18.  Subsequent Events

On January 25, 2019, the Company closed an underwritten public offering of 10,750,000 shares of common stock and warrants to purchase up to 10,750,000 shares of common stock, resulting in gross proceeds to the Company of approximately $8,600,000.  The common stock and warrants were sold in units, consisting of a share of common stock and a warrant to purchase a share of common stock, at a price of $0.80 per unit, with an exercise price for the warrants of $0.80 per share.  The warrants were immediately exercisable and will remain exercisable until January 25, 2024. 



Since December 31, 2018, the Company granted 374,968 stock options to officers and other employees.



The Company terminated its laboratory lease agreement on February 4, 2019 and surrendered the premises on February 28, 2019.