ContraFect (CFRXQ) 10-K 15 Mar 18 2017 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Mar. 07, 2018	Jun. 30, 2017
Document And Entity Information [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2017
Document Fiscal Year Focus	2,017
Document Fiscal Period Focus	FY
Trading Symbol	CFRX
Entity Registrant Name	CONTRAFECT Corp
Entity Central Index Key	1,478,069
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	No
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Filer Category	Accelerated Filer
Entity Common Stock, Shares Outstanding		73,656,006
Entity Public Float			$ 73.4

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($)	Dec. 31, 2017	Dec. 31, 2016
Current assets:
Cash and cash equivalents	$ 6,995,046	$ 3,806,984
Marketable securities	39,858,864	31,354,170
Prepaid expenses and other current assets	1,848,063	1,017,645
Total current assets	48,701,973	36,178,799
Property and equipment, net	1,093,903	1,281,152
Other assets	393,603	164,519
Total assets	50,189,479	37,624,470
Current liabilities:
Accounts payable	1,302,431	1,549,845
Accrued liabilities	3,118,237	2,868,352
Total current liabilities	4,420,668	4,418,197
Deferred rent	704,240	994,439
Warrant liabilities	13,549,437	12,698,980
Other liabilities	321,689
Total liabilities	18,996,034	18,111,616
Commitments and contingencies (Note 8)
Stockholders' equity:
Preferred stock, $0.0001 par value, 25,000,000 shares authorized and none outstanding at December 31, 2017 and 2016
Common stock, $0.0001 par value, 200,000,000 shares authorized, 73,656,006 shares issued and outstanding at December 31, 2017; 100,000,000 shares authorized, 41,656,006 shares issued and outstanding at December 31, 2016	7,366	4,166
Additional paid-in capital	192,896,367	165,678,164
Accumulated other comprehensive loss	(74,820)	(51,666)
Accumulated deficit	(161,635,468)	(146,117,810)
Total stockholders' equity	31,193,445	19,512,854
Total liabilities and stockholders' equity	$ 50,189,479	$ 37,624,470

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2017	Dec. 31, 2016
Statement of Financial Position [Abstract]
Preferred stock, par value	$ 0.0001	$ 0.0001
Preferred stock, shares authorized	25,000,000	25,000,000
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 0.0001	$ 0.0001
Common stock, shares authorized	200,000,000	100,000,000
Common stock, shares issued	73,656,006	41,656,006
Common stock, shares outstanding	73,656,006	41,656,006

Consolidated Statements of Oper

Consolidated Statements of Operations - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Operating expenses:
Research and development, including stock-based compensation of $451,334, $587,426 and $389,967, respectively	$ 17,314,086	$ 22,101,720	$ 15,004,512
General and administrative, including stock-based compensation of $1,171,794, $1,644,456 and $1,599,895, respectively	9,249,671	11,430,526	10,060,825
Total operating expenses	26,563,757	33,532,246	25,065,337
Loss from operations	(26,563,757)	(33,532,246)	(25,065,337)
Other income (expense):
Interest income	418,135	216,616	75,693
Other expense	(905,014)	(1,569,341)
Change in fair value of warrant and embedded derivative liabilities	11,532,978	6,346,572	(131,320)
Total other income (expense)	11,046,099	4,993,847	(55,627)
Net loss	$ (15,517,658)	$ (28,538,399)	$ (25,120,964)
Per share information:
Net loss per share of common stock, basic and diluted	$ (0.28)	$ (0.85)	$ (1.08)
Basic and diluted weighted average shares outstanding	55,595,732	33,539,465	23,328,922

Consolidated Statements of Ope5

Consolidated Statements of Operations (Parenthetical) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Stock-based compensation expense	$ 1,623,128	$ 2,231,883	$ 1,989,862
Research and Development Expense [Member]
Stock-based compensation expense	451,334	587,426	389,967
General and Administrative Expense [Member]
Stock-based compensation expense	$ 1,171,794	$ 1,644,456	$ 1,599,895

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Loss - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Statement of Comprehensive Income [Abstract]
Net loss	$ (15,517,658)	$ (28,538,399)	$ (25,120,964)
Other comprehensive loss:
Unrealized loss on available-for-sale securities	(23,154)	(21,293)	(29,746)
Comprehensive loss	$ (15,540,812)	$ (28,559,692)	$ (25,150,710)

Consolidated Statements of Stoc

Consolidated Statements of Stockholders' Equity - USD ($)	Total	Private Placement [Member]	Common Stock [Member]	Common Stock [Member]Private Placement [Member]	Additional Paid-in Capital [Member]	Additional Paid-in Capital [Member]Private Placement [Member]	Accumulated Other Comprehensive Loss [Member]	Accumulated Deficit [Member]
Beginning Balance at Dec. 31, 2014	$ 25,581,507		$ 2,021		$ 118,038,560		$ (627)	$ (92,458,447)
Beginning Balance, Shares at Dec. 31, 2014			20,217,263
Net shares issued in relation to vesting of performance grant	54,301		$ 1		54,300
Net shares issued in relation to vesting of performance grant, Shares			11,778
Issuance of common stock for services	167,538		$ 3		167,535
Issuance of common stock for services, Shares			28,445
Issuance of securities		$ 20,000,000		$ 474		$ 19,999,526
Issuance of securities, Shares				4,728,128
Financing cost of sale of securities	(1,665,554)				(1,665,554)
Issuance of common stock for exercise of options	2		$ 2
Issuance of common stock for exercise of options, Shares			23,235
Issuance of common stock for exercise of warrants	9,698,564		$ 247		9,698,317
Issuance of common stock for exercise of warrants, Shares			2,473,843
Share-based compensation	1,989,862				1,989,862
Unrealized loss on marketable securities	(29,746)						(29,746)
Net loss	(25,120,964)							(25,120,964)
Ending balance at Dec. 31, 2015	30,675,510		$ 2,748		148,282,546		(30,373)	(117,579,411)
Ending balance, Shares at Dec. 31, 2015			27,482,692
Issuance of common stock for services	93,930		$ 3		93,927
Issuance of common stock for services, Shares			31,206
Issuance of securities in registered offering	16,398,772		$ 1,400		16,397,372
Issuance of securities in registered offering, Shares			14,000,000
Financing cost of sale of securities	(1,383,548)				(1,383,548)
Issuance of common stock for exercise of options	1		$ 1
Issuance of common stock for exercise of options, Shares			2,850
Issuance of common stock for exercise of warrants	55,998		$ 14		55,984
Issuance of common stock for exercise of warrants, Shares			139,258
Share-based compensation	2,231,883				2,231,883
Unrealized loss on marketable securities	(21,293)						(21,293)
Net loss	(28,538,399)							(28,538,399)
Ending balance at Dec. 31, 2016	19,512,854		$ 4,166		165,678,164		(51,666)	(146,117,810)
Ending balance, Shares at Dec. 31, 2016			41,656,006
Issuance of securities in registered offering	27,616,565		$ 3,200		27,613,365
Issuance of securities in registered offering, Shares			32,000,000
Financing cost of sale of securities	$ (2,018,290)				(2,018,290)
Issuance of common stock for exercise of options, Shares	0
Share-based compensation	$ 1,623,128				1,623,128
Unrealized loss on marketable securities	(23,154)						(23,154)
Net loss	(15,517,658)							(15,517,658)
Ending balance at Dec. 31, 2017	$ 31,193,445		$ 7,366		$ 192,896,367		$ (74,820)	$ (161,635,468)
Ending balance, Shares at Dec. 31, 2017			73,656,006

Statements of Cash Flows

Statements of Cash Flows - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Cash flows from operating activities
Net loss	$ (15,517,658)	$ (28,538,399)	$ (25,120,964)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation	187,249	451,008	537,344
Stock-based compensation expense	1,623,128	2,231,883	1,989,862
Issuance of common stock in exchange for services		93,930	167,538
Issuance costs allocated to warrants	905,014	1,569,341
Change in fair value of warrant and embedded derivative liabilities	(11,532,978)	(6,346,572)	131,320
(Decrease) Increase in deferred rent	(290,199)	22,320	36,077
Net amortization of premium paid on marketable securities	831,793	428,783	283,915
Changes in operating assets and liabilities:
(Increase) decrease in prepaid expenses and other current and non-current assets	(1,059,502)	138,352	(808,108)
Increase in accounts payable and accrued liabilities	324,160	649,014	600,415
Net cash used in operating activities	(24,528,993)	(29,300,340)	(22,182,601)
Cash flows from investing activities
Purchases of marketable securities	(53,162,598)	(36,459,405)	(33,524,927)
Proceeds from maturities of marketable securities	43,802,957	27,604,030	11,933,000
Purchases of property and equipment		(113,192)	(8,157)
Net cash used in investing activities	(9,359,641)	(8,968,567)	(21,600,084)
Cash flows from financing activities
Proceeds from issuance of equity securities	40,000,000	35,000,000	20,000,000
Payment of financing costs of securities sold	(2,923,304)	(2,952,889)	(1,665,554)
Proceeds from exercise of warrants		55,998	9,698,567
Net cash provided by financing activities	37,076,696	32,103,109	28,033,013
Net increase (decrease) in cash and cash equivalents	3,188,062	(6,165,798)	(15,749,672)
Cash and cash equivalents at beginning of period	3,806,984	9,972,781	25,722,453
Cash and cash equivalents at end of period	6,995,046	3,806,984	9,972,781
Supplemental disclosures of cash flow information and non-cash investing and financing activities
Issuance of common stock for services		93,930	$ 167,538
Issuance of warrants to purchase common stock	$ 12,383,435	$ 18,601,228

Organization and Description of

Organization and Description of Business	12 Months Ended
	Dec. 31, 2017
Accounting Policies [Abstract]
Organization and Description of Business	1. Organization and Description of Business Organization and Business ContraFect Corporation (the “Company”) is a clinical-stage biotechnology company focused on protein and antibody therapeutic products for life-threatening infectious diseases, particularly those treated in hospital-based settings. The Company intends to address multi-drug resistant infections using its therapeutic product candidates from its lysin and monoclonal antibody platforms to target conserved regions of either bacteria or viruses. The Company’s most advanced product candidates are CF-301, Staph aureus CF-404, The Company has incurred losses from operations since inception as a research and development organization and has relied on its ability to fund its operations through public and private debt and equity financings. Management believes its cash, cash equivalents and marketable securities balances as of December 31, 2017 will be sufficient to fund operations into the second quarter of 2019 and expects operating losses and negative cash flows to continue at more significant levels in the future as it continues its clinical trials. Transition to profitability is dependent upon the successful development, approval, and commercialization of its product candidates and achieving a level of revenues adequate to support the Company’s cost structure. The Company may never achieve profitability, and unless and until it does, the Company will continue to need to raise additional capital. Management intends to fund future operations through additional public or private equity financings, and may seek additional capital through arrangements with strategic partners or from other sources. There can be no assurances that such financing will be available to the Company on satisfactory terms, or at all. In June 2015, the Company completed a private placement of securities to institutional investors whereby the investors received an aggregate of 4,728,128 shares of the Company’s common stock and warrants to purchase an additional 2,364,066 shares of common stock at an exercise price of $8.00 per share. The Company received net proceeds of $18.3 million, net of expenses. On November 2, 2015, the Company’s Class B Warrants to purchase common stock expired in accordance with their terms. As of November 2, 2015, holders of the Class B Warrants had exercised 4,812,328 Class B Warrants, resulting in the issuance of 2,406,164 shares of the Company’s common stock and the receipt by the Company of approximately $9.6 million in gross proceeds. The 2,068,005 Class B Warrants that were not exercised prior to expiration were terminated and are no longer exercisable. On July 27, 2016, the Company completed an underwritten public offering of 14,000,000 shares of its common stock and warrants to purchase an additional 14,000,000 shares of its common stock at an exercise price of $3.00 per share (the “2016 Offering”). The public offering price was $2.50 per share of common stock and accompanying warrant, resulting in net proceeds to the Company of approximately $32.0 million after underwriting discounts and commissions and offering expenses payable by the Company. On July 25, 2017, the Company completed an underwritten public offering of 32,000,000 shares of its common stock and warrants to purchase an additional 16,000,000 shares of its common stock at an exercise price of $1.55 per share (the “2017 Offering”). The public offering price was $1.25 per share of common stock and accompanying warrant, resulting in net proceeds to the Company of approximately $37.1 million after underwriting discounts and commissions and offering expenses payable by the Company. The significant increases in common stock outstanding are expected to impact the year-over-year comparability of the Company’s net loss per share calculations.

