Vaccinex (VCNX) 10-K 13 Mar 19 2018 FY Annual report Financial data

Document And Entity Information

Document And Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2018	Mar. 13, 2019	Jun. 30, 2018
Document And Entity Information [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2018
Document Fiscal Year Focus	2018
Document Fiscal Period Focus	FY
Trading Symbol	0001205922
Entity Registrant Name	Vaccinex, Inc.
Entity Central Index Key	0001205922
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Entity Seasoned Well Known Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Shell Company	false
Entity Ex Transition Period	false
Entity Public Float			$ 0
Entity Common Stock, Shares Outstanding		11,475,749

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Current assets:
Cash and cash equivalents	$ 5,618	$ 4,180
Marketable securities	14,106
Accounts receivable, net	639	117
Prepaid expenses and other current assets	1,061	677
Total current assets	21,424	4,974
Property and equipment, net	604	601
TOTAL ASSETS	22,028	5,575
Current liabilities:
Accounts payable	2,322	1,910
Accrued expenses	4,364	1,957
Deferred revenue		298
Total current liabilities	6,686	4,165
Convertible promissory notes to related party, net		2,813
Derivative liabilities		369
TOTAL LIABILITIES	6,686	7,347
Commitments and contingencies (Note 10)
Redeemable convertible preferred stock (Series B, B-1, B-2, C, D), par value of $0.001 per share; zero and 66,317,000 shares authorized as of December 31, 2018 and December 31, 2017; zero shares issued and outstanding as of December 31, 2018; 53,089,959 shares issued and 53,089,796 shares outstanding as of December 31, 2017 with aggregate liquidation preference of $0 and $140,261 as of December 31, 2018 and December 31, 2017		111,718
Stockholders’ equity (deficit):
Convertible preferred stock (Series A), par value of $0.001 per share; zero and 5,702,450 shares authorized, issued and outstanding as of December 31, 2018 and December 31, 2017 with aggregate liquidation preference of $0 and $7,684 as of December 31, 2018 and December 31, 2017		7,684
Common stock, par value of $0.0001 per share; 100,000,000 shares authorized as of December 31, 2018; 160,000,000 shares authorized as of December 31, 2017; 11,476,601 and 1,103,396 shares issued as of December 31, 2018 and December 31, 2017; 11,475,749 and 1,102,560 shares outstanding as of December 31, 2018 and December 31, 2017	1
Additional paid-in capital	208,156	54,123
Treasury stock, at cost; zero and 163 shares of redeemable convertible preferred stock as of December 31, 2018 and December 31, 2017, and 852 and 836 shares of common stock as of December 31, 2018 and December 31, 2017	(11)	(11)
Accumulated deficit	(216,767)	(187,249)
Total Vaccinex, Inc. stockholders’ deficit	(8,621)	(125,453)
Noncontrolling interests	23,963	11,963
TOTAL STOCKHOLDERS’ EQUITY (DEFICIT)	15,342	(113,490)
TOTAL LIABILITIES, REDEEMABLE CONVERTIBLE PREFERRED STOCK AND STOCKHOLDERS’ EQUITY	$ 22,028	$ 5,575

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Temporary equity, par value	$ 0.001	$ 0.001
Temporary equity, shares authorized	0	66,317,000
Temporary equity, shares issued	0	53,089,959
Temporary equity, shares outstanding	0	53,089,796
Temporary equity, aggregate liquidation preference	$ 0	$ 140,261
Common stock, par value	$ 0.0001	$ 0.0001
Common stock, shares authorized	100,000,000	160,000,000
Common stock, shares issued	11,476,601	1,103,396
Common stock, shares outstanding	11,475,749	1,102,560
Treasury stock, preferred shares	0	163
Treasury stock, common shares	852	836
Series A Convertible Preferred Stock
Preferred stock, par value	$ 0.001	$ 0.001
Preferred stock, shares authorized	0	5,702,450
Preferred stock, shares issued	0	5,702,450
Preferred stock, shares outstanding	0	5,702,450
Preferred stock, aggregate liquidation preference	$ 0	$ 7,684

Consolidated Statements of Oper

Consolidated Statements of Operations - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Income Statement [Abstract]
Revenue	$ 724,000	$ 90,000
Costs and expenses:
Cost of revenue	1,033,000	160,000
Research and development	22,353,000	16,551,000
General and administrative	4,619,000	4,483,000
Total costs and expenses	28,005,000	21,194,000
Loss from operations	(27,281,000)	(21,104,000)
Change in fair value of derivative liabilities	369,000	3,743,000
Interest expense	(392,000)	(1,358,000)
Loss on extinguishment of related party convertible promissory note	(2,379,000)
Other income (expense), net	165,000	(40,000)
Loss before provision for income taxes	(29,518,000)	(18,759,000)
Provision for income taxes	0	0
Net loss	(29,518,000)	(18,759,000)
Net loss attributable to noncontrolling interests	0	37,000
Net loss attributable to Vaccinex, Inc.	(29,518,000)	(18,722,000)
Cumulative dividends on redeemable convertible preferred stock		(3,211,000)
Net loss attributable to Vaccinex, Inc. common stockholders, basic and diluted	$ (29,518,000)	$ (21,933,000)
Net loss per share attributable to Vaccinex, Inc. common stockholders, basic and diluted	$ (5.65)	$ (19.90)
Weighted-average shares used in computing net loss per share attributable to Vaccinex, Inc. common stockholders, basic and diluted	5,223,635	1,101,937

Consolidated Statements of Rede

Consolidated Statements of Redeemable Convertible Preferred Stock and Stockholders' Equity (Deficit) - USD ($) $ in Thousands	Total	IPO	Redeemable Convertible Preferred Stock	Convertible Preferred Stock	Common Stock	Common StockIPO	Common StockSeries B Redeemable Convertible Preferred Stock	Common StockSeries A Convertible Preferred Stock	Additional Paid-in Capital	Additional Paid-in CapitalIPO	Additional Paid-in CapitalSeries B Redeemable Convertible Preferred Stock	Additional Paid-in CapitalSeries A Convertible Preferred Stock	Treasury Stock	Treasury StockRedeemable Convertible Preferred Stock	Accumulated Deficit	Total Vaccinex,Inc. Stockholders' Deficit	Total Vaccinex,Inc. Stockholders' DeficitIPO	Noncontrolling Interests
Balance at Dec. 31, 2016	$ (107,065)			$ 7,684					$ 53,789				$ (11)		$ (168,527)	$ (107,065)
Balance, Shares at Dec. 31, 2016			48,694,355
Balance at Dec. 31, 2016			$ 103,736
Balance, Shares at Dec. 31, 2016				5,702,450	1,101,359								836	163
Capital contribution	12,000																	$ 12,000
Stock-based compensation	319								319							319
Issuance of Series D redeemable convertible preferred stock, net of issuance cost			$ 7,982
Issuance of Series D redeemable convertible preferred stock, net of issuance cost, Shares			4,395,604
Exercise of stock options	$ 15								15							15
Exercise of stock options, Shares	2,037				2,037
Net loss	$ (18,759)														(18,722)	(18,722)		(37)
Balance at Dec. 31, 2017	$ (113,490)			$ 7,684					54,123				$ (11)		(187,249)	(125,453)		11,963
Balance, Shares at Dec. 31, 2017	53,089,959		53,089,959
Balance at Dec. 31, 2017	$ 111,718		$ 111,718
Balance, Shares at Dec. 31, 2017				5,702,450	1,103,396								836	163
Initial public offering, net of issuance costs of $5,551		$ 34,450								$ 34,450							$ 34,450
Initial public offering, net of issuance costs of $5,551, Shares						3,333,334
Conversion of convertible preferred stock to common stock	111,718		$ (111,718)	$ (7,684)			$ 1				$ 111,717	$ 7,684				111,718
Conversion of convertible preferred stock to common stock, Shares			(53,089,959)	(5,702,450)			6,468,933	570,238					16	(163)
Capital contribution	12,000																	12,000
Stock-based compensation	177								177							177
Exercise of stock options	$ 5								5							5
Exercise of stock options, Shares	700				700
Net loss	$ (29,518)														(29,518)	(29,518)
Balance at Dec. 31, 2018	$ 15,342				$ 1				$ 208,156				$ (11)		$ (216,767)	$ (8,621)		$ 23,963
Balance, Shares at Dec. 31, 2018	0
Balance, Shares at Dec. 31, 2018					11,476,601								852

Consolidated Statements of Re_2

Consolidated Statements of Redeemable Convertible Preferred Stock and Stockholders' Equity Deficit (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Redeemable convertible preferred stock, issuance cost		$ 18
IPO
Initial public offering, issuance costs	$ 5,551

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
CASH FLOWS FROM OPERATING ACTIVITIES:
Net loss	$ (29,518,000)	$ (18,759,000)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation	223,000	206,000
Amortization of debt discount	308,000	1,217,000
Net amortization of premiums and discounts on marketable securities	(100,000)
Stock-based compensation	177,000	319,000
Change in fair value of derivative liabilities	(369,000)	(3,743,000)
Loss on extinguishment of related party convertible promissory note	2,379,000
Changes in operating assets and liabilities:
Accounts receivable	(522,000)	(13,000)
Prepaid expenses and other current assets	(384,000)	(330,000)
Accounts payable	421,000	(555,000)
Accrued expenses	2,407,000	(27,000)
Deferred revenue	(298,000)	298,000
Net cash used in operating activities	(25,276,000)	(21,387,000)
CASH FLOWS FROM INVESTING ACTIVITIES:
Purchases of marketable securities	(20,756,000)
Sales of marketable securities	6,750,000
Purchase of property and equipment	(235,000)	(68,000)
Net cash used in investing activities	(14,241,000)	(68,000)
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from issuance of convertible promissory notes to related parties, net of issuance cost		9,977,000
Proceeds from initial public offering of common stock, net of commissions and underwriting discounts	37,125,000
Payment of initial public offering costs	(2,675,000)
Proceeds from exercise of stock options	5,000	15,000
Repayment of convertible promissory note, related party	(5,500,000)	(6,000,000)
Proceeds from capital contribution	12,000,000	12,000,000
Net cash provided by financing activities	40,955,000	23,974,000
NET INCREASE IN CASH AND CASH EQUIVALENTS	1,438,000	2,519,000
CASH AND CASH EQUIVALENTS–Beginning of period	4,180,000	1,661,000
CASH AND CASH EQUIVALENTS–End of period	5,618,000	4,180,000
SUPPLEMENTAL DISCLOSURES OF CASH FLOW INFORMATION:
Cash paid for interest	275,000	13,000
SUPPLEMENTAL DISCLOSURES OF NONCASH INVESTING AND FINANCING ACTIVITIES:
Purchase of property and equipment included in accounts payable		9,000
Conversion of redeemable convertible preferred stock into common stock	111,718,000
Conversion of convertible preferred stock into common stock	$ 7,684,000
Series D Redeemable Convertible Preferred Stock [Member]
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from issuance of Series D redeemable convertible preferred stock, net of issuance costs		$ 7,982,000

Company and Nature of Business

Company and Nature of Business	12 Months Ended
	Dec. 31, 2018
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Company and Nature of Business	1. COMPANY AND NATURE OF BUSINESS Vaccinex, Inc. (together with its subsidiaries, the Company) was incorporated in Delaware in April 2001 and is headquartered in Rochester, New York. The Company is a clinical-stage biotechnology company engaged in the discovery and development of targeted biotherapeutics to treat serious diseases and conditions with unmet medical needs, including cancer, neurodegenerative diseases, and autoimmune disorders. Since its inception, the Company has devoted substantially all of its efforts toward product research and development, marketing development and raising capital. The Company is subject to a number of risks common to other early-stage biotechnology companies including, but not limited to, the successful development and commercialization of its product candidates, rapid technological change and competition, dependence on key personnel and collaborative partners, uncertainty of protection of proprietary technology and patents, clinical trial uncertainty, fluctuation in operating results and financial performance, the need to obtain additional funding, potential product liability, compliance with governmental regulations, technological and medical risks, customer demand, management of growth and effectiveness of marketing by the Company. If the Company does not successfully commercialize or partner any of its product candidates, it will be unable to generate product revenue or achieve profitability. Going Concern These consolidated financial statements have been prepared on a going concern basis, which implies the Company will continue to realize its assets and discharge its liabilities in the normal course of business. The Company has incurred significant losses and negative cash flows from operations since inception and expects to incur additional losses until such time that it can generate significant revenue from the commercialization of its product candidates. The Company had negative cash flow from operations of $25.3 million and $21.4 million for the years ended December 31, 2018 and 2017, respectively, and an accumulated deficit of $216.8 million and $187.2 million as of December 31, 2018 and 2017. The Company’s ability to continue as a going concern is at issue due to its historical net losses and negative cash flows from operations, and its need for additional financing to fund future operations. These conditions raise substantial doubt about the Company’s ability to continue as a going concern. The consolidated financial statements do not include any adjustments relating to the recoverability and classification of recorded asset amounts or the amounts and classification of liabilities that might result from the outcome of this uncertainty. To date, the Company has relied on equity and debt financing to fund its operations. In addition, the Company also received $12.0 million in capital contributions from noncontrolling interests during each of the years ended December 31, 2018 and 2017. As the Company’s product candidates are still in their early stages of development, substantial additional financing will be needed by the Company to fund its operations and ongoing research and development efforts prior to the commercialization, if any, of its product candidates. Given our projected operating requirements and our existing cash and cash equivalents and marketable securities, we plan to complete an additional financing transaction prior to the commencement of the 2019 fourth quarter in order for us to continue operations. Management is currently evaluating different strategies to obtain the required funding of future operations. These strategies may include, but are not limited to, additional funding from current or new investors, refinancing of existing debt obligations or obtaining additional debt financing. There can be no assurances that the Company will be able to secure such additional financing, or if available, that it will be sufficient to meet its needs or on ideal terms. Initial Public Offering In August 2018, the Company completed its initial public offering (the “IPO”) in which it issued and sold 3,333,334 shares of its common stock, $0.0001 par value, at a public offering price of $12.00 per share. The Company received net proceeds of $37.2 million after deducting underwriting discounts and commissions of $2.8 million, but before deducting offering expenses of $2.7 million. In addition, in connection with the IPO: • all shares of the Company’s then-outstanding convertible preferred stock were automatically converted and reclassified into 7,039,155 shares of its common stock, $0.0001 par value; • a 1-for-10 reverse stock split of the Company’s common stock was affected; and • the Company repaid a $1.5 million convertible promissory note issued in June 2016 (the “June 2016 Note”), held by a related party, Vaccinex (Rochester), L.L.C. (“Vaccinex LLC”), which is majority owned and controlled by Dr. Maurice Zauderer, the Company’s President, Chief Executive Officer and a member of its board of directors.

