Document and Entity Information
| Document and Entity Information - shares | 6 Months Ended | |
| Jun. 30, 2018 | Aug. 07, 2018 | |
| Document And Entity Information [Abstract] | ||
| Document Type | 10-Q | |
| Amendment Flag | false | |
| Document Period End Date | Jun. 30, 2018 | |
| Document Fiscal Year Focus | 2,018 | |
| Document Fiscal Period Focus | Q2 | |
| Trading Symbol | CFRX | |
| Entity Registrant Name | CONTRAFECT Corp | |
| Entity Central Index Key | 1,478,069 | |
| Current Fiscal Year End Date | --12-31 | |
| Entity Filer Category | Accelerated Filer | |
| Entity Common Stock, Shares Outstanding | 79,409,556 |
Consolidated Balance Sheets
| Consolidated Balance Sheets - USD ($) | Jun. 30, 2018 | Dec. 31, 2017 |
| Current assets: | ||
| Cash and cash equivalents | $ 4,569,648 | $ 6,995,046 |
| Marketable securities | 28,724,373 | 39,858,864 |
| Prepaid expenses and other current assets | 2,201,899 | 1,848,063 |
| Total current assets | 35,495,920 | 48,701,973 |
| Property and equipment, net | 1,102,098 | 1,093,903 |
| Other assets | 355,420 | 393,603 |
| Total assets | 36,953,438 | 50,189,479 |
| Current liabilities: | ||
| Accounts payable | 1,094,997 | 1,302,431 |
| Accrued liabilities | 3,627,244 | 3,118,237 |
| Total current liabilities | 4,722,241 | 4,420,668 |
| Deferred rent | 690,714 | 704,240 |
| Warrant liabilities | 38,626,579 | 13,549,437 |
| Other liabilities | 72,747 | 321,689 |
| Total liabilities | 44,112,281 | 18,996,034 |
| Commitments and contingencies | ||
| Stockholders' (deficit) equity: | ||
| Preferred stock, $0.0001 par value, 25,000,000 shares authorized and none outstanding at June 30, 2018 and December 31, 2017 | ||
| Common stock, $0.0001 par value, 200,000,000 shares authorized; 73,659,556 and 73,656,006 shares issued and outstanding at June 30, 2018 and December 31, 2017, respectively | 7,366 | 7,366 |
| Additional paid-in capital | 193,755,684 | 192,896,367 |
| Accumulated other comprehensive loss | (44,052) | (74,820) |
| Accumulated deficit | (200,877,841) | (161,635,468) |
| Total stockholders' (deficit) equity | (7,158,843) | 31,193,445 |
| Total liabilities and stockholders' equity | $ 36,953,438 | $ 50,189,479 |
Consolidated Balance Sheets (Pa
| Consolidated Balance Sheets (Parenthetical) - $ / shares | Jun. 30, 2018 | Dec. 31, 2017 |
| 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 | 200,000,000 |
| Common stock, shares issued | 73,659,556 | 73,656,006 |
| Common stock, shares outstanding | 73,659,556 | 73,656,006 |
Consolidated Statements of Oper
| Consolidated Statements of Operations - USD ($) | 3 Months Ended | 6 Months Ended | ||
| Jun. 30, 2018 | Jun. 30, 2017 | Jun. 30, 2018 | Jun. 30, 2017 | |
| Operating expenses | ||||
| Research and development | $ 5,252,334 | $ 3,757,168 | $ 9,987,674 | $ 7,958,867 |
| General and administrative | 2,244,120 | 2,321,953 | 4,492,949 | 4,465,268 |
| Total operating expenses | 7,496,454 | 6,079,121 | 14,480,623 | 12,424,135 |
| Loss from operations | (7,496,454) | (6,079,121) | (14,480,623) | (12,424,135) |
| Other (expense) income: | ||||
| Interest income | 163,145 | 45,369 | 315,392 | 122,019 |
| Change in fair value of warrant liabilities | (12,802,583) | 3,196,865 | (25,077,142) | 3,117,064 |
| Total other (expense) income | (12,639,438) | 3,242,234 | (24,761,750) | 3,239,083 |
| Net loss | $ (20,135,892) | $ (2,836,887) | $ (39,242,373) | $ (9,185,052) |
| Per share information: | ||||
| Net loss per share of common stock, basic and diluted | $ (0.27) | $ (0.07) | $ (0.53) | $ (0.22) |
| Basic and diluted weighted average shares outstanding | 73,658,529 | 41,656,006 | 73,657,537 | 41,656,006 |
Consolidated Statements of Comp
| Consolidated Statements of Comprehensive Loss - USD ($) | 3 Months Ended | 6 Months Ended | ||
| Jun. 30, 2018 | Jun. 30, 2017 | Jun. 30, 2018 | Jun. 30, 2017 | |
| Statement of Comprehensive Income [Abstract] | ||||
| Net loss | $ (20,135,892) | $ (2,836,887) | $ (39,242,373) | $ (9,185,052) |
| Other comprehensive gain: | ||||
| Unrealized gain on available-for-sale securities | 47,568 | 26,472 | 30,768 | 32,367 |
| Comprehensive loss | $ (20,088,324) | $ (2,810,415) | $ (39,211,605) | $ (9,152,685) |
Consolidated Statements of Cash
| Consolidated Statements of Cash Flows - USD ($) | 6 Months Ended | |
| Jun. 30, 2018 | Jun. 30, 2017 | |
| Cash flows from operating activities | ||
| Net loss | $ (39,242,373) | $ (9,185,052) |
| Adjustments to reconcile net loss to net cash used in operating activities: | ||
| Depreciation | 71,081 | 91,099 |
| Stock-based compensation expense | 853,814 | 727,803 |
| Change in fair value of warrant liabilities | 25,077,142 | (3,117,064) |
| Decrease in deferred rent | (13,526) | (1,779) |
| Net amortization of premium on marketable securities | 315,673 | 319,313 |
| Changes in operating assets and liabilities: | ||
| Increase in prepaid expenses and other current and non-current assets | (315,653) | (1,212,252) |
| Increase (decrease) in accounts payable, accrued liabilities and other liabilities | 52,631 | (787,286) |
| Net cash used in operating activities | (13,201,211) | (13,165,218) |
| Cash flows from investing activities | ||
| Purchases of marketable securities | (11,129,302) | (1,953,630) |
| Proceeds from sales of marketable securities | 21,978,888 | 16,191,000 |
| Purchases of property and equipment | (79,276) | |
| Net cash provided by investing activities | 10,770,310 | 14,237,370 |
| Cash flows from financing activities | ||
| Proceeds from exercise of warrants | 5,503 | |
| Net cash provided by financing activities | 5,503 | |
| Net (decrease) increase in cash and cash equivalents | (2,425,398) | 1,072,152 |
| Cash and cash equivalents at beginning of period | 6,995,046 | 3,806,984 |
| Cash and cash equivalents at end of period | $ 4,569,648 | $ 4,879,136 |
Organization and Description of
| Organization and Description of Business | 6 Months Ended |
| Jun. 30, 2018 | |