Summary of Significant Accounti

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2017
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	2. Summary of Significant Accounting Policies Basis of Presentation The accompanying financial information has been prepared in accordance with U.S. generally accepted accounting principles (“U.S. GAAP”). Principles of Consolidation The Company has a wholly-owned subsidiary, ContraFect International Limited, in Scotland that establishes legal status for interactions with the European Economic Area. This subsidiary is dormant or is otherwise non-operative. Segment and Geographic Information Operating segments are identified as components of an enterprise about which separate discrete financial information is available for evaluation by the chief operating decision maker, or decision making group, in making decisions on how to allocate resources and assess performance. The Company’s chief operating decision maker is the chief executive officer. The Company and the chief decision maker view the Company’s operations and manage its business as one operating segment. The Company operates in only one geographic segment. Significant Risks and Uncertainties The Company’s operations are subject to a number of factors that can affect its operating results and financial condition. Such factors include, but are not limited to: the results of clinical testing and trial activities of the Company’s products, the Company’s ability to obtain regulatory approval to market its products, competition from products manufactured and sold or being developed by other companies, the price of, and demand for, the Company’s products, the Company’s ability to negotiate favorable licensing or other manufacturing and marketing agreements for its products and the Company’s ability to raise capital. Use of Estimates The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of expenses during the reporting period. The Company bases estimates and assumptions on historical experience when available and on various factors that it believes to be reasonable under the circumstances. On an ongoing basis, the Company evaluates its estimates and assumptions, including those related to accruals, fair value measurements, stock-based compensation, warrant valuation and income taxes. The Company’s actual results may differ from these estimates under different assumptions or conditions. There have been no significant changes from the Company’s original estimates in any periods presented. Concentrations of Credit Risk Financial instruments which potentially subject the Company to credit risk consist primarily of cash, cash equivalents and marketable securities. The Company holds these investments in highly rated financial institutions, and, by policy, limits the amounts of credit exposure to any one financial institution. These amounts at times may exceed federally insured limits. The Company has not experienced any credit losses in such accounts and does not believe it is exposed to any significant credit risk on these funds. The Company has no off-balance Cash and Cash Equivalents The Company considers all highly liquid investments with maturities at 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. Marketable Securities Marketable securities consist of investments in corporate debt securities. Management determines the appropriate classification of the securities at the time they are acquired and evaluates the appropriateness of such classifications at each balance sheet date. The Company classifies its marketable securities as available-for-sale pursuant to ASC 320, Investments – Debt and Equity Securities The Company reviews marketable securities for other-than-temporary impairment whenever the fair value of a marketable security is less than the amortized cost and evidence indicates that a marketable security’s carrying amount is not recoverable within a reasonable period of time. Other-than-temporary impairments of investments are recognized in the consolidated statements of operations if the Company has experienced a credit loss, has the intent to sell the marketable security, or if it is more likely than not that the Company will be required to sell the marketable security before recovery of the amortized cost basis. Evidence considered in this assessment includes reasons for the impairment, compliance with the Company’s investment policy, the severity and the duration of the impairment and changes in value subsequent to the end of the period. Fair Value of Financial Instruments The Company’s financial instruments consist of cash and cash equivalents, marketable securities, accounts payable, accrued liabilities and warrant liabilities. Fair value estimates of these instruments are made at a specific point in time, based on relevant market information. These estimates may be subjective in nature and involve uncertainties and matters of significant judgment and therefore cannot be determined with precision. The fair value of the Company’s warrant liabilities are based upon unobservable inputs, as described further below. The Company is required to disclose information on all assets and liabilities reported at fair value that enables an assessment of the inputs used in determining the reported fair values. FASB ASC Topic 820, Fair Value Measurements and Disclosures Level 1—Valuations based on unadjusted quoted prices in active markets for identical assets or liabilities that the Company has the ability to access at the measurement date. Level 2—Valuations based on quoted prices for similar assets or liabilities in markets that are not active or for which all significant inputs are observable, either directly or indirectly. Level 3—Valuations that require inputs that reflect the Company’s own assumptions that are both significant to the fair value measurement and unobservable. To the extent that valuation is based on models or inputs that are less observable or unobservable in the market, the determination of fair value requires more judgment. Accordingly, the degree of judgment exercised by the Company in determining fair value is greatest for instruments categorized in Level 3. A financial instrument’s level within the fair value hierarchy is based on the lowest level of any input that is significant to the fair value measurement. The Company had no liabilities classified as Level 1 or Level 2. The carrying amounts reported in the accompanying financial statements for accounts payable and accrued expenses approximate their respective fair values due to their short-term maturities. The fair value of the warrant and embedded derivative liabilities are discussed in Note 4, “Fair Value Measurements.” Property, Office Equipment, and Leasehold Improvements Property and equipment are recorded at cost less accumulated depreciation. Depreciation of property and equipment is provided by the straight-line method over their estimated useful lives, ranging from three to five years. Leasehold improvements are amortized on a straight line basis over the useful life of the improvement or the initial lease term, whichever is shorter. Costs for normal repair and maintenance are charged to expense as incurred. Impairment of Long-lived Assets In accordance with ASC 360, Property, Plant, and Equipment Deferred Rent The Company has an operating lease for office and laboratory space. Rent expense is recorded on a straight-line basis over the initial lease term. The difference between the actual cash paid and the straight-line rent expense is recorded as deferred rent. Research and Development Costs Research and development costs are charged to expense as incurred and are typically made up of salaries and benefits, clinical trial activities, drug development and manufacturing costs, and third-party service fees, including for clinical research organizations and investigative sites. 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 by vendors on 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 financial statements as prepaid or accrued expenses. Share-based Compensation The Company accounts for stock-based compensation in accordance with ASC 718, Compensation—Stock Compensation, non-employee The fair value of options is calculated using the Black-Scholes option pricing model on the date of grant based on key assumptions such as stock price, risk free interest rates, expected volatility and expected term. The Company’s estimates of these assumptions are primarily based on historical data, peer company data and judgment regarding future trends and factors. Income Taxes The Company uses the asset and liability method to calculate deferred tax assets and liabilities. Deferred taxes are recognized based on the differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax bases using enacted tax rates expected to apply to taxable income in the years in which those differences are expected to be recovered or settled. The Company records a valuation allowance against a deferred tax asset when it is more-likely-than-not The Company is subject to federal, state and local taxes and follows a recognition threshold and measurement attribute for the financial statement recognition and measurement of a tax position taken or expected to be taken in a tax return. The Company recognizes tax benefits or expenses of uncertain tax positions in the year such determination is made when the position is “more likely than not” to be sustained assuming examination by tax authorities. Management has reviewed the Company’s tax positions for all open tax years (tax years ended December 31, 2008 through December 31, 2016) and concluded that no provision for unrecognized tax benefits or expense is required in these financial statements. There are no income tax audits in progress as of December 31, 2017. Grants The Company recognizes a receivable and the related reduction in its research and development expenses when the actual reimbursable costs have been incurred and there is reasonable assurance that the Company has complied with the conditions of the grants and the amounts will be received. For the year ended December 31, 2017, the Company recognized a reduction to its research and development expense in the amount of approximately $1.2 million. There were no similar grants recognized for the year ended December 31, 2016 or 2015. The receivable for grants as of December 31, 2017 was $343,372 and is included in prepaid expenses and other current assets. The Company has $2,054,290 of approved grant award funding remaining as of December 31, 2017. Net Loss per Share Applicable to Common Stockholders Basic net loss per share applicable to common stockholders is calculated by dividing net loss applicable to common stockholders by the weighted average shares outstanding during the period, without consideration for common stock equivalents. Diluted net loss per share applicable to common stockholders is calculated by adjusting weighted average shares outstanding for the dilutive effect of common stock equivalents outstanding for the period, determined using the treasury-stock method. For purposes of the dilutive net loss per share applicable to common stockholders calculation, stock options and warrant are considered to be common stock equivalents but are excluded from the calculation of diluted net loss per share applicable to common stockholders, as their effect would be anti-dilutive; therefore, basic and diluted net loss per share applicable to common stockholders were the same for all periods presented. 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 available-for-sale Recently Adopted Accounting Pronouncements In March 2016, the FASB issued Accounting Standards Update, Improvements to Employee Share-Based Payment Accounting 2016-09). 2016-09 paid-in-capital 2016-09 Recent Accounting Pronouncements Not Yet Adopted In January 2016, the FASB issued a new Accounting Standards Update, Recognition and Measurement of Financial Assets and Financial Liabilities (ASU 2016-01). 2016-01 2016-01. In February 2016, the FASB issued a new Accounting Standards Update , Leases (ASU 2016-02), 2016-02 right-of-use 2016-02 In June 2016, the FASB issued a new Accounting Standards Update, Financial Instruments-Credit Losses (ASU 2016-13). 2016-13 available-for-sale In August 2016, the FASB issued Accounting Standards Update No. 2016-15 , Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments 2016-15), 2016-15 2016-15 In November 2016, the FASB issued Accounting Standards Update No. 2016-18 , Statement of Cash Flows (Topic 230): Restricted Cash 2016-18), beginning-of-period end-of-period 2016-18 2016-18 In May 2017, the FASB issued Accounting Standards Update 2017-09, Compensation – Stock Compensation 2017-09). 2017-09

Marketable Securities

Marketable Securities	12 Months Ended
	Dec. 31, 2017
Investments, Debt and Equity Securities [Abstract]
Marketable Securities	3. Marketable Securities Marketable securities at December 31, 2017 consisted of the following: Marketable Securities Amortized Cost Unrealized Gains Unrealized Losses Fair Value Current: Corporate debt $ 39,933,685 $ — $ (74,820 ) $ 39,858,864 Marketable securities at December 31, 2016 consisted of the following: Marketable Securities Amortized Cost Unrealized Gains Unrealized Losses Fair Value Current: Corporate debt $ 31,405,836 $ 24 $ (51,690 ) $ 31,354,170 Corporate debt includes obligations issued by investment-grade corporations, and may include issues that have been guaranteed by governments and government agencies. The duration periods of available-for-sale Amortized Cost Fair Value Duration of one year or less $ 38,213,753 $ 38,144,760 Duration of more than one year 1,719,932 1,714,104 Total $ 39,933,685 $ 39,858,864 At December 31, 2017 and December 31, 2016, the Company held 32 and 29 debt securities, respectively, that individually and in total were in an immaterial unrealized loss position for less than one year. The aggregate fair value of debt securities in an unrealized loss position at December 31, 2017 and December 31, 2016 was $39,858,864 and $29,343,892, respectively. The Company evaluated its securities for other-than-temporary impairment and considered the decline in market value for the securities to be primarily attributable to current economic and market conditions. It is not more likely than not that the Company will be required to sell the securities prior to the recovery of the amortized cost basis. Based on this analysis, these marketable securities were not considered to be other-than-temporarily impaired as of December 31, 2017 and December 31, 2016.

Fair Value Measurements

Fair Value Measurements	12 Months Ended
	Dec. 31, 2017
Fair Value Disclosures [Abstract]
Fair Value Measurements	4. Fair Value Measurements 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, 2017 and December 31, 2016: Fair Value Measurement As of December 31, 2017 Quoted Prices Significant Significant Cash equivalents $ 5,949,477 $ — $ — Marketable securities 39,858,864 — — Warrant liabilities — — 13,549,437 Total $ 45,808,341 $ — $ 13,549,437 Fair Value Measurement As of December 31, 2016 Quoted Prices Significant Significant Cash equivalents $ 3,411,058 $ — $ — Marketable securities 31,354,170 — — Warrant liabilities — — 12,698,980 Total $ 34,765,228 $ — $ 12,698,980 The Company issued a warrant to the representative of the underwriter of its initial public offering (the “Representative’s Warrant”). The Company determined that this warrant should be classified as a liability and considers it as a Level 3 financial instrument (see also Note 9, “Capital Structure”). The Representative’s Warrant will be re-measured As of As of Expected volatility 88.1 % 73.9 % Remaining contractual term (in years) 1.67 2.67 Risk-free interest rate 1.89 % 1.47 % Expected dividend yield — % — % The Company issued warrants to the purchasers of its 2016 Offering (the “2016 Warrants”). The Company determined that these warrants should be classified as a liability and considered as a Level 3 financial instrument (see also Note 9, “Capital Structure”). The 2016 Warrants will be re-measured As of December 31, 2017 As of Expected volatility 80.3 % 79.9 % Remaining contractual term (in years) 3.58 4.58 Risk-free interest rate 2.09 % 1.93 % Expected dividend yield — % — % The Company issued warrants to the purchasers of its 2017 Offering (the “2017 Warrants”). The Company determined that these warrants should be classified as a liability and considered as a Level 3 financial instrument (see also Note 9, “Capital Structure”). The 2017 Warrants will be re-measured As of December 31, 2017 At Issuance on Expected volatility 81.5 % 82.0 % Remaining contractual term (in years) 4.58 5.00 Risk-free interest rate 2.20 % 1.90 % Expected dividend yield — % — % The following tables present a reconciliation of the Company’s financial liabilities measured at fair value on a recurring basis using significant unobservable inputs (Level 3) for the years ended December 31, 2017, 2016 and 2015: Warrant liabilities Year Ended December 31, 2017 2016 2015 Balance at beginning of period $ 12,698,980 $ 444,324 $ 313,004 Issuance of 2017 Warrants 12,383,435 — — Issuance of 2016 Warrants — 18,601,228 — Change in fair value (11,532,978 ) (6,346,572 ) 131,320 Balance at end of period $ 13,549,437 $ 12,698,980 $ 444,324 The key inputs into the Black-Scholes option pricing model are the per share value and the expected volatility of the Company’s common stock. Significant changes in these inputs will directly increase or decrease the estimated fair value of the Company’s warrant liability.

