Entity Central Index Key Document and entity information. Document And Entity Information [Abstract] Document Type Document Type Amendment Flag Amendment Flag Document Period End Date Document Period End Date Document Fiscal Year Focus Document Fiscal Year Focus Document Fiscal Period Focus Document Fiscal Period Focus Trading Symbol Trading Symbol Entity Registrant Name Entity Registrant Name Entity Central Index Key Current Fiscal Year End Date Current Fiscal Year End Date Entity Filer Category Entity Filer Category Entity Common Stock, Shares Outstanding Entity Common Stock Shares Outstanding Entity Emerging Growth Company Entity Emerging Growth Company Entity Ex Transition Period Entity Ex Transition Period Entity Small Business Entity Small Business Entity Current Reporting Status Entity Current Reporting Status Entity Shell Company Entity Shell Company Entity File Number Entity File Number Entity Tax Identification Number Entity Tax Identification Number Entity Address, Address Line One Entity Address Address Line1 Entity Address, Address Line Two Entity Address Address Line2 Entity Address, Address Line Three Entity Address Address Line3 Entity Address, City or Town Entity Address City Or Town Entity Address, State or Province Entity Address State Or Province Entity Address, Postal Zip Code Entity Address Postal Zip Code City Area Code City Area Code Local Phone Number Local Phone Number Statement Of Financial Position [Abstract] Assets Assets [Abstract] Current assets: Assets Current [Abstract] Cash and cash equivalents Cash And Cash Equivalents At Carrying Value Prepaid expenses and other current assets Prepaid Expense And Other Assets Current Total current assets Assets Current Property and equipment, net Property Plant And Equipment Net Other assets Other Assets Noncurrent Total assets Assets Liabilities and stockholders’ equity Liabilities And Stockholders Equity [Abstract] Current liabilities: Liabilities Current [Abstract] Accounts payable Accounts Payable Current Accrued expenses and other current liabilities Accrued Liabilities Current Total current liabilities Liabilities Current Deferred rent, net of current portion Deferred Rent Credit Noncurrent Total liabilities Liabilities Commitments and contingencies (Note 11) Commitments And Contingencies Stockholders’ equity: Stockholders Equity [Abstract] Preferred stock, $0.0001 par value; 10,000,000 shares authorized and no shares issued or outstanding as of June 30, 2019 and December 31, 2018 Preferred Stock Value Common stock, $0.0001 par value; 150,000,000 shares authorized as of June 30, 2019 and December 31, 2018; 24,187,052 and 23,959,903 shares issued as of June 30, 2019 and December 31, 2018, respectively; 24,095,287 and 23,806,628 shares outstanding as of June 30, 2019 and December 31, 2018, respectively Common Stock Value Additional paid-in capital Additional Paid In Capital Common Stock Accumulated deficit Retained Earnings Accumulated Deficit Total stockholders’ equity Stockholders Equity Total liabilities and stockholders’ equity Liabilities And Stockholders Equity Preferred stock, par value Preferred Stock Par Or Stated Value Per Share Preferred stock, authorized Preferred Stock Shares Authorized Preferred stock, issued Preferred Stock Shares Issued Preferred stock, outstanding Preferred Stock Shares Outstanding Common stock, par value Common Stock Par Or Stated Value Per Share Common stock, authorized Common Stock Shares Authorized Common stock, issued Common Stock Shares Issued Common stock, outstanding Common Stock Shares Outstanding Net income loss available to common stockholders basic and diluted. Statement Of Income And Comprehensive Income [Abstract] Operating expenses: Operating Expenses [Abstract] Research and development Research And Development Expense General and administrative General And Administrative Expense Total operating expenses Operating Expenses Loss from operations Operating Income Loss Other income (expense): Nonoperating Income Expense [Abstract] Interest income Investment Income Interest Change in fair value of preferred stock warrant liability Fair Value Adjustment Of Warrants Change in fair value of derivative liability Gain Loss On Derivative Instruments Net Pretax Other expense Other Nonoperating Expense Total other income (expense), net Nonoperating Income Expense Net loss Net Income Loss Comprehensive loss Comprehensive Income Net Of Tax Reconciliation of net loss to net loss attributable to common stockholders: Net Income Loss Available To Common Stockholders Basic [Abstract] Net loss Accretion of issuance costs on redeemable convertible preferred stock Preferred Stock Accretion Of Redemption Discount Net loss attributable to common stockholders—basic and diluted Net Income Loss Available To Common Stockholders Basic And Diluted Net loss per share attributable to common stockholders—basic and diluted (Note 10) Earnings Per Share Basic And Diluted