UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 8-K

CURRENT REPORT

Pursuant to Section 13 or 15(d) of the

Securities Exchange Act of 1934

Date of Report (Date of earliest event reported):

July 3, 2017

IMMUNE DESIGN CORP.

(Exact name of registrant as specified in its charter)

Registrant’s telephone number, including area code: (206) 682-0645

(Former name or former address, if changed since last report)

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions (see General Instruction A.2. below):

Indicate by check mark whether the registrant is an emerging growth company as defined in as defined in Rule 405 of the Securities Act of 1933 (§ 230.405 of this chapter) or Rule 12b–2 of the Securities Exchange Act of 1934 (§ 240.12b–2 of this chapter).

Emerging growth company  ☒

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act.  ☒

Item 1.01 Entry into a Material Definitive Agreement.

On July 3, 2017, Immune Design Corp. (the “Company”) entered into a Sales Agreement (the “Agreement”) with Cowen and Company, LLC (“Cowen”) under which the Company may offer and sell, from time to time at its sole discretion through Cowen, as its sales agent, shares of its common stock, par value $0.001 per share (the “Common Stock”), having an aggregate offering price of up to $50,000,000.

Cowen may sell the Common Stock by any method permitted by law deemed to be an “at the market offering” as defined in Rule 415(a)(4) of the Securities Act of 1933, as amended (the “Securities Act”), including sales made directly on or through the NASDAQ Global Market or on any other existing trading market for the Common Stock. Subject to the terms and conditions of the Agreement, Cowen will use its commercially reasonable efforts to sell the Common Stock from time to time, based upon instructions from the Company (including any price, time or size limits or other customary parameters or conditions the Company may impose). The Company or Cowen may suspend the offering of the Common Stock being made through Cowen under the Agreement upon proper notice to the other party. The Company will pay Cowen a commission equal to 3.0% of the gross sales proceeds of any Common Stock sold through Cowen under the Agreement and also has provided Cowen with indemnification and contribution rights. In addition, the Company has agreed to reimburse certain legal expenses and filing fees incurred by Cowen up to a maximum of $60,000 in connection with the transactions contemplated by the Agreement.

The Company is not obligated to make any sales of Common Stock under the Agreement. The offering of the Common Stock pursuant to the Agreement will terminate upon the earlier of (i) the sale of all Common Stock subject to the Agreement, or (ii) termination of the Agreement in accordance with its terms.

The foregoing description of the Agreement is not complete and is qualified in its entirety by reference to the full text of the Agreement, a copy of which is filed as Exhibit 1.1 to this Current Report on Form 8-K and is incorporated herein by reference.

The Common Stock will be offered and sold pursuant to the Company’s shelf registration statement on Form S-3 (File No. 333-206324) filed by the Company with the U.S. Securities and Exchange Commission (the “SEC”) on August 12, 2015. On July 3, 2017, the Company filed a prospectus supplement with the SEC in connection with the offer and sale of the Common Stock pursuant to the Agreement (the “Prospectus Supplement”).

The legal opinion of Cooley LLP relating to the Common Stock being offered pursuant to the Agreement is filed as Exhibit 5.1 to this Current Report on Form 8-K.

This Current Report on Form 8-K shall not constitute an offer to sell or the solicitation of an offer to buy the securities discussed herein, nor shall there be any offer, solicitation, or sale of the securities in any state in which such offer, solicitation or sale would be unlawful prior to registration or qualification under the securities laws of any such state.

Item 8.01 Other Events.

The Prospectus Supplement contains an updated description of certain aspects of the Company’s business. Accordingly, the Company is filing this information with this Current Report on Form 8-K for the purpose of updating the description of certain aspects of its business from the disclosure contained in the Company’s prior filings with the SEC, including the Company’s most recent Annual Report on Form 10-K for the year ended December 31, 2016, filed with the SEC on March 7, 2017. The updated disclosures are filed herewith as Exhibit 99.1 and are incorporated herein by reference.

Item 9.01 Financial Statements and Exhibits.

SIGNATURE

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.

Dated: July 3, 2017

EXHIBIT INDEX