Property, Equipment, and Leaseh

Property, Equipment, and Leasehold Improvements	12 Months Ended
	Dec. 31, 2017
Property, Plant and Equipment [Abstract]
Property, Equipment, and Leasehold Improvements	5. Property, Equipment, and Leasehold Improvements Property, equipment, and leasehold improvements, at cost, consisted of: December 31, 2017 2016 Computer equipment $ 19,691 $ 19,691 Furniture 434,697 434,697 Lab equipment 1,710,881 1,710,881 Leasehold improvements 1,855,004 1,855,004 4,020,273 4,020,273 Less: accumulated depreciation and amortization (2,926,370 ) (2,739,121 ) $1,093,903 $1,281,152 Depreciation expense was $187,249, $451,008 and $537,344 for the years ended December 31, 2017, 2016 and 2015, respectively.

Accrued Expenses

Accrued Expenses	12 Months Ended
	Dec. 31, 2017
Payables and Accruals [Abstract]
Accrued Expenses	6. Accrued Expenses Accrued expenses consisted of the following: December 31, 2017 2016 Accrued compensation costs $ 2,107,118 $ 1,597,414 Accrued research and development service fees 578,562 504,193 Accrued facilities operation expenses 221,103 236,296 Accrued professional fees 168,168 299,912 Accrued licensing fees — 180,000 Other accrued expenses 43,286 50,537 $ 3,118,237 $ 2,868,352

Net Loss Per Share of Common St

Net Loss Per Share of Common Stock	12 Months Ended
	Dec. 31, 2017
Earnings Per Share [Abstract]
Net Loss Per Share of Common Stock	7. Net Loss Per Share of Common Stock Diluted loss per share is the same as basic loss per share for all periods presented because the effects of potentially dilutive items were anti-dilutive given the Company’s net loss. Basic loss per share is computed by dividing net loss available to common stockholders by the weighted-average number of common shares outstanding. The following table sets forth the computation of basic and diluted loss per share for common stockholders: Year Ended December 31, 2017 2016 2015 Net loss applicable to common stockholders $ (15,517,658 ) $ (28,538,399 ) $ (25,120,964 ) Weighted average shares of common stock outstanding 55,595,732 33,539,465 23,328,922 Net loss per share of common stock—basic and diluted $ (0.28 ) $ (0.85 ) $ (1.08 ) The following potentially dilutive securities outstanding at December 31, 2017, 2016 and 2015 have been excluded from the computation of diluted weighted average shares outstanding, as they would have been antidilutive given the Company’s net loss: December 31, 2017 2016 2015 Options to purchase common stock 6,200,151 4,691,746 4,313,755 Warrants to purchase common stock 36,270,103 27,214,775 13,503,107 42,470,254 31,906,521 17,816,862

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2017
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	8. Commitments and Contingencies Operating Leases In December 2010, the Company entered into a non-cancellable In January 2012, the Company entered into a non-cancellable Amount Year ending December 31: 2018 $ 640,514 2019 653,324 2020 666,391 2021 679,719 2022 693,313 Thereafter 3,680,190 $ 7,013,451 Rent expense is recognized on the straight-line method over the terms of each lease. Rent expense for the years ended December 31, 2017, 2016 and 2015, was approximately $587,000, $880,000 and $873,000, respectively. Rockefeller University License Agreements The Company has entered into the following license agreements with The Rockefeller University: • On July 12, 2011, the Company entered into a license agreement for the worldwide, exclusive right to a patent covering the composition of matter for the lysin PlySS2 for the treatment and prevention of diseases caused by gram-positive bacteria (the “CF-301 CF-301. • On June 1, 2011, the Company entered into a license agreement for the exclusive rights to The Rockefeller University’s interest in a joint patent application covering the method of delivering antibodies through the cell wall of gram-positive bacteria to the periplasmic space. This intellectual property was developed as a result of the sponsored research agreement between the Company and The Rockefeller University, and was jointly discovered and filed by the two parties. • On September 23, 2010, the Company entered into a license agreement for the worldwide, exclusive right to develop, make, have made, use, import, lease, sell, and offer for sale products that would otherwise infringe a claim of the suite of patents and patent applications covering the composition of matter for eight individual lysin molecules for the treatment and prevention of diseases caused by gram-positive bacteria. The lysins in this suite have activity against Group B Streptococci Staphylococcus aureus, Streptococcus pneumonia, Bacillus anthracis, Enterococcus faecalis and Enterococcus faecium In consideration for the licenses, we paid Rockefeller license initiation fees in cash and stock and are required to pay annual maintenance fees of $170,000 in 2018 and $200,000 each year thereafter, milestone payments and royalties of up to 5% on net sales from products to Rockefeller. We are allowed to grant sublicenses to third parties without prior approval, subject to certain conditions and the payment of a certain percentage of all payments we receive from sublicensees. Each license agreement terminates upon the later of (i) the expiration or abandonment of the last licensed patent under the license agreement to expire or become abandoned, or (ii) 10 years after the first commercial sale of the first licensed product. The Rockefeller University may terminate any license agreement in the event of a breach of such agreement by the Company or if the Company challenges the validity or enforceability of the underlying patent rights. The Company may terminate any license agreement at any time on 60 days’ notice. Collaborative Research Agreements Beginning in October 2009, we entered into a research agreement with Rockefeller where we provided funding for the research. The initial agreement focused on producing and testing monoclonal antibodies against proteins of Staph aureus Clostridia difficile P. aeruginosa, E. coli, K. pneumoniae Our current agreement runs through October 24, 2019 for which we will provide funding of $493,187 in 2018 and $249,749 in 2019. Either party may terminate the agreement upon breach of the agreement, following 30 days written notice and failure to cure such breach. Following the expiration or termination of the agreement, each party will have a non-exclusive right-of-first Trellis Biosciences, LLC On January 29, 2014, the Company entered into a license agreement with Trellis Biosciences, LLC (“Trellis”) that gives it exclusive rights to all Trellis mAbs in the field of influenza discovered from the Trellis CellSpot platform. Particularly, the license provides the Company with three fully human mAbs that bind, neutralize and protect animals from all strains of H1, H3 and B influenza, and that will also cross bind, neutralize and protect animals from all other seasonal or pandemic influenza strains that may arise (including H5N1 and H7N9). The Company will also be required to make payments to Trellis upon the achievement of specified development and regulatory milestones and upon the achievement of future sales and for royalty on future net sales from products of up to 4%. The Company is allowed to grant sublicenses to third parties. The license agreement terminates upon the earlier of (i) the Company’s decision to terminate the agreement at will or for safety reasons, (ii) material breach by either party that is not cured within ninety (90) days, or (iii) either party’s insolvency. Separation Agreement On December 12, 2017, the Company notified Lisa R. Ricciardi that she would no longer be needed to serve as Chief Operating Officer of the Company effective December 31, 2017. Subject to Ms. Ricciardi entering into a separation agreement, the Company accrued expense of $0.7 million for the severance payments and continued medical, dental and vision coverage under the Company’s group healthcare plans, to be provided for a period of 18 months following the effective date of Ms. Ricciardi’s termination, and recognized share-based compensation expense of $0.2 million for the accelerated vesting of all unvested portions of Ms. Ricciardi’s stock option grants. The total amount of these charges was recognized as part of general and administrative expenses in the consolidated statement of operations. Ms. Ricciardi currently remains a member of the Company’s board of directors. Legal Contingencies From time to time, the Company may be involved in disputes and legal proceedings in the ordinary course of its business. These proceedings may include allegations of infringement of intellectual property, employment or other matters. The Company records a liability in its financial statements for these matters when a loss is known or considered probable and the amount can be reasonably estimated. The Company reviews these estimates each accounting period as additional information is known and adjusts the loss provision when appropriate. If a matter is both probable to result in a liability and the amounts of loss can be reasonably estimated, the Company estimates and discloses the possible loss or range of loss to the extent necessary to make the financial statements not misleading. If the loss is not probable or cannot be reasonably estimated, a liability is not recorded in the Company’s financial statements. The Company currently has no legal proceedings ongoing that management estimates could have a material effect on the Company’s financial statements.

Capital Structure

Capital Structure	12 Months Ended
	Dec. 31, 2017
Equity [Abstract]
Capital Structure	9. Capital Structure Common Stock As of December 31, 2017, the Company was authorized to issue 200,000,000 shares of common stock at $0.0001 par value per share. Follow-on On July 25, 2017, the Company sold 32,000,000 shares of its common stock and warrants to purchase an additional 16,000,000 shares of its common stock in an underwritten follow-on On July 27, 2016, the Company sold 14,000,000 shares of its common stock and warrants to purchase an additional 14,000,000 shares of its common stock in an underwritten Follow-on The Company issued warrants in both follow-on re-measured Private Placement On June 12, 2015, the Company closed a private placement of its securities with a group of institutional investors (the “PIPE”). Each investor received one share of common stock and a warrant to purchase one-half The placement agents in the PIPE received warrants to purchase 4% of the total number of shares of common stock sold in the PIPE (the “Placement Agent Warrants”), for a total of 189,126 shares of common stock underlying the Placement Agent Warrants. The Placement Warrants became exercisable upon issuance at an exercise price of $4.65 per share and expire on June 11, 2020. The common stock and accompanying PIPE Warrants and Placement Agent Warrants have been classified to stockholders’ equity in the Company’s balance sheet. Initial Public Offering In July 2014, the shareholders approved an amended certificate of incorporation that became effectively immediately upon the closing of the Company’s initial public offering (“IPO”). The approved certificate increased the number of authorized shares of common stock to 100,000,000 shares. On August 1, 2014, the Company closed its IPO. Each Unit consisted of one share of common stock, one Class A Warrant to purchase one share of common stock at an exercise price of $4.80 per share and one Class B Warrant to purchase one-half On November 2, 2015, the Company’s Class B Warrants to purchase common stock expired in accordance with their terms. As of November 2, 2015, holders of the Class B Warrants had exercised 4,812,328 Class B Warrants, resulting in the issuance of 2,406,164 shares of the Company’s common stock and the receipt by the Company of approximately $9.6 million in gross proceeds. The 2,068,005 Class B Warrants that were not exercised prior to expiration have terminated and are no longer exercisable. Representative’s Warrant The Maxim Group, LLC, the representative of the underwriters in the IPO, received the Representative’s Warrant to purchase 3% of the total number of shares of common stock sold in the IPO, including those shares sold upon the exercise of the over-allotment, for a total of 206,410 shares of common stock underlying the Representative’s Warrant. The Representative’s Warrant became exercisable at an exercise price of $7.50 per share beginning 180 days after the effective date of the Company’s registration statement (January 24, 2015) and expires on August 27, 2019. The Company classified the Representative’s Warrant as a liability since it did not meet the requirements to be included in equity. The fair value of the Representative’s Warrant will be re-measured Convertible Notes The Company issued approximately $15.0 million aggregate principal amount of its 8.00% Convertible Notes due May 31, 2015 (the “Convertible Notes”) from June 2013 through June 2014. On August 1, 2014, in conjunction with the closing of the Company’s IPO, the principal amount of the Convertible Notes, and all accrued and unpaid interest thereon, automatically converted into 5,109,988 shares of common stock. Each purchaser of the Convertible Notes also received a warrant which included an exercise price “cap” that was analogous to “down round protection” (the “Note Warrants”). Upon the closing of the IPO and based on the terms of the Note Warrants, the Company determined the total number of shares of the Company’s common stock underlying the Note Warrants to be 3,321,416 at an exercise price of $3.00 per share. There were 3,315,878 shares of common stock underlying the outstanding Note Warrants as of December 31, 2017 and 2016. The Note Warrants expire five years from the date of issuance. Sales Agreement In January 2016, the Company entered into a Sales Agreement with Cowen and Company, LLC (“Cowen”) to sell shares of the Company’s common stock, with aggregate gross sales proceeds of up to $30 million, through an “at the market” equity offering program under which Cowen was to act as sales agent. On July 21, 2016, the Company terminated the Sales Agreement. The Company did not sell any shares under the program. Voting The holders of shares of common stock are entitled to one vote for each share of common stock held at all meetings of stockholders and written actions in lieu of meetings. Dividends The holders of shares of common stock are entitled to receive dividends, if and when declared by the board of directors. As of December 31, 2017, no dividends have been declared or paid on the Company’s common stock since inception. Reserved for Future Issuance The Company has reserved for future issuance the following number of shares of common stock as of December 31, 2017 and 2016: December 31, 2017 2016 Options to purchase common stock 6,200,151 4,691,746 Warrants to purchase common stock 36,270,103 27,214,775 42,470,254 31,906,521