Weighted-average number of common shares used in computing net loss per share attributable to common stockholders— basic and diluted Weighted Average Number Of Share Outstanding Basic And Diluted Temporary equity stock issued during period value new issues to settled accrued liability of license cost. Statement Of Stockholders Equity [Abstract] Statement [Table] Statement [Table] Class of Stock Statement Class Of Stock [Axis] Class of Stock Class Of Stock [Domain] Series Seed Convertible Preferred Stock. Series Seed Redeemable Convertible Preferred Stock [Member] Series Seed Convertible Preferred Stock [Member] Series A Convertible Preferred Stock [Member] Series A Redeemable Convertible Preferred Stock [Member] Series A Convertible Preferred Stock [Member] Series B Convertible Preferred Stock [Member] Series B Redeemable Convertible Preferred Stock [Member] Series B Convertible Preferred Stock [Member] Common Stock [Member] Common Stock [Member] Additional Paid-in Capital [Member] Additional Paid In Capital [Member] Accumulated Deficit [Member] Retained Earnings [Member] Statement [Line Items] Statement [Line Items] Beginning balance Beginning balance, shares Shares Outstanding Issuance of redeemable convertible preferred stock, Temporary Equity Stock Issued During Period Value New Issues Temporary Equity Stock Issued During Period Share New Issues Issuance of redeemable convertible preferred stock, shares Temporary Equity Stock Issued During Period Share New Issues Issuance of series B redeemable convertible preferred stock to settled accrued liability of license cost Temporary Equity Stock Issued During Period Value New Issues To Settled Accrued Liability Of License Cost Temporary equity stock issued during period shares new issues to settled accrued liability of license. Issuance of series B redeemable convertible preferred stock to settle accrued liability of license cost, shares Temporary Equity Stock Issued During Period Shares New Issues To Settled Accrued Liability Of License Accretion of issuance costs related to redeemable convertible preferred stock Temporary Equity Accretion To Redemption Value Adjustment Issuance of common stock upon IPO Stock Issued During Period Value New Issues Issuance of common stock upon IPO, shares Stock Issued During Period Shares New Issues Stock-based compensation expense Adjustments To Additional Paid In Capital Sharebased Compensation Requisite Service Period Recognition Value Exercise of stock options Stock Issued During Period Value Stock Options Exercised Exercise of stock options, shares Stock Issued During Period Shares Stock Options Exercised Vesting of restricted stock awards Stock Issued During Period Value Restricted Stock Award Gross Vesting of restricted stock awards, shares Stock Issued During Period Shares Restricted Stock Award Gross Conversion of redeemable convertible preferred stock into common stock Stock Issued During Period Value Conversion Of Convertible Securities Conversion of redeemable convertible preferred stock into common stock, shares Stock Issued During Period Shares Conversion Of Convertible Securities Reclassification of warrants to purchase shares of redeemable convertible preferred stock into warrants to purchase common stock Adjustments To Additional Paid In Capital Warrant Issued Ending balance Ending balance, shares Temporary equity issuance of redeemable convertible preferred stock net of issuance costs. Issuance of common stock net of issuance costs. Issuance of redeemable convertible preferred stock, net of issuance costs Temporary Equity Issuance Of Redeemable Convertible Preferred Stock Net Of Issuance Costs Issuance of common stock upon IPO, net of issuance costs Issuance Of Common Stock Net Of Issuance Costs Deferred rent expense. Property and equipment held for sale. Deferred offering costs included in accrued expenses. Purchases of property and equipment paid for by landlord. Accretion of issuance costs related to redeemable convertible preferred stock. Statement Of Cash Flows [Abstract] Cash flows from operating activities: Net Cash Provided By Used In Operating Activities [Abstract] Net loss Profit Loss Adjustments to reconcile net loss to net cash used in operating activities: Adjustments To Reconcile Net Income Loss To Cash Provided By Used In Operating Activities [Abstract] Depreciation and amortization expense Depreciation Depletion And Amortization Stock-based compensation expense Share Based Compensation Amortization of deferred offering costs Amortization Of Deferred Charges Impairment loss of property and equipment Impairment Of Long Lived Assets Held For Use Deferred rent expense Deferred Rent Expense Change in fair value of preferred stock warrant liability Change in fair value of derivative liability Changes in operating assets and liabilities: Increase Decrease In Operating Capital [Abstract] Prepaid expenses and other current assets Increase Decrease In Prepaid