Summary of Significant Accounti

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2018
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	2. SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES The accompanying consolidated financial statements reflect the consolidated application of certain significant accounting policies, as described below and elsewhere in the accompanying notes to the consolidated financial statements. Basis of Presentation and Consolidation These consolidated financial statements reflect the accounts and operations of the Company and those of its subsidiaries in which the Company has a controlling financial interest. As of December 31, 2018 and 2017, the Company’s accounts include Vaccinex Products and VX3 (DE) LP, a Delaware limited partnership (VX3). VX3 was established in October 2017 by a group of Canadian investors and was determined to be a variable interest entity (“VIE”) in which the Company is the primary beneficiary. The Company consolidates any VIE of which it is the primary beneficiary. The Company presents its noncontrolling interests as a separate component of stockholders’ equity (deficit) and net loss from noncontrolling interests as a separate component within its consolidated statements of operations. The financial position of Vaccinex Products was not material as of December 31, 2018 and 2017, and there were no gains or losses for Vaccinex Products for the years ended December 31, 2018 and 2017. During the year ended December 31, 2017, VX3 had a net loss attributable to noncontrolling interests of $37,000. There were no gains or losses for VX3 for the year ended December 31, 2018. Intercompany transactions and balances have been eliminated. Use of Estimates These consolidated financial statements have been prepared in conformity with accounting principles generally accepted in the United States of America (“U.S. GAAP”). 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 the disclosure of contingent assets and liabilities as of the date of the consolidated financial statements and the reported amount of expenses during the reporting period. Such management estimates include those relating to assumptions used in the valuation of stock option awards, the valuation of derivative instruments, and valuation allowances against deferred income tax assets. Actual results could differ from those estimates. Cash and Cash Equivalents The Company considers all highly liquid investments with an original maturity of three months or less at the date of purchase to be cash equivalents. The Company deposits its cash primarily in checking and money market accounts. Concentration of Credit Risk, Other Risks and Uncertainties Financial instruments that potentially subject the Company to concentrations of credit risk consist primarily of cash and cash equivalents. Cash equivalents are deposited in interest-bearing money market accounts. Although the Company deposits the cash with multiple financial institutions, cash balances may occasionally be in excess of the amounts insured by the Federal Deposit Insurance Corporation. Management believes the financial risk associated with these balances is minimal and has not experienced any losses to date. The Company depends on third-party manufacturers for the manufacture of drug substance and drug product for clinical trials. The Company also relies on certain third parties for its supply chain. Disputes with these third- party manufacturers or shortages in goods or services from third-party suppliers could delay the manufacturing of the Company’s product candidates and adversely impact its results of operations. Marketable Securities Marketable securities consist of investments with original maturities greater than 90 days at their acquisition date. The Company classifies all of its marketable securities as available-for-sale securities. The Company’s marketable securities are measured and reported at fair value using quoted prices in active markets for similar securities. Unrealized gains and losses on available-for-sale securities are reported as accumulated other comprehensive loss. The cost of securities sold is determined on a specific identification basis, and realized gains and losses are included in other income (expense), net in the consolidated statements of operations and comprehensive loss. The Company evaluates its marketable securities with unrealized losses for other-than-temporary impairment. When assessing marketable securities for other-than-temporary declines in value, the Company considers such factors as, among other things, how significant the decline in value is as a percentage of the original cost, how long the market value of the investment has been less than its original cost, the Company’s ability and intent to retain the investment for a period of time sufficient to allow for any anticipated recovery in fair value and market conditions in general. If any adjustment to fair value reflects a decline in the value of the investment that the Company considers to be “other-than-temporary,” the Company reduces the investment to fair value through a charge to the statement of operations and comprehensive loss. No such adjustments were necessary during the periods presented. Fair Value of Financial Instruments Financial instruments consist of cash and cash equivalents, marketable securities, prepaid expenses and other current assets, accounts payable, accrued expenses, convertible promissory notes, and derivative liabilities. Cash equivalents and marketable securities are stated at fair value. Prepaid expenses and other current assets, accounts payable and accrued expenses are stated at their carrying value, which approximates fair value due to the short time to the expected receipt or payment date. The principal amount of the Company’s convertible promissory notes approximates fair value as the stated interest rate approximates market rates currently available to the Company. The derivative liabilities are stated at fair value. Property and Equipment, Net Property and equipment are recorded at cost. Depreciation is computed over estimated useful lives of the related assets using the straight-line method. Leasehold improvements are amortized on a straight-line basis over the shorter of the useful life or term of the lease. Upon retirement or disposal, the cost and related accumulated depreciation are removed from the consolidated balance sheets and the resulting gain or loss is recorded to general and administrative expense in the consolidated statements of operations. Routine expenditures for maintenance and repairs are expensed as incurred. Estimated useful lives for property and equipment are as follows: Property and Equipment Estimated Useful Life Research equipment 5 years Furniture and fixtures 5 years Computer equipment 3 years Leasehold improvements Lesser of estimated useful life or remaining lease term Impairment of Long-Lived Assets The Company reviews the recoverability of its long-lived assets when events or changes in circumstances occur that indicate that the carrying value of the asset may not be recoverable. The assessment of possible impairment is based on the ability to recover the carrying value of the assets from the expected future cash flows (undiscounted and without interest expense) of the related operations. If these cash flows are less than the carrying value of such assets, an impairment loss for the difference between the estimated fair value and carrying value is recorded. There was no impairment loss recognized during the years ended December 31, 2018 and 2017. Derivative Liabilities The Company has outstanding derivative instruments related to certain features embedded within the Company’s outstanding convertible promissory notes, and an outstanding derivative instrument related to an arrangement providing a holder of one of the Company’s convertible promissory notes an option to purchase shares of equity in a future qualifying financing event. These derivatives are accounted for as derivative liabilities and remeasured to fair value as of each balance sheet date and the related remeasurement adjustments are recognized in the consolidated statements of operations. The Company records adjustments to the fair value of the derivative liabilities until the conversion or repayment of the related convertible promissory notes as discussed further in Note 8. Treasury Stock The Company records treasury stock activities under the cost method whereby the cost of the acquired stock is recorded as treasury stock. The Company’s accounting policy upon the formal retirement of treasury stock is to deduct the par value from common stock and to reflect any excess of cost over par value as a reduction to additional paid-in capital (to the extent created by previous issuances of the shares) and then retained earnings. There was no treasury stock repurchased for the years ended December 31, 2018 and 2017. Comprehensive Loss The Company did not have any other comprehensive income or loss for any of the periods presented and therefore comprehensive loss did not differ from net loss. Revenue Recognition The Company derives revenue primarily from service fees generated from collaboration agreements. Under the collaboration agreements, the Company recognizes service revenue when there is persuasive evidence of the arrangement, the fee is fixed or determinable, collection of the fee is reasonably assured, and delivery has occurred. Nonrefundable upfront payments, if any, are recorded as deferred revenue upon receipt and recognized as revenue over the service period. The Company accounts for revenue arrangements with multiple deliverables by dividing items into separate units of accounting if certain criteria are met, including: (1) whether the delivered item has stand-alone value to the customer; (2) whether the arrangement includes a general right of return relative to the delivered item; and (3) there is objective and reliable evidence of the fair value for the undelivered items. The Company allocates the consideration it receives among the separate units of accounting based on their respective fair value and applies the applicable revenue recognition criteria to each of the separate units. A deliverable that does not qualify as a separate unit of accounting within the arrangement is combined with the other applicable undelivered item within the arrangement. The Company determines the estimated selling price for deliverables under the collaboration agreements using the following hierarchy: (1) vender-specific objective evidence (“VSOE”); (2) third-party evidence (“TPE”); or (3) best estimate of selling price if neither VSOE nor TPE is available. Determining the best estimate of selling price for a deliverable requires significant judgment of various factors including market conditions, items contemplated during agreement negotiation as well as internally developed net present value models. Research and Development Costs Expenditures, including payroll, contractor expenses and supplies, for research and development of products are expensed as incurred. Clinical trial and other development costs incurred by third parties are expensed as the contracted work is performed. Where contingent milestone payments are due to third parties under research and development arrangements, the milestone payment obligations are expensed when the milestone results are probable of being achieved. Stock-Based Compensation The Company utilizes the Black-Scholes stock option-pricing model as the method for estimating the grant date fair value of its stock option awards. The Black-Scholes stock option-pricing model requires the use of highly subjective and complex assumptions, including the stock options’ expected term and the price volatility of the underlying stock. The grant date fair value of the portion of the stock option award that is ultimately expected to vest is recognized as compensation expense over the stock option awards’ requisite service periods. The Company recognizes stock-based compensation to expense using the straight-line method over the requisite service period. If there are any modifications or cancelations of stock option awards, the Company may be required to accelerate, increase or decrease any remaining unrecognized stock-based compensation expense. Income Taxes The Company uses the asset and liability method of accounting for income taxes. Deferred tax assets and liabilities are recognized for the estimated future tax consequences attributable to temporary differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax bases. Deferred tax assets and liabilities, which relate primarily to the carrying amount of the Company’s property and equipment and its net operating loss carryforward, are measured using enacted tax rates expected to apply to taxable income in the years in which those temporary differences are expected to be recovered or settled. Deferred tax expense or benefit is the result of changes in the deferred tax assets and liabilities. Valuation allowances are established when necessary to reduce deferred tax assets where, based upon the available evidence, management concludes that it is more likely than not that the deferred tax assets will not be realized. In evaluating its ability to recover deferred tax assets, the Company considers all available positive and negative evidence, including its operating results, ongoing tax planning and forecasts of future taxable income on a jurisdiction-by-jurisdiction basis. Because of the uncertainty of the realization of the deferred tax assets, the Company has recorded a full valuation allowance against its deferred tax assets. Reserves are provided for tax benefits for which realization is uncertain. Such benefits are only recognized when the underlying tax position is considered more likely than not to be sustained on examination by a taxing authority, assuming they possess full knowledge of the position and facts. Interest and penalties related to uncertain tax positions are recognized in the provision for income taxes; however, the Company currently has no interest or penalties related to income taxes. Segment and Geographic Information The Company’s chief operating decision maker, its Chief Executive Officer, reviews its operating results on an aggregate basis for purposes of allocating resources and evaluating financial performance. The Company has one business activity, the discovery and development of targeted biotherapeutics to treat serious diseases and conditions with unmet medical needs, and there are no segment managers who are held accountable for operations or operating results. Accordingly, the Company operates in one segment. As of December 31, 2018 and 2017, all long-lived assets are located in the United States. Net Loss Per Share Attributable to Vaccinex, Inc. Common Stockholders The Company calculates its basic and diluted net loss per share attributable to Vaccinex, Inc. common stockholders in conformity with the two-class method required for companies with participating securities. The Company considers all series of its preferred stock to be participating securities. In the event a dividend is declared or paid on the Company’s common stock, holders of preferred stock are entitled to a proportionate share of such dividend in proportion to the holders of common stock on an as-if converted basis. Under the two-class method, basic net loss per share attributable to Vaccinex, Inc. common stockholders is calculated by dividing the net loss attributable to Vaccinex, Inc. common stockholders by the weighted-average number of shares of common stock outstanding for the period. Net loss attributable to Vaccinex, Inc. common stockholders is determined by allocating undistributed earnings between common and preferred stockholders. The diluted net loss per share attributable to Vaccinex, Inc. common stockholders is computed by giving effect to all potential dilutive common stock equivalents outstanding for the period determined using the treasury stock method. The net loss attributable to Vaccinex, Inc. common stockholders was not allocated to the preferred stock under the two-class method as the preferred stock do not have a contractual obligation to share in the Company’s losses. For purposes of this calculation, redeemable convertible preferred stock, convertible preferred stock, and stock options to purchase common stock are considered common stock equivalents but have been excluded from the calculation of diluted net loss per share attributable to Vaccinex, Inc. common stockholders as their effect is anti-dilutive. Recent Accounting Pronouncements Not Yet Adopted In May 2014, the Financial Accounting Standards Board (FASB) issued Accounting Standard Update (ASU) No. 2014-09, Revenue from Contracts with Customers Revenue Recognition In February 2016, the FASB issued ASU No. 2016-02, Leases, which supersedes the ASC No. 840, Leases Recently Adopted Accounting Pronouncements In August 2016, the FASB issued ASU No. 2016-15, Statement of Cash Flows: Classification of Certain Cash Receipts and Cash Payments, In May 2017, the FASB issued ASU No. 2017-09, Compensation-Stock Compensation: Scope of Modification Accounting

Balance Sheet Components

Balance Sheet Components	12 Months Ended
	Dec. 31, 2018
Balance Sheet Related Disclosures [Abstract]
Balance Sheet Components	3. Property and Equipment Property and equipment consist of the following (in thousands): As of December 31, 2018 2017 Leasehold improvements $ 3,145 $ 3,140 Research equipment 3,219 2,998 Furniture and fixtures 350 350 Computer equipment 214 214 Property and equipment, gross 6,928 6,702 Less: accumulated depreciation and amortization (6,324 ) (6,101 ) Property and equipment, net $ 604 $ 601 Depreciation and amortization expense related to property and equipment was $223,000 and $206,000 for the years ended December 31, 2018 and 2017. Accrued Expenses Accrued expenses consist of the following (in thousands): As of December 31, 2018 2017 Accrued clinical trial cost $ 3,796 $ 891 Accrued payroll and related benefits 296 311 Accrued consulting and legal 236 239 Accrued other 36 324 Accrued interest - 192 Accrued expenses $ 4,364 $ 1,957

Marketable Securities

Marketable Securities	12 Months Ended
	Dec. 31, 2018
Investments Debt And Equity Securities [Abstract]
Marketable Securities	4. MARKETABLE SECURITIES As of December 31, 2018, the fair value of available-for-sale marketable securities was as follows (in thousands): As of December 31, 2018 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value Marketable securities: U.S. Treasury securities $ 14,106 $ - $ - $ 14,106 $ 14,106 $ - $ - $ 14,106 All of the Company’s available-for-sale marketable securities at December 31, 2018 are maturing in one year or less.

