Fair value of financial instruments (Tables)

12 Months Ended

Dec. 31, 2019

Fair value of financial instruments

Schedule of hierarchy for financial instruments measured at fair value on a recurring basis

	Fair Value as of December 31, 2019
	Level 1		Level 2		Level 3		Total
	(in thousands)
Cash and cash equivalents	$	12,338	$	4,492	$	—	$	16,830
Short-term investments		1,261		6,803		—		8,064
Total financial assets	$	13,599	$	11,295	$	—	$	24,894
Earnout liability	$	—	$	—	$	30	$	30
Derivative liabilities (see Note 11)		—		—		1,135		1,135
Total financial liabilities	$	—	$	—	$	1,165	$	1,165

	Fair Value as of December 31, 2018
	Level 1		Level 2		Level 3		Total
	(in thousands)
Cash and cash equivalents	$	27,419	$	19,059	$	—	$	46,478
Total financial assets	$	27,419	$	19,059	$	—	$	46,478
Earnout liability	$	—	$	—	$	37	$	37
Derivative liability (see Note 11)		—		—		2,017		2,017
Total financial liabilities	$	—	$	—	$	2,054	$	2,054

Schedule of cash and cash equivalents and short-term investments

	December 31, 2019
	Amortized		Unrealized		Market
	Cost		Gain / (Loss)		Value
		(in thousands)
Bank deposits and money market funds	$	13,599	$	—	$	13,599
Financial and corporate debt securities		11,294		1		11,295
	$	24,893	$	1	$	24,894

	December 31, 2018
	Amortized		Unrealized		Market
	Cost		Gain / (Loss)		Value
	(in thousands)
Bank deposits and money market funds	$	27,419	$	—	$	27,419
Financial and corporate debt securities		19,059		—		19,059
	$	46,478	$	—	$	46,478

Schedule of changes in Level 3 liabilities measured at fair value

	Level 3
	Liabilities
	(in thousands)
Balance at December 31, 2017		1,830
Change in fair value		224
Balance at December 31, 2018		2,054
Addition of Encina derivative liability		69
Change in fair value		(958)
Balance at December 31, 2019	$	1,165

Earnout liability

Fair value of financial instruments

Methodologies and significant inputs used in determination of fair value

	Earnout Liability
Date of Valuation		12/31/2019		12/31/2018
Valuation Method		Monte Carlo		Monte Carlo
Volatility (annual)		36%		42%
Risk‑free rate (annual)		1.53% - 2.58%		2.53% - 3.29%
Time period from valuation until end of earnout		0.5 ‑ 9.5		0.5 ‑ 9.5
Earnout Target 1 (thousands)	$	13,700	$	13,700
Earnout Target 2 (thousands)	$	18,200	$	18,200
Discount rate		22.88% - 23.35%		21.35% - 21.68%
Fair value of liability at valuation date (thousands)	$	30	$	37

Derivative liability

Fair value of financial instruments

Methodologies and significant inputs used in determination of fair value

	Encina Derivative Liability						Deerfield Derivative Liability
Date of Valuation		12/31/2019			10/02/2019			12/31/2019			12/31/2018
Valuation Method		Discounted Cash Flow			Discounted Cash Flow			Monte Carlo			Monte Carlo
Volatility (annual)		N/A			N/A			N/A			N/A
Time period from valuation until maturity of debt (yrs.)		2.4			2.6			2.4			3.4
Cumulative probability of a change in control prepayment implied by model		23.9	%		24.7	%		23	%		25.1	%
Cumulative probability of other accelerated prepayments implied by model		N/A			N/A			10	%		13.7	%
Discount rate		6.0	%		6.0	%		25.34	%		23.12	%
Fair value of liability at valuation date (thousands)	$	66		$	69		$	1,069		$	2,017