 31, 2017 or any future periods. This Form 10-Q should be read in conjunction with the audited financial statements and accompanying notes in the Company’s Annual Report on Form 10-K for the year ended December 31, 2016 (“2016 Form 10-K”). The Company believes that its existing cash, cash equivalents, short-term investments and long-term investments will be sufficient to cover its cash flow requirements for at least the next two years. Use of Estimates The preparation of financial statements in conformity with generally accepted accounting principles in the U.S. (U.S. GAAP) requires management to make estimates and assumptions that affect the reported financial position at the date of the financial statements and the reported results of operations during the reporting period. Such estimates and assumptions affect the reported amounts of assets, liabilities, revenues and expenses and disclosure of contingent assets and liabilities in the financial statements and accompanying notes. Actual results could differ from those estimates. Reclassifications Certain reclassifications totaling $43,258 have been made to the Statement of Cash Flows for the period ended September 30, 2016 to conform to the employee stock purchase plan compensation expense presentation in the Statement of Cash Flows for the period ended September 30, 2017. These reclassifications to adjust stock-based compensation expense had no impact on previously reported cash used in operations in the Statement of Cash Flows.

Summary of Significant Accounti

Summary of Significant Accounting Policies	9 Months Ended
	Sep. 30, 2017
Summary of Significant Accounting Policies
Summary of Significant Accounting Policies	2. Summary of Significant Accounting Policies The Company’s significant accounting policies are described in Note 2 of the Notes to the Financial Statements included in the 2016 Form 10-K. There have been no changes to those policies. Recently Issued Accounting Pronouncements In May 2014, the Financial Accounting Standards Board (“FASB”), issued Accounting Standards Update (“ASU”) 2014-09, Revenue from Contracts with Customers (ASC 606) , to supersede nearly all existing revenue recognition guidance under GAAP. The core principle of ASU 2014-09 is to recognize revenues when promised goods or services are transferred to customers in an amount that reflects the consideration that is expected to be received for those goods or services. ASU 2014-09 defines a five-step process to achieve this core principle and, in doing so, it is possible more judgment and estimates may be required within the revenue recognition process than are required under existing GAAP, including identifying performance obligations in a contract, estimating the amount of variable consideration to include in the transaction price and allocating the transaction price to each separate performance obligation. In addition, disclosure is required about the nature, amount, timing and uncertainty of revenue and cash flows arising from customer contracts, including significant judgments and changes in judgments and assets recognized from costs incurred to obtain or fulfill a contract. The new standard is required to be applied either retrospectively to each prior reporting period presented (“full retrospective approach”) or retrospectively with the cumulative effect of initial application recognized at the date of initial application (“modified retrospective approach”). The new standard is effective for reporting periods beginning after December 15, 2017. In March, April, May and December 2016, the FASB issued ASU 2016-08, Revenue from Contracts with Customers: Principal versus Agent Considerations , ASU 2016-10, Revenue from Contracts with Customers: Identifying Performance Obligations and Licensing , ASU 2016-12, Revenue from Contracts with Customers: Narrow-Scope Improvements and Practical Expedients to provide supplemental adoption guidance and clarification to ASU 2014-09 , and ASU 2016-20, Technical Corrections and Improvements to Topic 606, Revenue from Contracts with Customers , respectively. The effective date for these new standards is the same as the effective date and transition requirements for ASU 2014-09. The Company will adopt this amendment on January 1, 2018, and it expects to utilize the full retrospective approach for a transition method. In November 2015, the FASB issued ASU No. 2015-17, Balance Sheet Classification of Deferred Taxes, which amended income tax guidance. This ASU simplifies the disclosure rules related to deferred taxes and requires that all deferred taxes be classified as non-current on the balance sheet. The amendments in this ASU are effective for interim and annual periods beginning after December 15, 2016. The Company has adopted this ASU as of January 1, 2017, and the adoption did not have a material impact on the financial statements. As of January 1, 2017, the Company adopted ASU No. 2016-09, Improvements to Employee Share-Based Payment Accounting , or ASU 2016-09, which amends Accounting Standards Codification, or ASC, Topic 718 , Compensation — Stock Compensation , and is effective for fiscal years beginning after December 15, 2016, and interim periods within those fiscal years. ASU 2016-09 simplifies several aspects of the accounting for share-based payment transactions, including the accounting for forfeitures, income tax consequences, classification of awards as either equity or liabilities, and classification on the statement of cash flows. Certain of the amendments will be applied using a modified retrospective transition method by means of a cumulative-effect adjustment to equity as of January 1, 2017, while other amendments will be applied retrospectively, prospectively or using either a prospective or a retrospective transition method. Upon adoption, the Company is beginning to account for forfeitures as they occur rather than estimate a forfeiture rate and has recorded a cumulative-effect adjustment in equity of $0.7 million on the date of initial adoption. In periods subsequent to adoption, a higher expense will be recognized earlier during the respective vesting periods of stock-based awards that are not forfeited. As a result of the valuation allowance against the Company’s deferred tax assets, there was no net adjustment to retained earnings for the change in accounting for unrecognized windfall tax benefits.

Liquidity and Capital Resources

Liquidity and Capital Resources	9 Months Ended
	Sep. 30, 2017
Liquidity and Capital Resources
Liquidity and Capital Resources	3. Liquidity and Capital Resources As of September 30, 2017, the Company has approximately $79.9 million in cash, cash equivalents, short and long-term investment securities. The Company primarily invests in highly liquid cash equivalents, short-term investments and long-term investments in U.S. Treasury and Agency securities and related money market funds and FDIC-insured bank certificates of deposit, with the balance in commercial bank operating accounts.

Prepaid Expenses and Other Curr

Prepaid Expenses and Other Current Assets	9 Months Ended
	Sep. 30, 2017
Prepaid Expenses and Other Current Assets
Prepaid Expenses and Other Current Assets	4. Prepaid Expenses and Other Current Assets Prepaid expenses and other current assets consist of the following at September 30, 2017 and December 31, 2016: September 30, December 31, 2017 2016 Prepaid third party vendor costs $ $ Prepaid insurance Other receivable Total $ $

Property and Equipment, Net

Property and Equipment, Net	9 Months Ended
	Sep. 30, 2017
Property and Equipment, Net
Property and Equipment, Net	5. Property and Equipment, Net Property and equipment, net, consist of the following at September 30, 2017 and December 31, 2016: September 30, December 31, 2017 2016 Office furniture and fixtures $ $ Leasehold improvements — Manufacturing equipment — Property and equipment Less accumulated depreciation ) ) Property and equipment, net $ $ Depreciation expense was $2,856 and $79,306 for the nine-month periods ended September 30, 2017 and 2016, respectively. Depreciation expense was $952 for the three-month periods ended September 30, 2017 and 2016, respectively.

