The Company has authorized 150,000,000 shares of common stock, $0.0001 par value per share, of which 57,237,496 shares and 55,603,427 shares were issued and outstanding as of September 30, 2018 and December 31, 2017, respectively.

During the three and nine months ended September 30, 2018, the Company issued 40,000 and 129,069 shares of common stock upon the exercise of stock options to purchase common stock and the Company received proceeds of $34,378 and $337,645 from these exercises, respectively. During the three and nine months ended September 30, 2017, the Company issued 2,500 and 239,817 shares of common stock upon the exercise of stock options to purchase common stock and the Company received proceeds of $8,250 and $109,053 from these exercises, respectively.

On January 5, 2018, the Company entered into a sales agreement with Cantor Fitzgerald under which the Company may 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 second or third quarter of 2018. In the nine months ended September 30, 2017, the Company sold 1,413,633 shares of its common stock under a sales agreement that the Company entered into in November 2016 with Cantor Fitzgerald (“Sales Agreement”) for net proceeds of $13,268,208. The Sales Agreement was terminated in October 2017.

On February 28, 2017, the Company entered into a securities purchase agreement providing for the issuance and sale by the Company of 3,887,815 shares of its common stock in a registered direct offering to institutional and accredited investors at a purchase price of $7.00 per share with gross proceeds to the Company totaling $27,214,705 less issuance costs of $36,291.