Deferred Expense And Other Assets Other assets Increase Decrease In Other Operating Assets Accounts payable Increase Decrease In Accounts Payable Accrued expenses and other current liabilities Increase Decrease In Accrued Liabilities And Other Operating Liabilities Net cash used in operating activities Net Cash Provided By Used In Operating Activities Cash flows from investing activities: Net Cash Provided By Used In Investing Activities [Abstract] Change in restricted cash Increase Decrease In Restricted Cash Purchases of property and equipment Payments To Acquire Property Plant And Equipment Net cash used in investing activities Net Cash Provided By Used In Investing Activities Cash flows from financing activities: Net Cash Provided By Used In Financing Activities [Abstract] Proceeds from issuance of redeemable convertible preferred stock, net of issuance costs Proceeds From Issuance Of Redeemable Convertible Preferred Stock Proceeds from exercise of stock options Proceeds From Stock Options Exercised Proceeds from issuance of common shares upon completion of initial public offering costs, net of offering costs Proceeds From Issuance Initial Public Offering Net cash provided by financing activities Net Cash Provided By Used In Financing Activities Net (decrease) increase in cash, cash equivalents and restricted cash Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Period Increase Decrease Including Exchange Rate Effect Cash, cash equivalents and restricted cash at beginning of period Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Cash, cash equivalents and restricted cash at end of period Supplemental disclosure of non-cash investing and financing activities: Cash Flow Noncash Investing And Financing Activities Disclosure [Abstract] Purchases of property and equipment included in accounts payable and accrued expenses Capital Expenditures Incurred But Not Yet Paid Property and equipment held for sale Property And Equipment Held For Sale Deferred offering costs included in accrued expenses Deferred Offering Costs Included In Accrued Expenses Purchase of property and equipment paid for by landlord Purchases Of Property And Equipment Paid For By Landlord Accretion of issuance costs related to redeemable convertible preferred stock Accretion Of Issuance Costs Related To Redeemable Convertible Preferred Stock Reconciliation of cash, cash equivalents and restricted cash reported within the condensed consolidated balance sheets: Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Period Increase Decrease Excluding Exchange Rate Effect [Abstract] Long-term restricted cash (included in other assets) Restricted Cash Noncurrent Organization Consolidation And Presentation Of Financial Statements [Abstract] Nature of the Business Nature Of Operations Accounting Policies [Abstract] Summary of Significant Accounting Policies Significant Accounting Policies [Text Block] Fair Value Disclosures [Abstract] Fair Value of Financial Assets and Liabilities Fair Value Disclosures [Text Block] Prepaid expenses and other current assets disclosure. Text Block [Abstract] Prepaid Expenses and Other Current Assets Prepaid Expenses And Other Current Assets Disclosure [Text Block] Property Plant And Equipment [Abstract] Property and Equipment, Net Property Plant And Equipment Disclosure [Text Block] Payables And Accruals [Abstract] Accrued Expenses and Other Current Liabilities Accounts Payable Accrued Liabilities And Other Liabilities Disclosure Current [Text Block] Temporary equity. Redeemable Convertible Preferred Stock and Common Stock Temporary Equity [Text Block] Disclosure Of Compensation Related Costs Sharebased Payments [Abstract] Stock-Based Compensation Disclosure Of Compensation Related Costs Share Based Payments [Text Block] License agreement disclosure. License Agreements License Agreement Disclosure [Text Block] Earnings Per Share [Abstract] Net Loss per Share Attributable to Common Stockholders Earnings Per Share [Text Block] Commitments And Contingencies Disclosure [Abstract] Commitments and Contingencies Commitments And Contingencies Disclosure [Text Block] Related Party Transactions [Abstract] Related Party Transactions Related Party Transactions Disclosure [Text Block] Subsequent Events [Abstract] Subsequents Events Subsequent Events [Text Block] Basis of Presentation Basis Of Accounting Policy Policy [Text Block] Use of Estimates Use Of Estimates Emerging growth company status. Emerging Growth Company Status Emerging Growth Company Status Policy [Text Block] Subsequent Event Considerations Subsequent Events Policy Policy [Text Block] Recently Issued Accounting Pronouncements New Accounting Pronouncements Policy Policy [Text Block] Summary of Financial Assets and Liabilities Measured at Fair Value on Recurring Basis Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Table [Text Block] Summary of Prepaid Expenses and Other Current Assets Deferred Costs Capitalized