Organization, Basis of Presentation and Summary of Significant Accounting Policies - Additional Information (Details)			4 Months Ended	12 Months Ended		24 Months Ended
	Oct. 29, 2019 USD ($) shares	Oct. 11, 2019 shares	May 06, 2019 shares	Dec. 31, 2019 USD ($) Segment shares	Dec. 31, 2018 USD ($) $ / shares shares	Dec. 31, 2019 USD ($) shares	May 07, 2019 USD ($)
Organization Basis of Presentation and Summary of Significant Accounting Policies [Line Items]
Proceeds from Initial Public Offering (IPO)				$ 191,472,000
Description of forward stock split		2.168-for-1			1,559.1183-for-1
Forward stock split conversion ratio		2.168			1,559.1183
Common stock, authorized shares | shares		50,000,000		400,000,000		400,000,000
Fair value liabilities, level 1 to level 2 transfers, amount				$ 0	$ 0	$ 0
Fair value liabilities, level 2 to level 1 transfers, amount				0	0	0
Fair value liability, transfers into level 3				0	0
Fair value liability, transfers out of level 3				$ 0	$ 0
Expected dividend yield				0.00%
Impairment losses				$ 0
Number of operating segment | Segment				1
Operating lease right-of-use assets				$ 933,000		933,000
Lease liabilities				$ 796,000		796,000
Unvested Shares
Organization Basis of Presentation and Summary of Significant Accounting Policies [Line Items]
Weighted-average unvested shares | shares				3,593,034	0
Furniture and Fixtures
Organization Basis of Presentation and Summary of Significant Accounting Policies [Line Items]
Property and equipment, useful life				3 years
Minimum | Computer Equipment and Related Software
Organization Basis of Presentation and Summary of Significant Accounting Policies [Line Items]
Property and equipment, useful life				2 years
Maximum | Computer Equipment and Related Software
Organization Basis of Presentation and Summary of Significant Accounting Policies [Line Items]
Property and equipment, useful life				3 years
Frazier Notes
Organization Basis of Presentation and Summary of Significant Accounting Policies [Line Items]
Fair value of convertible notes					$ 2,000,000
May 2019 Notes
Organization Basis of Presentation and Summary of Significant Accounting Policies [Line Items]
Fair value of convertible notes							$ 2,400,000
Lender Warrants
Organization Basis of Presentation and Summary of Significant Accounting Policies [Line Items]
Fair value of warrants				$ 400,000		400,000
Takeda Warrant
Organization Basis of Presentation and Summary of Significant Accounting Policies [Line Items]
Common stock, authorized shares | shares		50,000,000
Shares of common stock included in calculation of basic weighted-average common shares | shares				7,588,000
Fair Value, Recurring
Organization Basis of Presentation and Summary of Significant Accounting Policies [Line Items]
Financial assets fair value disclosure				$ 0		0
Fair Value, Nonrecurring
Organization Basis of Presentation and Summary of Significant Accounting Policies [Line Items]
Non-financial assets fair value disclosure				0		0
Non-financial liabilities fair value disclosure				$ 0		$ 0
YamadaCo
Organization Basis of Presentation and Summary of Significant Accounting Policies [Line Items]
Merger of entities under common control into the Company, shares | shares					6,760,334
Common Stock
Organization Basis of Presentation and Summary of Significant Accounting Policies [Line Items]
Common stock shares issued | shares			2,524,852		1,000
Purchase price | $ / shares					$ 1.00
Convertible securities converted into shares of common stock | shares				6,107,918
Merger of entities under common control into the Company, shares | shares				6,760,334
Common Stock | May 2019 Notes
Organization Basis of Presentation and Summary of Significant Accounting Policies [Line Items]
Convertible securities converted into shares of common stock | shares				6,107,918
Common Stock | YamadaCo
Organization Basis of Presentation and Summary of Significant Accounting Policies [Line Items]
Convertible securities converted into shares of common stock | shares					1,559.1183
IPO | Common Stock
Organization Basis of Presentation and Summary of Significant Accounting Policies [Line Items]
Common stock shares issued | shares	10,997,630			10,997,630		10,997,630
Proceeds from Initial Public Offering (IPO)	$ 191,500,000					$ 191,500,000