Fair Value Measurements

Fair Value Measurements	9 Months Ended
	Sep. 30, 2017
Fair Value Measurements
Fair Value Measurements	6. 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 at the measurement date. Assets and liabilities that are measured at fair value are reported using a three-level fair value hierarchy that prioritizes the inputs used to measure fair value. This hierarchy maximizes the use of observable inputs and minimizes the use of unobservable inputs. The three levels of inputs used to measure fair value are as follows: Level 1 — Quoted prices in active markets for identical assets or liabilities that the Company has the ability to access at the measurement date. Level 2 — Inputs other than quoted prices in active markets that are observable for the asset or liability, either directly or indirectly. Level 3 — Inputs that are unobservable for the asset or liability. The following fair value hierarchy table presents information about each major category of the Company’s financial assets and liability measured at fair value on a recurring basis as of September 30, 2017 and December 31, 2016: September 30, 2017 Quoted Prices in Active Significant Markets for Other Significant Balance Identical Observable Unobservable at Assets Inputs Inputs September 30, (Level 1) (Level 2) (Level 3) 2017 Assets: Fixed-income treasury portfolio $ $ — $ — $ Certificate of Deposits — — Cash and cash equivalents — — Total assets at fair value $ $ $ — $ December 31, 2016 Quoted Prices in Active Significant Markets for Other Significant Balance Identical Observable Unobservable at Assets Inputs Inputs December 31, (Level 1) (Level 2) (Level 3) 2016 Assets: Fixed-income treasury portfolio $ $ — $ — $ Certificate of Deposits — — Cash and cash equivalents — — Total assets at fair value $ $ $ — $ The following is a summary of cash equivalents and available-for-sale investments held by the Company at September 30, 2017 and December 31, 2016: September 30, 2017 Gross Gross Estimated Amortized Unrealized Unrealized Fair Cost Gains* Losses* Value Cash: Cash from operating accounts $ $ — $ — $ Cash equivalents: Money market funds $ — — Total cash and cash equivalents $ — — $ Short-term investments: Fixed-income treasury portfolio: Fannie Mae — ) Federal farm credit bank — ) Federal home loan bank — ) Freddie Mac — ) U.S. Treasury Securities — ) Others — ) Certificate of Deposits — Total short-term investments ) Long-term investments: Fixed-income treasury portfolio: Fannie Mae — ) Federal home loan bank — ) Freddie Mac — ) U.S. Treasury Securities — ) Certificate of Deposits — — Total long-term investments — ) Total $ $ $ ) $ December 31, 2016 Gross Gross Estimated Amortized Unrealized Unrealized Fair Cost Gains* Losses* Value Cash: Cash from operating accounts $ $ — $ — $ Cash equivalents: Money market funds — — Total cash and cash equivalents — — Short-term investments: Fixed-income treasury portfolio: Fannie Mae — ) Federal farm credit bank ) Federal home loan bank ) Freddie Mac ) Certificate of Deposits — Total short-term investments ) Long-term investments: Fixed-income treasury portfolio: Fannie Mae — ) Federal home loan bank — ) Freddie Mac — ) Certificate of Deposits — Total long-term investments ) Total $ $ $ ) $ *The gross unrealized gains and losses captured in this footnote is before tax. At September 30, 2017 and December 31, 2016, the remaining contractual maturities of available-for-sale investments classified as current on the balance sheet were less than 12 months, and the remaining contractual maturities of available-for-sale investments classified as long-term were less than two years. There were no available-for-sale securities in a continuous unrealized loss position for greater than twelve months at September 30, 2017 and December 31, 2016. The Company has the ability to hold such securities with an unrealized loss until its forecasted recovery. The Company determined that there was no material change in the credit risk of the above investments. As a result, the Company determined it did not hold any investments with an other-than-temporary impairment as of September 30, 2017. Fair Value of Financial Instruments The Company’s financial instruments consist principally of cash and cash equivalents, investments, other current assets, accounts payable and accrued expenses. Cash and cash equivalents, short-term investments and long-term investments are carried at fair value (see above). Financial instruments including other current assets, accounts payable and accrued expenses are carried at cost, which approximate fair value given their short-term nature.

Accounts Payable and Accrued Ex

Accounts Payable and Accrued Expenses	9 Months Ended
	Sep. 30, 2017
Accounts Payable and Accrued Expenses
Accounts Payable and Accrued Expenses	7. Accounts Payable and Accrued Expenses Accounts payable and accrued expenses consist of the following at September 30, 2017 and December 31, 2016: September 30, December 31, 2017 2016 Accrued research and development costs $ $ Accrued compensation Accrued legal Other accrued liabilities Total accounts payable and accrued expenses $ $

Common Stock

Common Stock	9 Months Ended
	Sep. 30, 2017
Common Stock
Common Stock	8. Common Stock On January 20, 2017, the Company completed a third follow-on public offering, selling 4,500,000 shares at an offering price of $10 per share. Additionally, the underwriters exercised in full their over-allotment option to purchase an additional 675,000 shares at an offering price of $10 per share. Aggregate gross proceeds from this follow-on public offering, including the exercise of the over-allotment option, were $51.8 million, and net proceeds received, after underwriting fees of $3.2 million and offering expenses of $0.4 million, were approximately $48.2 million. As of September 30, 2017 and December 31, 2016, the Company was authorized to issue 53,750,000 and 33,750,000 shares of common stock, respectively. Dividends on common stock will be paid when, and if, declared by the board of directors. Each holder of common stock is entitled to vote on all matters and is entitled to one vote for each share held. The Company will, at all times, reserve and keep available, out of its authorized but unissued shares of common stock, sufficient shares to affect the conversion of shares from the exercise of stock options. In January 2013, the Company issued warrants to purchase up to 99,529 shares of the Company’s common stock. The warrants became exercisable during January 2014. The warrants are exercisable for cash or on a cashless basis at a price per share equal to $15.00. The term of the warrants is five years and they expire on January 28, 2018.

Accumulated Other Comprehensive

Accumulated Other Comprehensive Loss	9 Months Ended
	Sep. 30, 2017
Accumulated Other Comprehensive Loss
Accumulated Other Comprehensive Loss	9. Accumulated Other Comprehensive Loss The changes in accumulated balances for each component of other comprehensive loss are as follows: Three Months Ended September 30, Nine Months Ended September 30, 2017 2016 2017 2016 Balance at beginning of period $ ) $ ) $ ) $ ) Other comprehensive (loss) income before reclassification ) Amounts reclassified from accumulated other comprehensive (gain) loss* ) ) Income tax provision — — ) Total other comprehensive income (loss) ) Balance at end of period $ ) $ ) $ ) $ ) *Amounts reclassified affect other income in the statements of operations.

Net (Loss) Income Per Common Sh

Net (Loss) Income Per Common Share	9 Months Ended
	Sep. 30, 2017
Net (Loss) Income Per Common Share
Net (Loss) Income Per Common Share	10. Net (Loss) Income Per Common Share The Company accounts for and discloses net loss per share using the treasury stock method. Net loss per common share, or basic loss per share, is computed by dividing net loss by the weighted-average number of common shares outstanding. Since the Company is in a net loss for all periods presented, diluted net loss per share is not presented since the common stock equivalents would have an anti-dilutive effect on the per share calculation. The following table sets forth the computation of basic and diluted net loss per share for the periods indicated: Three Months Ended September 30, Nine Months Ended September 30, 2017 2016 2017 2016 Basic and diluted net loss per common share calculation: Net loss $ ) $ ) $ ) $ ) Basic and diluted weighted-average common shares Basic and diluted net loss per share $ ) $ ) $ ) $ ) The difference between basic and diluted weighted-average common shares generally results from the assumption that dilutive stock options outstanding were exercised, dilutive restricted stock has vested, and outstanding warrants are issued. For the nine-month periods ended September 30, 2017 and 2016, the Company reported a loss from operations and therefore, all potentially dilutive stock options, restricted stock, and outstanding warrants as of such date were excluded from the computation of diluted net loss per share as their effect would have been anti-dilutive. The total shares of stock options, restricted stock, and outstanding warrants that could potentially dilute earnings per share in the future, but which were not included in the calculation of diluted net loss per share because their affect would have been anti-dilutive were as follows: Nine Months Ended 2017 2016 Restricted stock Options outstanding Warrants Total

Grant Revenue

Grant Revenue	9 Months Ended
	Sep. 30, 2017
Grant Revenue
Grant Revenue	11. Grant Revenue In October 2013, the Company entered into a contract relating to the Therapy Acceleration Program (“the TAP Agreement”) with The Leukemia and Lymphoma Society (“LLS”). LLS is a national voluntary health agency which, among other activities, encourages and sponsors research relating to blood cancers to develop therapies to cure or mitigate these diseases. To further its mission, LLS provides research funding to entities that can demonstrate after LLS’s review process that their proposed research projects have scientific promise to advance LLS’s effort to find treatments and cures for blood cancers and their complications. Pursuant to the TAP Agreement, LLS agreed to provide funding to the Company not to exceed $3.5 million to fund the Company’s development program related to the Company’s preclinical and clinical product development activities. Through September 30, 2017, the Company has received $3.0 million based on milestones achieved. The Company could receive the additional $0.5 million based on the completion of a milestone event. The Company has recognized approximately $0.9 million and $0.7 million of revenue related to the LLS grant for the nine-month periods ended September 30, 2017 and 2016, respectively, which reflects revenue recognized on a straight-line basis based on the Company’s best estimates of work performed and qualifying costs incurred. The Company recognized approximately $0.3 million of revenue related to this funding for the three-month periods ended September 30, 2017 and September 30, 2016, respectively. The TAP Agreement terminates when there are no longer any payment obligations for either LLS or Stemline.

