Commitments and Contingencies - Narrative (Details) - USD ($)	12 Months Ended
	Apr. 30, 2016	Apr. 30, 2015
Commitments and Contingencies [Line Items]
Operating leases, rent expense	$ 304,000	$ 222,000
Corporate Headquarters [Member]
Commitments and Contingencies [Line Items]
Lease expiration date	Nov. 30, 2016
Operating leases, rent expense	$ 85,000	85,000
Laboratories and Office Space [Member]
Commitments and Contingencies [Line Items]
Lease expiration date	Dec. 30, 2017
Operating leases, rent expense	$ 83,000	86,000
New York Laboratory [Member]
Commitments and Contingencies [Line Items]
Lease expiration date	Sep. 30, 2016
Renewal term	1 year
Operating leases, rent expense	$ 136,000	$ 47,000