Prepaid And Other Assets Disclosure [Text Block] Summary of Property and Equipment, Net Property Plant And Equipment [Text Block] Schedule Of Accrued Expenses And Other Current Liabilities [Table Text Block] Summary of Accrued Expenses and Other Current Liabilities Schedule Of Accrued Expenses And Other Current Liabilities Table [Text Block] Summary of Common Stock Reserved for Future Issuance Schedule Of Stock By Class [Text Block] Summary of Assumptions that Used to Determine Grant-Date Fair Value of Stock Options Granted to Employees and Members of Board Schedule Of Share Based Payment Award Stock Options Valuation Assumptions Table [Text Block] Summary of Stock Option Activity Schedule Of Share Based Compensation Stock Options Activity Table [Text Block] Summary of Restricted Stock Unit Activity Schedule Of Sharebased Compensation Restricted Stock And Restricted Stock Units Activity Table [Text Block] Schedule of Stock-based Compensation Expense Schedule Of Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Text Block] Schedule of Dilutive Common Stock Equivalents Excluded from Computation of Diluted Net Loss per Share Schedule Of Antidilutive Securities Excluded From Computation Of Earnings Per Share [Text Block] Other Cash Issuance Costs Related To Offering Nature of organization and operations. Nature Of Organization And Operations [Table] Nature Of Organization And Operations [Table] Nature Of Organization And Operations [Table] Equity Components Statement Equity Components [Axis] Equity Component Equity Component [Domain] Sale of Stock Subsidiary Sale Of Stock [Axis] Sale of Stock Sale Of Stock Name Of Transaction [Domain] IPO [Member] I P O [Member] Over-Allotment Option [Member] Over Allotment Option [Member] Underwritten public offering. Underwritten Public Offering [Member] Underwritten Public Offering [Member] Nature Of Organization And Operations [Line Items] Nature Of Organization And Operations [Line Items] Common stock, shares issued and sold Issuance price per shares Shares Issued Price Per Share Net proceeds from issuance of common stock Proceeds From Issuance Of Common Stock Underwriting discounts and commissions and offering costs Payments Of Stock Issuance Costs Other offering expenses Other Cash Issuance Costs Related To Offering Convertible preferred stock converted into common stock Convertible Preferred Stock Shares Issued Upon Conversion Debt Instrument Fair Value Carrying Value [Abstract] Debt Instrument Fair Value Carrying Value [Abstract] Fair value of assets and liabilities measured on non recurring basis. Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Table] Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Table] Measurement Frequency Fair Value By Measurement Frequency [Axis] Fair Value, Measurement Frequency Fair Value Measurement Frequency [Domain] Fair Value on Recurring Basis [Member] Fair Value Measurements Recurring [Member] Fair Value Hierarchy and NAV Fair Value By Fair Value Hierarchy Level [Axis] Fair Value Hierarchy and NAV Fair Value Measurements Fair Value Hierarchy [Domain] Level 1 [Member] Fair Value Inputs Level1 [Member] Level 2 [Member] Fair Value Inputs Level2 [Member] Level 3 [Member] Fair Value Inputs Level3 [Member] Asset Class Fair Value By Asset Class [Axis] Asset Class Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation By Asset Class [Domain] Money Market Funds [Member] Money Market Funds [Member] Restricted cash. Restricted Cash [Member] Restricted Cash [Member] Fair Value of Assets and Liabilities Measured on Non Recurring Basis [Line Items] Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items] Assets Fair Value Disclosure Assets Fair Value Disclosure [Abstract] Assets Fair Value Disclosure Assets Fair Value Disclosure The fair value input amount of assets and liabilities between levels. Type of Arrangement and Non-arrangement Transactions Type Of Arrangement [Axis] Arrangements and Non-arrangement Transactions Arrangements And Nonarrangement Transactions [Member] License agreement. License Agreement [Member] License Agreement [Member] Award Type Award Type [Axis] Equity Award Share Based Compensation Arrangements By Share Based Payment Award Award Type And Plan Name [Domain] Stock purchase agreement. Stock Purchase Agreement [Member] Stock Purchase Agreement [Member] Fair value input transfer between levels Fair Value Input Amount Transfer Between Levels Provision for maximum cash payment. Common stock issued for initial consideration for license Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Grants In Period Provision for maximum cash payment Provision For Maximum Cash Payment Dilution Payment Payable Current Increase in fair value of derivative Dilution payment Dilution Payment Payable Current Tax incentive refund current . Prepaid research and development costs current. Prepaid Expense And Other Assets Current [Abstract] Tax incentive refund Tax Incentive Refund Current