| 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 candidate is CF-301 Staph aureus On August 3, 2018, the Company completed an underwritten public offering of 5,750,000 shares of its common stock, including shares sold pursuant to the fully exercised overallotment option granted to the underwriters in connection with the offering, at a public offering price of $2.00 per share, resulting in net proceeds to the Company of approximately $10.4 million after underwriting discounts and commissions and offering expenses payable by the Company. 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 June 30, 2018, together with the net proceeds from the offering completed on August 3, 2018 will be sufficient to fund operations into the first quarter of 2020 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. |
Summary of Significant Accounti
| Summary of Significant Accounting Policies | 6 Months Ended |
| Jun. 30, 2018 | |
| Accounting Policies [Abstract] | |
| Summary of Significant Accounting Policies | 2. Summary of Significant Accounting Policies Basis of Presentation The accompanying financial information as of June 30, 2018 and for the three and six months ended June 30, 2018 and 2017 has been prepared by the Company pursuant to the rules and regulations of the Securities and Exchange Commission (the “SEC”). Certain information and footnote disclosures normally included in consolidated financial statements prepared in accordance with U.S. generally accepted accounting principles (“U.S. GAAP”) have been condensed or omitted pursuant to such rules and regulations. The consolidated balance sheet as of December 31, 2017 was derived from the Company’s audited consolidated financial statements. The Company’s audited consolidated financial statements as of and for the year ended December 31, 2017, including all related disclosures and the complete listing of significant accounting policies as described in Note 2 thereof, are included in the Company’s Annual Report on Form 10-K In the opinion of management, the unaudited financial information as of June 30, 2018 and for the three and six months ended June 30, 2018 and 2017 reflects all adjustments, which are normal recurring adjustments, necessary to present a fair statement of financial position, results of operations and cash flows. The results of operations for the three months ended June 30, 2018 are not necessarily indicative of the operating results for the full fiscal year or any future periods. 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. 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 the consolidated 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 consolidated 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 that potentially subject the Company to concentration of 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 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. Financial Accounting Standards Board (“FASB”) Accounting Standard Codification (“ASC”) Topic 820, Fair Value Measurements and Disclosures The three levels of the fair value hierarchy are described below: 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 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 liabilities is discussed in Note 4, “Fair Value Measurements.” 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 to determine the fair value of stock options on the date of grant based on key assumptions such as stock price, 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. 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 three and six months ended June 30, 2018 and 2017, the Company recognized a reduction to its research and development expense in the amount of approximately $394,000, $764,000, $474,000 and $556,000, respectively. The receivable for grants as of June 30, 2018 was approximately $498,000 and is included in prepaid expenses and other current assets. The Company has $1,290,621 of approved grant award funding remaining as of June 30, 2018. Net Loss Per Share Basic net loss per share is calculated by dividing net loss by the weighted average shares outstanding during the period, without consideration for common stock equivalents. Diluted net loss per share 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 calculation, stock options and warrants are considered to be common stock equivalents but are excluded from the calculation of diluted net loss per share, as their effect would be anti-dilutive given the Company’s net loss; therefore, basic and diluted net loss per share were the same for all periods presented. Recently Adopted Accounting Pronouncements 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 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 No. 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 No. 2016-18 In May 2017, the FASB issued Accounting Standards Update 2017-09, Compensation – Stock Compensation 2017-09). 2017-09 No. 2017-09 Recent Accounting Pronouncements Not Yet Adopted 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 June 2018, the FASB issued Accounting Standards Update, Compensation-Stock Compensation (ASU 2018-07), which simplifies the accounting for share-based payments granted to nonemployees by aligning the accounting with the requirements for employee share-based compensation. The new guidance is effective for fiscal years beginning after December 15, 2018, and interim periods within those fiscal years, with early adoption permitted. The Company is assessing the impact of the adoption of this guidance on its consolidated financial statements and whether or not to adopt early. |
Marketable Securities
| Marketable Securities | 6 Months Ended |
| Jun. 30, 2018 | |
| Investments, Debt and Equity Securities [Abstract] | |
| Marketable Securities | 3. Marketable Securities Marketable securities at June 30, 2018 consist of the following: Marketable Securities Amortized Unrealized Unrealized Fair Value Current: Corporate debt $ 28,768,425 $ 187 $ (44,239 ) $ 28,724,373 Marketable securities at December 31, 2017 consisted of the following: Marketable Securities Amortized Unrealized Unrealized Fair Value Current: Corporate debt $ 39,933,685 $ — $ (74,820 ) $ 39,858,864 At June 30, 2018, the Company held only investments that have maturities of less than one year. At June 30, 2018 and December 31, 2017, the Company held 26 and 32 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 June 30, 2018 and December 31, 2017 was $26,937,473 and $39,858,864, 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 June 30, 2018 and December 31, 2017. |
Fair Value Measurements
| Fair Value Measurements | 6 Months Ended |