Fair Value of Financial Measure

Fair Value of Financial Measurements	12 Months Ended
	Dec. 31, 2018
Fair Value Disclosures [Abstract]
Fair Value of Financial Measurements	5. Assets and liabilities recorded at fair value on a recurring basis in the consolidated balance sheets are categorized based upon the level of judgment associated with the inputs used to measure their fair values. Fair value is defined as the exchange price that would be received for an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. Valuation techniques used to measure fair value must maximize the use of observable inputs and minimize the use of unobservable inputs. ASC 820 describes a fair value Level 1 – Quoted prices in active markets for identical assets or liabilities. Level 2 – Inputs other than Level 1 that are observable, either directly or indirectly, such as quoted prices for similar assets or liabilities; quoted prices in markets that are not active; or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities. Level 3 – Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities. The assets’ or liabilities’ fair value measurement level within the fair value hierarchy is based on the lowest level of any input that is significant to the fair value measurement. The following table sets forth the fair value of the Company’s financial assets by level within the fair value hierarchy (in thousands): As of December 31, 2018 Fair Value Level 1 Level 2 Level 3 Financial Assets: Cash equivalents: Money market fund $ 4,881 $ 4,881 $ - $ - Marketable securities: U. S. Treasury securities 14,106 - 14,106 - Total Financial Assets $ 18,987 $ 4,881 $ 14,106 $ - As of December 31, 2017 Fair Value Level 1 Level 2 Level 3 Financial Assets: Cash equivalents: Money market fund $ 1,011 $ 1,011 $ - $ - Total Financial Assets $ 1,011 $ 1,011 $ - $ - Financial Liabilities: Derivative liability $ 369 $ - $ - $ 369 Total Financial Liabilities $ 369 $ - $ - $ 369 The Company did not transfer any assets measured at fair value on a recurring basis to or from Level 1 and Level 2 during the years ended December 31, 2018 and 2017. The following table sets forth a summary of the changes in the fair value of the Company’s Level 3 financial instruments as follows (in thousands): Derivative Liability Balance – January 1, 2017 $ 694 Issuance of the January 2017 Notes 3,418 Change in fair value (3,743 ) Balance – December 31, 2017 369 Change in fair value (369 ) Balance – December 31, 2018 $ - Level 3 instruments consist of the Company’s embedded derivative liabilities related to conversion features within the outstanding convertible promissory notes as of December 31, 2017, and a free-standing derivative related to an option to purchase shares in a future equity financing as of December 31, 2017. The fair value of the derivative liabilities was measured using a with-and-without valuation methodology. Inputs used to determine the estimated fair value of the derivative instruments include the probability estimates of potential settlement scenarios for the convertible promissory notes, a present value discount rate and an estimate of the expected timing of settlement. Certain unobservable inputs used in the fair value measurement of the derivative instruments associated with the convertible promissory notes are the scenario probabilities and the discount rate estimated at the valuation date. Generally, an increase or decrease in the discount rate would result in a directionally opposite impact to the fair value measurement of the derivative instruments. Also, changes in the probability scenarios would have varying impacts depending on the weighting of each specific scenario. As discussed further in Note 8, heavier weighting towards a qualified financing, including an IPO, would result in an increase in the fair value of the derivative instruments associated with the conversion option. From the proceeds of the convertible promissory notes, a portion equal to the fair value of the derivative instruments was recognized as an additional debt discount and as derivative liabilities on the consolidated balance sheet upon issuance of the respective convertible promissory notes. The derivative liabilities require periodic remeasurements to fair value while the derivative is outstanding and, accordingly, the Company recognized a gain of $369,000 and $3.7 million from the remeasurement of the derivative liabilities associated with the convertible promissory notes for the years ended December 31, 2018 and 2017, respectively, and presents such amounts in its consolidated statements of operations as changes in fair value of derivative liabilities.

License and Services Agreement

License and Services Agreement	12 Months Ended
	Dec. 31, 2018
Research And Development [Abstract]
License and Services Agreement	6 . LICENSE AND SERVICES AGREEMENT In November 2017, the Company entered into a license agreement (the “VX3 License Agreement”) with VX3 (DE) LLP (“VX3”), which was formed by a group of Canadian investors including the Company’s majority stockholder, FCMI Parent Co. (“FCMI Parent”). VX3 was created for the purpose of funding the Company’s research and development activities for pepinemab, our most advanced product candidate. Under the VX3 License Agreement, the Company granted VX3 the license to use, make, have made, sell, offer and import pepinemab for the treatment of Huntington’s disease in the U.S. and Canada and, in return, VX3 agreed to fund research and development activities with up to an aggregate of $32.0 million in milestone payments to the Company and to share any pepinemab profits and sublicensing revenue under the agreement in an amount based on a calculation set forth in the agreement. The Company also entered into a services agreement with VX3 (the “Services Agreement”), pursuant to which the Company will carry out development activities for pepinemab for the treatment of Huntington’s disease in the U.S. and Canada in exchange for services payments from VX3, including a payment of $11.9 million in 2017. The VX3 License Agreement expires upon the last to expire licensed patent and may be terminated by either party upon uncured material breach, the occurrence of certain transactions or financings including the consummation of an initial public offering by the Company, uncured failure of VX3 to make any payment due under the Services Agreement, or upon written notice after November 6, 2020. The Services Agreement may be terminated by either party upon an uncured material breach and is automatically terminated upon termination of the VX3 License Agreement. The VX3 License Agreement provides that upon termination, the Company will issue to VX3 or its designees the number of shares of the Company’s common stock equal to the lesser of (1) the aggregate of all payments made to VX3 by the Canadian investors divided by $18.20 and (2) the then fair market value of VX3 divided by the then fair market value of one share of the Company’s common stock. The Company has a variable interest in VX3 through FCMI Parent, which is majority owned and controlled by the Company’s chairman, and it controls 90% and 96% of VX3’s voting interest as of December 31, 2018 and 2017, respectively. VX3 does not have any business operations or generate any income or expenses and is primarily a funding mechanism specifically for the benefit of the Company, as its only activities consist of the receipt of funding and the contribution of such funding to the Company. Therefore, the Company determined that it is the primary beneficiary of VX3 and that the operating results of VX3 should be incorporated into the Company’s consolidated financial statements accordingly. In February, May and June 2018, the Services Agreement was amended to allow VX3 to provide additional funding for future research and development activities to take place in the year ended December 31, 2018 and to repay an outstanding convertible note in the amount of $4.0 million (Note 8). No other terms of the Services Agreement were amended; therefore, the above assessment resulting in the Company being the primary beneficiary of the VX3 entity remained unchanged as of December 31, 2018. For each of the years ended December 31, 2018 and 2017, the Company recorded the gross proceeds of $12.0 million, received from VX3 as capital contributions from noncontrolling interests on the consolidated financial statements.

Collaboration Agreements

Collaboration Agreements	12 Months Ended
	Dec. 31, 2018
Collaboration Agreements [Abstract]
Collaboration Agreements	7 . COLLABORATION AGREEMENTS Merck Sharp & Dohme Corp. In September 2017, the Company entered into a research agreement with Merck Sharp & Dohme Corp. (“Merck”) to test vaccinia strain Modified Vaccinia Ankara. Under the research agreement, the Company designed genetic sequence for all constructs listed in the agreement and conducted research in accordance with the research protocol and a mutually agreed scope of work outlined in the agreement. Merck supplied the Company sufficient samples of the antibodies to carry out the research and has sole ownership of all right, title, interest and copy rights of the research results. The Company received quarterly service payments in the amount of $138,000 under the research agreement, of which $69,000 and $69,000 was recognized as service revenue for the years ended December 31, 2018 and 2017, respectively. The research agreement expired in June 2018. In the fourth quarter of 2018, the Company entered into a second agreement with Merck to test these antigen particles in an antibody discovery campaign. Surface Oncology, Inc. In November 2017, the Company entered into a research collaboration and license option agreement with Surface Oncology, Inc. (“Surface”) to identify and select antibodies against two target antigens, using the Company’s proprietary technology as described in the agreement. The term for each research program is nine to twelve months (not exceeding twelve months unless extended by written agreement) including time necessary for any functional assessment conducted by Surface following the commencement of the research program. Surface will provide the Company material to carry out the research activities. During the research program term, the Company also grants Surface non-exclusive, worldwide, limited-purpose license for each target to use the Company’s research program materials for conducting the research work pursuant to the agreement. Under the agreement, Surface has been granted exclusive options, exercisable by providing a written notice to the Company, to obtain (i) an exclusive product license to make, use, sell and import products incorporating the antibody targeting the first antigen and (ii) an exclusive research tool license to use the antibody targeting the second antigen to perform research. Under the agreement, Surface will pay an upfront technology access fee of $250,000 and milestone payments upon completion of each of four designated milestones for the first target antigen specified in the agreement. For the second target antigen, Surface will make payments to the Company based on time incurred by the Company in the conduct of the work plan described in the agreement. Surface will reimburse the Company for expenses incurred (i) in the conduct of the work plan as detailed in the research funding budget and (ii) for patent filings and prosecution of the Company’s program intellectual property as described in the agreement. The exercise of each option would also entail a license fee and annual maintenance fees, and in the case of the product license, royalties and additional milestone payments. During the year ended December 31, 2017, the Company received the upfront technology access fee of $250,000, of which $229,166 and $20,834 were recognized as revenue from the amortization of this upfront fee for the years ended December 31, 2018 and 2017, respectively. The Company also received $282,171 service fee payments for work conducted under the agreement for the year ended December 31, 2018. This agreement will expire upon the expiration of both research programs and all evaluation and testing periods. Heptares Therapeutics, Ltd. In June 2018, the Company entered into a research service agreement with Heptares Therapeutics, Ltd. (“Heptares”) to provide research services to Heptares. Under the agreement, Heptares provides the Company compounds, materials or samples, and the Company performs feasibility services to allow Heptares to evaluate the feasibility of the Company’s technology. The Company recognized service revenue of $138,556 from the Heptares research agreement for the year ended December 31, 2018.

Convertible Promissory Notes

Convertible Promissory Notes	12 Months Ended
	Dec. 31, 2018
Debt Disclosure [Abstract]
Convertible Promissory Notes	8 . CONVERTIBLE PROMISSORY NOTES The following table sets forth a summary of the outstanding convertible promissory notes (in thousands): As of December 31, 2017 June 2016 Note $ 1,500 Unamortized debt discount (316 ) Net June 2016 Note 1,184 January 2017 Notes 4,000 Unamortized debt discount (2,371 ) Net January 2017 Notes 1,629 Total convertible promissory notes, related parties $ 2,813 As of December 31, 2018, the Company did not have any convertible promissory notes outstanding. See “Repayment of Convertible Promissory Notes” below. June 2016 Note In June 2016, the Company issued a $1.5 million convertible promissory note to a related party (the June 2016 Note). January 2017 Notes In January 2017, the Company entered into a convertible promissory note agreement whereby it agreed to issue, in the aggregate, $10.0 million of convertible promissory notes to a related party (the “January 2017 Notes”). The $4.0 million of the January 2017 Notes issued in January 2017 did not accrue interest, but the other $6.0 million of the January 2017 Notes issued in April, August and October 2017 accrued interest at an annual rate of 2%. The January 2017 Notes had a maturity date three years from issuance. Upon maturity, the holder of these convertible promissory notes was to be repaid the outstanding principal plus all accrued interest. The Company was also authorized to prepay the January 2017 Notes, plus accrued interest, without penalty. The debt issuance costs for these convertible promissory notes were not material. Of the January 2017 Notes, $6.0 million were paid in 2017 and the balance was paid in full on March 8, 2018. See “Repayment of Convertible Promissory Notes” below. Derivative Liabilities From the proceeds of the convertible promissory notes, the portion equal to the fair value of the embedded derivative liabilities and the option derivative at the time of each respective issuance was recognized as a debt discount to be amortized to interest expense over the term of the related convertible promissory notes. The Company recognized interest expense of $308,000 and $1.2 million for the amortization of the debt discounts during the years ended December 31, 2018 and 2017, respectively. Repayment of Convertible Promissory Notes Of the January 2017 Notes, $2.0 million issued in April 2017 was repaid along with accrued interest in May 2017, $4.0 million issued in August and October 2017 was repaid along with accrued interest in November 2017 and $4.0 million issued in January 2017 was repaid in March 2018. The option arrangement associated with the January 2017 Notes was also waived upon the repayment of the January 2017 Notes. As a result of this repayment, the related $0.3 million derivative liabilities associated with the conversion feature and the option arrangement were written off and the $2.2 million unamortized debt discount was recognized as a loss on extinguishment of related party convertible promissory note in the consolidated statements of operations in the year ended December 31, 2018. The June 2016 Note was repaid along with accrued interest in August 2018. As a result of this repayment, the related $31,000 derivative liability associated with the conversion feature and the option arrangement was written off and the $199,000 unamortized debt discount was recognized as a loss on extinguishment of related party convertible promissory note in the consolidated statements of operations in the year ended December 31, 2018.