Prepaid research and development costs Prepaid Research And Development Costs Current Prepaid insurance Prepaid Insurance Interest income receivable Interest Receivable Current Prepaid rent Prepaid Rent Other current assets Other Assets Current Total Schedule Of Property Plant And Equipment [Table] Schedule Of Property Plant And Equipment [Table] Property, Plant and Equipment, Type Property Plant And Equipment By Type [Axis] Property, Plant and Equipment, Type Property Plant And Equipment Type [Domain] Laboratory and Office Equipment [Member] Office Equipment [Member] Leasehold Improvements [Member] Leasehold Improvements [Member] Computer Equipment and Software [Member] Computer Equipment [Member] Property, Plant and Equipment [Line Items] Property Plant And Equipment [Line Items] Property plant and equipment, gross Property Plant And Equipment Gross Less: Accumulated depreciation and amortization Accumulated Depreciation Depletion And Amortization Property Plant And Equipment Property plant and equipment, net Depreciation and amortization expense Depreciation And Amortization Accrued research and development expense current. Accrued Liabilities Current [Abstract] Compensation and benefit costs Employee Related Liabilities Current Research and development costs Accrued Research And Development Expense Current Consulting and professional fees Accrued Professional Fees Current Other liabilities Other Accrued Liabilities Current Accrued expenses Temporary Equity Disclosure [Abstract] Temporary Equity By Class Of Stock [Table] Temporary Equity By Class Of Stock [Table] Series A- Redeemable Convertible Preferred Stock. Series A Redeemable Convertible Preferred Stock [Member] Series A Redeemable Convertible Preferred Stock [Member] Series B Redeemable Convertible Preferred Stock. Series B Redeemable Convertible Preferred Stock [Member] Series B Redeemable Convertible Preferred Stock [Member] Temporary Equity [Line Items] Temporary Equity [Line Items] Redeemable convertible preferred stock, shares authorized Temporary Equity Shares Authorized Redeemable convertible preferred stock, par value Temporary Equity Par Or Stated Value Per Share Temporary equity stock issuance costs. Redeemable convertible preferred stock, shares issued and sold Temporary Equity Shares Issued Redeemable convertible preferred stock, sales price per share Proceeds from issuance of redeemable convertible preferred stock Redeemable convertible preferred stock, net of issuance costs Temporary Equity Stock Issuance Costs Preferred stock converted into common stock Conversion Of Stock Shares Issued1 Undesignated preferred stock. Undesignated preferred stock outstanding. Common stock, shares authorized Undesignated preferred stock Undesignated Preferred Stock Undesignated preferred stock outstanding Undesignated Preferred Stock Outstanding Cash dividends Dividends Cash Equity [Abstract] Schedule Of Stock By Class [Table] Schedule Of Stock By Class [Table] Restricted Stock [Member] Restricted Stock [Member] Employee Stock Option [Member] Employee Stock Option [Member] 2018 stock option and incentive plan. 2018 Stock Option and Incentive Plan [Member] Two Thousand Eighteen Stock Option And Incentive Plan [Member] 2018 employee stock purchase plan. 2018 Employee Stock Purchase Plan [Member] Two Thousand Eighteen Employee Stock Purchase Plan [Member] Class of Stock [Line Items] Class Of Stock [Line Items] Total shares of authorized common stock reserved for future issuance Common Stock Capital Shares Reserved For Future Issuance Share Based Compensation Arrangement By Share Based Payment Award Fair Value Assumptions And Methodology [Abstract] Expected option life (years) Sharebased Compensation Arrangement By Sharebased Payment Award Fair Value Assumptions Expected Term1 Risk-free interest rate Share Based Compensation Arrangement By Share Based Payment Award Fair Value Assumptions Risk Free Interest Rate Expected volatility Share Based Compensation Arrangement By Share Based Payment Award Fair Value Assumptions Expected Volatility Rate Expected dividend yield Share Based Compensation Arrangement By Share Based Payment Award Fair Value Assumptions Expected Dividend Rate Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Roll Forward Number of options, Outstanding beginning balance Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Number Number of options, Granted Share Based Compensation Arrangement By Share Based Payment Award Options Grants In Period Gross Number of options, Exercised Number of options, Cancelled or forfeited Share Based Compensation Arrangement By Share Based Payment Award Options Forfeitures In Period Number of options, Outstanding ending balance Number of options, Exercisable Share Based Compensation Arrangement By Share Based Payment Award Options Exercisable Number Number of options, Vested and expected to vest Share Based Compensation Arrangement By Share Based Payment Award