Stock Warrants

Stock Warrants	12 Months Ended
	Dec. 31, 2017
Text Block [Abstract]
Stock Warrants	10. Stock Warrants As of December 31, 2017 and 2016, the Company had warrants outstanding as shown in the table below. December 31, 2017 2016 Note Warrants 3,315,878 3,315,878 Class A Warrants (1) — 6,880,333 PIPE Warrants 2,364,066 2,364,066 2017 Warrants 16,000,000 — 2016 Warrants 14,000,000 14,000,000 Representative’s Warrant 206,410 206,410 Placement Agent Warrants 189,126 189,126 Other warrants (2) 194,623 258,962 Warrants to purchase common stock 36,270,103 27,214,775 Weighted-average exercise price per share $ 2.74 $ 3.97 (1) On February 1, 2017, the Class A Warrants to purchase common stock expired in accordance with their terms. As none of the Class A Warrants were exercised prior to expiration, the Class A Warrants have been terminated and are no longer exercisable. (2) Other warrants are comprised of warrants issued prior to the Company’s IPO, generally in exchange for services rendered to the Company. The following table summarizes information regarding the Company’s warrants outstanding and the corresponding exercise price at December 31, 2017: Exercise Prices Shares Expiration Date £ 16,005,714 September 1, 2021 – July 25, 2022 $2.01 - $4.99 17,606,105 June 18, 2018 – July 27, 2021 $5.00 - $7.99 231,409 April 30, 2018 – July 22, 2019 ³ 2,426,875 June 11, 2018 – January 5, 2022 36,270,103

Stock Option and Incentive Plan

Stock Option and Incentive Plans	12 Months Ended
	Dec. 31, 2017
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Stock Option and Incentive Plans	11. Stock Option and Incentive Plans Amended and Restated 2008 Equity Incentive Plan In July 2008, the Company adopted the 2008 Equity Incentive Plan (the “Plan”). On February 26, 2013, the board of directors approved an amended and restated plan (the “Amended Plan”) to increase the number of shares of common stock available under the Amended Plan to 1,571,428 and, for new awards, to reduce the period that vested awards would remain exercisable upon termination of service from ten years to two years. The board of directors also approved an option exchange offer (the “Exchange Offer”) for eligible option holders with outstanding options with an exercise price in excess of $3.50 per share. The offering period for the Exchange Offer commenced on March 11, 2013 and expired on April 9, 2013. Participation in the Exchange Offer was voluntary. Options to purchase 647,521 shares of the Company’s common stock, held by a total of 26 participants, including 20 employees, were exchanged under the tender offer. The exchanged option grants were granted at an exercise price of $3.50 per share. The Company recorded expense associated with the modification with an immediate charge for the vested portion of option grants exchanged and additional charges as the remaining unvested portions become vested. The board of directors also increased the number of shares of common stock available under the Company’s Amended Plan on February 24, 2014 and April 29, 2014 to 1,857,142 and 2,357,142, respectively. As of the closing of the Company’s IPO, there will be no further grants made under the Amended Plan. 2014 Omnibus Incentive Plan In April 2014, the Company’s board of directors adopted the 2014 Omnibus Incentive Plan (the “2014 Plan”). The 2014 Plan was approved by the Company’s shareholders on July 3, 2014. The 2014 Plan allows for the granting of incentive and non-qualified The Company recognizes compensation expense for share-based compensation based on the fair value of the underlying instrument. The fair value of each stock option grant is estimated on the date of grant using the Black-Scholes option-pricing model. A summary of stock option activity for the year ended December 31, 2017, is summarized as follows: Number of Weighted Weighted Aggregate Options outstanding at December 31, 2016 4,691,746 $ 4.62 Granted 1,770,000 1.62 Exercised — — Expired (162,633 ) 4.35 Forfeited (98,962 ) 2.29 Options outstanding at December 31, 2017 6,200,151 $ 3.81 5.96 $ 150 Vested and exercisable at December 31, 2017 4,663,733 $ 4.23 5.12 $ 38 Of the option grants outstanding to purchase 6,200,151 shares of common stock, grants to purchase 657,156 shares of common stock were issued and are outstanding outside the Company’s incentive plans. The fair value of each option grant is estimated on the date of the grant using the Black-Scholes option-pricing model. The weighted average grant date fair value of options granted during the years ended December 31, 2017, 2016 and 2015 was $1.62, $3.25 and $4.64, respectively. Total compensation expense recognized amounted to $1,623,128, $2,231,883 and $1,929,112 for the years ended December 31, 2017, 2016 and 2015, respectively. As of December 31, 2017, the total remaining unrecognized compensation cost related to unvested stock options was $1,973,756 which will be recognized over a weighted average period of approximately 2.36 years. The following weighted average assumptions were used to compute the fair value of stock option grants: Year Ended December 31, 2017 2016 2015 Risk free interest rate 2.07 % 1.22 % 1.62 % Expected dividend yield — — — Expected term (in years) 6.01 5.01 5.75 Expected volatility 79.6 % 79.5 % 74.4 % Expected volatility— Expected term— Risk-free interest rate— Expected dividend yield—

401k Savings Plan

401k Savings Plan	12 Months Ended
	Dec. 31, 2017
Retirement Benefits [Abstract]
401k Savings Plan	12. 401k Savings Plan In 2010, the Company established a defined-contribution savings plan under Section 401(k) of the Internal Revenue Code (the 401(k) Plan). The 401(k) Plan covers all employees who meet defined minimum age and service requirements, and allows participants to defer a portion of their annual compensation on a pre-tax

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Income Taxes	13. Income Taxes The Company has available approximately $145,676,000 and $156,023,000 of unused operating loss carryforwards for federal and state tax purposes, respectively, that may be applied against future taxable income. The net operating loss carryforwards will expire through the year 2037 if not utilized prior to that date. The Company has evaluated the positive and negative evidence bearing upon the realizability of its net deferred tax assets. Based on the Company’s history of operating losses since inception, the Company has concluded that it is more likely than not that the benefit of its deferred tax assets will not be realized. Accordingly, no provision for a deferred tax asset has been made for the tax benefits of the net operating loss carryforwards as the entire amount is offset by a valuation allowance. The valuation allowance decreased by approximately $7,797,000 and increased by approximately $12,846,000 during the years 2017 and 2016, respectively, and was approximately $45,146,000 and $52,943,000 at December 31, 2017 and 2016, respectively. The Internal Revenue Code of 1986, as amended (the Code) provides for a limitation of the annual use of net operating losses and other tax attributes (such as research and development tax credit carryforwards) following certain ownership changes (as defined by the Code) that could limit the Company’s ability to utilize these carryforwards. At this time, the Company has not completed a study to assess whether an ownership change under Section 382 of the Code has occurred, or whether there have been multiple ownership changes since the Company’s formation, due to the costs and complexities associated with such a study. The Company may have experienced various ownership changes, as defined by the Code, as a result of past financing transactions. Accordingly, the Company’s ability to utilize the aforementioned carryforwards may be limited. Additionally, U.S. tax laws limit the time during which these carryforwards may be applied against future taxes. Therefore, the Company may not be able to take full advantage of these carryforwards for federal or state income tax purposes. 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 following resolution of any potential contingencies present related to the tax benefit. For the three years ended December 31, 2017, the Company had no unrecognized tax benefits or related interest and penalties accrued. The Company has not, as yet, conducted a study of research and development (R&D) credit carryforwards. This study may result in an adjustment to the Company’s R&D credit carryforwards; however, until a study is completed and any adjustment is known, no amounts are being presented as an uncertain tax position. A full valuation allowance has been provided against the Company’s R&D credits and, if an adjustment is required, this adjustment would be offset by an adjustment to the valuation allowance. Thus, there would be no impact to the balance sheet or statement of operations if an adjustment were required. The Company would recognize both accrued interest and penalties related to unrecognized benefits in income tax expense. The Company’s uncertain tax positions are related to years that remain subject to examination by relevant tax authorities. Since the Company is in a loss carryforward position, the Company is generally subject to examination by the U.S. federal, state and local income tax authorities for all tax years in which a loss carryforward is available. On December 22, 2017, the Tax Cuts and Jobs Act” (the “2017 Tax Act”) was enacted. The 2017 Tax Act lowered the U.S. federal corporate income tax rate from 35% to 21% effective January 1, 2018. As a result, the change in the U.S. federal tax rate required the Company to re-measure On December 22, 2017, the SEC issued Staff Accounting Bulletin No. 118 (“SAB 118”) which also provides guidance on accounting for the impacts of the 2017 Tax Act. SAB 118 provides a measurement period of up to one year from enactment for a company to complete its tax accounting under ASC 740. Once a company is able to make a reasonable estimate and record a provisional amount for effects of the 2017 Tax Act, it is required to do so. Given the substantial uncertainties surrounding the Tax Act and the short period of time between December 22, 2017 and December 31, 2017 to calculate the impacts of the 2017 Tax Act, the Company is accounting for its impact on a provisional (estimated) basis as allowed by SAB 118. Such provisional measurement amounts are anticipated to change as remaining analysis and review are completed, until the Company records a final amount within the measurement period. During the fourth quarter of 2017, the Company reduced its net deferred tax asset balance and offsetting valuation allowance by $18,284,538 as a provisional amount for the re-measurement The principal components of the Company’s deferred tax assets and liabilities are as follows: December 31, 2017 2016 Deferred tax assets/liabilities: Net operating loss carryovers $ 40,879,826 $ 47,860,522 Share-based compensation 1,702,036 2,168,126 R&D tax credits 1,750,785 1,783,716 Accrued compensation and severance 659,458 902,688 Depreciation (201,288 ) (386,758 ) Deferred rent 200,968 392,715 Intangible assets 154,669 221,783 45,146,454 52,942,793 Valuation allowance (45,146,454 ) (52,942,793 ) Net deferred tax assets (liabilities) $ — $ — A reconciliation of the statutory U.S. Federal rate to the company’s effective tax rate is as follows: Year Ended December 31, 2017 2016 2015 Federal income tax benefit at statutory rate (34.00 )% (34.00 )% (34.00 )% State income tax, net of federal benefit (9.95 ) (5.49 ) (5.49 ) Permanent items including change in fair value of warrants (22.03 ) (1.54 ) 1.99 Change in valuation allowance (50.33 ) 42.12 39.70 R&D tax credits (3.02 ) (1.03 ) (0.99 ) Deferred re-measurement 118.03 — — Other (1.30 ) (0.06 ) (1.21 ) Effective income tax (benefit) expense rate 0 % 0 % 0 %

Selected Quarterly Financial Da

Selected Quarterly Financial Data (Unaudited)	12 Months Ended
	Dec. 31, 2017
Quarterly Financial Information Disclosure [Abstract]
Selected Quarterly Financial Data (Unaudited)	14. Selected Quarterly Financial Data (Unaudited) The following tables show a summary of the Company’s unaudited quarterly financial data for each of the four quarters of 2017 and 2016: 2017 1 st 2 nd 3 rd 4 th Loss from operations $ (6,345,013 ) $ (6,079,121 ) $ (6,735,188 ) $ (7,404,435 ) Net loss $ (6,348,164 ) $ (2,836,887 ) $ (1,575,098 ) $ (4,757,509 ) Net loss per share of common stock, basic and diluted $ (0.15 ) $ (0.07 ) $ (0.02 ) $ (0.06 ) 2016 1 st 2 nd 3 rd 4 th Loss from operations $ (9,154,803 ) $ (9,777,796 ) $ (7,891,510 ) $ (6,708,137 ) Net income (loss) $ (8,923,162 ) $ (9,679,022 ) $ (10,530,584 ) $ 594,369 Net income (loss) per share of common stock, basic and diluted $ (0.32 ) $ (0.35 ) $ (0.28 ) $ 0.01