Preferred Stock

Preferred Stock	12 Months Ended
	Dec. 31, 2018
Equity [Abstract]
Preferred Stock	9. PREFERRED STOCK The company had outstanding preferred stock as of December 31, 2017 which was converted to common stock in 2018 in connection with the Company’s IPO. The following paragraphs disclose the terms of the preferred stock outstanding as of December 31, 2017. The Company’s then outstanding preferred stock was issued in series, consisting of Series A convertible preferred stock and Series B, B-1, B-2, C and D redeemable convertible preferred stock (collectively referred to as preferred stock). In addition to the designations by series, the Company also designated the preferred stock as either convertible (i.e., not redeemable) or redeemable convertible (i.e., contingently redeemable). As discussed further below, the Series A preferred stock was designated as convertible preferred stock as these shares were only redeemable in a true liquidation scenario whereby the Company was liquidated, dissolved, or wound down. The Series B, B-1, B-2, C and D preferred stock was designated as redeemable convertible preferred stock as these shares were redeemable only upon a “Deemed Liquidation Event” as discussed further in the Redemption section below. In May and June 2017, the Company raised $8.0 million from the issuance of 4,395,604 shares of Series D redeemable convertible preferred stock to one investor at $1.82 per share. The issuance of Series D redeemable convertible preferred stock at the price of $1.82 per share triggered the downward revision to the conversion price of Series B-2 redeemable convertible preferred stock and resulted in the conversion price to decrease from $25.30 to $25.00 per share, effective May 31, 2017. In August 2018, upon the closing of the Company’s IPO, all outstanding shares of convertible preferred stock were automatically converted and reclassified into 7,039,155 shares of its common stock. The Company’s redeemable convertible preferred stock consisted of the following (dollars in thousands): As of December 31, 2017 Designated Shares Authorized Shares Issued Shares Outstanding Aggregate Liquidation Preference Net Carrying Value Series B 6,500,000 6,335,543 6,335,380 $ 27,242 $ 9,717 Series B-1 6,417,000 6,416,144 6,416,144 18,725 9,945 Series B-2 7,500,000 5,344,748 5,344,748 19,220 16,568 Series C 12,400,000 7,205,882 7,205,882 24,500 33,579 Series D 33,500,000 27,787,642 27,787,642 50,574 41,909 Total 66,317,000 53,089,959 53,089,796 $ 140,261 $ 111,718 As of December 31, 2017, the Company had authorized, issued and outstanding 5,702,450 shares designated as Series A convertible preferred stock with an aggregate liquidation preference and net carrying value of $7.7 million. The Company’s preferred stock had the following rights, preferences, privileges and restrictions: Dividends The holders of Series D redeemable convertible preferred stock were entitled to receive dividends only when (1) the board of directors declared a dividend payable upon outstanding shares of the Series D redeemable convertible preferred stock or (2) the board of directors declared a dividend payable upon outstanding shares of Series A convertible preferred stock and Series B, B-1, B-2, and C redeemable convertible preferred stock and common stock, in which event, the board of directors would contemporaneously also declare a dividend to the holders of the Series D redeemable convertible preferred stock as though the shares had been fully converted into shares of common stock on the declaration date. The second scenario would not apply if the dividend payable declared by the board of directors were preferential dividends for Series B, B-1 and B-2 redeemable convertible preferred stock. The holders of Series C redeemable convertible preferred stock were entitled to receive annual cumulative dividends at the per annum rate of 3% of the purchase price of $3.40 per share, if declared by the board of directors, prior and in preference to any declaration or payment of any dividends on the Series A convertible preferred stock and Series B, B-1 and B-2 redeemable convertible preferred stock and common stock. However, in July 2016 upon the issuance of Series D redeemable convertible preferred stock, the $2.3 million cumulative and unpaid dividend of Series C redeemable convertible preferred stock was forgiven, and the annual dividends rate of 3% per annum of the purchase price of $3.40 per share became non-cumulative. The holders of Series B, B-1 and B-2 redeemable convertible preferred stock were entitled to annual cumulative dividends at the per annum rate of 8% of each respective purchase price of $2.15, $1.55 and $3.10 per share, if declared by the board of directors, prior and in preference to any declaration or payment of any dividends on the Series A convertible preferred stock and common stock. The holders of Series A convertible preferred stock were entitled to receive non-cumulative dividends, if declared by the board of directors on either Series A convertible preferred stock or common stock, and in the event of the latter, the holders of Series A convertible preferred stock would participate in such dividend payment on an as-if-converted basis. The Company has not recorded a liability for cumulative and unpaid dividends as of December 31, 2017, as no dividends have been declared by the Company. Voting Rights Each share of preferred stock is entitled to voting rights equal to the number of shares of common stock into which each share could be converted. The holders of shares of the preferred stock vote with holders of the common stock as a single class on all matters. Conversion Rights Each share of Series A convertible preferred stock and Series B, B-1, B-2, C and D redeemable convertible preferred stock was convertible by the holder at any time into common stock. The conversion rate was determined by dividing the original purchase price of $1.3475, $2.15, $1.55, $3.40 and $1.82 per share for Series A convertible preferred stock and Series B, B-1, C and D redeemable convertible preferred stock by the conversion price of $13.475, $13.1, $15.5, $18.2, $18.2 per share for Series A convertible preferred stock and Series B, B-1, C and D redeemable convertible preferred stock as of December 31, 2017. The conversion rate for Series B-2 redeemable convertible preferred stock was determined by dividing the original purchase price of $3.10 per share by the conversion price of $25.00 as of December 31, 2017. The shares of Series C and Series D redeemable convertible preferred stock would automatically convert upon the occurrence of (i) the closing of an underwritten public offering at an offering price per share of not less than $5.00 per share and with gross proceeds to the Company of not less than $30.0 million or (ii) on the date specified by written consent or vote by the majority of the holders of the then outstanding shares of Series B, B-1, B-2, C and D redeemable convertible preferred stock voting as a single class on an as-converted basis. The shares of Series B, B-1 or B-2 redeemable convertible preferred stock would automatically convert upon the occurrence of: (i) the closing of an underwritten public offering at an offering per share price of not less than two times the then applicable conversion prices for each series (in the event of Series B and B-1 redeemable convertible preferred stock) or not less than $5.00 per share (in the event of Series B-2 redeemable convertible preferred stock) and with gross proceeds to the Company of not less than $15.0 million; (ii) a qualified sale of the Company whereby the holders of common stock then issued and outstanding, including the conversion of outstanding shares of Series B, B-1 or B-2 redeemable convertible preferred stock, will be entitled to receive gross proceeds from such transaction on a per share basis of no less than two times of then applicable conversion prices for each Series; or (iii) on the date specified by written consent or vote by the majority of the holders of the then outstanding shares of Series B, B-1 or B-2 redeemable convertible preferred stock. The shares of Series B-1 and B-2 redeemable convertible preferred stock also would automatically convert on the date specified by written consent or vote of two-thirds of the holders of the then outstanding shares of Series B-1 and B-2 redeemable convertible preferred stock, voting as a single class on an as-converted basis. The shares of Series A convertible preferred stock would automatically convert into common stock upon the earlier of (i) the closing of an underwritten public offering or (ii) the affirmative vote of a majority of the holders of the then outstanding shares of Series A convertible preferred stock. Liquidation Preference Upon any liquidation, dissolution, or winding up of the Company, whether voluntary or involuntary, the holders of the Series C and D redeemable convertible preferred stock were entitled to receive, before any distribution or payment was made upon any shares of the Series A convertible preferred stock and Series B, B-1 and B-2 redeemable convertible preferred stock and common stock, an amount equal to $3.40 per share and $1.82 per share, respectively, plus any declared or accrued but unpaid dividends, for Series C and Series D redeemable convertible preferred stock. After payment to the holders of Series C and Series D redeemable convertible preferred stock, the holders of Series B, B-1 and B-2 redeemable convertible preferred stock, prior to any distribution to the holders of Series A convertible preferred stock and common stock, were entitled to receive an amount equal to $2.15, $1.55 and $3.10 per share, plus any declared or accrued but unpaid dividends. After payment to the holders of Series B, B-1, B-2, C and D redeemable convertible preferred stock, the holders of Series A convertible preferred stock were entitled to receive an amount equal to $1.3475 per share plus all declared or accrued but unpaid dividends. Redemption The shares of Series B, B-1, B-2, C and D redeemable convertible preferred stock were only redeemable upon a “Deemed Liquidation Event,” which included certain events that were outside the control of the Company such as the sale or merger of the Company in certain scenarios. Further, these shares did not contain any provisions that would ensure the holders were entitled to the same form of consideration upon the occurrence of a “Deemed Liquidation Event.” Accordingly, the shares of Series B, B-1, B-2, C and D redeemable convertible preferred stock were considered contingently redeemable and, therefore, classified outside of stockholders’ equity (deficit). The shares of Series A were only redeemable upon a regular liquidation event within the Company’s control and were not redeemable at the option of the holder or under any other scenarios. Therefore, the shares of Series A convertible preferred stock were classified within stockholders’ equity (deficit).

Commitment and Contingencies

Commitment and Contingencies	12 Months Ended
	Dec. 31, 2018
Commitments And Contingencies Disclosure [Abstract]
Commitments and Contingencies	10 . COMMITMENTS AND CONTINGENCIES Sublicense Termination Payments In 2006, the Company licensed certain technology to EUSA Pharma SAS (“EUSA”) and in 2008, this technology was sublicensed by EUSA to Glaxo Group Limited (“GSK”) for development. GSK terminated its sub-license with EUSA in March 2010 and ownership of the technology reverted back to the Company. The Company may be required to pay EUSA up to $25.5 million plus ongoing royalty payments of 1% of net sales upon the occurrence of certain events involving the previously licensed technology, including Phase 3 clinical trial, FDA acceptance and approval and product sales. The Company is not planning any further commercialization efforts related to the previously licensed technology, and therefore does not anticipate any of the above described amounts will be paid. Operating Lease The Company leases its facilities from 1895 Management, Ltd., a New York corporation controlled by an entity affiliated with a director of the Company, under non-cancellable operating leases. Following entry into a lease extension agreement in July 2018, the lease agreement requires monthly rental payments of $14,000 through October 31, 2020. The Company is responsible for all maintenance, utilities, insurance and taxes related to the facility. As of December 31, 2018, the future minimum payments for the operating leases is $168,000 in 2019 and $140,000 in 2020. Rent expense incurred under the operating lease was $168,000 for each of the years ended December 31, 2018 and 2017. Contingencies The Company is subject to claims and assessments from time to time in the ordinary course of business. The Company records a provision for a liability when it believes that it is both probable that a liability has been incurred and the amount can be reasonably estimated. Significant judgment is required to determine both probability and the estimated amount. In the normal course of business, the Company may become involved in legal proceedings. The Company will accrue a liability for such matters when it is probable that a liability has been incurred and the amount can be reasonably estimated. When only a range of possible loss can be established, the most probable amount in the range is accrued. If no amount within this range is a better estimate than any other amount within the range, the minimum amount in the range is accrued. The accrual for a litigation loss contingency might include, for example, estimates of potential damages, outside legal fees and other directly related costs expected to be incurred. As of December 31, 2018 and 2017, the Company was not involved in any material legal proceedings.

Common Stock Reserved For Issua

Common Stock Reserved For Issuance	12 Months Ended
	Dec. 31, 2018
Equity [Abstract]
Common Stock Reserved For Issuance	1 1 . COMMON STOCK RESERVED FOR ISSUANCE Common stock has been reserved for the following potential future issuances: As of December 31, 2018 2017 Conversion of outstanding preferred stock - 7,039,155 Shares underlying outstanding stock options 405,683 420,956 Shares available for future stock option grants 423,000 19,034 Exchange of Vaccinex Products, LP units 1,202,566 1,202,566 Conversion of VX3 units 1,318,797 659,400 Total shares of common stock reserved 3,350,046 9,341,111

Stock-Based Compensation

Stock-Based Compensation	12 Months Ended
	Dec. 31, 2018
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Stock-Based Compensation	1 2 . STOCK-BASED COMPENSATION 2011 Employee Equity Plan The Company’s 2011 Employee Equity Plan (the “2011 Plan”) was terminated in connection with the adoption of the Company’s 2018 Omnibus Incentive Plan (the “2018 Plan”) in August 2018, and the Company will not grant any additional stock options under the 2011 Plan. However, the 2011 Plan will continue to govern the terms and conditions of the outstanding stock options previously granted thereunder. Stock options granted under the 2011 Plan expire in five or ten years from the date of grant. 2018 Omnibus Incentive Plan In August 2018, the Company’s Board of Directors adopted, and its stockholders approved, the 2018 Plan, which allows for the granting of stock, stock option, and stock appreciation rights awards to employees, advisors and consultants. Stock options granted under the 2018 Plan may be either incentive stock options or non-statutory stock options. Incentive stock options may be granted to employees, advisors and consultants at exercise prices of no less than the fair value of the common stock on the grant date. If at the time of grant, the optionee owns stock representing more than 10% of the voting power of all classes of stock of the Company, the exercise price must be at least 110% of the fair value of the common stock on the grant date as determined by the board of directors. Non-statutory stock options may be granted to employees, advisors and consultants at exercise prices of less than the fair market value of a share of common stock on the date the non-statutory stock option is granted but shall under no circumstances be less than adequate consideration as determined by the board of directors for such a share. Vesting period of stock option grants is determined by the board of directors, ranging from zero to eight years. Stock options granted under the 2018 Plan expire in five or ten years from the date of grant. The Company reserved 425,000 shares of common stock for issuance, subject to certain adjustments, pursuant to awards under the 2018 Plan. Any shares of common stock related to awards outstanding under the 2011 Plan as of the effective date of the 2018 Plan, which thereafter terminate by expiration, forfeiture, cancellation or otherwise without the issuance of such shares, will be added to, and included in, the number of shares of common stock available for grant under the 2018 Plan. In addition, effective January 1, 2020 and continuing until the expiration of the 2018 Plan, the number of shares of common stock available for issuance under the 2018 Plan will automatically increase annually by 2% of the total number of issued and outstanding shares of our common stock as of December 31 st A summary of the Company’s stock option activity and related information is as follows: Options Outstanding Shares Subject to Options Outstanding Weighted- Average Exercise Price Weighted- Average Remaining Contractual Life (Years) Aggregate Intrinsic Value Balance as of January 1, 2017 405,658 $ 9.01 8.1 $ 1,978 Granted 33,976 13.60 Exercised (2,037 ) 7.10 Canceled (16,641 ) 14.60 Balance as of December 31, 2017 420,956 9.20 7.4 5,021 Granted 30,000 13.10 Exercised (700 ) 7.10 Canceled (44,573 ) 7.10 Balance as of December 31, 2018 405,683 $ 9.69 6.5 $ - Exercisable as of December 31, 2018 366,463 $ 9.46 6.3 $ - The weighted-average grant date fair value of stock options granted to employees for the years ended December 31, 2018 and 2017 was $14.87 and $9.00 per share, respectively. The aggregate grant date fair value of stock options that vested during the years ended December 31, 2018 and 2017 was $234,466 and $300,000, respectively. The intrinsic value of stock options vested and expected to vest and exercisable is calculated based on the difference between the exercise price and the fair value of the Company’s common stock as of December 31, 2018 and 2017. The intrinsic value of exercised stock options is the difference between the fair value of the underlying common stock and the exercise price as of the exercise date. As of December 31, 2018, and 2017, total unrecognized compensation cost related to stock options granted to employees was $435,639 and $216,000, which is expected to be recognized over a weighted-average period of 2.8 and 1.9 years, respectively. Determination of Fair Value The determination of the fair value of stock options on the date of grant using the Black-Scholes option-pricing model is affected by the estimated fair value of the Company’s common stock, as well as assumptions regarding a number of variables that are complex, subjective and generally require significant judgment to determine. The assumptions used to calculate the fair value of stock options were: Fair Value of Common Stock Prior to the IPO, the fair value of the common stock underlying the stock options was determined by the Company’s board of directors, with input from management and third-party valuations. Subsequent to the IPO, the fair value of the Company’s common stock was based on its publicly traded price per share. Expected Term The expected term represents the period that the Company’s stock option awards are expected to be outstanding. Stock options granted have a maximum contractual life of ten years. The Company estimates the expected term of the stock option to be six years based on historical data on employee exercises and post-vesting employment termination behavior. Expected Volatility As the Company does not have a trading history for its common stock, the expected stock price volatility for the Company’s common stock was estimated by taking the average historic price volatility for industry peers based on daily price observations over a period equivalent to the expected term of the stock option grants. Industry peers consist of several public companies in the Company’s industry which are of similar size, complexity and stage of development. The Company intends to continue to consistently apply this process using the same or similar public companies until a sufficient amount of historical information regarding the volatility of its own share price becomes available, or unless circumstances change such that the identified companies are no longer similar to the Company, in which case, more suitable companies whose share prices are publicly available would be used in the calculation. Risk-Free Interest Rate The risk-free interest rate is based on the U.S. Treasury rate, with maturities similar to the expected term of the stock options. Expected Dividend Yield The Company does not anticipate paying any dividends in the foreseeable future and, therefore, uses an expected dividend yield of zero. On January 1, 2017, the Company adopted ASU No. 2016-09 and started to account for forfeitures of stock options as they occur. The Company recorded the cumulative effect adjustment to accumulated deficit and the impact was not material. The grant date fair value of employee stock options was estimated using a Black-Scholes option-pricing model with the following weighted-average assumptions: Year Ended December 31, 2018 2017 Expected term (in years) 6.0 6.0 Expected volatility 75.0 % 75.0 % Risk-free interest rate 2.6 % 2.0 % Expected dividend yield - % - % Total stock-based compensation expense recognized in the consolidated statements of operations is as follows (in thousands): Year Ended December 31, 2018 2017 Research and development $ 65 $ 54 General and administrative 112 265 Total stock-based compensation expense $ 177 $ 319

