On April 30, 2019, stock options to purchase 30,000 shares of common stock expired unexercised.

On May 1, 2019, the Company entered into a research collaboration agreement with the University of Taiwan to collect a total of 1,200 samples for a 2-year period for a cost to the Company of $320,000 payable over such period.

On May 3, 2019, Cotterford Company Limited partially exercised its warrant for 1,666,667 shares of our common stock at $3.00 per share resulting in the issuance of 1,666,667 shares of common stock for gross proceeds of $5.0 million. The warrant remains exercisable through August 10, 2019 for the remaining balance of 1,609,195 shares of common stock at a price of $3.00 per share.