| Jun. 30, 2018 | |
| 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 June 30, 2018 and December 31, 2017: Fair Value Measurement as of June 30, 2018 Quoted Prices Significant Significant Cash equivalents $ 4,136,112 $ — $ — Marketable securities 28,724,373 — — Warrant liabilities — — 38,626,579 Total $ 32,860,485 $ — $ 38,626,579 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 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 7, “Capital Structure”). The Representative’s Warrant is re-measured As of As of Expected volatility 69.2 % 88.1 % Remaining contractual term (in years) 1.17 1.67 Risk-free interest rate 2.33 % 1.89 % 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 7, “Capital Structure”). The 2016 Warrants are re-measured As of As of Expected volatility 83.5 % 80.3 % Remaining contractual term (in years) 3.08 3.58 Risk-free interest rate 2.63 % 2.09 % 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 7, “Capital Structure”). The 2017 Warrants are re-measured As of As of Expected volatility 78.8 % 81.5 % Remaining contractual term (in years) 4.08 4.58 Risk-free interest rate 2.68 % 2.20 % 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 three and six months ended June 30, 2018 and 2017: Warrant liabilities Three Months Ended Six Months Ended 2018 2017 2018 2017 Balance at beginning of period $ 25,823,996 $ 12,778,781 $ 13,549,437 $ 12,698,980 Increase (decrease) in fair value (1) 12,802,583 (3,196,865 ) 25,077,142 (3,117,064 ) Balance at end of period $ 38,626,579 $ 9,581,916 $ 38,626,579 $ 9,581,916 (1) The change in fair values of the warrant liabilities is recorded in other (expense) income in the consolidated statement of operations. The key inputs into the Black-Scholes option pricing model are the current per-share |
Accrued Liabilities
| Accrued Liabilities | 6 Months Ended |
| Jun. 30, 2018 | |
| Payables and Accruals [Abstract] | |
| Accrued Liabilities | 5. Accrued Liabilities Accrued liabilities consist of the following: June 30, December 31, Accrued research and development service fees $ 1,770,749 $ 578,562 Accrued compensation costs 1,170,573 2,107,118 Accrued professional fees 461,878 168,168 Accrued facilities operation expenses 207,450 221,103 Other accrued liabilities 16,594 43,286 Total accrued liabilities $ 3,627,244 $ 3,118,237 |
Net Loss Per Share of Common St
| Net Loss Per Share of Common Stock | 6 Months Ended |
| Jun. 30, 2018 | |
| Earnings Per Share [Abstract] | |
| Net Loss Per Share of Common Stock | 6. Net Loss Per Share of Common Stock Diluted net loss per share is the same as basic net loss per share for all periods presented because the effects of potentially dilutive items were anti-dilutive given the Company’s net loss. Basic net loss per share is computed by dividing net loss by the weighted-average number of shares of common stock outstanding. The following table sets forth the computation of basic and diluted net loss per share for common stockholders: Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 Net loss $ (20,135,892 ) $ (2,836,887 ) $ (39,242,373 ) $ (9,185,052 ) Weighted average shares of common stock outstanding 73,658,529 41,656,006 73,657,537 41,656,006 Net loss per share of common stock—basic and diluted $ (0.27 ) $ (0.07 ) $ (0.53 ) $ (0.22 ) The following potentially dilutive securities outstanding at June 30, 2018 and 2017 have been excluded from the computation of diluted weighted average shares outstanding, as they would have been anti-dilutive given the Company’s net loss: June 30, 2018 2017 Options to purchase common stock 7,266,054 6,036,984 Warrants to purchase common stock 31,678,614 20,272,873 Total 38,944,668 26,309,857 |
Capital Structure
| Capital Structure | 6 Months Ended |
| Jun. 30, 2018 | |
| Federal Home Loan Banks [Abstract] | |
| Capital Structure | 7. Capital Structure Common Stock As of June 30, 2018, 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 sold an aggregate of 4,728,128 common shares and warrants to purchase an additional 2,364,066 shares of common stock for gross proceeds of $20.0 million in a private placement (the “PIPE”). The Company received net proceeds from the PIPE of $18.3 million, after deducting expenses payable by the Company. The warrants had an exercise price of $8.00 per share and expired three years from the date of issuance (the “PIPE Warrants”). None of the PIPE Warrants were exercised prior to expiration on June 12, 2018 and therefore have been terminated and are no longer exercisable. The placement agents in the PIPE received warrants to purchase a total of 189,126 shares of common stock at an exercise price of $4.65 per share which expire on June 11, 2020 (the “Placement Agent Warrants”). The PIPE Warrants and Placement Agent Warrants have been classified as stockholders’ equity in the Company’s consolidated balance sheet. Initial Public Offering In August 2014, the Company completed an initial public offering (“IPO”), raising net proceeds of $35.0 million after underwriting discounts, commissions and offering expenses payable by us, through the issuance and sale of our units, which 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 Representative’s Warrant The Maxim Group, LLC, the representative of the underwriter 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 option, for a total of 206,410 shares of common stock underlying the Representative’s Warrant. The Representative’s Warrant is 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 expiring on July 28, 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 is 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 with 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 2,209,588 Note Warrants that expired in June 2018 and therefore have been terminated and are no longer exercisable. There are 1,106,290 shares of common stock underlying the remaining outstanding Note Warrants as of June 30, 2018. The Note Warrants expire five years from the date of issuance. 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 June 30, 2018, 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 June 30, 2018 and December 31, 2017: June 30, December 31, Options to purchase common stock 7,266,054 6,200,151 Warrants to purchase common stock 31,678,614 36,270,103 38,944,668 42,470,254 |
Stock Warrants