Summary of Significant Accoun23

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2017
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The accompanying financial information has been prepared in accordance with U.S. generally accepted accounting principles (“U.S. GAAP”).
Principles of Consolidation	Principles of Consolidation The Company has a wholly-owned subsidiary, ContraFect International Limited, in Scotland that establishes legal status for interactions with the European Economic Area. This subsidiary is dormant or is otherwise non-operative.
Segment and Geographic Information	Segment and Geographic Information Operating segments are identified as components of an enterprise about which separate discrete financial information is available for evaluation by the chief operating decision maker, or decision making group, in making decisions on how to allocate resources and assess performance. The Company’s chief operating decision maker is the chief executive officer. The Company and the chief decision maker view the Company’s operations and manage its business as one operating segment. The Company operates in only one geographic segment.
Significant Risks and Uncertainties	Significant Risks and Uncertainties The Company’s operations are subject to a number of factors that can affect its operating results and financial condition. Such factors include, but are not limited to: the results of clinical testing and trial activities of the Company’s products, the Company’s ability to obtain regulatory approval to market its products, competition from products manufactured and sold or being developed by other companies, the price of, and demand for, the Company’s products, the Company’s ability to negotiate favorable licensing or other manufacturing and marketing agreements for its products and the Company’s ability to raise capital.
Use of Estimates	Use of Estimates The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of expenses during the reporting period. The Company bases estimates and assumptions on historical experience when available and on various factors that it believes to be reasonable under the circumstances. On an ongoing basis, the Company evaluates its estimates and assumptions, including those related to accruals, fair value measurements, stock-based compensation, warrant valuation and income taxes. The Company’s actual results may differ from these estimates under different assumptions or conditions. There have been no significant changes from the Company’s original estimates in any periods presented.
Concentrations of Credit Risk	Concentrations of Credit Risk Financial instruments which potentially subject the Company to credit risk consist primarily of cash, cash equivalents and marketable securities. The Company holds these investments in highly rated financial institutions, and, by policy, limits the amounts of credit exposure to any one financial institution. These amounts at times may exceed federally insured limits. The Company has not experienced any credit losses in such accounts and does not believe it is exposed to any significant credit risk on these funds. The Company has no off-balance
Cash and Cash Equivalents	Cash and Cash Equivalents The Company considers all highly liquid investments with maturities at 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.
Marketable Securities	Marketable Securities Marketable securities consist of investments in corporate debt securities. Management determines the appropriate classification of the securities at the time they are acquired and evaluates the appropriateness of such classifications at each balance sheet date. The Company classifies its marketable securities as available-for-sale pursuant to ASC 320, Investments – Debt and Equity Securities The Company reviews marketable securities for other-than-temporary impairment whenever the fair value of a marketable security is less than the amortized cost and evidence indicates that a marketable security’s carrying amount is not recoverable within a reasonable period of time. Other-than-temporary impairments of investments are recognized in the consolidated statements of operations if the Company has experienced a credit loss, has the intent to sell the marketable security, or if it is more likely than not that the Company will be required to sell the marketable security before recovery of the amortized cost basis. Evidence considered in this assessment includes reasons for the impairment, compliance with the Company’s investment policy, the severity and the duration of the impairment and changes in value subsequent to the end of the period.
Fair Value of Financial Instruments	Fair Value of Financial Instruments The Company’s financial instruments consist of cash and cash equivalents, marketable securities, accounts payable, accrued liabilities and warrant liabilities. Fair value estimates of these instruments are made at a specific point in time, based on relevant market information. These estimates may be subjective in nature and involve uncertainties and matters of significant judgment and therefore cannot be determined with precision. The fair value of the Company’s warrant liabilities are based upon unobservable inputs, as described further below. The Company is required to disclose information on all assets and liabilities reported at fair value that enables an assessment of the inputs used in determining the reported fair values. FASB ASC Topic 820, Fair Value Measurements and Disclosures Level 1—Valuations based on unadjusted quoted prices in active markets for identical assets or liabilities that the Company has the ability to access at the measurement date. Level 2—Valuations based on quoted prices for similar assets or liabilities in markets that are not active or for which all significant inputs are observable, either directly or indirectly. Level 3—Valuations that require inputs that reflect the Company’s own assumptions that are both significant to the fair value measurement and unobservable. To the extent that valuation is based on models or inputs that are less observable or unobservable in the market, the determination of fair value requires more judgment. Accordingly, the degree of judgment exercised by the Company in determining fair value is greatest for instruments categorized in Level 3. A financial instrument’s level within the fair value hierarchy is based on the lowest level of any input that is significant to the fair value measurement. The Company had no liabilities classified as Level 1 or Level 2. The carrying amounts reported in the accompanying financial statements for accounts payable and accrued expenses approximate their respective fair values due to their short-term maturities. The fair value of the warrant and embedded derivative liabilities are discussed in Note 4, “Fair Value Measurements.”
Property, Office Equipment, and Leasehold Improvements	Property, Office Equipment, and Leasehold Improvements Property and equipment are recorded at cost less accumulated depreciation. Depreciation of property and equipment is provided by the straight-line method over their estimated useful lives, ranging from three to five years. Leasehold improvements are amortized on a straight line basis over the useful life of the improvement or the initial lease term, whichever is shorter. Costs for normal repair and maintenance are charged to expense as incurred.
Impairment of Long-lived Assets	Impairment of Long-lived Assets In accordance with ASC 360, Property, Plant, and Equipment
Deferred Rent	Deferred Rent The Company has an operating lease for office and laboratory space. Rent expense is recorded on a straight-line basis over the initial lease term. The difference between the actual cash paid and the straight-line rent expense is recorded as deferred rent.
Research and Development Costs	Research and Development Costs Research and development costs are charged to expense as incurred and are typically made up of salaries and benefits, clinical trial activities, drug development and manufacturing costs, and third-party service fees, including for clinical research organizations and investigative sites. 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 by vendors on 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 financial statements as prepaid or accrued expenses.
Share-based Compensation	Share-based Compensation The Company accounts for stock-based compensation in accordance with ASC 718, Compensation—Stock Compensation, non-employee The fair value of options is calculated using the Black-Scholes option pricing model on the date of grant based on key assumptions such as stock price, risk free interest rates, expected volatility and expected term. The Company’s estimates of these assumptions are primarily based on historical data, peer company data and judgment regarding future trends and factors.
Income Taxes	Income Taxes The Company uses the asset and liability method to calculate deferred tax assets and liabilities. Deferred taxes are recognized based on the differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax bases using enacted tax rates expected to apply to taxable income in the years in which those differences are expected to be recovered or settled. The Company records a valuation allowance against a deferred tax asset when it is more-likely-than-not The Company is subject to federal, state and local taxes and follows a recognition threshold and measurement attribute for the financial statement recognition and measurement of a tax position taken or expected to be taken in a tax return. The Company recognizes tax benefits or expenses of uncertain tax positions in the year such determination is made when the position is “more likely than not” to be sustained assuming examination by tax authorities. Management has reviewed the Company’s tax positions for all open tax years (tax years ended December 31, 2008 through December 31, 2016) and concluded that no provision for unrecognized tax benefits or expense is required in these financial statements. There are no income tax audits in progress as of December 31, 2017.
Grants	Grants The Company recognizes a receivable and the related reduction in its research and development expenses when the actual reimbursable costs have been incurred and there is reasonable assurance that the Company has complied with the conditions of the grants and the amounts will be received. For the year ended December 31, 2017, the Company recognized a reduction to its research and development expense in the amount of approximately $1.2 million. There were no similar grants recognized for the year ended December 31, 2016 or 2015. The receivable for grants as of December 31, 2017 was $343,372 and is included in prepaid expenses and other current assets. The Company has $2,054,290 of approved grant award funding remaining as of December 31, 2017.
Net Loss per Share Applicable to Common Stockholders	Net Loss per Share Applicable to Common Stockholders Basic net loss per share applicable to common stockholders is calculated by dividing net loss applicable to common stockholders by the weighted average shares outstanding during the period, without consideration for common stock equivalents. Diluted net loss per share applicable to common stockholders is calculated by adjusting weighted average shares outstanding for the dilutive effect of common stock equivalents outstanding for the period, determined using the treasury-stock method. For purposes of the dilutive net loss per share applicable to common stockholders calculation, stock options and warrant are considered to be common stock equivalents but are excluded from the calculation of diluted net loss per share applicable to common stockholders, as their effect would be anti-dilutive; therefore, basic and diluted net loss per share applicable to common stockholders were the same for all periods presented.
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 available-for-sale
Recently Adopted Accounting Pronouncements	Recently Adopted Accounting Pronouncements In March 2016, the FASB issued Accounting Standards Update, Improvements to Employee Share-Based Payment Accounting 2016-09). 2016-09 paid-in-capital 2016-09
Recent Accounting Pronouncements Not Yet Adopted	Recent Accounting Pronouncements Not Yet Adopted In January 2016, the FASB issued a new Accounting Standards Update, Recognition and Measurement of Financial Assets and Financial Liabilities (ASU 2016-01). 2016-01 2016-01. In February 2016, the FASB issued a new Accounting Standards Update , Leases (ASU 2016-02), 2016-02 right-of-use 2016-02 In June 2016, the FASB issued a new Accounting Standards Update, Financial Instruments-Credit Losses (ASU 2016-13). 2016-13 available-for-sale In August 2016, the FASB issued Accounting Standards Update No. 2016-15 , Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments 2016-15), 2016-15 2016-15 In November 2016, the FASB issued Accounting Standards Update No. 2016-18 , Statement of Cash Flows (Topic 230): Restricted Cash 2016-18), beginning-of-period end-of-period 2016-18 2016-18 In May 2017, the FASB issued Accounting Standards Update 2017-09, Compensation – Stock Compensation 2017-09). 2017-09

Marketable Securities (Tables)

Marketable Securities (Tables)	12 Months Ended
	Dec. 31, 2017
Investments, Debt and Equity Securities [Abstract]
Schedule of Marketable Securities	Marketable securities at December 31, 2017 consisted of the following: Marketable Securities Amortized Cost Unrealized Gains Unrealized Losses Fair Value Current: Corporate debt $ 39,933,685 $ — $ (74,820 ) $ 39,858,864 Marketable securities at December 31, 2016 consisted of the following: Marketable Securities Amortized Cost Unrealized Gains Unrealized Losses Fair Value Current: Corporate debt $ 31,405,836 $ 24 $ (51,690 ) $ 31,354,170
Schedule of Duration Periods of Available-for-sale Debt Securities	The duration periods of available-for-sale Amortized Cost Fair Value Duration of one year or less $ 38,213,753 $ 38,144,760 Duration of more than one year 1,719,932 1,714,104 Total $ 39,933,685 $ 39,858,864

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	12 Months Ended
	Dec. 31, 2017
Information about Company's Financial Assets and Liabilities Measured at Fair Value on Recurring Basis	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, 2017 and December 31, 2016: Fair Value Measurement As of December 31, 2017 Quoted Prices Significant Significant Cash equivalents $ 5,949,477 $ — $ — Marketable securities 39,858,864 — — Warrant liabilities — — 13,549,437 Total $ 45,808,341 $ — $ 13,549,437 Fair Value Measurement As of December 31, 2016 Quoted Prices Significant Significant Cash equivalents $ 3,411,058 $ — $ — Marketable securities 31,354,170 — — Warrant liabilities — — 12,698,980 Total $ 34,765,228 $ — $ 12,698,980
Reconciliation of Company's Financial Liabilities Measured at Fair Value on Recurring Basis Using Significant Unobservable Inputs (Level 3)	The following tables present a reconciliation of the Company’s financial liabilities measured at fair value on a recurring basis using significant unobservable inputs (Level 3) for the years ended December 31, 2017, 2016 and 2015: Warrant liabilities Year Ended December 31, 2017 2016 2015 Balance at beginning of period $ 12,698,980 $ 444,324 $ 313,004 Issuance of 2017 Warrants 12,383,435 — — Issuance of 2016 Warrants — 18,601,228 — Change in fair value (11,532,978 ) (6,346,572 ) 131,320 Balance at end of period $ 13,549,437 $ 12,698,980 $ 444,324
Representative's Warrant [Member]
Assumption Used to Determine Fair Value of Warrant Liability	The following assumptions were used in a Black-Scholes option-pricing model to determine the fair value of the warrant liability: As of As of Expected volatility 88.1 % 73.9 % Remaining contractual term (in years) 1.67 2.67 Risk-free interest rate 1.89 % 1.47 % Expected dividend yield — % — %
2016 Warrants [Member]
Assumption Used to Determine Fair Value of Warrant Liability	The following assumptions were used in a Black-Scholes option-pricing model to determine the fair value of the warrant liability: As of December 31, 2017 As of Expected volatility 80.3 % 79.9 % Remaining contractual term (in years) 3.58 4.58 Risk-free interest rate 2.09 % 1.93 % Expected dividend yield — % — %
2017 Warrants [Member]
Assumption Used to Determine Fair Value of Warrant Liability	The following assumptions were used in a Black-Scholes option-pricing model to determine the fair value of the warrant liability: As of December 31, 2017 At Issuance on Expected volatility 81.5 % 82.0 % Remaining contractual term (in years) 4.58 5.00 Risk-free interest rate 2.20 % 1.90 % Expected dividend yield — % — %