Options Vested And Expected To Vest Outstanding Number Weighted average exercise price, Outstanding beginning balance Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Weighted Average Exercise Price Weighted average exercise price, Granted Share Based Compensation Arrangements By Share Based Payment Award Options Grants In Period Weighted Average Exercise Price Weighted average exercise price, Exercised Share Based Compensation Arrangements By Share Based Payment Award Options Exercises In Period Weighted Average Exercise Price Weighted average exercise price, Cancelled or forfeited Share Based Compensation Arrangement By Share Based Payment Award Options Forfeitures And Expirations In Period Weighted Average Exercise Price Weighted average exercise price, Outstanding ending balance Weighted average exercise price, Exercisable Share Based Compensation Arrangement By Share Based Payment Award Options Exercisable Weighted Average Exercise Price Weighted average exercise price, Vested and expected to vest Share Based Compensation Arrangement By Share Based Payment Award Options Vested And Expected To Vest Outstanding Weighted Average Exercise Price Weighted average remaining contractual term, Outstanding balance Sharebased Compensation Arrangement By Sharebased Payment Award Options Outstanding Weighted Average Remaining Contractual Term2 Weighted average remaining contractual term, Exercisable Sharebased Compensation Arrangement By Sharebased Payment Award Options Exercisable Weighted Average Remaining Contractual Term1 Weighted average remaining contractual term, vested and expected to vest Sharebased Compensation Arrangement By Sharebased Payment Award Options Vested And Expected To Vest Outstanding Weighted Average Remaining Contractual Term1 Aggregate intrinsic value, Outstanding balance Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Intrinsic Value Aggregate intrinsic value, Exercisable Sharebased Compensation Arrangement By Sharebased Payment Award Options Exercisable Intrinsic Value1 Aggregate intrinsic value, vested and expected to vest Share Based Compensation Arrangement By Share Based Payment Award Options Vested And Expected To Vest Outstanding Aggregate Intrinsic Value Options Granted, Weighted-average grant-date fair value Share Based Compensation Arrangement By Share Based Payment Award Options Grants In Period Weighted Average Grant Date Fair Value Share based compensation arrangement by share based payment award equity instruments other than options forfeited and expirations in period. Number of shares, Issued and unvested beginning balance Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Nonvested Number Number of shares, Granted Number of shares, Vested Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Vested In Period Number of shares, Forfeited, cancelled or expired Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Forfeited And Expirations In Period Number of shares, Issued and unvested ending balance Weighted average grant date fair value, Issued and unvested, beginning balance Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Nonvested Weighted Average Grant Date Fair Value Weighted average grant date fair value, Granted Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Grants In Period Weighted Average Grant Date Fair Value Weighted average grant date fair value, Vested Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Vested In Period Weighted Average Grant Date Fair Value Weighted average grant date fair value, Forfeited, canceled or expired Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Forfeitures Weighted Average Grant Date Fair Value Weighted average grant date fair value, Issued and unvested, ending balance Total fair value of restricted common stock vested Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Vested In Period Total Fair Value Schedule Of Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Table] Schedule Of Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Table] Income Statement Location Income Statement Location [Axis] Income Statement Location Income Statement Location [Domain] Research and Development Expense [Member] Research And Development Expense [Member] General and Administrative Expense [Member] General And Administrative Expense [Member] Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items] Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items] Total stock-based compensation expense Allocated Share Based Compensation Expense Unrecognized stock-based compensation expenses Employee Service Share Based Compensation Nonvested Awards Total Compensation Cost Not Yet Recognized Stock Options Unrecognized stock-based compensation expense, period for recognition Employee Service Share Based Compensation Nonvested Awards Total Compensation Cost Not Yet Recognized Period For Recognition1 Option fee. Represents the amount of the upfront license fees. Milestone payments. License