| Stock Warrants | 6 Months Ended |
| Jun. 30, 2018 | |
| Text Block [Abstract] | |
| Stock Warrants | 8. Stock Warrants As of June 30, 2018 and December 31, 2017, the Company had warrants outstanding as shown in the table below. June 30, December 31, Note Warrants 1,106,290 3,315,878 PIPE Warrants — 2,364,066 2017 Warrants 15,996,450 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 (1) 180,338 194,623 Warrants to purchase common stock 31,678,614 36,270,103 Weighted-average exercise price per share $ 2.32 $ 2.74 (1) 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 at June 30, 2018: Exercise Prices Shares Expiration Date £ 16,002,164 September 1, 2021 – July 25, 2022 $2.01 - $4.99 15,396,517 August 19, 2018 – July 27, 2021 ³ 279,933 July 22, 2019 – January 5, 2022 31,678,614 |
Stock Option and Incentive Plan
| Stock Option and Incentive Plans | 6 Months Ended |
| Jun. 30, 2018 | |
| Disclosure of Compensation Related Costs, Share-based Payments [Abstract] | |
| Stock Option and Incentive Plans | 9. 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”). The Plan allows for the granting of non- 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 stockholders on July 3, 2014. The 2014 Plan allows for the granting of incentive and non-qualified The Company recognized 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 six months ended June 30, 2018, is summarized as follows: Number of Weighted Weighted Aggregate Options outstanding at December 31, 2017 6,200,151 $ 3.81 Granted 2,280,000 1.45 Exercised — — Expired (862,035 ) 3.93 Forfeited (352,062 ) 1.74 Options outstanding at June 30, 2018 7,266,054 3.15 7.15 $ 2,501,000 Vested and exercisable at June 30, 2018 4,413,576 4.00 5.96 $ 810,006 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 three and six months ended June 30, 2018 and 2017 was $1.63, $1.45, $1.60 and $1.73, respectively. Total compensation expense recognized amounted to $416,133, $853,814, $346,892 and $727,803, for the three and six months ended June 30, 2018 and 2017, respectively. As of June 30, 2018, the total remaining unrecognized compensation cost related to unvested stock options was approximately $3.0 million which will be recognized over a weighted average period of approximately 2.85 years. The following assumptions were used to compute the fair value of stock option grants: Three Months Ended Six Months Ended 2018 2017 2018 2017 Risk free interest rate 2.81 % 1.89 % 2.57 % 2.08 % Expected dividend yield — — — — Expected term (in years) 5.40 5.54 6.02 6.00 Expected volatility 82.5 % 81.7 % 82.3 % 79.1 % Expected volatility— Expected term— Risk-free interest rate Expected dividend yield— |
Income Taxes
| Income Taxes | 6 Months Ended |
| Jun. 30, 2018 | |
| Income Tax Disclosure [Abstract] | |
| Income Taxes | 10. Income Taxes Deferred tax assets and deferred tax liabilities are recognized based on temporary differences between the financial reporting and tax basis of assets and liabilities using statutory rates. A valuation allowance is recorded against deferred tax assets if it is more likely than not that some or all of the deferred tax assets will not be realized. Due to the uncertainty surrounding the realization of the favorable tax attributes in future tax returns, the Company has recorded a full valuation allowance against the Company’s otherwise recognizable net deferred tax assets. On December 22, 2017, the SEC staff issued Staff Accounting Bulletin No. 118, Income Tax Accounting Implications of the Tax Cuts and Jobs Act (“SAB 118”), which allows the recording of provisional amounts during a measurement period not to extend beyond one year of the enactment date. In accordance with SAB 118, the Company determined a provisional amount for the impact on its prior year deferred tax assets and valuation allowance in its prior year financial statements. The Company has not updated the provisional amounts and expects to complete the final assessment of the impact within the measurement period. |
Subsequent Events
| Subsequent Events | 6 Months Ended |
| Jun. 30, 2018 | |
| Subsequent Events [Abstract] | |
| Subsequent Events | 11. Subsequent Events On August 3, 2018, the Company completed an underwritten public offering of 5,750,000 shares of its common stock, including shares sold pursuant to the fully exercised overallotment option granted to the underwriters in connection with the offering, at a public offering price of $2.00 per share, resulting in net proceeds to the Company of approximately $10.4 million after underwriting discounts and commissions and offering expenses payable by the Company. |
Summary of Significant Accoun18
| Summary of Significant Accounting Policies (Policies) | 6 Months Ended |
| Jun. 30, 2018 | |
| Accounting Policies [Abstract] | |
| Basis of Presentation | Basis of Presentation The accompanying financial information as of June 30, 2018 and for the three and six months ended June 30, 2018 and 2017 has been prepared by the Company pursuant to the rules and regulations of the Securities and Exchange Commission (the “SEC”). Certain information and footnote disclosures normally included in consolidated financial statements prepared in accordance with U.S. generally accepted accounting principles (“U.S. GAAP”) have been condensed or omitted pursuant to such rules and regulations. The consolidated balance sheet as of December 31, 2017 was derived from the Company’s audited consolidated financial statements. The Company’s audited consolidated financial statements as of and for the year ended December 31, 2017, including all related disclosures and the complete listing of significant accounting policies as described in Note 2 thereof, are included in the Company’s Annual Report on Form 10-K In the opinion of management, the unaudited financial information as of June 30, 2018 and for the three and six months ended June 30, 2018 and 2017 reflects all adjustments, which are normal recurring adjustments, necessary to present a fair statement of financial position, results of operations and cash flows. The results of operations for the three months ended June 30, 2018 are not necessarily indicative of the operating results for the full fiscal year or any future periods. |
| 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. |