Property, Equipment, and Leas26

Property, Equipment, and Leasehold Improvements (Tables)	12 Months Ended
	Dec. 31, 2017
Property, Plant and Equipment [Abstract]
Schedule of Property, Equipment and Leasehold Improvements, at Cost	Property, equipment, and leasehold improvements, at cost, consisted of: December 31, 2017 2016 Computer equipment $ 19,691 $ 19,691 Furniture 434,697 434,697 Lab equipment 1,710,881 1,710,881 Leasehold improvements 1,855,004 1,855,004 4,020,273 4,020,273 Less: accumulated depreciation and amortization (2,926,370 ) (2,739,121 ) $1,093,903 $1,281,152

Accrued Expenses (Tables)

Accrued Expenses (Tables)	12 Months Ended
	Dec. 31, 2017
Payables and Accruals [Abstract]
Summary of Accrued Expenses	Accrued expenses consisted of the following: December 31, 2017 2016 Accrued compensation costs $ 2,107,118 $ 1,597,414 Accrued research and development service fees 578,562 504,193 Accrued facilities operation expenses 221,103 236,296 Accrued professional fees 168,168 299,912 Accrued licensing fees — 180,000 Other accrued expenses 43,286 50,537 $ 3,118,237 $ 2,868,352

Net Loss Per Share of Common 28

Net Loss Per Share of Common Stock (Tables)	12 Months Ended
	Dec. 31, 2017
Earnings Per Share [Abstract]
Schedule of Computation of Basic and Diluted Loss Per Share for Common Stockholders	The following table sets forth the computation of basic and diluted loss per share for common stockholders: Year Ended December 31, 2017 2016 2015 Net loss applicable to common stockholders $ (15,517,658 ) $ (28,538,399 ) $ (25,120,964 ) Weighted average shares of common stock outstanding 55,595,732 33,539,465 23,328,922 Net loss per share of common stock—basic and diluted $ (0.28 ) $ (0.85 ) $ (1.08 )
Schedule of Antidilutive Securities Excluded from Computation of Diluted Weighted Average Shares Outstanding	The following potentially dilutive securities outstanding at December 31, 2017, 2016 and 2015 have been excluded from the computation of diluted weighted average shares outstanding, as they would have been antidilutive given the Company’s net loss: December 31, 2017 2016 2015 Options to purchase common stock 6,200,151 4,691,746 4,313,755 Warrants to purchase common stock 36,270,103 27,214,775 13,503,107 42,470,254 31,906,521 17,816,862

Commitments and Contingencies (

Commitments and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2017
Commitments and Contingencies Disclosure [Abstract]
Summary of Future Minimum Lease Payments	Future minimum lease payments are as follows: Amount Year ending December 31: 2018 $ 640,514 2019 653,324 2020 666,391 2021 679,719 2022 693,313 Thereafter 3,680,190 $ 7,013,451

Capital Structure (Tables)

Capital Structure (Tables)	12 Months Ended
	Dec. 31, 2017
Equity [Abstract]
Summary of Common Stock Reserved for Future Issuance	The Company has reserved for future issuance the following number of shares of common stock as of December 31, 2017 and 2016: December 31, 2017 2016 Options to purchase common stock 6,200,151 4,691,746 Warrants to purchase common stock 36,270,103 27,214,775 42,470,254 31,906,521

Stock Warrants (Tables)

Stock Warrants (Tables)	12 Months Ended
	Dec. 31, 2017
Text Block [Abstract]
Schedule of Warrants Outstanding	As of December 31, 2017 and 2016, the Company had warrants outstanding as shown in the table below. December 31, 2017 2016 Note Warrants 3,315,878 3,315,878 Class A Warrants (1) — 6,880,333 PIPE Warrants 2,364,066 2,364,066 2017 Warrants 16,000,000 — 2016 Warrants 14,000,000 14,000,000 Representative’s Warrant 206,410 206,410 Placement Agent Warrants 189,126 189,126 Other warrants (2) 194,623 258,962 Warrants to purchase common stock 36,270,103 27,214,775 Weighted-average exercise price per share $ 2.74 $ 3.97 (1) On February 1, 2017, the Class A Warrants to purchase common stock expired in accordance with their terms. As none of the Class A Warrants were exercised prior to expiration, the Class A Warrants have been terminated and are no longer exercisable. (2) Other warrants are comprised of warrants issued prior to the Company’s IPO, generally in exchange for services rendered to the Company. The following table summarizes information regarding the Company’s warrants outstanding and the corresponding exercise price at December 31, 2017: Exercise Prices Shares Expiration Date £ 16,005,714 September 1, 2021 – July 25, 2022 $2.01 - $4.99 17,606,105 June 18, 2018 – July 27, 2021 $5.00 - $7.99 231,409 April 30, 2018 – July 22, 2019 ³ 2,426,875 June 11, 2018 – January 5, 2022 36,270,103

Stock Option and Incentive Pl32

Stock Option and Incentive Plans (Tables)	12 Months Ended
	Dec. 31, 2017
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Summary of Stock Option Activity	A summary of stock option activity for the year ended December 31, 2017, is summarized as follows: Number of Weighted Weighted Aggregate Options outstanding at December 31, 2016 4,691,746 $ 4.62 Granted 1,770,000 1.62 Exercised — — Expired (162,633 ) 4.35 Forfeited (98,962 ) 2.29 Options outstanding at December 31, 2017 6,200,151 $ 3.81 5.96 $ 150 Vested and exercisable at December 31, 2017 4,663,733 $ 4.23 5.12 $ 38
Assumptions to Compute Fair Value of Stock Option Grants	The following weighted average assumptions were used to compute the fair value of stock option grants: Year Ended December 31, 2017 2016 2015 Risk free interest rate 2.07 % 1.22 % 1.62 % Expected dividend yield — — — Expected term (in years) 6.01 5.01 5.75 Expected volatility 79.6 % 79.5 % 74.4 %

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Components of Deferred Tax Assets and Liabilities	The principal components of the Company’s deferred tax assets and liabilities are as follows: December 31, 2017 2016 Deferred tax assets/liabilities: Net operating loss carryovers $ 40,879,826 $ 47,860,522 Share-based compensation 1,702,036 2,168,126 R&D tax credits 1,750,785 1,783,716 Accrued compensation and severance 659,458 902,688 Depreciation (201,288 ) (386,758 ) Deferred rent 200,968 392,715 Intangible assets 154,669 221,783 45,146,454 52,942,793 Valuation allowance (45,146,454 ) (52,942,793 ) Net deferred tax assets (liabilities) $ — $ —
Summary of Reconciliation of Statutory U.S. Federal Rate to Company's Effective Tax Rate	A reconciliation of the statutory U.S. Federal rate to the company’s effective tax rate is as follows: Year Ended December 31, 2017 2016 2015 Federal income tax benefit at statutory rate (34.00 )% (34.00 )% (34.00 )% State income tax, net of federal benefit (9.95 ) (5.49 ) (5.49 ) Permanent items including change in fair value of warrants (22.03 ) (1.54 ) 1.99 Change in valuation allowance (50.33 ) 42.12 39.70 R&D tax credits (3.02 ) (1.03 ) (0.99 ) Deferred re-measurement 118.03 — — Other (1.30 ) (0.06 ) (1.21 ) Effective income tax (benefit) expense rate 0 % 0 % 0 %

Selected Quarterly Financial 34

Selected Quarterly Financial Data (Unaudited) (Tables)	12 Months Ended
	Dec. 31, 2017
Quarterly Financial Information Disclosure [Abstract]
Summary of Unaudited Quarterly Financial Data	The following tables show a summary of the Company’s unaudited quarterly financial data for each of the four quarters of 2017 and 2016: 2017 1 st 2 nd 3 rd 4 th Loss from operations $ (6,345,013 ) $ (6,079,121 ) $ (6,735,188 ) $ (7,404,435 ) Net loss $ (6,348,164 ) $ (2,836,887 ) $ (1,575,098 ) $ (4,757,509 ) Net loss per share of common stock, basic and diluted $ (0.15 ) $ (0.07 ) $ (0.02 ) $ (0.06 ) 2016 1 st 2 nd 3 rd 4 th Loss from operations $ (9,154,803 ) $ (9,777,796 ) $ (7,891,510 ) $ (6,708,137 ) Net income (loss) $ (8,923,162 ) $ (9,679,022 ) $ (10,530,584 ) $ 594,369 Net income (loss) per share of common stock, basic and diluted $ (0.32 ) $ (0.35 ) $ (0.28 ) $ 0.01

Organization and Description 35

Organization and Description of Business - Additional Information (Detail) - USD ($)	Jul. 25, 2017	Jul. 27, 2016	Nov. 02, 2015	Jun. 12, 2015	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Organization And Description Of Business [Line Items]
Proceeds from exercise of warrants						$ 55,998	$ 9,698,567
Private Placement [Member]
Organization And Description Of Business [Line Items]
Number of shares issued				4,728,128
Warrants to purchase shares of common stock				2,364,066	189,126
Warrant exercise price per share				$ 8	$ 4.65
Net proceeds received				$ 18,300,000
Warrants expiration date					Jun. 11, 2020
Follow-on Offering [Member]
Organization And Description Of Business [Line Items]
Number of shares issued	32,000,000	14,000,000
Warrants to purchase shares of common stock	16,000,000	14,000,000
Warrant exercise price per share	$ 1.55	$ 3
Net proceeds received	$ 37,100,000	$ 32,000,000
Public offering price, per unit	$ 1.25	$ 2.50
Class B Warrants [Member]
Organization And Description Of Business [Line Items]
Warrants exercised			4,812,328
Common stock shares issued upon exercise of warrants			2,406,164
Proceeds from exercise of warrants			$ 9,600,000
Unexercised warrants terminated			2,068,005
Warrants expiration date					Nov. 2, 2015

Summary of Significant Accoun36

Summary of Significant Accounting Policies - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2017USD ($)GeographicalAreasSegment	Dec. 31, 2016USD ($)	Dec. 31, 2015USD ($)
Summary Of Significant Accounting Policies [Line Items]
Number of operating segment | Segment	1
Number of geographic segment | GeographicalAreas	1
Maturity period of highly liquid investments	Three months or less
Realized gains or losses on marketable securities	$ 0	$ 0	$ 0
Number of securities in unrealized loss position for more than 12 months	0	0
Impairment of long-lived assets	$ 0
Provision for unrecognized tax benefits or expense	0
Grants receivable recognized	1,200,000	$ 0	$ 0
Grants receivable	343,372
Grants remaining to be awarded	$ 2,054,290
Earliest Tax Year [Member]
Summary Of Significant Accounting Policies [Line Items]
Tax position for all open tax years	2,008
Latest Tax Year [Member]
Summary Of Significant Accounting Policies [Line Items]
Tax position for all open tax years	2,016
Minimum [Member]
Summary Of Significant Accounting Policies [Line Items]
Property and equipment, estimated useful lives	3 years
Maximum [Member]
Summary Of Significant Accounting Policies [Line Items]
Property and equipment, estimated useful lives	5 years
Level 1 [Member]
Summary Of Significant Accounting Policies [Line Items]
Liabilities	$ 0
Level 2 [Member]
Summary Of Significant Accounting Policies [Line Items]
Liabilities	$ 0

Marketable Securities - Schedul

Marketable Securities - Schedule of Marketable Securities (Detail) - USD ($)	Dec. 31, 2017	Dec. 31, 2016
Schedule of Available-for-sale Securities [Line Items]
Marketable Securities, Amortized Cost	$ 39,933,685
Marketable Securities, Fair Value	39,858,864
Corporate Debt [Member]
Schedule of Available-for-sale Securities [Line Items]
Marketable Securities, Amortized Cost	39,933,685	$ 31,405,836
Marketable Securities, Unrealized Gains		24
Marketable Securities, Unrealized Losses	(74,820)	(51,690)
Marketable Securities, Fair Value	$ 39,858,864	$ 31,354,170

Marketable Securities - Sched38

Marketable Securities - Schedule of Duration Periods of Available-for-sale Debt Securities (Detail)	Dec. 31, 2017USD ($)
Available-for-sale Securities, Debt Maturities [Abstract]
Duration of one year or less, Amortized Cost	$ 38,213,753
Duration of more than one year, Amortized Cost	1,719,932
Marketable Securities, Amortized Cost	39,933,685
Duration of one year or less, Fair Value	38,144,760
Duration of more than one year, Fair Value	1,714,104
Total, Fair Value	$ 39,858,864

Marketable Securities - Additio

Marketable Securities - Additional Information (Detail)	Dec. 31, 2017USD ($)Security	Dec. 31, 2016USD ($)Security
Marketable Securities [Abstract]
Number of securities in unrealized loss position for less than one year | Security	32	29
Aggregate fair value of debt securities | $	$ 39,858,864	$ 29,343,892