Income Taxes

Income Taxes	9 Months Ended
	Sep. 30, 2017
Income Taxes
Income Taxes	12. Income Taxes The Company did not record any other income tax provisions or benefits relating to its net operating losses for the nine-month periods ended September 30, 2017, respectively, due to the fact that the Company cannot benefit from its net operating losses or other deferred tax assets. The Company does not currently have the ability to carry back losses to previous years to recover taxes paid and future utilization of these losses is uncertain. The Company files income tax returns in the United States and in the State of New York. The Company is not currently being audited by the Internal Revenue Service or any state taxing jurisdiction. Deferred income taxes reflect the net tax effects of temporary differences between the carrying amounts of assets and liabilities for financial reporting purposes and their basis for income tax purposes and the tax effects of net operating loss and tax credit carryforwards. Valuation allowances reduce deferred tax assets to the amounts that are more likely than not to be realized. As of September 30, 2017, the Company has recorded additional deferred tax assets which are fully offset by a valuation allowance. Realization of the deferred tax assets is dependent on generating sufficient taxable income in the future. At present, the likelihood of the Company being able to fully utilize its deferred income tax benefits against future income is uncertain.

Stock-Based Compensation

Stock-Based Compensation	9 Months Ended
	Sep. 30, 2017
Stock-Based Compensation
Stock-Based Compensation	13. Stock-Based Compensation The Company’s 2016 Stock Equity Incentive Plan (the “2016 Plan”) was adopted by the board of directors and approved by the stockholders in May 2016. The 2016 Plan authorizes the Company to grant up to 1,812,932 shares of common stock to eligible employees, directors, and non-employee consultants and advisors to the Company. During June 2017, an amendment was approved by the stockholders to increase the authorized shares under the 2016 plan by 1,200,000 shares. Under the provisions of the 2016 Plan, no option will have a term in excess of 10 years. The Company’s 2012 Stock Equity Incentive Plan (the “2012 Plan”), which was adopted by the board of directors and approved by the stockholders in July 2012, became effective immediately prior to the closing of the Company’s initial public offering. In addition, the Company’s 2004 Stock Option and Grant Plan (the “2004 Plan”) was terminated effective immediately prior to the closing of the Company’s initial public offering. The 2012 Plan authorized the Company to grant up to 1,663,727 shares of common stock to eligible employees, directors, and non-employee consultants and advisors to the Company in the form of options to purchase common stock of the Company at a price not less than the estimated fair value at the date of grant. Under the provisions of the 2012 Plan, no option will have a term in excess of 10 years. With the adoption of the 2016 plan, all authorized but un-issued shares, totaling 12,932, under the 2012 plan were converted to the 2016 plan. All future awards will be granted out of the 2016 plan. As of September 30, 2017, there were 1,060,680 shares of common stock available for future grants under the 2016 Plan. Total compensation cost that has been charged against operations related to the above plans was approximately $6.2 million and $5.7 million for the nine-month periods ended September 30, 2017 and 2016, respectively. As a result of the valuation allowance against the Company’s deferred tax assets, there was no net adjustment to retained earnings for the change in accounting for unrecognized windfall tax benefits. The following table summarizes stock-based compensation related to the above plans by expense category for the three-month and nine-month periods ended September 30, 2017 and 2016, respectively: Three Months Ended September 30, Nine Months Ended September 30, 2017 2016 2017 2016 Research and development $ $ $ $ General and administrative Total $ $ $ $ Stock Options The Company grants stock options to employees, directors and non-employee consultants, with exercise prices equal to the closing price of the underlying shares of the Company’s common stock on the date that the options are granted. Options granted have a term of 10 years from the grant date. Options granted to employees generally vest over a four-year period from date of grant or if vesting based on market condition, awards vest based on the derived service period which is the estimated period of time that would be required to satisfy the market condition. Options granted to directors vest in equal yearly installments over a three-year period from the date of grant. Options to directors are granted on an annual basis and represent compensation for services performed on the Board of Directors. Compensation cost for stock options granted to employees and directors is charged against operations using the straight-line attribution method between the grant date for the option and each vesting date. The Company estimates the fair value of stock options on the grant date by applying the Black-Scholes option pricing valuation model. The application of this valuation model involves assumptions that are highly subjective, judgmental and sensitive in the determination of compensation cost. The weighted-average key assumptions used in determining the fair value of options granted for the three-month and nine-month periods ended September 30, 2017 and 2016, respectively are as follows: Three Months Ended September 30, Nine Months Ended September 30, 2017 2016 2017 2016 Weighted-average volatility % % % % Weighted-average risk-free interest rate % % % % Weighted-average expected term in years Dividend yield % % % % Due to the lack of trading history, the Company’s computation of stock-price volatility is based on the volatility rates of comparable publicly held companies over a period equal to the estimated useful life of the options granted by the Company. The Company’s computation of expected life was determined using the “simplified” method which is the midpoint between the vesting date and the end of the contractual term. The Company believes that it does not have sufficient reliable exercise data in order to justify the use of a method other than the “simplified” method of estimating the expected exercise term of employee stock option grants. The Company has paid no dividends to stockholders. The risk-free interest rate is based on the zero-coupon U.S. Treasury yield at the date of grant for a term equivalent to the expected term of the option. For the nine-month periods ended September 30, 2017 and 2016, the Company issued 1,175 and 33,751 shares, respectively, of the Company’s common stock upon the exercise of outstanding stock options and received proceeds of $7,179 and $111,378, respectively. As of September 30, 2017, there was approximately $5.9 million of unrecognized compensation cost related to unamortized stock option compensation which is expected to be recognized over a remaining weighted-average period of approximately 1.60 years. The following table summarizes the activity related to the Company’s stock options for the nine months ended September 30, 2017: Options Weighted- Weighted- Aggregate Outstanding at December 31, 2016 $ Options granted Options exercised ) Options forfeited ) Outstanding at September 30, 2017 $ $ Options exercisable at September 30, 2017 $ $ The aggregate intrinsic value in the previous table reflects the total pretax intrinsic value (the difference between the Company’s closing stock price on the last trading day of the quarter ended September 30, 2017 and the exercise price of the options, multiplied by the number of in-the-money stock options) that would have been received by the option holders had all option holders exercised their options on September 30, 2017. The intrinsic value of the Company’s stock options changes based on the closing price of the Company’s common stock. Restricted Stock The Company grants restricted stock to its employees, directors, and non-employee consultants. Restricted stock is recorded as deferred compensation and charged against income on a straight-line basis over the vesting period, which ranges from immediate to four years in duration. If vesting of the award is based on a performance or market condition, awards vest based on the derived service period which is the estimated period of time that would be required to satisfy the performance or market condition. Restricted stock awards to directors vest in equal installments over a three-year period from the grant date. Compensation cost for restricted stock is based on the award’s grant date fair value, which is the closing market price of the Company’s common stock on the grant date, multiplied by the number of shares awarded. The following table summarizes the activity related to the Company’s restricted stock for the nine months ended September 30, 2017: Number of Shares Weighted- Outstanding at December 31, 2016 $ Shares granted Shares vested ) Shares forfeited ) Outstanding at September 30, 2017 $ For the nine-month period ended September 30, 2017, the Company granted 899,950 shares of restricted stock, at a weighted-average grant date fair value of $8.87 per share amounting to approximately $8.0 million in total aggregate fair value. As of September 30, 2017, 1,796,749 shares remained unvested and there was approximately $10.8 million of unrecognized compensation cost related to restricted stock which is expected to be recognized over a remaining weighted-average period of approximately 2.19 years. The total fair value of restricted stock vested during the nine-month periods ended September 30, 2017 and 2016 was approximately $3.0 million and $2.0 million, respectively. Awards Granted to Non-Employee Consultants The Company grants stock options, restricted stock, and unrestricted stock to non-employee consultants. The Company periodically re-measures the fair value of stock-based awards issued to non-employees and records expense over the requisite service period. Total compensation cost charged against operations related to stock-based awards granted to non-employee consultants was approximately $0.5 million and $0.3 million for the nine-month periods ended September 30, 2017 and 2016, respectively. Employee Stock Purchase Plan In September 2015, the Company adopted its 2015 Employee Stock Purchase Plan (the “2015 ESPP”). The 2015 ESPP is qualified as an employee stock purchase plan under Section 423 of the Internal Revenue Code of 1986, as amended (the “IRC”). Under the 2015 ESPP, the Company will grant rights to purchase shares of common stock under the 2015 ESPP (“Rights”) at prices not less than 85% of the lesser of (i) the fair value of the shares on the date of grant of such Rights or (ii) the fair value of the shares on the date such Rights are exercised. Therefore, the 2015 ESPP is considered compensatory under FASB ASC 718 since, along with other factors, it includes a purchase discount of greater than 5%. The Company recorded approximately $38,897 and $43,258 of compensation expense for the nine months ended September 30, 2017 and 2016, respectively, related to participation in the 2015 ESPP.

