Type of Arrangement and Non-arrangement Transactions [Axis] Aratana Agreement [Member] Amgen Agreement [Member] Award Type [Axis] Restricted Stock Units (RSUs) [Member] Related Party [Axis] Especificos Stendhal SA de CV [Member] Equity Components [Axis] Warrant Liability [Member] Fair Value Hierarchy and NAV [Axis] Fair Value, Inputs, Level 1 [Member] Fair Value, Hierarchy [Axis] Fair Value, Inputs, Level 2 [Member] Fair Value, Inputs, Level 3 [Member] Product and Service [Axis] Royalty [Member] Global BioPharma, Inc [Member] License and Service [Member] Restatement [Axis] Adjustments [Member] Balances Without Adoption of ASC 606 [Member] Employee Stock Awards [Member] Director Stock Awards [Member] Plan Name [Axis] 2018 Employee Stock Purchase Plan [Member] Income Statement Location [Axis] Research and Development [Member] General and Administrative [Member] Range [Axis] Minimum [Member] Maximum [Member] Antidilutive Securities [Axis] Warrants [Member] Stock Options [Member] Private Exchange Agreement [Member] Sale of Stock [Axis] Public Offering [Member] Preferred Stock [Member] Common Stock [Member] Additional Paid-In Capital [Member] Accumulated Deficit [Member] Title of Individual [Axis] Investor [Member] Derivative Instrument [Axis] Exercise Price Range One [Member] Exercise Price Range Two [Member] Exercise Price Range Three [Member] Chief Financial Officer [Member] Two Former Board Members [Member] Scenario [Axis] Forecast [Member] Fiscal Year 2020 [Member] Equity Warrants [Member] Measurement Input Type [Axis] Exercise Price [Member] Stock Price [Member] Expected Term [Member] Volatility [Member] Risk Free Interest Rate [Member] Exercise Price Range Four [Member] 2011 & 2018 Employee Stock Purchase Plans [Member] Underwritten Public Offering [Member] Pre-funded Warrants [Member] Subsequent Event Type [Axis] Subsequent Event [Member] Document And Entity Information Entity Registrant Name Entity Central Index Key Document Type Document Period End Date Amendment Flag Current Fiscal Year End Date Entity Current Reporting Status Entity Interactive Data Current Entity Filer Category Entity Small Business Flag Entity Emerging Growth Company Entity Ex Transition Period Entity Shell Company Entity Common Stock, Shares Outstanding Document Fiscal Period Focus Document Fiscal Year Focus Statement of Financial Position [Abstract] ASSETS Current Assets: Cash and cash equivalents Restricted cash Accounts receivable Deferred expenses Prepaid expenses and other current assets Total current assets Property and equipment (net of accumulated depreciation) Intangible assets (net of accumulated amortization) Other assets Total assets LIABILITIES AND STOCKHOLDERS' EQUITY Current liabilities: Accounts payable Accrued expenses Deferred revenue Common stock warrant liability Other current liabilities Total current liabilities Deferred revenue-net of current portion Other liabilities Total liabilities Commitments and contingencies - Note 9 Stockholders' equity: Preferred stock, $0.001 par value; 5,000,000 shares authorized; Series B Preferred Stock; 0 shares issued and outstanding at July 31, 2019 and October 31, 2018 Liquidation preference of $0 at July 31, 2019 and October 31, 2018 Common stock - $0.001 par value; 170,000,000 shares authorized, 19,248,851 and 4,634,189 shares issued and outstanding at July 31, 2019 and October 31, 2018, respectively Additional paid-in capital Accumulated deficit Total stockholders' equity Total liabilities and stockholders' equity Preferred stock, par value Preferred stock, shares authorized Series B Preferred stock, shares issued Series B Preferred stock, shares outstanding Preferred stock, liquidation preference value Common stock, par value Common stock, shares authorized Common stock, shares issued Common stock, shares outstanding Income Statement [Abstract] Revenue Operating expenses: Research and development expenses General and administrative expenses Total operating expenses Loss from operations Other income (expense): Interest income, net Net changes in fair value of derivative liabilities Loss on shares issued in settlement of warrants Other expense Net loss before benefit for income taxes Income tax expense Net loss Net loss per common share, basic and diluted Weighted average number of common shares outstanding, basic and diluted Statement of Cash Flows [Abstract] OPERATING ACTIVITIES Net loss Adjustments to reconcile net loss to net cash used in operating activities: Stock compensation Employee stock purchase plan expense Gain on change in value of warrants Loss on shares issued in settlement of warrants Loss on disposal of property and equipment Abandonment of intangible assets Depreciation expense Amortization expense of intangible assets Net accretion of premiums Change in operating assets and liabilities: Accounts receivable Prepaid expenses and other current assets Income tax receivable Other assets Accounts payable and accrued expenses Deferred revenue Other liabilities Net cash used in operating activities INVESTING ACTIVITIES Purchases of short-term investment securities Proceeds from maturities of short-term investment securities Purchase of property and equipment Proceeds from disposal of property and equipment Cost of intangible assets Net cash (used in) provided by investing activities FINANCING ACTIVITIES Net proceeds of issuance of common stock and pre-funded warrants Warrant exercise Proceeds from employee stock purchase plan Tax withholdings paid related to net share settlement of equity awards Employee tax withholdings paid on equity awards Tax shares sold to pay for employee tax withholdings on equity awards Net cash provided by financing activities Net (decrease) increase in cash, cash equivalents and restricted cash Cash, cash equivalents and restricted cash at beginning of year Cash, cash equivalents and restricted cash at end of year The following table provides a reconciliation of cash, cash equivalents and restricted cash reported within the condensed balance sheets that sum to the total of the same such amounts shown in the condensed statements of cash flows: Cash and cash equivalents Restricted cash Total cash, cash equivalents and restricted cash shown in condensed statements of cash flows SUPPLEMENTAL CASH FLOW INFORMATION Cash paid for taxes SUPPLEMENTAL DISCLOSURE OF NON-CASH AND FINANCING ACTIVITIES Property and equipment included in accounts payable and accrued expenses Shares issued in settlement of warrants Warrant liability reclassified into equity Pre-funded warrant exercises Organization, Consolidation and Presentation of Financial Statements [Abstract] Nature of Operations Accounting Policies [Abstract] Summary of Significant Accounting Policies and Basis of Presentation Property, Plant and Equipment [Abstract] Property and Equipment Goodwill and Intangible Assets Disclosure [Abstract]