| 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 the consolidated 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 consolidated 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 that potentially subject the Company to concentration of 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 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. Financial Accounting Standards Board (“FASB”) Accounting Standard Codification (“ASC”) Topic 820, Fair Value Measurements and Disclosures The three levels of the fair value hierarchy are described below: 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 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 liabilities is discussed in Note 4, “Fair Value Measurements.” |
| 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 to determine the fair value of stock options on the date of grant based on key assumptions such as stock price, 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. |
| 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 three and six months ended June 30, 2018 and 2017, the Company recognized a reduction to its research and development expense in the amount of approximately $394,000, $764,000, $474,000 and $556,000, respectively. The receivable for grants as of June 30, 2018 was approximately $498,000 and is included in prepaid expenses and other current assets. The Company has $1,290,621 of approved grant award funding remaining as of June 30, 2018. |
| Net Loss Per Share | Net Loss Per Share Basic net loss per share is calculated by dividing net loss by the weighted average shares outstanding during the period, without consideration for common stock equivalents. Diluted net loss per share 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 calculation, stock options and warrants are considered to be common stock equivalents but are excluded from the calculation of diluted net loss per share, as their effect would be anti-dilutive given the Company’s net loss; therefore, basic and diluted net loss per share were the same for all periods presented. |
| Recently Adopted Accounting Pronouncements | Recently Adopted Accounting Pronouncements 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 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 No. 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 No. 2016-18 In May 2017, the FASB issued Accounting Standards Update 2017-09, Compensation – Stock Compensation 2017-09). 2017-09 No. 2017-09 |
| Recent Accounting Pronouncements Not Yet Adopted | Recent Accounting Pronouncements Not Yet Adopted 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 |
Marketable Securities (Tables)
| Marketable Securities (Tables) | 6 Months Ended |
| Jun. 30, 2018 | |
| Investments, Debt and Equity Securities [Abstract] | |
| Schedule of Marketable Securities | Marketable securities at June 30, 2018 consist of the following: Marketable Securities Amortized Unrealized Unrealized Fair Value Current: Corporate debt $ 28,768,425 $ 187 $ (44,239 ) $ 28,724,373 Marketable securities at December 31, 2017 consisted of the following: Marketable Securities Amortized Unrealized Unrealized Fair Value Current: Corporate debt $ 39,933,685 $ — $ (74,820 ) $ 39,858,864 |
Fair Value Measurements (Tables
| Fair Value Measurements (Tables) | 6 Months Ended |
| Jun. 30, 2018 | |
| 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 June 30, 2018 and December 31, 2017: Fair Value Measurement as of June 30, 2018 Quoted Prices Significant Significant Cash equivalents $ 4,136,112 $ — $ — Marketable securities 28,724,373 — — Warrant liabilities — — 38,626,579 Total $ 32,860,485 $ — $ 38,626,579 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 |
| 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 three and six months ended June 30, 2018 and 2017: Warrant liabilities Three Months Ended Six Months Ended 2018 2017 2018 2017 Balance at beginning of period $ 25,823,996 $ 12,778,781 $ 13,549,437 $ 12,698,980 Increase (decrease) in fair value (1) 12,802,583 (3,196,865 ) 25,077,142 (3,117,064 ) Balance at end of period $ 38,626,579 $ 9,581,916 $ 38,626,579 $ 9,581,916 (1) The change in fair values of the warrant liabilities is recorded in other (expense) income in the consolidated statement of operations. |
| 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 69.2 % 88.1 % Remaining contractual term (in years) 1.17 1.67 Risk-free interest rate 2.33 % 1.89 % 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 As of Expected volatility 83.5 % 80.3 % Remaining contractual term (in years) 3.08 3.58 Risk-free interest rate 2.63 % 2.09 % 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 As of Expected volatility 78.8 % 81.5 % Remaining contractual term (in years) 4.08 4.58 Risk-free interest rate 2.68 % 2.20 % Expected dividend yield — % — % |
Accrued Liabilities (Tables)
| Accrued Liabilities (Tables) | 6 Months Ended |
| Jun. 30, 2018 | |
| Payables and Accruals [Abstract] | |
| Summary of Accrued Liabilities | Accrued liabilities consist of the following: June 30, December 31, Accrued research and development service fees $ 1,770,749 $ 578,562 Accrued compensation costs 1,170,573 2,107,118 Accrued professional fees 461,878 168,168 Accrued facilities operation expenses 207,450 221,103 Other accrued liabilities 16,594 43,286 Total accrued liabilities $ 3,627,244 $ 3,118,237 |
Net Loss Per Share of Common 22
| Net Loss Per Share of Common Stock (Tables) | 6 Months Ended |
| Jun. 30, 2018 | |
| 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 net loss per share for common stockholders: Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 Net loss $ (20,135,892 ) $ (2,836,887 ) $ (39,242,373 ) $ (9,185,052 ) Weighted average shares of common stock outstanding 73,658,529 41,656,006 73,657,537 41,656,006 Net loss per share of common stock—basic and diluted $ (0.27 ) $ (0.07 ) $ (0.53 ) $ (0.22 ) |
| Schedule of Antidilutive Securities Excluded from Computation of Diluted Weighted Average Shares Outstanding | The following potentially dilutive securities outstanding at June 30, 2018 and 2017 have been excluded from the computation of diluted weighted average shares outstanding, as they would have been anti-dilutive given the Company’s net loss: June 30, 2018 2017 Options to purchase common stock 7,266,054 6,036,984 Warrants to purchase common stock 31,678,614 20,272,873 Total 38,944,668 26,309,857 |