Commitments and Contingencies

Commitments and Contingencies	9 Months Ended
	Sep. 30, 2017
Commitments and Contingencies
Commitments and Contingencies	14. Commitments and Contingencies The Company has entered into research and development agreements with third-parties for the development of oncology products and technologies. According to these agreements, the Company typically funds the development of such assets and potentially makes development-based milestone payments, and royalty and sales-based milestone payments based on net sales should the product candidates be approved for marketing. The timing and the amount of milestone and royalty payments in the future are not certain. The Company has also entered into license agreements, including ones with licenses to certain intellectual property rights, in the field of oncology and other indications. The Company is generally required to make upfront payments as well as other payments upon successful completion of preclinical, clinical, regulatory or sales milestones, should such milestones occur. In addition, these agreements generally would require the Company to pay royalties on sales of the products arising from these agreements, should a product candidate under the license agreement receive regulatory approval. These agreements generally permit the Company to terminate the agreement with no significant continuing obligation. Under the Company’s research and development and/or license agreements, if the Company were to achieve certain milestones, primarily late stage clinical trial events, marketing approval, and sales, the Company could be required to pay up to a total of $112.9 million in future periods. As of September 30, 2017, the Company has paid or accrued $5.6 million in payments pursuant to such agreements. If a product candidate under such agreements were to receive marketing approval, royalty payments, largely single digit, are payable on commercial sales of certain products. The Company has committed to make potential future milestone and royalty payments to third-parties as part of its research and development and licensing agreements. Payments generally become due and payable only upon the achievement of certain developmental, regulatory and/or commercial milestones. Because the achievement of these milestones is neither guaranteed nor reasonably estimable, the Company has not recorded a liability on its balance sheet for any such contingencies. Contractual Agreements In February 2013, the Company entered into a bioprocessing services agreement with a vendor for approximately $2.9 million if all services are performed under the contract. As of December 31, 2014, the contract services were performed on the initial work order and had been paid by the Company. During 2014 through 2017, the Company entered into new work order agreements with this vendor totaling approximately $20.4 million, with services to be rendered on these agreements through 2018. The Company has received and paid for services relating to these agreements in the amount of $10.0 million. The Company has agreements in place with contract research organizations, or CROs, in connection with its clinical programs. The Company’s total expenditures in the future would be approximately $6.1 million assuming the successful advancement of its programs. Lease Agreement In July 2013, the Company entered into a leasing agreement with respect to its corporate offices at 750 Lexington Avenue, New York, New York, for a monthly rent of $50,625. The term of this lease agreement was 36 months. In February 2016, the Company entered into a leasing agreement with respect to its corporate offices at 750 Lexington Avenue, New York, New York, for a monthly rent of $69,750 and a 42-month term. The term of this lease agreement commenced on July 1, 2016 and is set to expire on December 31, 2019. The aggregate minimum lease commitment over the 42-month term of the lease is approximately $2.7 million. The Company has provided the landlord with a security deposit equal to three months rent, totaling $209,250. The Company’s future annual minimum lease payments for each of the following calendar years are as follows: Remainder of 2017 $ 2018 2019 Total minimum payments $ Rent expense charged to operations was $598,175 and $533,305 for the nine-month periods ended September 30, 2017 and 2016, respectively. Rent expense is included in general and administrative expenses in the Company’s Statements of Operations. Contingencies On February 3, 2017, a putative class action lawsuit was filed in the United States District Court for the Southern District of New York against Stemline, its Chief Executive Officer, and its Chief Accounting Officer, alleging violations of the Exchange Act and Rule 10b-5 promulgated thereunder during the period from January 19, 2017 through February 1, 2017, as well as violations of Section 11 and 15 of the Securities Act of 1933 (the “1933 Act”) arising from the Company’s January 2017 follow-on public offering. On February 3, 2017, a putative class action lawsuit was filed in the United States District Court for the Southern District of New York against Stemline, its Chief Executive Officer, and its Chief Accounting Officer, alleging violations of the Exchange Act and Rule 10b-5 promulgated thereunder during the period from January 19, 2017 and February 1, 2017. On February 8, 2017, a putative class action lawsuit was filed in the United States District Court for the Southern District of New York against Stemline, its Chief Executive Officer, and its Chief Accounting Officer, alleging violations of the Exchange Act and Rule 10b-5 promulgated thereunder during the period from January 19, 2017 through February 1, 2017, as well as violations of 1933 Act arising from the Company’s January 2017 follow-on public offering. On February 10, 2017, a putative class action lawsuit was filed in the United States District Court for the Southern District of New York against Stemline, its Chief Executive Officer, and its Chief Operating Officer, alleging violations of the Exchange Act and Rule 10b-5 promulgated thereunder during the period from January 6, 2017 through February 1, 2017. Each of the above lawsuits is premised upon allegations that the defendants made false and misleading statements and/or omissions by failing to earlier disclose that a cancer patient in a Stemline clinical trial of SL-401 who experienced the side effect of capillary leak syndrome, or CLS, died on January 18, 2017. Additionally, the complaint alleges that, as a result of the foregoing, certain of the defendants’ statements about Stemline’s business, operations, and prospects were materially false and misleading and/or lacked a reasonable basis. In April 2017, the United States District Court for the Southern District of New York consolidated these four shareholder actions into a single action, and appointed three purported individual investors in the Company as Lead Plaintiff to represent the proposed class. This class appointed Pomerantz LLP and the Rosen Law Firm as Co-Lead Counsel. On June 26, 2017, Lead Plaintiffs filed an amended complaint in the consolidated action, naming as defendants, the Company, its directors, certain of its officers, and Jefferies LLC, and alleging violations of the Exchange Act and Rule 10b-5 promulgated thereunder during the period from January 20, 2017 through February 1, 2017, as well as violations of the 1933 Act arising from the Company’s January 2017 follow-on public offering. On May 2, 2017, a shareholder derivative litigation was filed in New York Supreme Court in New York County against all of the Company’s directors and certain of its officers in litigation captioned Hancock v. Bergstein . The Company is named only as a nominal defendant. The suit alleges that the officers and directors breached their fiduciary duties to the Company, unjustly enriched themselves, wasted corporate assets, abused their control, and grossly mismanaged the Company. The claims are based on allegations that the defendants engaged in improper conduct by failing to disclose in connection with its follow-on public offering of stock on January 20, 2017, that a cancer patient in a Stemline clinical trial died on January 18, 2017. It is alleged that the non-disclosure of that adverse event in the follow-on public offering has lead the Company to incur losses, including defense and investigation costs, and allowed the defendants to reap substantial financial rewards in the form of bonuses and other compensation. The Company intends to vigorously defend against these actions. However, there is no assurance that the Company will be successful in its defense or that insurance will be available or adequate to fund any settlement or judgment or the litigation costs of the actions. The Company is unable to predict the outcome or reasonably estimate a range of possible loss at this time. The Company is obligated to indemnify its officers and directors against all reasonable costs and expenses related to stockholder and other claims pertaining to actions taken in their capacity as officers and directors which are not covered by the Company’s directors and officer’s insurance policy. These indemnification obligations are in the regular course of business and in most cases do not include a limit on maximum potential future payments, nor are there any recourse provisions or collateral that may offset the cost.