Fair Value Measurements - Infor

Fair Value Measurements - Information about Company's Financial Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) - USD ($)	Dec. 31, 2017	Dec. 31, 2016
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	$ 39,858,864	$ 31,354,170
Warrant liabilities	(13,549,437)	(12,698,980)
Fair Value, Measurements, Recurring [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	5,949,477	3,411,058
Marketable securities	39,858,864	31,354,170
Total assets (liabilities)	45,808,341	34,765,228
Fair Value, Measurements, Recurring [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Warrant liabilities	13,549,437	12,698,980
Total assets (liabilities)	$ 13,549,437	$ 12,698,980

Fair Value Measurements - Assum

Fair Value Measurements - Assumption Used to Determine Fair Value of Warrant Liability (Detail)	Dec. 31, 2017	Jul. 25, 2017	Dec. 31, 2016
Representative's Warrant [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Expected volatility	88.10%		73.90%
Remaining contractual term (in years)	1 year 8 months 2 days		2 years 8 months 2 days
Risk-free interest rate	1.89%		1.47%
Expected dividend yield	0.00%		0.00%
2016 Warrants [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Expected volatility	80.30%		79.90%
Remaining contractual term (in years)	3 years 6 months 29 days		4 years 6 months 29 days
Risk-free interest rate	2.09%		1.93%
Expected dividend yield	0.00%		0.00%
2017 Warrants [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Expected volatility	81.50%	82.00%
Remaining contractual term (in years)	4 years 6 months 29 days	5 years
Risk-free interest rate	2.20%	1.90%
Expected dividend yield	0.00%	0.00%

Fair Value Measurements - Recon

Fair Value Measurements - Reconciliation of Company's Financial Liabilities Measured at Fair Value on Recurring Basis Using Significant Unobservable Inputs (Level 3) (Detail) - Warrant Liabilities [Member] - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Balance at beginning of period	$ 12,698,980	$ 444,324	$ 313,004
Change in fair value	(11,532,978)	(6,346,572)	131,320
Balance at end of period	13,549,437	12,698,980	$ 444,324
2017 Warrants [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Issuance of warrants	$ 12,383,435
2016 Warrants [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Issuance of warrants		$ 18,601,228

Property, Equipment, and Leas43

Property, Equipment, and Leasehold Improvements - Schedule of Property, Equipment and Leasehold Improvements, at Cost (Detail) - USD ($)	Dec. 31, 2017	Dec. 31, 2016
Property, Plant and Equipment [Line Items]
Property, equipment, and leasehold improvements, at cost, gross	$ 4,020,273	$ 4,020,273
Less: accumulated depreciation and amortization	(2,926,370)	(2,739,121)
Property, equipment, and leasehold improvements, at cost, net	1,093,903	1,281,152
Computer Equipment [Member]
Property, Plant and Equipment [Line Items]
Property, equipment, and leasehold improvements, at cost, gross	19,691	19,691
Furniture [Member]
Property, Plant and Equipment [Line Items]
Property, equipment, and leasehold improvements, at cost, gross	434,697	434,697
Lab Equipment [Member]
Property, Plant and Equipment [Line Items]
Property, equipment, and leasehold improvements, at cost, gross	1,710,881	1,710,881
Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Property, equipment, and leasehold improvements, at cost, gross	$ 1,855,004	$ 1,855,004

Property, Equipment, and Leas44

Property, Equipment, and Leasehold Improvements - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Property, Plant and Equipment [Abstract]
Depreciation expense	$ 187,249	$ 451,008	$ 537,344

Accrued Expenses - Summary of A

Accrued Expenses - Summary of Accrued Expenses (Detail) - USD ($)	Dec. 31, 2017	Dec. 31, 2016
Payables and Accruals [Abstract]
Accrued compensation costs	$ 2,107,118	$ 1,597,414
Accrued research and development service fees	578,562	504,193
Accrued facilities operation expenses	221,103	236,296
Accrued professional fees	168,168	299,912
Accrued licensing fees		180,000
Other accrued expenses	43,286	50,537
Total accrued expenses	$ 3,118,237	$ 2,868,352

Net Loss Per Share of Common 46

Net Loss Per Share of Common Stock - Schedule of Computation of Basic and Diluted Loss Per Share for Common Stockholders (Detail) - USD ($)	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Earnings Per Share [Abstract]
Net loss applicable to common stockholders									$ (15,517,658)	$ (28,538,399)	$ (25,120,964)
Weighted average shares of common stock outstanding									55,595,732	33,539,465	23,328,922
Net loss per share of common stock-basic and diluted	$ (0.06)	$ (0.02)	$ (0.07)	$ (0.15)	$ 0.01	$ (0.28)	$ (0.35)	$ (0.32)	$ (0.28)	$ (0.85)	$ (1.08)

Net Loss Per Share of Common 47

Net Loss Per Share of Common Stock - Schedule of Antidilutive Securities Excluded from Computation of Diluted Weighted Average Shares Outstanding (Detail) - shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potentially antidilutive securities outstanding excluded from the computation of diluted weighted average shares	42,470,254	31,906,521	17,816,862
Employee Stock Options [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potentially antidilutive securities outstanding excluded from the computation of diluted weighted average shares	6,200,151	4,691,746	4,313,755
Warrants [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potentially antidilutive securities outstanding excluded from the computation of diluted weighted average shares	36,270,103	27,214,775	13,503,107

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Detail)	1 Months Ended			12 Months Ended
	Jan. 31, 2012ft²ExtensionOptions	Dec. 31, 2011ExtensionOptions	Dec. 31, 2010	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)	Dec. 31, 2015USD ($)
Loss Contingencies [Line Items]
Non-cancellable operating lease, expiration date	2027-12		2025-12
Extended lease agreement, date		2027-12
Number of lease extension options | ExtensionOptions	2	2
Lease renewal termination period	5 years	5 years
Area of space relinquished from lease agreement | ft²	10,912
Rent expense						$ 587,000	$ 880,000	$ 873,000
General and Administrative Expense [Member] | Supplemental Employee Retirement Plan [Member]
Loss Contingencies [Line Items]
Separation agreement date						Dec. 12, 2017
Severance payments period following the effective date of retirement						18 months
Agreement description						On December 12, 2017, the Company notified Lisa R. Ricciardi that she would no longer be needed to serve as Chief Operating Officer of the Company effective December 31, 2017. Subject to Ms. Ricciardi entering into a separation agreement, the Company accrued expense of $0.7 million for the severance payments and continued medical, dental and vision coverage under the Company’s group healthcare plans, to be provided for a period of 18 months following the effective date of Ms. Ricciardi’s termination, and recognized share-based compensation expense of $0.2 million for the accelerated vesting of all unvested portions of Ms. Ricciardi’s stock option grants. The total amount of these charges was recognized as part of general and administrative expenses in the consolidated statement of operations. Ms. Ricciardi currently remains a member of the Company’s board of directors.
Severance payment on effective date of retirement, as per the agreement						$ 700,000
Share-based compensation expense						200,000
Rockefeller University [Member]
Loss Contingencies [Line Items]
Annual maintenance fees payable in 2018						170,000
Annual maintenance fees payable after 2018						$ 200,000
Percentage of royalty on net sales						5.00%
License agreement termination notice period						60 days
Period of termination after first commercial sale of first licensed product						10 years
License agreement termination description						Each license agreement terminates upon the later of (i) the expiration or abandonment of the last licensed patent under the license agreement to expire or become abandoned, or (ii) 10 years after the first commercial sale of the first licensed product. The Rockefeller University may terminate any license agreement in the event of a breach of such agreement by the Company or if the Company challenges the validity or enforceability of the underlying patent rights. The Company may terminate any license agreement at any time on 60 days’ notice.
Trellis Biosciences, LLC [Member]
Loss Contingencies [Line Items]
License agreement, date						Jan. 29, 2014
License agreement, description						The license provides the Company with three fully human mAbs
License agreement expiration period						90 days
Maximum future net product sales percentage						4.00%
Collaborative Research Agreement [Member]
Loss Contingencies [Line Items]
License agreement termination notice period						30 days
License agreement expiration date						Oct. 24, 2019
Collaborative Research Agreement [Member] | Scenario, Forecast [Member]
Loss Contingencies [Line Items]
Collaborative agreement research funding amount				$ 249,749	$ 493,187

Commitments and Contingencies49

Commitments and Contingencies - Summary of Future Minimum Lease Payments (Detail)	Dec. 31, 2017USD ($)
Commitments and Contingencies Disclosure [Abstract]
2,018	$ 640,514
2,019	653,324
2,020	666,391
2,021	679,719
2,022	693,313
Thereafter	3,680,190
Total future minimum lease payments	$ 7,013,451

Capital Structure - Additional

Capital Structure - Additional Information (Detail) - USD ($)

Dec. 31, 2017

Jul. 25, 2017

Jan. 31, 2017

Jul. 27, 2016

Nov. 02, 2015

Jun. 12, 2015

Aug. 01, 2014

Jan. 31, 2016

Dec. 31, 2017

Dec. 31, 2016

Dec. 31, 2015

Jun. 30, 2014

Jul. 31, 2014

Class of Stock [Line Items]

Common stock, shares authorized

200,000,000

200,000,000

100,000,000

100,000,000

Common stock, par value

$ 0.0001

$ 0.0001

$ 0.0001

Issuance costs allocated to warrants

$ 905,014

$ 1,569,341

Initial public offering, closing date

Aug. 1, 2014

Initial public offering, units description

Each Unit consisted of one share of common stock, one Class A Warrant to purchase one share of common stock at an exercise price of $4.80 per share and one Class B Warrant to purchase one-half share of common stock at an exercise price of $4.00 per full share.

Net proceeds from initial public offering

$ 35,000,000

Proceeds from exercise of warrants

$ 55,998

$ 9,698,567

Number of warrants or rights outstanding

36,270,103

36,270,103

27,214,775

Common stock, voting rights

The holders of shares of common stock are entitled to one vote for each share of common stock held at all meetings of stockholders and written actions in lieu of meetings.

Dividends declared or paid

$ 0

8.00% Convertible Notes due May 31, 2015 [Member]

Class of Stock [Line Items]

Convertible Notes, principal amount

$ 15,000,000

Convertible Notes, interest rate

8.00%

Convertible Notes, due date

May 31, 2015

2016 Warrants [Member]

Class of Stock [Line Items]

Number of warrants or rights outstanding

14,000,000

14,000,000

14,000,000

2017 Warrants [Member]

Class of Stock [Line Items]

Number of warrants or rights outstanding

16,000,000

16,000,000

Private Placement [Member]

Class of Stock [Line Items]

Number of shares issued

4,728,128

Warrants to purchase shares of common stock

189,126

2,364,066

189,126

Net proceeds received

$ 18,300,000

Warrant exercise price per share

$ 4.65

$ 8

$ 4.65

Private placement, securities description

Each investor received one share of common stock and a warrant to purchase one-half share of common stock at a price of $4.23 per common share purchased.

Warrants expiration period

3 years

Exercise price per common share

$ 4.23

Class of warrant purchase percentage

4.00%

4.00%

Warrant expiration date

Jun. 11, 2020

Initial Public Offering [Member]

Class of Stock [Line Items]

Number of shares issued

6,880,333

Public offering price, per unit

$ 6

Common stock units issued upon exercise of option by underwriters

880,333

Conversion of Convertible Notes together with accrued and unpaid interest into common stock, shares

5,109,988

At the Market Equity Offering Program [Member] | Maximum [Member] | Cowen and Company, LLC [Member]

Class of Stock [Line Items]

Aggregate gross sales proceeds from common stock

$ 30,000,000

Follow-on Offering [Member]

Class of Stock [Line Items]

Number of shares issued

32,000,000

14,000,000

Warrants to purchase shares of common stock

16,000,000

14,000,000

Aggregate gross sales proceeds from common stock

$ 40,000,000

$ 35,000,000

Net proceeds received

$ 37,100,000

$ 32,000,000

Warrant exercise price per share

$ 1.55

$ 3

Public offering price, per unit

$ 1.25

$ 2.50

Follow-on Offering [Member] | CMPO Warrants [Member]

Class of Stock [Line Items]

Warrants to purchase shares of common stock

16,000,000

14,000,000

Follow-on Offering [Member] | 2016 Warrants [Member]

Class of Stock [Line Items]

Warrant exercise price per share

$ 3

Warrant expiration term

5 years

Fair value of warrants

$ 18,600,000

Issuance costs allocated to warrants

$ 1,600,000

Follow-on Offering [Member] | 2017 Warrants [Member]

Class of Stock [Line Items]

Warrant exercise price per share

$ 1.55

Warrant expiration term

5 years

Fair value of warrants

$ 12,400,000

Issuance costs allocated to warrants

$ 900,000

Note Warrants [Member]

Class of Stock [Line Items]

Warrant exercise price per share

$ 3

Warrants expiration period

5 years

Number of warrants or rights outstanding

3,315,878

3,321,416

3,315,878

3,315,878

Class B Warrants [Member]

Class of Stock [Line Items]