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Income Taxes	1 3 . INCOME TAXES No provision for income taxes was recorded in the years ended December 31, 2018 and 2017. The Company remains in a cumulative loss position with a full valuation allowance recorded against its net deferred income tax assets as of December 31, 2018. On December 22, 2017, the Tax Cuts and Jobs Act (the “Tax Act”) was signed into law. The Tax Act makes broad and complex changes to the U.S. tax code including, but not limited to, reducing the U.S. federal corporate income tax rate. While the Tax Act reduces the U.S. federal corporate income tax rate from 35% to 21% for tax years beginning after December 31, 2017, ASC 740 required the Company to remeasure its deferred tax balances in 2017 in accordance with the 2018 rate reduction. The SEC staff issued Staff Accounting Bulletin 118 (“SAB 118”), which provides guidance on accounting for the tax effects of the Tax Act. SAB 118 provides a measurement period that should not extend beyond one year from the U.S. tax reform enactment date for companies to complete the accounting under ASC 740. In accordance with SAB 118, a company must reflect the income tax effects of those aspects of the U.S. tax reform for which the accounting under ASC 740 is complete. Specifically, the Company revalued its U.S. deferred tax assets and liabilities due to the federal income tax rate reduction from 35% to 21%. Since the Company has provided a full valuation allowance against its deferred tax assets, the revaluation of the deferred tax assets did not have a material impact on any period presented. The Company did not record provision for income taxes for the years ended December 31, 2018 and 2017. The Company’s deferred income tax assets continue to be offset by a valuation allowance. The Company has recorded a reduction of deferred income tax assets of $20.7 million in the year ended December 31, 2017 related to the remeasurement of our net deferred tax assets to reflect the U.S. federal corporate income tax rate reduction to 21%, which was fully offset by a change to the Company’s valuation allowance. The reconciliation of federal statutory income tax rate to the Company’s effective income tax rate is as follows: Year Ended December 31, 2018 2017 Expected income tax benefit at the federal statutory rate 21.0 % 34.0 % Federal tax rate change effect - (110.3 ) State taxes, net of federal benefit 5.2 5.4 Research and development credit, net 10.3 17.0 Non-deductible items and others (0.4 ) 0.7 Change in valuation allowance (36.1 ) 53.2 Total 0.0 % 0.0 % Deferred income taxes reflect the net effects of temporary differences between the carrying amounts of assets and liabilities for financial reporting purposes and the amounts used for income tax purposes. The principal components of the Company’s deferred tax assets consisted of the following as of December 31, 2018 and 2017 (in thousands): As of December 31, 2018 2017 Deferred tax assets: Federal and state net operating loss carryforwards $ 52,362 $ 45,057 Research and development tax credits 14,592 11,542 Depreciation and amortization 468 504 Reserves and accruals 56 115 Derivative liabilities - 96 Deferred revenue - 78 Other 202 330 Total deferred tax assets 67,680 57,722 Less: valuation allowance (67,680 ) (57,026 ) Net deferred tax assets - 696 Deferred tax liability: Debt discount - (696 ) Net deferred tax assets and liability $ - $ - The Company’s valuation allowance increased by $10.7 million and decreased by $10.0 million for the years ended December 31, 2018 and 2017, respectively, in order to maintain a full valuation allowance against its deferred tax assets. Based on the Company’s history of losses, the Company recorded a full valuation allowance against its deferred tax assets as of December 31, 2018 and 2017. The Company intends to maintain a valuation allowance until sufficient positive evidence exists to support a reversal of the valuation allowance. As of December 31, 2018, the Company had federal and state operating loss carryforwards of $198.2 million and $209.3 million, which begin to expire in the years ending December 31, 2024 and 2034, respectively. The Company had federal research and development tax credit carryforwards of $14.6 million as of December 31, 2018. This credit begins to expire from in the year ending December 31, 2021. Under the provisions of Section 382 of the Internal Revenue Code (the IRC), net operating loss and credit carryforwards and other tax attributes may be subject to limitation if there has been a significant change in ownership of the Company, as defined by the IRC. Future owner or equity shifts, including an IPO, could result in limitations on net operating loss and credit carryforwards. The Company files income tax returns in the U.S. federal jurisdiction as well as many U.S. state jurisdictions. The tax years from January 1, 2015 to December 31, 2018 remain open to examination by the major jurisdictions in which the Company is subject to tax. Fiscal years outside the normal statute of limitations remain open to audit by tax authorities due to tax attributes generated in those early years, which have been carried forward and may be audited in subsequent years when utilized. The Company evaluates tax positions for recognition using a more-likely-than-not recognition threshold, and those tax positions eligible for recognition are measured as the largest amount of tax benefit that is greater than 50% likely of being realized upon the effective settlement with a taxing authority that has full knowledge of all relevant information. As of December 31, 2018, and 2017, the Company had no unrecognized income tax benefits that would affect the Company’s effective tax rate if recognized.

Net Loss Per Share Attributable

Net Loss Per Share Attributable to Common Stockholders	12 Months Ended
	Dec. 31, 2018
Earnings Per Share [Abstract]
Net Loss Per Share Attributable to Common Stockholders	1 4 . NET LOSS PER SHARE ATTRIBUTABLE TO COMMON STOCKHOLDERS The following table sets forth the computation of the Company’s basic and diluted net loss per share for the periods presented (in thousands, except share and per share data): Year Ended December 31, 2018 2017 Net loss $ (29,518 ) $ (18,759 ) Net loss attributable to noncontrolling interests - 37 Net loss attributable to Vaccinex, Inc. (29,518 ) (18,722 ) Cumulative dividends on preferred stock - (3,211 ) Net loss attributable to Vaccinex, Inc. common stockholders, basic and diluted $ (29,518 ) $ (21,933 ) Net loss per share attributable to Vaccinex, Inc. common stockholders, basic and diluted $ (5.65 ) $ (19.90 ) Weighted-average shares used in computing net loss per share attributable to Vaccinex, Inc. common stockholders, basic and diluted 5,223,635 1,101,937 The following weighted-average common stock equivalents were excluded from the calculation of diluted net loss per share for the periods presented as they had an anti-dilutive effect: Year Ended December 31, 2018 2017 Preferred stock (if converted) - 6,837,585 Options to purchase common stock 410,886 408,373 Contingently issuable common stock upon exchange of Vaccinex Products, LP units 1,202,566 1,202,566 Contingently issuable common stock upon exchange of VX3 units 1,158,009 99,361

Employee Benefit Plan

Employee Benefit Plan	12 Months Ended
	Dec. 31, 2018
Compensation And Retirement Disclosure [Abstract]
Employee Benefit Plan	1 5 . EMPLOYEE BENEFIT PLAN The Company sponsors a 401(k) plan that stipulates that eligible employees can elect to contribute to the 401(k) plan, subject to certain limitations, up to the lesser of the statutory maximum or 100% of eligible compensation on a pre-tax basis. Through December 31, 2018 and 2017, the Company has not elected to match employee contributions as permitted by the plan. The Company pays the administrative costs for the plan.

Related Party Transactions

Related Party Transactions	12 Months Ended
	Dec. 31, 2018
Related Party Transactions [Abstract]
Related Party Transactions	1 6 . RELATED PARTY TRANSACTIONS As discussed in Note 10, the Company also leases its facility from 1895 Management, Ltd., a New York corporation controlled by an entity affiliated with the Company’s chairman and major stockholder of the Company. Rent expense incurred under this operating lease was $168,000 for each of the years ended December 31, 2018 and 2017. In 2016, the Company issued in aggregate $3.0 million convertible promissory note to FCMI Parent Co. (“FCMI Parent”) and $1.5 million convertible promissory note to Vaccinex (Rochester), L.L.C. (“Vaccinex LLC”). FCMI Parent is majority owned and controlled by the Company’s chairman and Vaccinex LLC is majority owned and controlled by the Company’s Chief Executive Officer. During the year ended December 31, 2017, the Company issued an additional $10.0 million in convertible promissory notes to FCMI Parent, which was fully repaid in March 2018. The $1.5 million convertible promissory note to Vaccinex LLC was fully repaid in August 2018. The aggregate accrued interest payable and interest expense derived from these convertible promissory notes to related parties were $0 and $392,000 as of and for the year ended December 31, 2018, and $192,000 and $138,000 as of and for the year ended December 31, 2017. The aggregate balance of $2.8 million in convertible promissory notes to related parties was outstanding as of December 31, 2017. See Note 8 for more information. During the year ended December 31, 2017, the Company raised $8.0 million from the issuance of 4,395,604 shares of Series D redeemable convertible preferred stock to the Company’s chairman at $1.82 per share. See Note 9 for more information.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2018
Accounting Policies [Abstract]
Basis of Presentation and Consolidation	Basis of Presentation and Consolidation These consolidated financial statements reflect the accounts and operations of the Company and those of its subsidiaries in which the Company has a controlling financial interest. As of December 31, 2018 and 2017, the Company’s accounts include Vaccinex Products and VX3 (DE) LP, a Delaware limited partnership (VX3). VX3 was established in October 2017 by a group of Canadian investors and was determined to be a variable interest entity (“VIE”) in which the Company is the primary beneficiary. The Company consolidates any VIE of which it is the primary beneficiary. The Company presents its noncontrolling interests as a separate component of stockholders’ equity (deficit) and net loss from noncontrolling interests as a separate component within its consolidated statements of operations. The financial position of Vaccinex Products was not material as of December 31, 2018 and 2017, and there were no gains or losses for Vaccinex Products for the years ended December 31, 2018 and 2017. During the year ended December 31, 2017, VX3 had a net loss attributable to noncontrolling interests of $37,000. There were no gains or losses for VX3 for the year ended December 31, 2018. Intercompany transactions and balances have been eliminated.
Use of Estimates	Use of Estimates These consolidated financial statements have been prepared in conformity with accounting principles generally accepted in the United States of America (“U.S. GAAP”). 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 the disclosure of contingent assets and liabilities as of the date of the consolidated financial statements and the reported amount of expenses during the reporting period. Such management estimates include those relating to assumptions used in the valuation of stock option awards, the valuation of derivative instruments, and valuation allowances against deferred income tax assets. Actual results could differ from those estimates.
Cash and Cash Equivalents	Cash and Cash Equivalents The Company considers all highly liquid investments with an original maturity of three months or less at the date of purchase to be cash equivalents. The Company deposits its cash primarily in checking and money market accounts.
Concentration of Credit Risk, Other Risks and Uncertainties	Concentration of Credit Risk, Other Risks and Uncertainties Financial instruments that potentially subject the Company to concentrations of credit risk consist primarily of cash and cash equivalents. Cash equivalents are deposited in interest-bearing money market accounts. Although the Company deposits the cash with multiple financial institutions, cash balances may occasionally be in excess of the amounts insured by the Federal Deposit Insurance Corporation. Management believes the financial risk associated with these balances is minimal and has not experienced any losses to date. The Company depends on third-party manufacturers for the manufacture of drug substance and drug product for clinical trials. The Company also relies on certain third parties for its supply chain. Disputes with these third- party manufacturers or shortages in goods or services from third-party suppliers could delay the manufacturing of the Company’s product candidates and adversely impact its results of operations.
Marketable Securities	Marketable Securities Marketable securities consist of investments with original maturities greater than 90 days at their acquisition date. The Company classifies all of its marketable securities as available-for-sale securities. The Company’s marketable securities are measured and reported at fair value using quoted prices in active markets for similar securities. Unrealized gains and losses on available-for-sale securities are reported as accumulated other comprehensive loss. The cost of securities sold is determined on a specific identification basis, and realized gains and losses are included in other income (expense), net in the consolidated statements of operations and comprehensive loss. The Company evaluates its marketable securities with unrealized losses for other-than-temporary impairment. When assessing marketable securities for other-than-temporary declines in value, the Company considers such factors as, among other things, how significant the decline in value is as a percentage of the original cost, how long the market value of the investment has been less than its original cost, the Company’s ability and intent to retain the investment for a period of time sufficient to allow for any anticipated recovery in fair value and market conditions in general. If any adjustment to fair value reflects a decline in the value of the investment that the Company considers to be “other-than-temporary,” the Company reduces the investment to fair value through a charge to the statement of operations and comprehensive loss. No such adjustments were necessary during the periods presented.
Fair Value of Financial Instruments	Fair Value of Financial Instruments Financial instruments consist of cash and cash equivalents, marketable securities, prepaid expenses and other current assets, accounts payable, accrued expenses, convertible promissory notes, and derivative liabilities. Cash equivalents and marketable securities are stated at fair value. Prepaid expenses and other current assets, accounts payable and accrued expenses are stated at their carrying value, which approximates fair value due to the short time to the expected receipt or payment date. The principal amount of the Company’s convertible promissory notes approximates fair value as the stated interest rate approximates market rates currently available to the Company. The derivative liabilities are stated at fair value.
Property and Equipment, Net	Property and Equipment, Net Property and equipment are recorded at cost. Depreciation is computed over estimated useful lives of the related assets using the straight-line method. Leasehold improvements are amortized on a straight-line basis over the shorter of the useful life or term of the lease. Upon retirement or disposal, the cost and related accumulated depreciation are removed from the consolidated balance sheets and the resulting gain or loss is recorded to general and administrative expense in the consolidated statements of operations. Routine expenditures for maintenance and repairs are expensed as incurred. Estimated useful lives for property and equipment are as follows: Property and Equipment Estimated Useful Life Research equipment 5 years Furniture and fixtures 5 years Computer equipment 3 years Leasehold improvements Lesser of estimated useful life or remaining lease term
Impairment of Long-Lived Assets	Impairment of Long-Lived Assets The Company reviews the recoverability of its long-lived assets when events or changes in circumstances occur that indicate that the carrying value of the asset may not be recoverable. The assessment of possible impairment is based on the ability to recover the carrying value of the assets from the expected future cash flows (undiscounted and without interest expense) of the related operations. If these cash flows are less than the carrying value of such assets, an impairment loss for the difference between the estimated fair value and carrying value is recorded. There was no impairment loss recognized during the years ended December 31, 2018 and 2017.
Derivative Liabilities	Derivative Liabilities The Company has outstanding derivative instruments related to certain features embedded within the Company’s outstanding convertible promissory notes, and an outstanding derivative instrument related to an arrangement providing a holder of one of the Company’s convertible promissory notes an option to purchase shares of equity in a future qualifying financing event. These derivatives are accounted for as derivative liabilities and remeasured to fair value as of each balance sheet date and the related remeasurement adjustments are recognized in the consolidated statements of operations. The Company records adjustments to the fair value of the derivative liabilities until the conversion or repayment of the related convertible promissory notes as discussed further in Note 8.
Treasury Stock	Treasury Stock The Company records treasury stock activities under the cost method whereby the cost of the acquired stock is recorded as treasury stock. The Company’s accounting policy upon the formal retirement of treasury stock is to deduct the par value from common stock and to reflect any excess of cost over par value as a reduction to additional paid-in capital (to the extent created by previous issuances of the shares) and then retained earnings. There was no treasury stock repurchased for the years ended December 31, 2018 and 2017.
Comprehensive Loss	Comprehensive Loss The Company did not have any other comprehensive income or loss for any of the periods presented and therefore comprehensive loss did not differ from net loss.
Revenue Recognition	Revenue Recognition The Company derives revenue primarily from service fees generated from collaboration agreements. Under the collaboration agreements, the Company recognizes service revenue when there is persuasive evidence of the arrangement, the fee is fixed or determinable, collection of the fee is reasonably assured, and delivery has occurred. Nonrefundable upfront payments, if any, are recorded as deferred revenue upon receipt and recognized as revenue over the service period. The Company accounts for revenue arrangements with multiple deliverables by dividing items into separate units of accounting if certain criteria are met, including: (1) whether the delivered item has stand-alone value to the customer; (2) whether the arrangement includes a general right of return relative to the delivered item; and (3) there is objective and reliable evidence of the fair value for the undelivered items. The Company allocates the consideration it receives among the separate units of accounting based on their respective fair value and applies the applicable revenue recognition criteria to each of the separate units. A deliverable that does not qualify as a separate unit of accounting within the arrangement is combined with the other applicable undelivered item within the arrangement. The Company determines the estimated selling price for deliverables under the collaboration agreements using the following hierarchy: (1) vender-specific objective evidence (“VSOE”); (2) third-party evidence (“TPE”); or (3) best estimate of selling price if neither VSOE nor TPE is available. Determining the best estimate of selling price for a deliverable requires significant judgment of various factors including market conditions, items contemplated during agreement negotiation as well as internally developed net present value models.
Research and Development Costs	Research and Development Costs Expenditures, including payroll, contractor expenses and supplies, for research and development of products are expensed as incurred. Clinical trial and other development costs incurred by third parties are expensed as the contracted work is performed. Where contingent milestone payments are due to third parties under research and development arrangements, the milestone payment obligations are expensed when the milestone results are probable of being achieved.
Stock-Based Compensation	Stock-Based Compensation The Company utilizes the Black-Scholes stock option-pricing model as the method for estimating the grant date fair value of its stock option awards. The Black-Scholes stock option-pricing model requires the use of highly subjective and complex assumptions, including the stock options’ expected term and the price volatility of the underlying stock. The grant date fair value of the portion of the stock option award that is ultimately expected to vest is recognized as compensation expense over the stock option awards’ requisite service periods. The Company recognizes stock-based compensation to expense using the straight-line method over the requisite service period. If there are any modifications or cancelations of stock option awards, the Company may be required to accelerate, increase or decrease any remaining unrecognized stock-based compensation expense.
Income Taxes	Income Taxes The Company uses the asset and liability method of accounting for income taxes. Deferred tax assets and liabilities are recognized for the estimated future tax consequences attributable to temporary differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax bases. Deferred tax assets and liabilities, which relate primarily to the carrying amount of the Company’s property and equipment and its net operating loss carryforward, are measured using enacted tax rates expected to apply to taxable income in the years in which those temporary differences are expected to be recovered or settled. Deferred tax expense or benefit is the result of changes in the deferred tax assets and liabilities. Valuation allowances are established when necessary to reduce deferred tax assets where, based upon the available evidence, management concludes that it is more likely than not that the deferred tax assets will not be realized. In evaluating its ability to recover deferred tax assets, the Company considers all available positive and negative evidence, including its operating results, ongoing tax planning and forecasts of future taxable income on a jurisdiction-by-jurisdiction basis. Because of the uncertainty of the realization of the deferred tax assets, the Company has recorded a full valuation allowance against its deferred tax assets. Reserves are provided for tax benefits for which realization is uncertain. Such benefits are only recognized when the underlying tax position is considered more likely than not to be sustained on examination by a taxing authority, assuming they possess full knowledge of the position and facts. Interest and penalties related to uncertain tax positions are recognized in the provision for income taxes; however, the Company currently has no interest or penalties related to income taxes.
Segment and Geographic Information	Segment and Geographic Information The Company’s chief operating decision maker, its Chief Executive Officer, reviews its operating results on an aggregate basis for purposes of allocating resources and evaluating financial performance. The Company has one business activity, the discovery and development of targeted biotherapeutics to treat serious diseases and conditions with unmet medical needs, and there are no segment managers who are held accountable for operations or operating results. Accordingly, the Company operates in one segment. As of December 31, 2018 and 2017, all long-lived assets are located in the United States.
Net Loss Per Share Attributable to Vaccinex, Inc. Common Stockholders	Net Loss Per Share Attributable to Vaccinex, Inc. Common Stockholders The Company calculates its basic and diluted net loss per share attributable to Vaccinex, Inc. common stockholders in conformity with the two-class method required for companies with participating securities. The Company considers all series of its preferred stock to be participating securities. In the event a dividend is declared or paid on the Company’s common stock, holders of preferred stock are entitled to a proportionate share of such dividend in proportion to the holders of common stock on an as-if converted basis. Under the two-class method, basic net loss per share attributable to Vaccinex, Inc. common stockholders is calculated by dividing the net loss attributable to Vaccinex, Inc. common stockholders by the weighted-average number of shares of common stock outstanding for the period. Net loss attributable to Vaccinex, Inc. common stockholders is determined by allocating undistributed earnings between common and preferred stockholders. The diluted net loss per share attributable to Vaccinex, Inc. common stockholders is computed by giving effect to all potential dilutive common stock equivalents outstanding for the period determined using the treasury stock method. The net loss attributable to Vaccinex, Inc. common stockholders was not allocated to the preferred stock under the two-class method as the preferred stock do not have a contractual obligation to share in the Company’s losses. For purposes of this calculation, redeemable convertible preferred stock, convertible preferred stock, and stock options to purchase common stock are considered common stock equivalents but have been excluded from the calculation of diluted net loss per share attributable to Vaccinex, Inc. common stockholders as their effect is anti-dilutive.
Recent Accounting Pronouncements	Recent Accounting Pronouncements Not Yet Adopted In May 2014, the Financial Accounting Standards Board (FASB) issued Accounting Standard Update (ASU) No. 2014-09, Revenue from Contracts with Customers Revenue Recognition In February 2016, the FASB issued ASU No. 2016-02, Leases, which supersedes the ASC No. 840, Leases Recently Adopted Accounting Pronouncements In August 2016, the FASB issued ASU No. 2016-15, Statement of Cash Flows: Classification of Certain Cash Receipts and Cash Payments, In May 2017, the FASB issued ASU No. 2017-09, Compensation-Stock Compensation: Scope of Modification Accounting