Summary of Significant Accoun22

Summary of Significant Accounting Policies (Policies)	9 Months Ended
	Sep. 30, 2017
Summary of Significant Accounting Policies
Recently Issued Accounting Pronouncements	Recently Issued Accounting Pronouncements In May 2014, the Financial Accounting Standards Board (“FASB”), issued Accounting Standards Update (“ASU”) 2014-09, Revenue from Contracts with Customers (ASC 606) , to supersede nearly all existing revenue recognition guidance under GAAP. The core principle of ASU 2014-09 is to recognize revenues when promised goods or services are transferred to customers in an amount that reflects the consideration that is expected to be received for those goods or services. ASU 2014-09 defines a five-step process to achieve this core principle and, in doing so, it is possible more judgment and estimates may be required within the revenue recognition process than are required under existing GAAP, including identifying performance obligations in a contract, estimating the amount of variable consideration to include in the transaction price and allocating the transaction price to each separate performance obligation. In addition, disclosure is required about the nature, amount, timing and uncertainty of revenue and cash flows arising from customer contracts, including significant judgments and changes in judgments and assets recognized from costs incurred to obtain or fulfill a contract. The new standard is required to be applied either retrospectively to each prior reporting period presented (“full retrospective approach”) or retrospectively with the cumulative effect of initial application recognized at the date of initial application (“modified retrospective approach”). The new standard is effective for reporting periods beginning after December 15, 2017. In March, April, May and December 2016, the FASB issued ASU 2016-08, Revenue from Contracts with Customers: Principal versus Agent Considerations , ASU 2016-10, Revenue from Contracts with Customers: Identifying Performance Obligations and Licensing , ASU 2016-12, Revenue from Contracts with Customers: Narrow-Scope Improvements and Practical Expedients to provide supplemental adoption guidance and clarification to ASU 2014-09 , and ASU 2016-20, Technical Corrections and Improvements to Topic 606, Revenue from Contracts with Customers , respectively. The effective date for these new standards is the same as the effective date and transition requirements for ASU 2014-09. The Company will adopt this amendment on January 1, 2018, and it expects to utilize the full retrospective approach for a transition method. In November 2015, the FASB issued ASU No. 2015-17, Balance Sheet Classification of Deferred Taxes, which amended income tax guidance. This ASU simplifies the disclosure rules related to deferred taxes and requires that all deferred taxes be classified as non-current on the balance sheet. The amendments in this ASU are effective for interim and annual periods beginning after December 15, 2016. The Company has adopted this ASU as of January 1, 2017, and the adoption did not have a material impact on the financial statements. As of January 1, 2017, the Company adopted ASU No. 2016-09, Improvements to Employee Share-Based Payment Accounting , or ASU 2016-09, which amends Accounting Standards Codification, or ASC, Topic 718 , Compensation — Stock Compensation , and is effective for fiscal years beginning after December 15, 2016, and interim periods within those fiscal years. ASU 2016-09 simplifies several aspects of the accounting for share-based payment transactions, including the accounting for forfeitures, income tax consequences, classification of awards as either equity or liabilities, and classification on the statement of cash flows. Certain of the amendments will be applied using a modified retrospective transition method by means of a cumulative-effect adjustment to equity as of January 1, 2017, while other amendments will be applied retrospectively, prospectively or using either a prospective or a retrospective transition method. Upon adoption, the Company is beginning to account for forfeitures as they occur rather than estimate a forfeiture rate and has recorded a cumulative-effect adjustment in equity of $0.7 million on the date of initial adoption. In periods subsequent to adoption, a higher expense will be recognized earlier during the respective vesting periods of stock-based awards that are not forfeited. As a result of the valuation allowance against the Company’s deferred tax assets, there was no net adjustment to retained earnings for the change in accounting for unrecognized windfall tax benefits.

Prepaid Expenses and Other Cu23

Prepaid Expenses and Other Current Assets (Tables)	9 Months Ended
	Sep. 30, 2017
Prepaid Expenses and Other Current Assets
Schedule of prepaid expenses and other current assets	September 30, December 31, 2017 2016 Prepaid third party vendor costs $ $ Prepaid insurance Other receivable Total $ $

Property and Equipment, Net (Ta

Property and Equipment, Net (Tables)	9 Months Ended
	Sep. 30, 2017
Property and Equipment, Net
Schedule of property and equipment, net	September 30, December 31, 2017 2016 Office furniture and fixtures $ $ Leasehold improvements — Manufacturing equipment — Property and equipment Less accumulated depreciation ) ) Property and equipment, net $ $

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	9 Months Ended
	Sep. 30, 2017
Fair Value Measurements
Schedule of the Company's financial assets and liabilities measured at fair value on a recurring basis	September 30, 2017 Quoted Prices in Active Significant Markets for Other Significant Balance Identical Observable Unobservable at Assets Inputs Inputs September 30, (Level 1) (Level 2) (Level 3) 2017 Assets: Fixed-income treasury portfolio $ $ — $ — $ Certificate of Deposits — — Cash and cash equivalents — — Total assets at fair value $ $ $ — $ December 31, 2016 Quoted Prices in Active Significant Markets for Other Significant Balance Identical Observable Unobservable at Assets Inputs Inputs December 31, (Level 1) (Level 2) (Level 3) 2016 Assets: Fixed-income treasury portfolio $ $ — $ — $ Certificate of Deposits — — Cash and cash equivalents — — Total assets at fair value $ $ $ — $
Summary of cash equivalents and available-for-sale investments held by the Company	September 30, 2017 Gross Gross Estimated Amortized Unrealized Unrealized Fair Cost Gains* Losses* Value Cash: Cash from operating accounts $ $ — $ — $ Cash equivalents: Money market funds $ — — Total cash and cash equivalents $ — — $ Short-term investments: Fixed-income treasury portfolio: Fannie Mae — ) Federal farm credit bank — ) Federal home loan bank — ) Freddie Mac — ) U.S. Treasury Securities — ) Others — ) Certificate of Deposits — Total short-term investments ) Long-term investments: Fixed-income treasury portfolio: Fannie Mae — ) Federal home loan bank — ) Freddie Mac — ) U.S. Treasury Securities — ) Certificate of Deposits — — Total long-term investments — ) Total $ $ $ ) $ December 31, 2016 Gross Gross Estimated Amortized Unrealized Unrealized Fair Cost Gains* Losses* Value Cash: Cash from operating accounts $ $ — $ — $ Cash equivalents: Money market funds — — Total cash and cash equivalents — — Short-term investments: Fixed-income treasury portfolio: Fannie Mae — ) Federal farm credit bank ) Federal home loan bank ) Freddie Mac ) Certificate of Deposits — Total short-term investments ) Long-term investments: Fixed-income treasury portfolio: Fannie Mae — ) Federal home loan bank — ) Freddie Mac — ) Certificate of Deposits — Total long-term investments ) Total $ $ $ ) $ *The gross unrealized gains and losses captured in this footnote is before tax.