Warrant expiration date

Nov. 2, 2015

Warrants exercised

4,812,328

Common stock shares issued upon exercise of warrants

2,406,164

Proceeds from exercise of warrants

$ 9,600,000

Unexercised warrants terminated

2,068,005

Class B Warrants [Member] | Initial Public Offering [Member]

Class of Stock [Line Items]

Warrant exercise price per share

$ 4

Representative's Warrant [Member]

Class of Stock [Line Items]

Warrants to purchase shares of common stock

206,410

206,410

Warrant exercise price per share

$ 7.50

$ 7.50

Class of warrant purchase percentage

3.00%

3.00%

Warrant expiration date

Aug. 27, 2019

Warrant exercisable period

180 days

Number of warrants or rights outstanding

206,410

206,410

206,410

Class A Warrants [Member]

Class of Stock [Line Items]

Warrant expiration date

Feb. 1, 2017

Warrants exercised

0

Number of warrants or rights outstanding

6,880,333

Class A Warrants [Member] | Initial Public Offering [Member]

Class of Stock [Line Items]

Warrant exercise price per share

$ 4.80

Capital Structure - Summary of

Capital Structure - Summary of Common Stock Reserved for Future Issuance (Detail) - shares	Dec. 31, 2017	Dec. 31, 2016
Class of Stock [Line Items]
Common Stock reserved for future issuance	42,470,254	31,906,521
Stock Options [Member]
Class of Stock [Line Items]
Common Stock reserved for future issuance	6,200,151	4,691,746
Warrants [Member]
Class of Stock [Line Items]
Common Stock reserved for future issuance	36,270,103	27,214,775

Stock Warrants - Schedule of Wa

Stock Warrants - Schedule of Warrants Outstanding (Detail) - $ / shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Jun. 12, 2015	Aug. 01, 2014
Class of Warrant or Right [Line Items]
Shares Underlying Outstanding Warrants	36,270,103	27,214,775
Weighted-average exercise price per share	$ 2.74	$ 3.97
Placement Agent Warrants [Member]
Class of Warrant or Right [Line Items]
Shares Underlying Outstanding Warrants	189,126	189,126
Class A Warrants [Member]
Class of Warrant or Right [Line Items]
Shares Underlying Outstanding Warrants		6,880,333
Representative's Warrant [Member]
Class of Warrant or Right [Line Items]
Exercise Prices	$ 7.50
Shares Underlying Outstanding Warrants	206,410	206,410
Other Warrants [Member]
Class of Warrant or Right [Line Items]
Shares Underlying Outstanding Warrants	194,623	258,962
Exercise Price Less Than or Equal to $2.00 [Member]
Class of Warrant or Right [Line Items]
Shares Underlying Outstanding Warrants	16,005,714
Expiration Start Date	Sep. 1, 2021
Expiration End Date	Jul. 25, 2022
Exercise Price $2.01 - $4.99 [Member]
Class of Warrant or Right [Line Items]
Shares Underlying Outstanding Warrants	17,606,105
Expiration Start Date	Jun. 18, 2018
Expiration End Date	Jul. 27, 2021
Exercise Price $5.00 - $7.99 [Member]
Class of Warrant or Right [Line Items]
Shares Underlying Outstanding Warrants	231,409
Expiration Start Date	Apr. 30, 2018
Expiration End Date	Jul. 22, 2019
Exercise Price Greater Than or Equal to $8.00 [Member]
Class of Warrant or Right [Line Items]
Shares Underlying Outstanding Warrants	2,426,875
Expiration Start Date	Jun. 11, 2018
Expiration End Date	Jan. 5, 2022
Minimum [Member] | Exercise Price $2.01 - $4.99 [Member]
Class of Warrant or Right [Line Items]
Exercise Prices	$ 2.01
Minimum [Member] | Exercise Price $5.00 - $7.99 [Member]
Class of Warrant or Right [Line Items]
Exercise Prices	5
Minimum [Member] | Exercise Price Greater Than or Equal to $8.00 [Member]
Class of Warrant or Right [Line Items]
Exercise Prices	8
Maximum [Member] | Exercise Price Less Than or Equal to $2.00 [Member]
Class of Warrant or Right [Line Items]
Exercise Prices	2
Maximum [Member] | Exercise Price $2.01 - $4.99 [Member]
Class of Warrant or Right [Line Items]
Exercise Prices	4.99
Maximum [Member] | Exercise Price $5.00 - $7.99 [Member]
Class of Warrant or Right [Line Items]
Exercise Prices	$ 7.99
Note Warrants [Member]
Class of Warrant or Right [Line Items]
Exercise Prices				$ 3
Shares Underlying Outstanding Warrants	3,315,878	3,315,878		3,321,416
Private Placement [Member]
Class of Warrant or Right [Line Items]
Exercise Prices	$ 4.65		$ 8
Warrants [Member] | Private Placement [Member]
Class of Warrant or Right [Line Items]
Shares Underlying Outstanding Warrants	2,364,066	2,364,066
2016 Warrants [Member]
Class of Warrant or Right [Line Items]
Shares Underlying Outstanding Warrants	14,000,000	14,000,000
2017 Warrants [Member]
Class of Warrant or Right [Line Items]
Shares Underlying Outstanding Warrants	16,000,000

Stock Warrants - Schedule of 53

Stock Warrants - Schedule of Warrants Outstanding (Parenthetical) (Detail) - Class A Warrants [Member] - shares	Jan. 31, 2017	Dec. 31, 2017
Class of Warrant or Right [Line Items]
Warrants expiration date		Feb. 1, 2017
Warrants exercised	0

Stock Option and Incentive Pl54

Stock Option and Incentive Plans - Additional Information (Detail)	Dec. 31, 2015	Feb. 26, 2013ParticipantEmployees$ / sharesshares	Dec. 31, 2017USD ($)$ / sharesshares	Dec. 31, 2016USD ($)$ / sharesshares	Dec. 31, 2015USD ($)$ / shares	Jul. 28, 2014shares	Apr. 29, 2014shares	Feb. 24, 2014shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares of common stock reserved pursuant to the plan			42,470,254	31,906,521
Exercise price per share, Granted | $ / shares			$ 1.62
Number of common stock shares outstanding			6,200,151	4,691,746
Number of common stock available for grant			657,156
Weighted average grant date fair value of options | $ / shares			$ 1.62	$ 3.25	$ 4.64
Unrecognized compensation cost related to unvested stock options | $			$ 1,973,756
Weighted average period of unvested stock options			2 years 4 months 9 days
Employee Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation expense recognized | $			$ 1,623,128	$ 2,231,883	$ 1,929,112
Amended and Restated 2008 Equity Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares of common stock reserved pursuant to the plan		1,571,428					2,357,142	1,857,142
Termination of service, Period		2 years
Exercise price per share, Granted | $ / shares		$ 3.50
Number of participants | Participant		26
Number of employees | Employees		20
Options to purchase Company's Common Stock		647,521
2008 Equity Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Termination of service, Period		10 years
2014 Omnibus Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares of common stock reserved pursuant to the plan						571,429
Number of additional shares increases of common stock reserved pursuant to the plan			3,574,237
2014 Omnibus Incentive Plan [Member] | Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Annual increase of plan, percentage of common stock shares outstanding	4.00%

Stock Option and Incentive Pl55

Stock Option and Incentive Plans - Summary of Stock Option Activity (Detail)	12 Months Ended
	Dec. 31, 2017USD ($)$ / sharesshares
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Number of Options, Options outstanding, Beginning balance | shares	4,691,746
Number of Options, Granted | shares	1,770,000
Number of Options, Exercised | shares	0
Number of Options, Expired | shares	(162,633)
Number of Options, Forfeited | shares	(98,962)
Number of Options, Options outstanding, Ending balance | shares	6,200,151
Number of Options, Vested and exercisable, Ending Balance | shares	4,663,733
Weighted Average Exercise Price, Options outstanding, Beginning balance | $ / shares	$ 4.62
Weighted Average Exercise Price, Granted | $ / shares	1.62
Weighted Average Exercise Price, Exercised | $ / shares	0
Weighted Average Exercise Price, Expired | $ / shares	4.35
Weighted Average Exercise Price, Forfeited | $ / shares	2.29
Weighted Average Exercise Price, Options outstanding, Ending balance | $ / shares	3.81
Weighted Average Exercise Price, Vested and exercisable, Ending balance | $ / shares	$ 4.23
Weighted Average Remaining Contractual Life (in years), Options outstanding	5 years 11 months 15 days
Weighted Average Remaining Contractual Life (in years), Vested and exercisable	5 years 1 month 13 days
Aggregate Intrinsic value, Options outstanding | $	$ 150
Aggregate Intrinsic value, Vested and exercisable | $	$ 38

Stock Option and Incentive Pl56

Stock Option and Incentive Plans - Assumptions to Compute Fair Value of Stock Option Grants (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Risk free interest rate	2.07%	1.22%	1.62%
Expected dividend yield	$ 0	$ 0	$ 0
Expected term (in years)	6 years 4 days	5 years 4 days	5 years 9 months
Expected volatility	79.60%	79.50%	74.40%

401k Savings Plan - Additional

401k Savings Plan - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
401k Savings Plan [Member]
Defined Contribution Plan Disclosure [Line Items]
Expense for matching contributions	$ 100,000	$ 124,000	$ 88,000

Income Taxes - Additional Infor

Income Taxes - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Contingency [Line Items]
Unused operating loss carryforwards for federal tax purposes		$ 145,676,000
Unused operating loss carryforwards for state tax purposes		$ 156,023,000
Net operating loss carryforwards, expiration year		2,037
Deferred tax valuation allowance		$ 45,146,454	$ 52,942,793
Increase (decrease) in valuation allowance		7,797,000	$ (12,846,000)
Unrecognized tax benefits		0
Unrecognized interest		0
Unrecognized penalties accrued		$ 0
U.S. federal corporate income tax rate		34.00%	34.00%	34.00%
Tax Cuts and Jobs Act, decrease in deferred tax assets valuation allowance		$ 18,284,538
Maximum [Member]
Income Tax Contingency [Line Items]
U.S. federal corporate income tax rate		35.00%
Executive Officer [Member] | Minimum [Member]
Income Tax Contingency [Line Items]
Tax Cuts and Jobs Act, compensation deducted		$ 1,000,000
Scenario, Plan [Member]
Income Tax Contingency [Line Items]
U.S. federal corporate income tax rate	21.00%

Income Taxes - Components of De

Income Taxes - Components of Deferred Tax Assets and Liabilities (Detail) - USD ($)	Dec. 31, 2017	Dec. 31, 2016
Deferred tax assets/liabilities:
Net operating loss carryovers	$ 40,879,826	$ 47,860,522
Share-based compensation	1,702,036	2,168,126
R&D tax credits	1,750,785	1,783,716
Accrued compensation and severance	659,458	902,688
Depreciation	(201,288)	(386,758)
Deferred rent	200,968	392,715
Intangible assets	154,669	221,783
Deferred tax assets/liabilities gross	45,146,454	52,942,793
Valuation allowance	(45,146,454)	(52,942,793)
Net deferred tax assets (liabilities)	$ 0	$ 0

Income Taxes - Summary of Recon

Income Taxes - Summary of Reconciliation of Statutory U.S. Federal Rate to Company's Effective Tax Rate (Detail)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Federal income tax benefit at statutory rate	(34.00%)	(34.00%)	(34.00%)
State income tax, net of federal benefit	(9.95%)	(5.49%)	(5.49%)
Permanent items including change in fair value of warrants	(22.03%)	(1.54%)	1.99%
Change in valuation allowance	(50.33%)	42.12%	39.70%
R&D tax credits	(3.02%)	(1.03%)	(0.99%)
Deferred re-measurement	118.03%
Other	(1.30%)	(0.06%)	(1.21%)
Effective income tax (benefit) expense rate	0.00%	0.00%	0.00%

Selected Quarterly Financial 61

Selected Quarterly Financial Data (Unaudited) - Summary of Unaudited Quarterly Financial Data (Detail) - USD ($)	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Quarterly Financial Information Disclosure [Abstract]
Loss from operations	$ (7,404,435)	$ (6,735,188)	$ (6,079,121)	$ (6,345,013)	$ (6,708,137)	$ (7,891,510)	$ (9,777,796)	$ (9,154,803)	$ (26,563,757)	$ (33,532,246)	$ (25,065,337)
Net income (loss)	$ (4,757,509)	$ (1,575,098)	$ (2,836,887)	$ (6,348,164)	$ 594,369	$ (10,530,584)	$ (9,679,022)	$ (8,923,162)	$ (15,517,658)	$ (28,538,399)	$ (25,120,964)
Net income (loss) per share of common stock, basic and diluted	$ (0.06)	$ (0.02)	$ (0.07)	$ (0.15)	$ 0.01	$ (0.28)	$ (0.35)	$ (0.32)	$ (0.28)	$ (0.85)	$ (1.08)