Capital Structure (Tables)
| Capital Structure (Tables) | 6 Months Ended |
| Jun. 30, 2018 | |
| Federal Home Loan Banks [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 June 30, 2018 and December 31, 2017: June 30, December 31, Options to purchase common stock 7,266,054 6,200,151 Warrants to purchase common stock 31,678,614 36,270,103 38,944,668 42,470,254 |
Stock Warrants (Tables)
| Stock Warrants (Tables) | 6 Months Ended |
| Jun. 30, 2018 | |
| Text Block [Abstract] | |
| Schedule of Warrants Outstanding | As of June 30, 2018 and December 31, 2017, the Company had warrants outstanding as shown in the table below. June 30, December 31, Note Warrants 1,106,290 3,315,878 PIPE Warrants — 2,364,066 2017 Warrants 15,996,450 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 (1) 180,338 194,623 Warrants to purchase common stock 31,678,614 36,270,103 Weighted-average exercise price per share $ 2.32 $ 2.74 (1) 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 at June 30, 2018: Exercise Prices Shares Expiration Date £ 16,002,164 September 1, 2021 – July 25, 2022 $2.01 - $4.99 15,396,517 August 19, 2018 – July 27, 2021 ³ 279,933 July 22, 2019 – January 5, 2022 31,678,614 |
Stock Option and Incentive Pl25
| Stock Option and Incentive Plans (Tables) | 6 Months Ended |
| Jun. 30, 2018 | |
| Disclosure of Compensation Related Costs, Share-based Payments [Abstract] | |
| Summary of Stock Option Activity | A summary of stock option activity for the six months ended June 30, 2018, is summarized as follows: Number of Weighted Weighted Aggregate Options outstanding at December 31, 2017 6,200,151 $ 3.81 Granted 2,280,000 1.45 Exercised — — Expired (862,035 ) 3.93 Forfeited (352,062 ) 1.74 Options outstanding at June 30, 2018 7,266,054 3.15 7.15 $ 2,501,000 Vested and exercisable at June 30, 2018 4,413,576 4.00 5.96 $ 810,006 |
| Assumptions to Compute Fair Value of Stock Option Grants | The following assumptions were used to compute the fair value of stock option grants: Three Months Ended Six Months Ended 2018 2017 2018 2017 Risk free interest rate 2.81 % 1.89 % 2.57 % 2.08 % Expected dividend yield — — — — Expected term (in years) 5.40 5.54 6.02 6.00 Expected volatility 82.5 % 81.7 % 82.3 % 79.1 % |
Organization and Description 26
| Organization and Description of Business - Additional Information (Detail) - Follow-on Offering [Member] - USD ($) $ / shares in Units, $ in Millions | Aug. 03, 2018 | Jul. 25, 2017 | Jul. 27, 2016 |
| Organization And Description Of Business [Line Items] | |||
| Number of shares issued | 32,000,000 | 14,000,000 | |
| Net proceeds received | $ 37.1 | $ 32 | |
| Subsequent Event [Member] | |||
| Organization And Description Of Business [Line Items] | |||
| Number of shares issued | 5,750,000 | ||
| Public offering price, per unit | $ 2 | ||
| Net proceeds received | $ 10.4 |
Summary of Significant Accoun27
| Summary of Significant Accounting Policies - Additional Information (Detail) | 3 Months Ended | 6 Months Ended | ||
| Jun. 30, 2018USD ($)Securities | Jun. 30, 2017USD ($)Securities | Jun. 30, 2018USD ($)Securities | Jun. 30, 2017USD ($)Securities | |
| Accounting Policies [Abstract] | ||||
| Maturity period of highly liquid investments | Three months or less | |||
| Realized gains or losses on marketable securities | $ 0 | $ 0 | $ 0 | $ 0 |
| Number of securities in unrealized loss position for more than 12 months | Securities | 0 | 0 | 0 | 0 |
| Grants receivable recognized | $ 394,000 | $ 474,000 | $ 764,000 | $ 556,000 |
| Grants receivable | 498,000 | 498,000 | ||
| Grants remaining to be awarded | $ 1,290,621 | $ 1,290,621 | ||
Marketable Securities - Schedul
| Marketable Securities - Schedule of Marketable Securities (Detail) - Corporate Debt [Member] - USD ($) | Jun. 30, 2018 | Dec. 31, 2017 |
| Schedule of Available-for-sale Securities [Line Items] | ||
| Marketable Securities, Amortized Cost | $ 28,768,425 | $ 39,933,685 |
| Marketable Securities, Unrealized Gains | 187 | |
| Marketable Securities, Unrealized Losses | (44,239) | (74,820) |
| Marketable Securities, Fair Value | $ 28,724,373 | $ 39,858,864 |
Marketable Securities - Additio
| Marketable Securities - Additional Information (Detail) | 6 Months Ended | |
| Jun. 30, 2018USD ($)Security | Dec. 31, 2017USD ($)Security | |
| Marketable Securities [Abstract] | ||
| Maturity period classified current investments | Less than one year | |
| Number of securities in unrealized loss position for less than one year | Security | 26 | 32 |
| Aggregate fair value of debt securities | $ | $ 26,937,473 | $ 39,858,864 |
Fair Value Measurements - Infor
| Fair Value Measurements - Information about Company's Financial Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) - USD ($) | Jun. 30, 2018 | Dec. 31, 2017 |
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ||
| Marketable securities | $ 28,724,373 | $ 39,858,864 |
| Warrant liabilities | (38,626,579) | (13,549,437) |
| Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | ||
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ||
| Cash equivalents | 4,136,112 | 5,949,477 |
| Marketable securities | 28,724,373 | 39,858,864 |
| Total assets (liabilities) | 32,860,485 | 45,808,341 |
| Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | ||
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ||
| Warrant liabilities | 38,626,579 | 13,549,437 |
| Total assets (liabilities) | $ 38,626,579 | $ 13,549,437 |
Fair Value Measurements - Assum
| Fair Value Measurements - Assumption Used to Determine Fair Value of Warrant Liability (Detail) | Jun. 30, 2018yr | Dec. 31, 2017yr |
| Representative's Warrant [Member] | Expected Volatility [Member] | ||
| Fair Value Measurement Inputs and Valuation Techniques [Line Items] | ||
| Fair value of warrant liability | 69.2 | 88.1 |
| Representative's Warrant [Member] | Remaining Contractual term (in years) [Member] | ||
| Fair Value Measurement Inputs and Valuation Techniques [Line Items] | ||
| Fair value of warrant liability | 1.17 | 1.67 |
| Representative's Warrant [Member] | Risk-free Interest Rate [Member] | ||
| Fair Value Measurement Inputs and Valuation Techniques [Line Items] | ||