Accounts Payable and Accrued 26

Accounts Payable and Accrued Expenses (Tables)	9 Months Ended
	Sep. 30, 2017
Accounts Payable and Accrued Expenses
Schedule of components of accounts payable and accrued expenses	September 30, December 31, 2017 2016 Accrued research and development costs $ $ Accrued compensation Accrued legal Other accrued liabilities Total accounts payable and accrued expenses $ $

Accumulated Other Comprehensi27

Accumulated Other Comprehensive Loss (Tables)	9 Months Ended
	Sep. 30, 2017
Accumulated Other Comprehensive Loss
Schedule of change in accumulated other comprehensive loss	Three Months Ended September 30, Nine Months Ended September 30, 2017 2016 2017 2016 Balance at beginning of period $ ) $ ) $ ) $ ) Other comprehensive (loss) income before reclassification ) Amounts reclassified from accumulated other comprehensive (gain) loss* ) ) Income tax provision — — ) Total other comprehensive income (loss) ) Balance at end of period $ ) $ ) $ ) $ ) *Amounts reclassified affect other income in the statements of operations.

Net (Loss) Income Per Common 28

Net (Loss) Income Per Common Share (Tables)	9 Months Ended
	Sep. 30, 2017
Net (Loss) Income Per Common Share
Schedule of computation of basic and diluted net loss per share	Three Months Ended September 30, Nine Months Ended September 30, 2017 2016 2017 2016 Basic and diluted net loss per common share calculation: Net loss $ ) $ ) $ ) $ ) Basic and diluted weighted-average common shares Basic and diluted net loss per share $ ) $ ) $ ) $ )
Schedule of total shares of stock options, restricted stock, and outstanding warrants that could potentially dilute earnings per share in the future, but which were not included in the calculation of diluted net loss per share because their effect would have been anti-dilutive	Nine Months Ended 2017 2016 Restricted stock Options outstanding Warrants Total

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	9 Months Ended
	Sep. 30, 2017
Stock-Based Compensation
Schedule of stock-based compensation by expense category	Three Months Ended September 30, Nine Months Ended September 30, 2017 2016 2017 2016 Research and development $ $ $ $ General and administrative Total $ $ $ $
Schedule of weighted-average key assumptions used in determining the fair value of options	Three Months Ended September 30, Nine Months Ended September 30, 2017 2016 2017 2016 Weighted-average volatility % % % % Weighted-average risk-free interest rate % % % % Weighted-average expected term in years Dividend yield % % % %
Summary of stock options activity	Options Weighted- Weighted- Aggregate Outstanding at December 31, 2016 $ Options granted Options exercised ) Options forfeited ) Outstanding at September 30, 2017 $ $ Options exercisable at September 30, 2017 $ $
Summary of activity related to the Company's restricted stock	Number of Shares Weighted- Outstanding at December 31, 2016 $ Shares granted Shares vested ) Shares forfeited ) Outstanding at September 30, 2017 $

Commitments and Contingencies (

Commitments and Contingencies (Tables)	9 Months Ended
	Sep. 30, 2017
Commitments and Contingencies
Schedule of future annual minimum lease payments	Remainder of 2017 $ 2018 2019 Total minimum payments $

Organization and Basis of Pre31

Organization and Basis of Presentation (Details) - USD ($)	Dec. 31, 2016	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017
Organization and Basis of Presentation
Net loss		$ 16,056,147	$ 9,923,222	$ 46,079,093	$ 28,293,909	$ (194,000,000)
Minimum term for which anticipated operating cash requirements are funded				2 years
Employee Stock Purchase Plan compensation expense				$ 38,897	43,258
Restatement adjustment
Organization and Basis of Presentation
Employee Stock Purchase Plan compensation expense					$ 43,258
Reclassifications impact on previously reported cash used in operations in the statements of cash flows	$ 0

Summary of Significant Accoun32

Summary of Significant Accounting Policies (Details) $ in Millions	Sep. 30, 2017USD ($)
Accounting Standards Update 2016-09
Increase (Decrease) in Stockholders' Equity
Cumulative-effect adjustment in equity	$ 0.7

Liquidity and Capital Resourc33

Liquidity and Capital Resources (Details) $ in Millions	Sep. 30, 2017USD ($)
Liquidity and Capital Resources
Cash, cash equivalents, short and long-term investment balance	$ 79.9

Prepaid Expenses and Other Cu34

Prepaid Expenses and Other Current Assets (Details) - USD ($)	Sep. 30, 2017	Dec. 31, 2016
Prepaid Expenses and Other Current Assets
Prepaid third party vendor costs	$ 360,314	$ 208,196
Prepaid insurance	154,367	48,048
Other receivable	83,675	34,503
Total	$ 598,356	$ 290,747

Property and Equipment, Net (De

Property and Equipment, Net (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Property and Equipment, Net
Office furniture and fixtures	$ 519,675		$ 519,675		$ 486,586
Leasehold improvements	80,204		80,204
Manufacturing equipment	13,000		13,000
Property and equipment, gross	612,879		612,879		486,586
Less accumulated depreciation	(466,911)		(466,911)		(464,055)
Property and equipment, net	145,968		145,968		$ 22,531
Depreciation expense	$ 952	$ 952	$ 2,856	$ 79,306

Fair Value Measurements - Hiera

Fair Value Measurements - Hierarchy (Details) - Recurring basis - USD ($)	Sep. 30, 2017	Dec. 31, 2016
Fair Value Measurements
Fixed-income treasury portfolio	$ 46,009,240	$ 37,385,869
Certificate of Deposits	23,599,115	19,891,582
Cash and cash equivalents	10,265,356	10,316,064
Total assets at fair value	79,873,711	67,593,515
Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value Measurements
Fixed-income treasury portfolio	46,009,240	37,385,869
Cash and cash equivalents	10,265,356	10,316,064
Total assets at fair value	56,274,596	47,701,933
Significant Other Observable Inputs (Level 2)
Fair Value Measurements
Certificate of Deposits	23,599,115	19,891,582
Total assets at fair value	$ 23,599,115	$ 19,891,582