Summary of Significant Accoun_3

Summary of Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2018
Accounting Policies [Abstract]
Summary of Estimated Useful Lives for Property and Equipment	Estimated useful lives for property and equipment are as follows: Property and Equipment Estimated Useful Life Research equipment 5 years Furniture and fixtures 5 years Computer equipment 3 years Leasehold improvements Lesser of estimated useful life or remaining lease term

Balance Sheet Components (Table

Balance Sheet Components (Tables)	12 Months Ended
	Dec. 31, 2018
Balance Sheet Related Disclosures [Abstract]
Property and Equipment	Property and equipment consist of the following (in thousands): As of December 31, 2018 2017 Leasehold improvements $ 3,145 $ 3,140 Research equipment 3,219 2,998 Furniture and fixtures 350 350 Computer equipment 214 214 Property and equipment, gross 6,928 6,702 Less: accumulated depreciation and amortization (6,324 ) (6,101 ) Property and equipment, net $ 604 $ 601
Accrued Expenses	Accrued expenses consist of the following (in thousands): As of December 31, 2018 2017 Accrued clinical trial cost $ 3,796 $ 891 Accrued payroll and related benefits 296 311 Accrued consulting and legal 236 239 Accrued other 36 324 Accrued interest - 192 Accrued expenses $ 4,364 $ 1,957

Marketable Securities (Tables)

Marketable Securities (Tables)	12 Months Ended
	Dec. 31, 2018
Investments Debt And Equity Securities [Abstract]
Summary of the Fair Value of Available-for-sale Marketable Securities	As of December 31, 2018, the fair value of available-for-sale marketable securities was as follows (in thousands): As of December 31, 2018 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value Marketable securities: U.S. Treasury securities $ 14,106 $ - $ - $ 14,106 $ 14,106 $ - $ - $ 14,106

Fair Value of Financial Measu_2

Fair Value of Financial Measurements (Tables)	12 Months Ended
	Dec. 31, 2018
Fair Value Disclosures [Abstract]
Summary of Fair Value of Financial Assets by Level within Fair Value Hierarchy	The following table sets forth the fair value of the Company’s financial assets by level within the fair value hierarchy (in thousands): As of December 31, 2018 Fair Value Level 1 Level 2 Level 3 Financial Assets: Cash equivalents: Money market fund $ 4,881 $ 4,881 $ - $ - Marketable securities: U. S. Treasury securities 14,106 - 14,106 - Total Financial Assets $ 18,987 $ 4,881 $ 14,106 $ - As of December 31, 2017 Fair Value Level 1 Level 2 Level 3 Financial Assets: Cash equivalents: Money market fund $ 1,011 $ 1,011 $ - $ - Total Financial Assets $ 1,011 $ 1,011 $ - $ - Financial Liabilities: Derivative liability $ 369 $ - $ - $ 369 Total Financial Liabilities $ 369 $ - $ - $ 369
Summary of Changes in Fair Value of Level 3 Financial Instruments	The following table sets forth a summary of the changes in the fair value of the Company’s Level 3 financial instruments as follows (in thousands): Derivative Liability Balance – January 1, 2017 $ 694 Issuance of the January 2017 Notes 3,418 Change in fair value (3,743 ) Balance – December 31, 2017 369 Change in fair value (369 ) Balance – December 31, 2018 $ -

Convertible Promissory Notes (T

Convertible Promissory Notes (Tables)	12 Months Ended
	Dec. 31, 2018
Debt Disclosure [Abstract]
Summary of Outstanding Convertible Promissory Notes	The following table sets forth a summary of the outstanding convertible promissory notes (in thousands): As of December 31, 2017 June 2016 Note $ 1,500 Unamortized debt discount (316 ) Net June 2016 Note 1,184 January 2017 Notes 4,000 Unamortized debt discount (2,371 ) Net January 2017 Notes 1,629 Total convertible promissory notes, related parties $ 2,813

Preferred Stock (Tables)

Preferred Stock (Tables)	12 Months Ended
	Dec. 31, 2018
Equity [Abstract]
Summary of Redeemable Convertible Preferred Stock	The Company’s redeemable convertible preferred stock consisted of the following (dollars in thousands): As of December 31, 2017 Designated Shares Authorized Shares Issued Shares Outstanding Aggregate Liquidation Preference Net Carrying Value Series B 6,500,000 6,335,543 6,335,380 $ 27,242 $ 9,717 Series B-1 6,417,000 6,416,144 6,416,144 18,725 9,945 Series B-2 7,500,000 5,344,748 5,344,748 19,220 16,568 Series C 12,400,000 7,205,882 7,205,882 24,500 33,579 Series D 33,500,000 27,787,642 27,787,642 50,574 41,909 Total 66,317,000 53,089,959 53,089,796 $ 140,261 $ 111,718

Common Stock Reserved For Iss_2

Common Stock Reserved For Issuance (Tables)	12 Months Ended
	Dec. 31, 2018
Equity [Abstract]
Common Stock Reserved for Potential Future Issuances	Common stock has been reserved for the following potential future issuances: As of December 31, 2018 2017 Conversion of outstanding preferred stock - 7,039,155 Shares underlying outstanding stock options 405,683 420,956 Shares available for future stock option grants 423,000 19,034 Exchange of Vaccinex Products, LP units 1,202,566 1,202,566 Conversion of VX3 units 1,318,797 659,400 Total shares of common stock reserved 3,350,046 9,341,111

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	12 Months Ended
	Dec. 31, 2018
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Summary of Stock Option Activity and Related Information	A summary of the Company’s stock option activity and related information is as follows: Options Outstanding Shares Subject to Options Outstanding Weighted- Average Exercise Price Weighted- Average Remaining Contractual Life (Years) Aggregate Intrinsic Value Balance as of January 1, 2017 405,658 $ 9.01 8.1 $ 1,978 Granted 33,976 13.60 Exercised (2,037 ) 7.10 Canceled (16,641 ) 14.60 Balance as of December 31, 2017 420,956 9.20 7.4 5,021 Granted 30,000 13.10 Exercised (700 ) 7.10 Canceled (44,573 ) 7.10 Balance as of December 31, 2018 405,683 $ 9.69 6.5 $ - Exercisable as of December 31, 2018 366,463 $ 9.46 6.3 $ -
Grant Date Fair Value of Employee Stock Options Estimated Using Black-Scholes Option-Pricing Model with Weighted-Average Assumptions	The grant date fair value of employee stock options was estimated using a Black-Scholes option-pricing model with the following weighted-average assumptions: Year Ended December 31, 2018 2017 Expected term (in years) 6.0 6.0 Expected volatility 75.0 % 75.0 % Risk-free interest rate 2.6 % 2.0 % Expected dividend yield - % - %
Total Stock-Based Compensation Expense Recognized in Condensed Consolidated Statements of Operations	Total stock-based compensation expense recognized in the consolidated statements of operations is as follows (in thousands): Year Ended December 31, 2018 2017 Research and development $ 65 $ 54 General and administrative 112 265 Total stock-based compensation expense $ 177 $ 319

Income Tax (Tables)

Income Tax (Tables)	12 Months Ended
	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Schedule of Effective Income Tax Rate Reconciliation	The reconciliation of federal statutory income tax rate to the Company’s effective income tax rate is as follows: Year Ended December 31, 2018 2017 Expected income tax benefit at the federal statutory rate 21.0 % 34.0 % Federal tax rate change effect - (110.3 ) State taxes, net of federal benefit 5.2 5.4 Research and development credit, net 10.3 17.0 Non-deductible items and others (0.4 ) 0.7 Change in valuation allowance (36.1 ) 53.2 Total 0.0 % 0.0 %
Schedule of Deferred Tax Assets and Liabilities	The principal components of the Company’s deferred tax assets consisted of the following as of December 31, 2018 and 2017 (in thousands): As of December 31, 2018 2017 Deferred tax assets: Federal and state net operating loss carryforwards $ 52,362 $ 45,057 Research and development tax credits 14,592 11,542 Depreciation and amortization 468 504 Reserves and accruals 56 115 Derivative liabilities - 96 Deferred revenue - 78 Other 202 330 Total deferred tax assets 67,680 57,722 Less: valuation allowance (67,680 ) (57,026 ) Net deferred tax assets - 696 Deferred tax liability: Debt discount - (696 ) Net deferred tax assets and liability $ - $ -

