On December 28, 2018, the Company entered into an At-the-Market Equity Offering Sales Agreement (the “2018 Sales Agreement”) with Stifel, as sales agent, pursuant to which the Company can sell through Stifel, from time to time, up to $75.0 million in shares of common stock in an at-the-market offering. All sales of shares will be made pursuant to an effective shelf registration statement on Form S-3 filed with the SEC. The Company pays Stifel a commission of approximately 3% of the aggregate gross proceeds received from all sales of common stock under the 2018 Sales Agreement. Unless otherwise terminated earlier, the 2018 Sales Agreement continues until all shares available under the Sales Agreement have been sold or termination of the 2018 Sales Agreement by the Company or by Stifel. As of March 31, 2019, there were no sales of common stock under the 2018 Sales Agreement.

On April 28, 2017, the Company sold 24.9 million units, each consisting of one share of the Company’s common stock, a Series A warrant to purchase one share of common stock, and a Series B warrant to purchase 0.75 shares of common stock, at a public offering price of $1.00 per unit for aggregate gross proceeds of $24.9 million in an underwritten firm commitment public offering. Net proceeds after issuance costs were $23.2 million, assuming no exercise of the warrants. The closing of the public offering occurred on May 3, 2017.

On August 31, 2017, the Company entered into an At-the-Market Equity Offering Sales Agreement (the “2017 Sales Agreement”) with Stifel, Nicolaus & Company, Incorporated (“Stifel”), as sales agent, pursuant to which the Company sold through Stifel, up to $50.0 million in shares of common stock in an at-the-market offering. The Company paid Stifel a commission of approximately 3% of the aggregate gross proceeds received from all sales of common stock under the 2017 Sales Agreement.

The amounts offered and sold under the 2017 Sales Agreement are as set forth below (in thousands, except per share amounts):

	2017 Sales Agreement
	Year Ended December 31, 2017
Total shares of common stock sold		15,998.5
Average price per share	$	3.13
Gross proceeds	$	50,000
Commissions earned by Cantor	$	1,500
Other issuance costs	$	97