Fair Value Measurements - Summa

Fair Value Measurements - Summary of Cash Equivalents and Available-for-Sale Investments Held (Details) - USD ($)	9 Months Ended	12 Months Ended
	Sep. 30, 2017	Dec. 31, 2016
Available-for-sale securities
Gross Unrealized Gains	$ 192	$ 3,961
Gross Unrealized Losses	(62,579)	(78,467)
Short-term investments
Available-for-sale securities
Amortized Cost	55,307,059	36,567,676
Gross Unrealized Gains	192	3,659
Gross Unrealized Losses	(47,328)	(8,435)
Estimated Fair Value	$ 55,259,923	$ 36,562,900
Short-term investments | Maximum
Available-for-sale securities
Remaining contractual maturity	12 months	12 months
Short-term investments | Fannie Mae
Available-for-sale securities
Amortized Cost	$ 14,121,749	$ 2,108,607
Gross Unrealized Losses	(24,591)	(1,366)
Estimated Fair Value	14,097,158	2,107,241
Short-term investments | Federal farm credit bank
Available-for-sale securities
Amortized Cost	4,160,161	4,357,111
Gross Unrealized Gains		830
Gross Unrealized Losses	(1,482)	(2,666)
Estimated Fair Value	4,158,679	4,355,275
Short-term investments | Federal home loan bank
Available-for-sale securities
Amortized Cost	4,159,219	7,816,214
Gross Unrealized Gains		1,284
Gross Unrealized Losses	(3,509)	(3,400)
Estimated Fair Value	4,155,710	7,814,098
Short-term investments | Freddie Mac
Available-for-sale securities
Amortized Cost	7,013,485	7,467,276
Gross Unrealized Gains		223
Gross Unrealized Losses	(11,889)	(1,003)
Estimated Fair Value	7,001,596	7,466,496
Short-term investments | U.S. Treasury Securities
Available-for-sale securities
Amortized Cost	9,561,388
Gross Unrealized Losses	(5,504)
Estimated Fair Value	9,555,884
Short-term investments | Others
Available-for-sale securities
Amortized Cost	1,038,783
Gross Unrealized Losses	(353)
Estimated Fair Value	1,038,430
Long-term investments
Available-for-sale securities
Amortized Cost	14,363,683	20,784,281
Gross Unrealized Gains		302
Gross Unrealized Losses	(15,251)	(70,032)
Estimated Fair Value	$ 14,348,432	$ 20,714,551
Long-term investments | Maximum
Available-for-sale securities
Remaining contractual maturity	2 years	2 years
Long-term investments | Fannie Mae
Available-for-sale securities
Amortized Cost	$ 1,502,417	$ 5,878,500
Gross Unrealized Losses	(3,371)	(29,885)
Estimated Fair Value	1,499,046	5,848,615
Long-term investments | Federal home loan bank
Available-for-sale securities
Amortized Cost	1,510,484	1,900,546
Gross Unrealized Losses	(3,593)	(10,773)
Estimated Fair Value	1,506,891	1,889,773
Long-term investments | Freddie Mac
Available-for-sale securities
Amortized Cost	750,283	7,933,745
Gross Unrealized Losses	(862)	(29,374)
Estimated Fair Value	749,421	7,904,371
Long-term investments | U.S. Treasury Securities
Available-for-sale securities
Amortized Cost	2,253,850
Gross Unrealized Losses	(7,425)
Estimated Fair Value	2,246,425
Amortized Cost
Available-for-sale securities
Cash equivalents	10,265,356	10,316,064
Estimated Fair Value
Available-for-sale securities
Cash equivalents	10,265,356	10,316,064
Total	79,873,711	67,593,515
Amortized Cost
Available-for-sale securities
Total	79,936,098	67,668,021
Cash from operating accounts | Amortized Cost
Available-for-sale securities
Cash equivalents	2,286,585	851,667
Cash from operating accounts | Estimated Fair Value
Available-for-sale securities
Cash equivalents	2,286,585	851,667
Money market funds | Amortized Cost
Available-for-sale securities
Cash equivalents	7,978,771	9,464,397
Money market funds | Estimated Fair Value
Available-for-sale securities
Cash equivalents	7,978,771	9,464,397
Certificates of Deposits | Short-term investments
Available-for-sale securities
Amortized Cost	15,252,274	14,818,468
Gross Unrealized Gains	192	1,322
Estimated Fair Value	15,252,466	14,819,790
Certificates of Deposits | Long-term investments
Available-for-sale securities
Amortized Cost	8,346,649	5,071,490
Gross Unrealized Gains		302
Estimated Fair Value	$ 8,346,649	$ 5,071,792

Fair Value Measurements - Avail

Fair Value Measurements - Available-for-Sale Securities in Continuous Loss Position (Details) - USD ($)	Sep. 30, 2017	Dec. 31, 2016
Fair Value Measurements
Available-for-sale securities in a continuous unrealized loss position for greater than twelve months	$ 0	$ 0

Accounts Payable and Accrued 39

Accounts Payable and Accrued Expenses (Details) - USD ($)	Sep. 30, 2017	Dec. 31, 2016
Accounts payable and accrued expenses
Accrued research and development costs	$ 11,687,301	$ 6,792,947
Accrued compensation	1,576,688	1,975,037
Accrued legal	631,286	71,554
Other accrued liabilities	473,054	444,976
Total accounts payable and accrued expenses	$ 14,368,329	$ 9,284,514

Common Stock (Details)

Common Stock (Details)	Jan. 20, 2017USD ($)$ / sharesshares	Jan. 31, 2013$ / sharesshares	Sep. 30, 2017USD ($)Voteshares	Dec. 31, 2016shares
Proceeds from follow-on public offering net of underwriting fees and offering expenses			$ 48,242,214
Number of shares of common stock authorized to be issued | shares			53,750,000	33,750,000
Number of votes to which holders of common shares are entitled for each share held | Vote			1
Number of shares of common stock that may be purchased by warrants | shares		99,529
Exercisable price of warrants (in dollars per share) | $ / shares		$ 15
Term of warrants		5 years
Follow on Public Offering
Issuance of common stock in connection with the public offerings (in shares) | shares	4,500,000
Share price (in dollars per share) | $ / shares	$ 10
Over-allotment Option
Share price (in dollars per share) | $ / shares	$ 10
Number of shares issued pursuant to an option granted to the underwriters to cover over-allotments | shares	675,000
Aggregate gross proceeds from public offering	$ 51,800,000
Underwriting fees	3,200,000
Offering expenses	400,000
Proceeds from follow-on public offering net of underwriting fees and offering expenses	$ 48,200,000

Accumulated Other Comprehensi41

Accumulated Other Comprehensive Loss (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Accumulated Other Comprehensive Loss
Balance at beginning of period	$ (120,897)	$ (35,159)	$ (99,802)	$ (153,690)
Other comprehensive (loss) income before reclassification	30,207	(17,339)	9,112	172,612
Amounts reclassified from accumulated other comprehensive (gain) loss	3,007	(1,378)	3,007	(11,736)
Income tax provision		6,364		(54,698)
Total other comprehensive income (loss)	33,214	(12,353)	12,119	106,178
Balance at end of period	$ (87,683)	$ (47,512)	$ (87,683)	$ (47,512)

Net (Loss) Income Per Common 42

Net (Loss) Income Per Common Share - Basic and Diluted (Details) - USD ($)	3 Months Ended		9 Months Ended		170 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017
Basic and diluted net loss per common share calculation:
Net loss	$ (16,056,147)	$ (9,923,222)	$ (46,079,093)	$ (28,293,909)	$ 194,000,000
Basic and diluted weighted-average common shares	23,464,505	17,831,022	22,901,883	17,777,675
Basic and diluted net loss per share (in dollars per share)	$ (0.68)	$ (0.56)	$ (2.01)	$ (1.59)

Net (Loss) Income Per Common 43

Net (Loss) Income Per Common Share - Anti-dilutive Securities (Details) - shares	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Net Loss Per Common Share
Potentially dilutive securities excluded from the computation of earnings per share (in shares)	5,096,489	4,552,048
Restricted stock
Net Loss Per Common Share
Potentially dilutive securities excluded from the computation of earnings per share (in shares)	1,796,749	1,304,974
Options outstanding
Net Loss Per Common Share
Potentially dilutive securities excluded from the computation of earnings per share (in shares)	3,200,211	3,147,545
Warrants
Net Loss Per Common Share
Potentially dilutive securities excluded from the computation of earnings per share (in shares)	99,529	99,529