| Fair value of warrant liability | 2.33 | 1.89 |
| 2016 Warrants [Member] | Expected Volatility [Member] | ||
| Fair Value Measurement Inputs and Valuation Techniques [Line Items] | ||
| Fair value of warrant liability | 83.5 | 80.3 |
| 2016 Warrants [Member] | Remaining Contractual term (in years) [Member] | ||
| Fair Value Measurement Inputs and Valuation Techniques [Line Items] | ||
| Fair value of warrant liability | 3.08 | 3.58 |
| 2016 Warrants [Member] | Risk-free Interest Rate [Member] | ||
| Fair Value Measurement Inputs and Valuation Techniques [Line Items] | ||
| Fair value of warrant liability | 2.63 | 2.09 |
| 2017 Warrants [Member] | Expected Volatility [Member] | ||
| Fair Value Measurement Inputs and Valuation Techniques [Line Items] | ||
| Fair value of warrant liability | 78.8 | 81.5 |
| 2017 Warrants [Member] | Remaining Contractual term (in years) [Member] | ||
| Fair Value Measurement Inputs and Valuation Techniques [Line Items] | ||
| Fair value of warrant liability | 4.08 | 4.58 |
| 2017 Warrants [Member] | Risk-free Interest Rate [Member] | ||
| Fair Value Measurement Inputs and Valuation Techniques [Line Items] | ||
| Fair value of warrant liability | 2.68 | 2.20 |
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 ($) | 3 Months Ended | 6 Months Ended | ||
| Jun. 30, 2018 | Jun. 30, 2017 | Jun. 30, 2018 | Jun. 30, 2017 | |
| Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] | ||||
| Balance at beginning of period | $ 25,823,996 | $ 12,778,781 | $ 13,549,437 | $ 12,698,980 |
| Increase (decrease) in fair value | 12,802,583 | (3,196,865) | 25,077,142 | (3,117,064) |
| Balance at end of period | $ 38,626,579 | $ 9,581,916 | $ 38,626,579 | $ 9,581,916 |
Accrued Liabilities - Summary o
| Accrued Liabilities - Summary of Accrued Liabilities (Detail) - USD ($) | Jun. 30, 2018 | Dec. 31, 2017 |
| Payables and Accruals [Abstract] | ||
| Accrued research and development service fees | $ 1,770,749 | $ 578,562 |
| Accrued compensation costs | 1,170,573 | 2,107,118 |
| Accrued professional fees | 461,878 | 168,168 |
| Accrued facilities operation expenses | 207,450 | 221,103 |
| Other accrued liabilities | 16,594 | 43,286 |
| Total accrued liabilities | $ 3,627,244 | $ 3,118,237 |
Net Loss Per Share of Common 34
| 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 | 6 Months Ended | ||
| Jun. 30, 2018 | Jun. 30, 2017 | Jun. 30, 2018 | Jun. 30, 2017 | |
| Earnings Per Share [Abstract] | ||||
| Net loss | $ (20,135,892) | $ (2,836,887) | $ (39,242,373) | $ (9,185,052) |
| Weighted average shares of common stock outstanding | 73,658,529 | 41,656,006 | 73,657,537 | 41,656,006 |
| Net loss per share of common stock-basic and diluted | $ (0.27) | $ (0.07) | $ (0.53) | $ (0.22) |
Net Loss Per Share of Common 35
| Net Loss Per Share of Common Stock - Schedule of Antidilutive Securities Excluded from Computation of Diluted Weighted Average Shares Outstanding (Detail) - shares | 6 Months Ended | |
| Jun. 30, 2018 | Jun. 30, 2017 | |
| Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] | ||
| Potentially antidilutive securities outstanding excluded from the computation of diluted weighted average shares | 38,944,668 | 26,309,857 |
| 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 | 7,266,054 | 6,036,984 |
| 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 | 31,678,614 | 20,272,873 |
Capital Structure - Additional
| Capital Structure - Additional Information (Detail) - USD ($) | Jun. 30, 2018 | Jul. 25, 2017 | Jul. 27, 2016 | Nov. 02, 2015 | Jun. 12, 2015 | Aug. 01, 2014 | Jun. 30, 2018 | Jun. 30, 2018 | Jun. 30, 2014 | Dec. 31, 2017 |
| Class of Stock [Line Items] | ||||||||||
| Common stock, shares authorized | 200,000,000 | 200,000,000 | 200,000,000 | 200,000,000 | ||||||
| Common stock, par value | $ 0.0001 | $ 0.0001 | $ 0.0001 | $ 0.0001 | ||||||
| Net proceeds from initial public offering | $ 35,000,000 | |||||||||
| Initial public offering, closing date | Aug. 1, 2014 | |||||||||
| Initial public offering, units description | In August 2014, the Company completed an initial public offering (“IPO”), raising net proceeds of $35.0 million after underwriting discounts, commissions and offering expenses payable by us, through the issuance and sale of our units, which 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 (“Units”). | |||||||||
| Proceeds from exercise of warrants | $ 5,503 | |||||||||
| Number of warrants or rights outstanding | 31,678,614 | 31,678,614 | 31,678,614 | 36,270,103 | ||||||
| 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 | 14,000,000 | ||||||
| 2017 Warrants [Member] | ||||||||||
| Class of Stock [Line Items] | ||||||||||
| Number of warrants or rights outstanding | 15,996,450 | 15,996,450 | 15,996,450 | 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 | 189,126 | ||||||
| Aggregate gross sales proceeds from common stock | $ 20,000,000 | |||||||||
| Net proceeds received | $ 18,300,000 | |||||||||
| Warrant exercise price per share | $ 4.65 | $ 8 | $ 4.65 | $ 4.65 | ||||||
| Warrant expiration term | 3 years | |||||||||
| Warrant expiration date | Jun. 11, 2020 | |||||||||
| Initial Public Offering [Member] | ||||||||||
| Class of Stock [Line Items] | ||||||||||
| Conversion of Convertible Notes together with accrued and unpaid interest into common stock, shares | 5,109,988 | |||||||||
| Follow-on Offering [Member] | ||||||||||
| Class of Stock [Line Items] | ||||||||||
| Number of shares issued | 32,000,000 | 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 | ||||||||
| Warrants to purchase shares of common stock | 1,050 | 3,550 | ||||||||
| 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 | |||||||||
| Warrant expiration term | 5 years | 5 years | 5 years | |||||||
| Number of warrants or rights outstanding | 1,106,290 | 3,321,416 | 1,106,290 | 1,106,290 | 3,315,878 | |||||
| Class of warrant or rights, expired | 2,209,588 | |||||||||
| 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 | |||||||||
| 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 | 206,410 | |||||||
| Warrant exercise price per share | $ 7.50 | $ 7.50 | $ 7.50 | |||||||
| Warrant expiration date | Jul. 28, 2019 | |||||||||
| Class of warrant purchase percentage | 3.00% | 3.00% | 3.00% | |||||||
| Warrant exercisable period | 180 days | |||||||||
