SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Details)	3 Months Ended	12 Months Ended
	Mar. 31, 2017 USD ($)	Dec. 31, 2019 USD ($) reporting_unit	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Jan. 01, 2019 USD ($)
Property, Plant and Equipment [Line Items]
Insurance coverage limit		$ 250,000
Impairment of long-lived assets		0	$ 0
Impairment of intangible assets		$ 0	0
Number of reporting units | reporting_unit		1
Goodwill impairment		$ 0	$ 0	$ 0
Operating lease current liabilities as of December 31, 2019		$ 112,000
Expected term		5 years 11 months 23 days	5 years 11 months 21 days	5 years 6 months 32 days
Dividend yield		0.00%	0.00%	0.00%
Lab equipment
Property, Plant and Equipment [Line Items]
Estimated useful life (in years)		5 years
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Estimated useful life (in years)		4 years
Computer equipment
Property, Plant and Equipment [Line Items]
Estimated useful life (in years)		3 years
Leasehold improvements
Property, Plant and Equipment [Line Items]
Estimated useful life (in years)		5 years
ASU 2016-02
Property, Plant and Equipment [Line Items]
Right-of-use asset					$ 200,000
Operating lease current liabilities as of December 31, 2019					$ 200,000
License revenue | Roche
Property, Plant and Equipment [Line Items]
Deferred revenue	$ 400,000
Performance-Based Awards
Property, Plant and Equipment [Line Items]
Award vesting period		4 years
Expected term		10 years