Grant Revenue (Details)

Grant Revenue (Details) - USD ($)	1 Months Ended	3 Months Ended		9 Months Ended		48 Months Ended
	Oct. 31, 2013	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017
Grant Revenue
Maximum amount of grants to be received from the Leukemia and Lymphoma Society	$ 3,500,000
Grant proceeds received						$ 3,000,000
Additional amount of grants to be received upon completion of certain additional milestone	$ 500,000
Grant revenue		$ 299,397	$ 299,401	$ 898,199	$ 741,953

Stock-Based Compensation - Equi

Stock-Based Compensation - Equity Incentive Plan (Details) - shares	1 Months Ended	9 Months Ended
	Jun. 30, 2017	Sep. 30, 2017
2016 Plan
Stock Option Plan
Number of common stock shares initially authorized for grant		1,812,932
Increase in number of authorized shares	1,200,000
Number of options with terms in excess of 10 years		0
Term of option		10 years
Shares available for future grants		1,060,680
2012 Plan
Stock Option Plan
Number of common stock shares initially authorized for grant		1,663,727
Number of options with terms in excess of 10 years		0
Term of option		10 years
Shares available for future grants		12,932

Stock-Based Compensation - Expe

Stock-Based Compensation - Expense Category (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Stock-Based Compensation
Stock-based compensation expense	$ 2,248,987	$ 2,717,878	$ 6,178,079	$ 5,666,813
Research and development
Stock-Based Compensation
Stock-based compensation expense	995,488	1,368,932	2,622,790	2,536,118
General and administrative
Stock-Based Compensation
Stock-based compensation expense	$ 1,253,499	$ 1,348,946	$ 3,555,289	$ 3,130,695

Stock-Based Compensation - Stoc

Stock-Based Compensation - Stock Options (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Weighted average assumptions used to estimate the weighted average fair value of the options granted on the date of grant using the Black-Scholes option-pricing model
Proceeds from exercise of stock options			$ 7,179	$ 111,378
Options
Options exercised (in shares)			(1,175)	(33,751)
Options outstanding
Stock-Based Compensation
Term of option			10 years
Weighted average assumptions used to estimate the weighted average fair value of the options granted on the date of grant using the Black-Scholes option-pricing model
Weighted-average volatility (as a percent)	75.36%	73.82%	75.76%	73.52%
Weighted-average risk-free interest rate (as a percent)	1.98%	1.22%	1.92%	1.56%
Weighted-average expected term in years	6 years 3 months	5 years 5 months 12 days	6 years 26 days	6 years 11 days
Dividend yield (as a percent)	0.00%	0.00%	0.00%	0.00%
Dividends paid to stockholders			$ 0
Proceeds from exercise of stock options			7,179	$ 111,378
Unrecognized compensation expense related to unvested stock options	$ 5,900,000		$ 5,900,000
Weighted average period over which unrecognized compensation expense is expected to be recognized			1 year 7 months 6 days
Options
Outstanding balance at the beginning of the period (in shares)			3,090,752
Options granted (in shares)			131,000
Options exercised (in shares)			(1,175)
Options forfeited (in shares)			(20,366)
Outstanding balance at the end of the period (in shares)	3,200,211		3,200,211
Options exercisable (in shares)	1,829,733		1,829,733
Weighted-Average Exercise Price
Outstanding balance at the beginning of the period (in dollars per share)			$ 8.78
Options granted (in dollars per share)			8.40
Options exercised (in dollars per share)			6.11
Options forfeited (in dollars per share)			17.15
Outstanding balance at the end of the period (in dollars per share)	$ 8.71		8.71
Options exercisable (in dollars per share)	$ 9.02		$ 9.02
Weighted-Average Remaining Contractual Life
Outstanding balance (in years)			6 years 6 months
Options exercisable (in years)			5 years 3 months 26 days
Aggregate Intrinsic Value
Outstanding balance (in dollars)	$ 14,125,379		$ 14,125,379
Options exercisable (in dollars)	$ 8,542,619		$ 8,542,619
Options outstanding | Employees
Stock-Based Compensation
Vesting period			4 years
Options outstanding | Directors
Stock-Based Compensation
Vesting period			3 years

Stock-Based Compensation - Rest

Stock-Based Compensation - Restricted Stock (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Stock-Based Compensation
Stock-based compensation expense	$ 2,248,987	$ 2,717,878	$ 6,178,079	$ 5,666,813
Non-employees
Stock-Based Compensation
Stock-based compensation expense			$ 500,000	300,000
Restricted stock
Number of Shares
Outstanding balance at the beginning of the period (in shares)			1,268,092
Shares granted			899,950
Shares vested			(329,245)
Shares forfeited			(42,048)
Outstanding balance at the end of the period (in shares)	1,796,749		1,796,749
Weighted-Average Grant Date Fair Value Per Share
Outstanding balance at the beginning of the period (in dollars per share)			$ 7.41
Shares granted (in dollars per share)			8.87
Shares vested (in dollars per share)			9
Shares forfeited (in dollars per share)			6.92
Outstanding balance at the end of the period (in dollars per share)	$ 7.86		$ 7.86
Total aggregate fair value of stock granted			$ 8,000,000
Number of shares remained unvested	1,796,749		1,796,749
Unrecognized compensation expense adjusted for estimated forfeitures, related to unvested restricted stock	$ 10,800,000		$ 10,800,000
Remaining weighted-average period for recognizing unrecognized compensation cost			2 years 2 months 9 days
Total fair value of restricted stock vested			$ 3,000,000	$ 2,000,000
Restricted stock | Directors
Stock-Based Compensation
Vesting period			3 years
Restricted stock | Maximum
Stock-Based Compensation
Vesting period			4 years

Stock-Based Compensation - St49

Stock-Based Compensation - Stock Based Compensation (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Stock-Based Compensation
Stock-based compensation expense	$ 2,248,987	$ 2,717,878	$ 6,178,079	$ 5,666,813
2015 Employee Stock Purchase Plan
Stock-Based Compensation
Stock-based compensation expense			$ 38,897	$ 43,258
2015 Employee Stock Purchase Plan | Minimum
Stock-Based Compensation
Purchase price expressed as percentage of fair market value of common stock on grant date or date of exercise			85.00%
Purchase discount			5.00%

Commitments and Contingencies50

Commitments and Contingencies (Details)	1 Months Ended			9 Months Ended
	Apr. 30, 2017shareholder	Feb. 29, 2016USD ($)	Jul. 31, 2013USD ($)	Sep. 30, 2017USD ($)	Sep. 30, 2016USD ($)	Feb. 28, 2013USD ($)
Compensation Arrangements
Monthly lease rent		$ 69,750	$ 50,625
Lease agreement term		42 months	36 months
Aggregate minimum lease payments		$ 2,700,000		$ 1,883,250
Security deposit paid to landlord		209,250
Future annual minimum lease payments
Remainder of 2017				209,250
2,018				837,000
2,019				837,000
Total minimum payments		$ 2,700,000		1,883,250
Rent expense				598,175	$ 533,305
Contingencies
Number of shareholders commenced separate actions | shareholder	4
Number of purported individual investors | shareholder	3
Research and development agreements with third parties
License Agreements
Amount required to be paid upon achievement of certain milestones				112,900,000
Amount paid or accrued				5,600,000
Bioprocessing services agreement
Contractual Agreement
Contractual agreement value						$ 2,900,000
New Service Agreements
Contractual Agreement
Contractual agreement value				20,400,000
Amount paid				10,000,000
Clinical programs with Clinical research organizations (CROs)
Contractual Agreement
Contractual agreement value				$ 6,100,000