| Number of warrants or rights outstanding | 206,410 | 206,410 | 206,410 | 206,410 | ||||||
| Class A Warrants [Member] | ||||||||||
| Class of Stock [Line Items] | ||||||||||
| Warrant expiration date | Feb. 1, 2017 | |||||||||
| 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 | Jun. 30, 2018 | Dec. 31, 2017 |
| Class of Stock [Line Items] | ||
| Common Stock reserved for future issuance | 38,944,668 | 42,470,254 |
| Stock Options [Member] | ||
| Class of Stock [Line Items] | ||
| Common Stock reserved for future issuance | 7,266,054 | 6,200,151 |
| Warrants [Member] | ||
| Class of Stock [Line Items] | ||
| Common Stock reserved for future issuance | 31,678,614 | 36,270,103 |
Stock Warrants - Schedule of Wa
| Stock Warrants - Schedule of Warrants Outstanding (Detail) - $ / shares | 6 Months Ended | |||
| Jun. 30, 2018 | Dec. 31, 2017 | Jun. 12, 2015 | Aug. 01, 2014 | |
| Class of Warrant or Right [Line Items] | ||||
| Shares Underlying Outstanding Warrants | 31,678,614 | 36,270,103 | ||
| Weighted-average exercise price per share | $ 2.32 | $ 2.74 | ||
| Placement Agent Warrants [Member] | ||||
| Class of Warrant or Right [Line Items] | ||||
| Shares Underlying Outstanding Warrants | 189,126 | 189,126 | ||
| 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 | 180,338 | 194,623 | ||
| Exercise Price Less Than or Equal to $2.00 [Member] | ||||
| Class of Warrant or Right [Line Items] | ||||
| Shares Underlying Outstanding Warrants | 16,002,164 | |||
| 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 | 15,396,517 | |||
| Expiration Start Date | Aug. 19, 2018 | |||
| Expiration End Date | Jul. 27, 2021 | |||
| Exercise Price Greater Than or Equal to $ 5.00 [Member] | ||||
| Class of Warrant or Right [Line Items] | ||||
| Shares Underlying Outstanding Warrants | 279,933 | |||
| Expiration Start Date | Jul. 22, 2019 | |||
| 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 Greater Than or Equal to $ 5.00 [Member] | ||||
| Class of Warrant or Right [Line Items] | ||||
| Exercise Prices | 5 | |||
| 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 | |||
| Note Warrants [Member] | ||||
| Class of Warrant or Right [Line Items] | ||||
| Exercise Prices | $ 3 | |||
| Shares Underlying Outstanding Warrants | 1,106,290 | 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 | |||
| 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 | 15,996,450 | 16,000,000 |
Stock Option and Incentive Pl39
| Stock Option and Incentive Plans - Additional Information (Detail) - USD ($) | Dec. 31, 2015 | Feb. 26, 2013 | Jun. 30, 2018 | Jun. 30, 2017 | Jun. 30, 2018 | Jun. 30, 2017 | Dec. 31, 2017 | Jul. 28, 2014 |
| Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | ||||||||
| Number of shares of common stock reserved pursuant to the plan | 38,944,668 | 38,944,668 | 42,470,254 | |||||
| Weighted average grant date fair value of options | $ 1.63 | $ 1.60 | $ 1.45 | $ 1.73 | ||||
| Unrecognized compensation cost related to unvested stock options | $ 3,000,000 | $ 3,000,000 | ||||||
| Weighted average period of unvested stock options | 2 years 10 months 6 days | |||||||
| Employee Stock Options [Member] | ||||||||
| Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | ||||||||
| Compensation expense recognized | $ 416,133 | $ 346,892 | $ 853,814 | $ 727,803 | ||||
| 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 | |||||||
| Termination of service, Period | 2 years | |||||||
| 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 | 6,520,477 | |||||||
| 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 Pl40
| Stock Option and Incentive Plans - Summary of Stock Option Activity (Detail) | 6 Months Ended |
| Jun. 30, 2018USD ($)$ / sharesshares | |
| Disclosure of Compensation Related Costs, Share-based Payments [Abstract] | |
| Number of Options, Options outstanding, Beginning balance | shares | 6,200,151 |
| Number of Options, Granted | shares | 2,280,000 |
| Number of Options, Exercised | shares | 0 |
| Number of Options, Expired | shares | (862,035) |
| Number of Options, Forfeited | shares | (352,062) |
| Number of Options, Options outstanding, Ending balance | shares | 7,266,054 |
| Number of Options, Vested and exercisable, Ending Balance | shares | 4,413,576 |
| Weighted Average Exercise Price, Options outstanding, Beginning balance | $ / shares | $ 3.81 |
| Weighted Average Exercise Price, Granted | $ / shares | 1.45 |
| Weighted Average Exercise Price, Exercised | $ / shares | 0 |
| Weighted Average Exercise Price, Expired | $ / shares | 3.93 |
| Weighted Average Exercise Price, Forfeited | $ / shares | 1.74 |
| Weighted Average Exercise Price, Options outstanding, Ending balance | $ / shares | 3.15 |
| Weighted Average Exercise Price, Vested and exercisable, Ending balance | $ / shares | $ 4 |
| Weighted Average Remaining Contractual Life (in years), Options outstanding | 7 years 1 month 24 days |
| Weighted Average Remaining Contractual Life (in years), Vested and exercisable | 5 years 11 months 15 days |
| Aggregate Intrinsic value, Options outstanding | $ | $ 2,501,000 |
| Aggregate Intrinsic value, Vested and exercisable | $ | $ 810,006 |
Stock Option and Incentive Pl41
| Stock Option and Incentive Plans - Assumptions to Compute Fair Value of Stock Option Grants (Detail) - USD ($) | 3 Months Ended | 6 Months Ended | ||
| Jun. 30, 2018 | Jun. 30, 2017 | Jun. 30, 2018 | Jun. 30, 2017 | |
| Disclosure of Compensation Related Costs, Share-based Payments [Abstract] | ||||
| Risk free interest rate | 2.81% | 1.89% | 2.57% | 2.08% |
| Expected dividend yield | $ 0 | $ 0 | $ 0 | $ 0 |
| Expected term (in years) | 5 years 4 months 24 days | 5 years 6 months 14 days | 6 years 7 days | 6 years |
| Expected volatility | 82.50% | 81.70% | 82.30% | 79.10% |
Subsequent Event - Additional I
| Subsequent Event - Additional Information (Detail) - Follow-on Offering [Member] - USD ($) $ / shares in Units, $ in Millions | Aug. 03, 2018 | Jul. 25, 2017 | Jul. 27, 2016 |
| Subsequent Event [Line Items] | |||
| Number of shares issued | 32,000,000 | 14,000,000 | |
| Net proceeds received | $ 37.1 | $ 32 | |
| Subsequent Event [Member] | |||
| Subsequent Event [Line Items] | |||
| Number of shares issued | 5,750,000 | ||
| Public offering price, per unit | $ 2 | ||
| Net proceeds received | $ 10.4 |