Net Loss Per Share Attributab_2

Net Loss Per Share Attributable to Common Stockholders (Tables)	12 Months Ended
	Dec. 31, 2018
Earnings Per Share [Abstract]
Computation of Basic and Diluted Net Loss Per Share	The following table sets forth the computation of the Company’s basic and diluted net loss per share for the periods presented (in thousands, except share and per share data): Year Ended December 31, 2018 2017 Net loss $ (29,518 ) $ (18,759 ) Net loss attributable to noncontrolling interests - 37 Net loss attributable to Vaccinex, Inc. (29,518 ) (18,722 ) Cumulative dividends on preferred stock - (3,211 ) Net loss attributable to Vaccinex, Inc. common stockholders, basic and diluted $ (29,518 ) $ (21,933 ) Net loss per share attributable to Vaccinex, Inc. common stockholders, basic and diluted $ (5.65 ) $ (19.90 ) Weighted-average shares used in computing net loss per share attributable to Vaccinex, Inc. common stockholders, basic and diluted 5,223,635 1,101,937
Weighted-Average Common Stock Equivalents Excluded from Calculation of Diluted Net Loss Per Share as They Had Anti-Dilutive Effect	The following weighted-average common stock equivalents were excluded from the calculation of diluted net loss per share for the periods presented as they had an anti-dilutive effect: Year Ended December 31, 2018 2017 Preferred stock (if converted) - 6,837,585 Options to purchase common stock 410,886 408,373 Contingently issuable common stock upon exchange of Vaccinex Products, LP units 1,202,566 1,202,566 Contingently issuable common stock upon exchange of VX3 units 1,158,009 99,361

Company and Nature of Business

Company and Nature of Business - Additional Information (Details) $ / shares in Units, $ in Thousands	Aug. 09, 2018USD ($)$ / sharesshares	Dec. 31, 2018USD ($)$ / sharesshares	Dec. 31, 2017USD ($)$ / shares	Aug. 31, 2018shares
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Cash flow from operations		$ (25,276)	$ (21,387)
Accumulated deficit		216,767	187,249
Proceeds from capital contribution		$ 12,000	$ 12,000
Common stock, par value | $ / shares		$ 0.0001	$ 0.0001
Net proceeds from initial public offering		$ 37,125
Offering expenses		2,675
Repayment of convertible promissory note, related party		$ 5,500	$ 6,000
IPO
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Common stock, par value | $ / shares	$ 0.0001
Public offering price, per share | $ / shares	$ 12
Net proceeds from initial public offering	$ 37,200
Underwriting discounts and commissions	2,800
Offering expenses	$ 2,700
Convertible preferred stock converted and reclassified into common stock | shares	7,039,155			7,039,155
Reverse stock split of common stock description	1-for-10
Reverse stock split of common stock	10
IPO | Vaccinex LLC | Convertible Promissory Notes
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Repayment of convertible promissory note, related party	$ 1,500
IPO | Common Stock
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Number of shares issued and sold | shares	3,333,334	3,333,334

Summary of Significant Accoun_4

Summary of Significant Accounting Policies - Additional Information (Details)	12 Months Ended
	Dec. 31, 2018USD ($)Segmentshares	Dec. 31, 2017USD ($)shares
Summary Of Significant Accounting Policies [Line Items]
Net gain (loss )attributable to noncontrolling interests	$ 0	$ (37,000)
Asset impairment charges	$ 0	$ 0
Treasury stock repurchased | shares	0	0
Interest related to income taxes	$ 0
Penalties related to income taxes	$ 0
Number of operating segments | Segment	1
Vaccinex Products
Summary Of Significant Accounting Policies [Line Items]
Gain or loss from VIE	$ 0	$ 0

Summary of Significant Accoun_5

Summary of Significant Accounting Policies - Summary of Estimated Useful Lives for Property and Equipment (Detail)	12 Months Ended
	Dec. 31, 2018
Property Plant And Equipment [Line Items]
Property, Plant and Equipment, Leasehold Improvements, Useful Life	Lesser of estimated useful life or remaining lease term
Research Equipment
Property Plant And Equipment [Line Items]
Property, Plant and Equipment, Useful Life	5 years
Furniture and Fixtures
Property Plant And Equipment [Line Items]
Property, Plant and Equipment, Useful Life	5 years
Computer Equipment
Property Plant And Equipment [Line Items]
Property, Plant and Equipment, Useful Life	3 years

Balance Sheet Components - Prop

Balance Sheet Components - Property and Equipment (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Property Plant And Equipment [Line Items]
Property and equipment, gross	$ 6,928	$ 6,702
Less: accumulated depreciation and amortization	(6,324)	(6,101)
Property and equipment, net	604	601
Leasehold Improvements
Property Plant And Equipment [Line Items]
Property and equipment, gross	3,145	3,140
Research Equipment
Property Plant And Equipment [Line Items]
Property and equipment, gross	3,219	2,998
Furniture and Fixtures
Property Plant And Equipment [Line Items]
Property and equipment, gross	350	350
Computer Equipment
Property Plant And Equipment [Line Items]
Property and equipment, gross	$ 214	$ 214

Balance Sheet Components - Addi

Balance Sheet Components - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Property Plant And Equipment [Abstract]
Depreciation and amortization expense	$ 223,000	$ 206,000

Balance Sheet Components - Sche

Balance Sheet Components - Schedule of Accrued Expenses (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Payables And Accruals [Abstract]
Accrued clinical trial cost	$ 3,796	$ 891
Accrued payroll and related benefits	296	311
Accrued consulting and legal	236	239
Accrued other	36	324
Accrued interest		192
Accrued expenses	$ 4,364	$ 1,957

Marketable Securities - Summary

Marketable Securities - Summary of the Fair Value of Available-for-sale Marketable Securities (Details) $ in Thousands	Dec. 31, 2018USD ($)
Marketable Securities [Line Items]
Securities Available for Sale, Amortized Cost	$ 14,106
Securities Available for Sale, Gross Unrealized Gains	0
Securities Available for Sale, Gross Unrealized Losses	0
Securities Available for Sale, Fair Value	14,106
U.S. Treasury Securities
Marketable Securities [Line Items]
Securities Available for Sale, Amortized Cost	14,106
Securities Available for Sale, Gross Unrealized Gains	0
Securities Available for Sale, Gross Unrealized Losses	0
Securities Available for Sale, Fair Value	$ 14,106

Marketable Securities - Additio

Marketable Securities - Additional Information (Details)	12 Months Ended
	Dec. 31, 2018
Maximum
Marketable Securities [Line Items]
Available for sale marketable securities maturity period	1 year

Fair Value of Financial Measu_3

Fair Value of Financial Measurements - Summary of Fair Value of Financial Assets by Level within Fair Value Hierarchy (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Financial Assets:
Marketable securities, Fair value disclosure	$ 14,106
Financial Liabilities:
Derivative liability		$ 369	$ 694
U.S. Treasury Securities
Financial Assets:
Marketable securities, Fair value disclosure	14,106
Fair Value Measurements Recurring
Financial Assets:
Total Financial Assets	18,987	1,011
Financial Liabilities:
Derivative liability		369
Total Financial Liabilities		369
Fair Value Measurements Recurring | Level 1
Financial Assets:
Total Financial Assets	4,881	1,011
Fair Value Measurements Recurring | Level 2
Financial Assets:
Total Financial Assets	14,106
Fair Value Measurements Recurring | Level 3
Financial Liabilities:
Derivative liability		369
Total Financial Liabilities		369
Fair Value Measurements Recurring | Money Market Funds
Financial Assets:
Cash equivalents, Fair value disclosure	4,881	1,011
Fair Value Measurements Recurring | Money Market Funds | Level 1
Financial Assets:
Cash equivalents, Fair value disclosure	4,881	$ 1,011
Fair Value Measurements Recurring | U.S. Treasury Securities
Financial Assets:
Marketable securities, Fair value disclosure	14,106
Fair Value Measurements Recurring | U.S. Treasury Securities | Level 2
Financial Assets:
Marketable securities, Fair value disclosure	$ 14,106

Fair Value of Financial Measu_4

Fair Value of Financial Measurements - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Gain (loss) on remeasurement of derivative liabilities associated with convertible promissory notes	$ 369,000	$ 3,743,000
Fair Value Measurements Recurring
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Financial assets, level 1 to level 2 transfers, amount	0	0
Financial assets, level 2 to level 1 transfers, amount	$ 0	$ 0

Fair Value of Financial Measu_5

Fair Value of Financial Measurements - Summary of Changes in Fair Value of Level 3 Financial Instruments (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Fair Value Disclosures [Abstract]
Beginning balance	$ 369	$ 694
Issuance of the January 2017 Notes		3,418
Change in fair value	$ (369)	(3,743)
Ending Balance		$ 369

License and Services Agreement

License and Services Agreement - Additional Information (Details) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended		12 Months Ended
	Mar. 31, 2018	Nov. 30, 2017	Dec. 31, 2018	Dec. 31, 2017
License And Services Agreement [Line Items]
Proceeds from capital contribution			$ 12,000	$ 12,000
January 2017 Notes
License And Services Agreement [Line Items]
Repay an outstanding convertible note	$ 4,000
VX3 License Agreement
License And Services Agreement [Line Items]
Research and development, milestone payments to company		$ 32,000
Terms of license agreement upon termination			the Company will issue to VX3 or its designees the number of shares of the Company’s common stock equal to the lesser of (1) the aggregate of all payments made to VX3 by the Canadian investors divided by $18.20 and (2) the then fair market value of VX3 divided by the then fair market value of one share of the Company’s common stock.
Base amount to determine issuance of common stock upon termination		$ 18.20
Services Agreement
License And Services Agreement [Line Items]
Services payments received				$ 11,900
VX3
License And Services Agreement [Line Items]
Percentage of voting interest			90.00%	96.00%
Proceeds from capital contribution			$ 12,000	$ 12,000

Collaboration Agreements - Addi

Collaboration Agreements - Additional Information (Details)	1 Months Ended		12 Months Ended
	Nov. 30, 2017USD ($)TargetAntigenMilestone	Sep. 30, 2017USD ($)	Dec. 31, 2018USD ($)	Dec. 31, 2017USD ($)
Merck Sharp & Dohme Corp.
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Service payments received under research agreement		$ 138,000
Service revenue recognized			$ 69,000	$ 69,000
Surface Oncology, Inc.
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Service payments received under research agreement			282,171	250,000
Service revenue recognized			229,166	$ 20,834
Number of target antigens against which antibodies are to be identified and selected | TargetAntigen	2
Upfront fee to be received	$ 250,000
Number of designated milestones | Milestone	4
Surface Oncology, Inc. | Minimum
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Term of research program	9 months
Surface Oncology, Inc. | Maximum
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Term of research program	12 months
Heptares Therapeutics, Ltd.
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Service revenue recognized			$ 138,556

Convertible Promissory Notes -

Convertible Promissory Notes - Summary of the Outstanding Convertible Promissory Notes (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Oct. 31, 2017	Aug. 31, 2017	Apr. 30, 2017	Jan. 31, 2017
Debt Instrument [Line Items]
Convertible promissory note to related party noncurrent	$ 2,813
June 2016 Note
Debt Instrument [Line Items]
Long-term debt, gross	1,500
Unamortized debt discount	(316)
Long-term debt	1,184
January 2017 Notes
Debt Instrument [Line Items]
Long-term debt, gross	4,000	$ 6,000	$ 6,000	$ 6,000	$ 4,000
Unamortized debt discount	(2,371)
Long-term debt	$ 1,629

Convertible Promissory Notes _2

Convertible Promissory Notes - Additional Information (Details) - USD ($)	Aug. 09, 2018	Mar. 31, 2018	Nov. 30, 2017	Oct. 31, 2017	Aug. 31, 2017	Apr. 30, 2017	Jan. 31, 2017	Jun. 30, 2016	Dec. 31, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Interest expense	$ 308,000									$ 1,200,000
Loss on extinguishment of related party convertible promissory note									$ 2,379,000
Embedded derivative, Derivative liability								$ 31,000
June 2016 Note
Debt Instrument [Line Items]
Debt Instrument Carrying Amount										1,500,000
Annual interest rate								8.00%
Debt instrument maturity term								3 years
Increase of interest rate								12.00%
Debt Instrument Face Amount								$ 1,500,000
June 2016 Note | Convertible Promissory Notes
Debt Instrument [Line Items]
Debt Instrument Carrying Amount									0
Loss on extinguishment of related party convertible promissory note									199,000
January 2017 Notes
Debt Instrument [Line Items]
Debt Instrument Carrying Amount				$ 6,000,000	$ 6,000,000	$ 6,000,000	$ 4,000,000			$ 4,000,000
Annual interest rate				2.00%	2.00%	2.00%	0.00%
Debt instrument maturity term							3 years
Debt Instrument Face Amount							$ 10,000,000
Debt Instrument Periodic Payment Principal							6,000,000
Repayments of convertible debt		$ 4,000,000
January 2017 Notes | Convertible Promissory Notes
Debt Instrument [Line Items]
Debt Instrument Carrying Amount				$ 4,000,000		$ 2,000,000	$ 4,000,000
Repayments of convertible debt		$ 4,000,000	$ 4,000,000			$ 2,000,000
Derivative liabilities written off with conversion of repayment									300,000
Loss on extinguishment of related party convertible promissory note									$ 2,200,000

