On January 5, 2018, the Company entered into a sales agreement with Cantor Fitzgerald under which the Company had the ability to direct Cantor Fitzgerald as its sales agent to sell common stock up to an aggregate offering of up to $50 million under an “At the Market Offering” (“January 2018 Sales Agreement”). Sales of common stock under the January 2018 Sales Agreement were made pursuant to an effective registration statement for an aggregate offering of up to $50 million. During the first quarter of 2018, the Company sold 1,500,000 shares of its common stock to an institutional investor under the January 2018 Sales Agreement for which the Company received net proceeds of approximately $11.2 million. The Company did not sell any shares under the January 2018 Sales Agreement in the remainder of 2018 and through February 8, 2019, the effective date of the Company’s termination of the January 2018 Sales Agreement.

On January 30, 2019, the Company consummated an underwritten public offering of shares of its common stock pursuant to which the Company sold an aggregate of 6,198,500 shares of its common stock, including 808,500 shares sold pursuant to the full exercise of the underwriters’ option to purchase additional shares, at a purchase price of $6.50 per share with gross proceeds to the Company totaling approximately $40.3 million, less issuance costs incurred of approximately $2.6 million.

During the three and six months ended June 30, 2019, the Company issued 16,458 and 78,229 shares of common stock upon the exercise of stock options to purchase common stock and the Company received proceeds of $102,708 and $306,711 from these exercises, respectively. During the three and six months ended June 30, 2018, the Company issued 52,604 and 89,069 shares of common stock upon the exercise of stock options to purchase common stock and the Company received proceeds of $146,612 and $303,266 from these exercises, respectively.

During the three and six months ended June 30, 2019, warrants to purchase 200,000 shares and 1,283,500 shares of common stock were exercised on a cashless basis resulting in the issuance of 172,414 and 1,119,868 shares of common stock, respectively. No warrants were exercised during the three and six months ended June 30, 2018.