Agreements [Abstract] License Agreements [Abstract] License agreement. License Agreement [Table] License Agreement [Table] License Agreement [Table] Counterparty Name Counterparty Name [Axis] Counterparty Name Repurchase Agreement Counterparty Name [Domain] UHN agreement. UHN Agreement [Member] U H Nagreement [Member] Fabry license agreement. Fabry License Agreement [Member] Fabrylicenseagreement [Member] Interleukin 12 license agreement. Interleukin 12 License Agreement [Member] Interleukin12 License Agreement [Member] BioMarin Pharmaceutical Inc. BioMarin Pharmaceutical Inc [Member] Bio Marin Pharmaceutical Inc [Member] Series B Preferred Stock [Member] Series B Preferred Stock [Member] GenStem Therapeutics Inc. GenStem Therapeutics Inc [Member] Genstem Therapeutics Inc [Member] Lund University Rights Holders Agreement. Lund University Rights Holders Agreement [Member] Lund University Rights Holders Agreement [Member] License Agreement [Line Items] License Agreement [Line Items] Option fee Option Fee Upfront license fee Upfront License Fees Milestone payments Milestone Payments Milestone fees. License Maintenance Fees Clinical trial cost related to research and development expense. Milestone fees Milestone Fees Annual maintenance fees License Maintenance Fees Research and development expense Clinical Trial Cost Related To Research And Development Expense Payments upon closing of initial public offering. Common stock, shares issued Fair value of shares issued Payments upon closing of an initial public offering Payments Upon Closing Of Initial Public Offering Fair value of derivative liability Derivative Fair Value Of Derivative Liability License Agreement Expenses Upfront payment paid in cash. Preferred stock issued Upfront cash payment Upfront Payment Paid In Cash Expenses related to license License Agreement Expenses Milestone payment. Milestone Payment Due Milestone payments Milestone Payment Milestone payment due Milestone Payment Due Schedule Of Antidilutive Securities Excluded From Computation Of Earnings Per Share [Table] Schedule Of Antidilutive Securities Excluded From Computation Of Earnings Per Share [Table] Antidilutive Securities Antidilutive Securities Excluded From Computation Of Earnings Per Share By Antidilutive Securities [Axis] Antidilutive Securities, Name Antidilutive Securities Name [Domain] Warrant [Member] Warrant [Member] Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items] Antidilutive securities excluded from computation of earnings per share amount Antidilutive Securities Excluded From Computation Of Earnings Per Share Amount Operating lease annual increase in rental percentage. Commitments and contingencies disclosure. Commitments And Contingencies Disclosure [Table] Commitments And Contingencies Disclosure [Table] Commitments And Contingencies Disclosure [Table] Sub-lease agreement. Sub-lease Agreement [Member] Sublease Agreement [Member] Commitments And Contingencies Disclosure [Line Items] Commitments And Contingencies Disclosure [Line Items] Lease agreement expiration date Lease Expiration Date1 Percentage of annual increase in rent Operating Lease Annual Increase In Rental Percentage Tenant incentive allowance Payments For Proceeds From Tenant Allowance Security deposit in connection with lease Security Deposit Schedule Of Related Party Transactions By Related Party [Table] Schedule Of Related Party Transactions By Related Party [Table] Title of Individual Title Of Individual [Axis] Relationship to Entity Title Of Individual With Relationship To Entity [Domain] Officers and board members. Officers and Board Members [Member] Officers And Board Members [Member] Related Party Related Party Transactions By Related Party [Axis] Related Party Related Party [Domain] Consulting services agreement. Consulting Services Agreement [Member] Consulting Services Agreement [Member] Related Party Transaction [Line Items] Related Party Transaction [Line Items] Research and development expense related to license agreements Expense related to related party Related Party Transaction Expenses From Transactions With Related Party Underwritten public offering closed for number of common stock registered under shelf. Number of common stock shares issued to underwriters at public offering price. Subsequent Event [Table] Subsequent Event [Table] Subsequent Event Type Subsequent Event Type [Axis] Subsequent Event Type Subsequent Event Type [Domain] Subsequent Event [Member] Subsequent Event [Member] Subsequent Event [Line Items] Subsequent Event [Line Items] Underwritten public offering closed for number of common stock registered under shelf Underwritten Public Offering Closed For Number Of Common Stock Registered Under Shelf Public offering price per share Share Price Number of common stock shares issued to underwriters at public offering price Number Of Common Stock Shares Issued To Underwriters At Public Offering Price Net proceeds from offerings