Preferred Stock - Additional In

Preferred Stock - Additional Information (Details) - USD ($)	1 Months Ended	2 Months Ended	12 Months Ended
	Jul. 31, 2016	Jun. 30, 2017	Dec. 31, 2018	Dec. 31, 2017	Aug. 31, 2018	Aug. 09, 2018	May 31, 2017
Class Of Stock [Line Items]
Liability for cumulative and unpaid dividends			$ 0	$ 0
Preferred Stock, Dividend declared			$ 0	0
IPO
Class Of Stock [Line Items]
Convertible preferred stock converted and reclassified into common stock					7,039,155	7,039,155
Series D Redeemable Convertible Preferred Stock [Member]
Class Of Stock [Line Items]
Issuance of Series D redeemable convertible preferred stock, net of issuance cost		$ 4,395,604
Proceeds from issuance of Series D redeemable convertible preferred stock, net of issuance costs		$ 8,000,000		$ 7,982,000
Convertible preferred stock issuance price per share		$ 1.82
Convertible preferred stock purchase price per share				$ 1.82
Convertible preferred stock, Conversion price				18.2
Convertible preferred stockholders entitle to receive per share amount upon liquidation			$ 1.82
Series D Redeemable Convertible Preferred Stock [Member] | Minimum
Class Of Stock [Line Items]
Proceeds from issuance of Series D redeemable convertible preferred stock, net of issuance costs			$ 30,000,000
Public offering price			$ 5
Series B-2 redeemable convertible preferred stock
Class Of Stock [Line Items]
Convertible conversion price per share							$ 25
Cumulative dividend per share			8.00%
Convertible preferred stock purchase price per share			$ 3.10	3.10
Convertible preferred stock, Conversion price				$ 25
Convertible preferred stockholders entitle to receive per share amount upon liquidation			$ 3.10
Series B-2 redeemable convertible preferred stock | Minimum
Class Of Stock [Line Items]
Proceeds from issuance of Series D redeemable convertible preferred stock, net of issuance costs			$ 15,000,000
Public offering price			$ 5
Series A Convertible Preferred Stock
Class Of Stock [Line Items]
Preferred stock, shares authorized			0	5,702,450
Preferred stock, shares issued			0	5,702,450
Preferred stock, shares outstanding			0	5,702,450
Preferred stock, aggregate liquidation preference			$ 0	$ 7,684,000
Convertible preferred stock purchase price per share				$ 1.3475
Convertible preferred stock, Conversion price				13.475
Convertible preferred stockholders entitle to receive per share amount upon liquidation			$ 1.3475
Series C redeemable convertible preferred stock
Class Of Stock [Line Items]
Cumulative dividend per share			3.00%
Convertible preferred stock purchase price per share			$ 3.40	3.40
Unpaid dividend of convertible preferred stock	$ 2,300,000
Convertible preferred stock, Conversion price				18.2
Convertible preferred stockholders entitle to receive per share amount upon liquidation			$ 3.40
Series C redeemable convertible preferred stock | Minimum
Class Of Stock [Line Items]
Proceeds from issuance of Series D redeemable convertible preferred stock, net of issuance costs			$ 30,000,000
Public offering price			$ 5
Series B Redeemable Convertible Preferred Stock
Class Of Stock [Line Items]
Cumulative dividend per share			8.00%
Convertible preferred stock purchase price per share			$ 2.15	2.15
Convertible preferred stock, Conversion price				13.1
Convertible preferred stockholders entitle to receive per share amount upon liquidation			$ 2.15
Series B Redeemable Convertible Preferred Stock | Minimum
Class Of Stock [Line Items]
Proceeds from issuance of Series D redeemable convertible preferred stock, net of issuance costs			$ 15,000,000
Public offering price			$ 5
Series B-1 redeemable convertible preferred stock
Class Of Stock [Line Items]
Cumulative dividend per share			8.00%
Convertible preferred stock purchase price per share			$ 1.55	1.55
Convertible preferred stock, Conversion price				$ 15.5
Convertible preferred stockholders entitle to receive per share amount upon liquidation			$ 1.55
Series B-1 redeemable convertible preferred stock | Minimum
Class Of Stock [Line Items]
Proceeds from issuance of Series D redeemable convertible preferred stock, net of issuance costs			$ 15,000,000
Public offering price			$ 5

Preferred Stock - Summary of Re

Preferred Stock - Summary of Redeemable Convertible Preferred Stock (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Class Of Stock [Line Items]
Designated Shares Authorized	0	66,317,000
Shares Issued	0	53,089,959
Shares Outstanding	0	53,089,796
Aggregate Liquidation Preference	$ 0	$ 140,261
Net Carrying Value		$ 111,718
Series B
Class Of Stock [Line Items]
Designated Shares Authorized		6,500,000
Shares Issued		6,335,543
Shares Outstanding		6,335,380
Aggregate Liquidation Preference		$ 27,242
Net Carrying Value		$ 9,717
Series B-1
Class Of Stock [Line Items]
Designated Shares Authorized		6,417,000
Shares Issued		6,416,144
Shares Outstanding		6,416,144
Aggregate Liquidation Preference		$ 18,725
Net Carrying Value		$ 9,945
Series B-2
Class Of Stock [Line Items]
Designated Shares Authorized		7,500,000
Shares Issued		5,344,748
Shares Outstanding		5,344,748
Aggregate Liquidation Preference		$ 19,220
Net Carrying Value		$ 16,568
Series C
Class Of Stock [Line Items]
Designated Shares Authorized		12,400,000
Shares Issued		7,205,882
Shares Outstanding		7,205,882
Aggregate Liquidation Preference		$ 24,500
Net Carrying Value		$ 33,579
Series D Redeemable Convertible Preferred Stock
Class Of Stock [Line Items]
Designated Shares Authorized		33,500,000
Shares Issued		27,787,642
Shares Outstanding		27,787,642
Aggregate Liquidation Preference		$ 50,574
Net Carrying Value		$ 41,909

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Commitments And Contingencies [Line Items]
Royalty payments, percent of net sales	1.00%
Monthly rental payments	$ 14,000
Future minimum operating leases payment in 2019	168,000
Future minimum operating leases payment in 2020	140,000
Rent expense incurred under operating lease	168,000	$ 168,000
Contract Termination
Commitments And Contingencies [Line Items]
Termination payment	$ 25,500,000

Common Stock Reserved For Iss_3

Common Stock Reserved For Issuance - Common Stock Reserved For Potential Future Issuances (Details) - shares	Dec. 31, 2018	Dec. 31, 2017
Class Of Stock [Line Items]
Total shares of common stock reserved	3,350,046	9,341,111
Shares Underlying Outstanding Stock Options
Class Of Stock [Line Items]
Total shares of common stock reserved	405,683	420,956
Shares Available For Future Stock Option Grants
Class Of Stock [Line Items]
Total shares of common stock reserved	423,000	19,034
Conversion of Outstanding Preferred Stock
Class Of Stock [Line Items]
Total shares of common stock reserved		7,039,155
Exchange of Vaccinex Products, LP Units
Class Of Stock [Line Items]
Total shares of common stock reserved	1,202,566	1,202,566
Conversion of VX3 Units
Class Of Stock [Line Items]
Total shares of common stock reserved	1,318,797	659,400

Stock-Based Compensation - Addi

Stock-Based Compensation - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total shares of common stock reserved	3,350,046	9,341,111
Weighted-average grant date fair value of stock options granted to employees	$ 14.87	$ 9
Options granted	30,000	33,976
Aggregate grant date fair value of stock options vested	$ 234,466	$ 300,000
Intrinsic value of stock options exercised	11,000	29,000
Total unrecognized compensation cost related to stock options granted to employees	$ 435,639	$ 216,000
Maximum contractual life for options granted	10 years
Expected dividend yield	0.00%
2018 Omnibus Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total shares of common stock reserved	425,000
Percentage of total shares of common stock reserved	2.00%
2018 Omnibus Incentive Plan | Minimum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Percentage of voting power of all classes of stock to be owned by optionee to determine the exercise price	10.00%
Exercise price as a percentage of fair value of common stock on grant date if optionee owns stock representing more than 10 percent of voting power of all classes of stock	110.00%
Employee Stock Options
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total unrecognized compensation cost related to stock options granted to employees, weighted-average recognition period	2 years 9 months 18 days	1 year 10 months 24 days
Expected term of stock option	6 years	6 years
Employee Stock Options | 2011 Employee Equity Plan | Minimum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock options granted, expiration year	5 years
Employee Stock Options | 2011 Employee Equity Plan | Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock options granted, expiration year	10 years
Employee Stock Options | 2018 Omnibus Incentive Plan | Minimum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock options granted, expiration year	5 years
Employee Stock Options | 2018 Omnibus Incentive Plan | Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock options granted, expiration year	10 years

Stock-Based Compensation - Summ

Stock-Based Compensation - Summary of Stock Option Activity and Related Information (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Options Outstanding, Shares Subject to Options Outstanding, Balance	420,956	405,658
Options Outstanding, Shares Subject to Options Outstanding, Granted	30,000	33,976
Options Outstanding, Shares Subject to Options Outstanding, Exercised	(700)	(2,037)
Options Outstanding, Shares Subject to Options Outstanding, Cancelled	(44,573)	(16,641)
Options Outstanding, Shares Subject to Options Outstanding, Balance	405,683	420,956	405,658
Options Outstanding, Shares Subject to Options Outstanding, Exercisable	366,463
Options Outstanding, Weighted-Average Exercise Price, Balance	$ 9.20	$ 9.01
Options Outstanding, Weighted-Average Exercise Price, Granted	13.10	13.60
Options Outstanding, Weighted-Average Exercise Price, Exercised	7.10	7.10
Options Outstanding, Weighted-Average Exercise Price, Canceled	7.10	14.60
Options Outstanding, Weighted-Average Exercise Price, Balance	9.69	$ 9.20	$ 9.01
Options Outstanding, Weighted-Average Exercise Price, Exercisable	$ 9.46
Options Outstanding Weighted-Average Remaining Contractual Life (Years), Balance	6 years 6 months	7 years 4 months 24 days	8 years 1 month 6 days
Options Outstanding Weighted-Average Remaining Contractual Life (Years), Exercisable	6 years 3 months 18 days
Options Outstanding, Aggregate Intrinsic Value, Balance	$ 5,021	$ 1,978
Options Outstanding, Aggregate Intrinsic Value, Balance		$ 5,021	$ 1,978

Stock-Based Compensation - Gran

Stock-Based Compensation - Grant Date Fair Value of Employee Stock Options Estimated Using Black-Scholes Option-Pricing Model with Weighted-Average Assumptions (Details)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected dividend yield	0.00%
Employee Stock Options
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected term of stock option	6 years	6 years
Expected volatility	75.00%	75.00%
Risk-free interest rate	2.60%	2.00%

Stock-Based Compensation - Tota

Stock-Based Compensation - Total Stock-Based Compensation Expense Recognized in Condensed Consolidated Statements of Operations (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total stock-based compensation expense	$ 177	$ 319
Research and Development
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total stock-based compensation expense	65	54
General and Administrative
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total stock-based compensation expense	$ 112	$ 265

Income Taxes - Additional Infor

Income Taxes - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Operating Loss Carryforwards [Line Items]
Provision for income taxes	$ 0	$ 0
U.S. federal corporate income tax rate	21.00%	34.00%
Deferred income tax assets, remeasurement due to change in tax act		$ 20,700,000
Increase (decrease) in valuation allowance for deferred tax asset	$ 10,700,000	(10,000,000)
Tax credit carryforwards, expiration date	Dec. 31, 2021
Unrecognized tax benefits that would impact effective tax rate	$ 0	$ 0
Description of tax years open to examination by major jurisdictions	from January 1, 2015 to December 31, 2018
Federal
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards	$ 198,200,000
Operating loss carryforwards, expiration date	Dec. 31, 2024
Federal | Research
Operating Loss Carryforwards [Line Items]
Tax credit carryforwards	$ 14,600,000
State
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards	$ 209,300,000
Operating loss carryforwards, expiration date	Dec. 31, 2034
Maximum
Operating Loss Carryforwards [Line Items]
U.S. federal corporate income tax rate		35.00%

Income Taxes - Schedule of Effe

Income Taxes - Schedule of Effective Income Tax Rate Reconciliation (Details)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Expected income tax benefit at the federal statutory rate	21.00%	34.00%
Federal tax rate change effect		(110.30%)
State taxes, net of federal benefit	5.20%	5.40%
Research and development credit, net	10.30%	17.00%
Non-deductible items and others	(0.40%)	0.70%
Change in valuation allowance	(36.10%)	53.20%
Total	0.00%	0.00%

Income Taxes - Schedule of Defe

Income Taxes - Schedule of Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Deferred tax assets:
Federal and state net operating loss carryforwards	$ 52,362	$ 45,057
Research and development tax credits	14,592	11,542
Depreciation and amortization	468	504
Reserves and accruals	56	115
Derivative liabilities		96
Deferred revenue		78
Other	202	330
Total deferred tax assets	67,680	57,722
Less: valuation allowance	(67,680)	(57,026)
Net deferred tax assets		696
Deferred tax liability:
Debt discount		(696)
Net deferred tax assets and liability	$ 0	$ 0

Net Loss Per Share Attributab_3

Net Loss Per Share Attributable to Common Stockholders - Computation of Basic and Diluted Net Loss Per Share (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Earnings Per Share [Abstract]
Net loss	$ (29,518,000)	$ (18,759,000)
Net loss attributable to noncontrolling interests	0	37,000
Net loss attributable to Vaccinex, Inc.	(29,518,000)	(18,722,000)
Cumulative dividends on preferred stock		(3,211,000)
Net loss attributable to Vaccinex, Inc. common stockholders, basic and diluted	$ (29,518,000)	$ (21,933,000)
Net loss per share attributable to Vaccinex, Inc. common stockholders, basic and diluted	$ (5.65)	$ (19.90)
Weighted-average shares used in computing net loss per share attributable to Vaccinex, Inc. common stockholders, basic and diluted	5,223,635	1,101,937

Net Loss Per Share Attributab_4

Net Loss Per Share Attributable to Common Stockholders - Weighted-Average Common Stock Equivalents Excluded from Calculation of Diluted Net Loss Per Share as They Had Anti-Dilutive Effect (Details) - shares	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Convertible Preferred Stock
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Weighted-average common stock equivalents excluded from calculation of diluted net loss per share		6,837,585
Employee Stock Options
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Weighted-average common stock equivalents excluded from calculation of diluted net loss per share	410,886	408,373
Vaccinex Products, LP Units
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Weighted-average common stock equivalents excluded from calculation of diluted net loss per share	1,202,566	1,202,566
VX3 Units
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Weighted-average common stock equivalents excluded from calculation of diluted net loss per share	1,158,009	99,361

Employee Benefit Plan - Additio

Employee Benefit Plan - Additional Information (Details)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Compensation And Retirement Disclosure [Abstract]
Maximum employee contribution to plan	100.00%	100.00%

Related Party Transactions - Ad

Related Party Transactions - Additional Information (Details) - USD ($)	1 Months Ended		12 Months Ended
	Aug. 31, 2018	Mar. 31, 2018	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Related Party Transaction [Line Items]
Rent expense incurred under operating lease			$ 168,000	$ 168,000
Proceeds from issuance of notes to related parties				9,977,000
Repayment of convertible promissory note, related party			5,500,000	6,000,000
Aggregate convertible promissory notes to related parties				$ 2,813,000
Redeemable Convertible Preferred Stock
Related Party Transaction [Line Items]
Series D redeemable convertible preferred stock, shares issued				4,395,604
Chairman | Redeemable Convertible Preferred Stock
Related Party Transaction [Line Items]
Proceeds from issuance of Series D redeemable convertible preferred stock				$ 8,000,000
Series D redeemable convertible preferred stock, shares issued				4,395,604
Series D redeemable convertible preferred stock, price per share				$ 1.82
Convertible Promissory Notes
Related Party Transaction [Line Items]
Accrued interest payable to related parties			0	$ 192,000
Interest expense, related parties			$ 392,000	138,000
Aggregate convertible promissory notes to related parties				2,800,000
FCMI Parent | Convertible Promissory Notes
Related Party Transaction [Line Items]
Proceeds from issuance of notes to related parties				$ 10,000,000	$ 3,000,000
Repayment of convertible promissory note, related party		$ 10,000,000
Loan repaid in full,date				Mar. 31, 2018
Vaccinex LLC | Convertible Promissory Notes
Related Party Transaction [Line Items]
Proceeds from issuance of notes to related parties					$ 1,500,000
Repayment of convertible promissory note, related party	$ 1,500,000
Loan repaid in full,date				Aug. 31, 2018