Share-Based Payments (Tables)

9 Months Ended

Jan. 31, 2020

Share-based Payment Arrangement [Abstract]

Allocation of Share Based Compensation Expense

Stock-based compensation expense was recognized as follows (table in thousands):

	Three Months Ended January 31,				Nine Months Ended January 31,
	2020		2019		2020		2019
General and administrative	$	110	$	251	$	281	$	326
Sales and marketing	95		53		144		100
Research and development	4		4		9		13
Cost of oncology services	20		27		3		59
Total stock-based compensation expense	$	229	$	335	$	437	$	498

Valuation Assumptions for Stock Options

Black-Scholes assumptions used to calculate the fair value of options granted during the three and nine months ended January 31, 2020 and 2019 were as follows:

	Three Months Ended January 31,		Nine Months Ended January 31,
	2020	2019	2020	2019
Expected term in years	3-6	3-6	3-6	3-6
Risk-free interest rates	1.57%-1.80%	2.57%-3.00%	1.57%-1.80%	2.57%-3.00%
Volatility	69.14%-70.99%	64.55%-84.91%	69.14%-71.11%	64.55%-84.91%
Dividend yield	—%	—%	—%	—%

Summary of Stock Option Activity

The Company’s stock options activity for the nine months ended January 31, 2020 was as follows:

	Directors and Employees		Non- Employees		Total		Weighted Average Exercise Price		Weighted Average Remaining Contractual Life (Years)	Aggregate Intrinsic Value
Outstanding, May 1, 2019	2,373,626		50,000		2,423,626		$	3.19	5.3	$	14,557,000
Granted	219,833		—		219,833		5.29
Exercised	(203,736	)	—		(203,736	)	2.10
Forfeited	(41,875	)	—		(41,875	)	7.99
Canceled	(4,583	)	—		(4,583	)	11.90
Expired	(70,001	)	(6,668	)	(76,669	)	8.04
Outstanding, January 31, 2020	2,273,264		43,332		2,316,596		3.22		5.21	$	10,594,000
Vested and expected to vest as of January 31, 2020	2,273,264		43,332		2,316,596		3.22		5.21	$	10,594,000
Exercisable as of January 31, 2020	1,896,534		17,501		1,914,035		2.72		4.53	$	9,695,000

Summary of Warrant Activity

Activity related to these warrants, which expire at various dates through March 2020, is summarized as follows:

	Number of Shares		Weighted Average Exercise Price		Weighted Average Remaining Contractual Life (Years)	Aggregate Intrinsic Value
Outstanding, May 1, 2019	1,671,440		$	6.20	0.9	$	5,730,000
Granted	—		—		—	—
Exercised	—		—		—	—
Canceled	—		—		—	—
Expired	(1,667	)	4.80		—	—
Outstanding, January 31, 2020	1,669,773		$	5.66	0.1	$	3,225,000