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): June 9, 2016

CHIASMA, INC.

(Exact name of registrant as specified in its charter)

275 Wyman Street, Suite 250

Waltham, MA 02451

(Address of principal executive offices, including zip code)

(617) 928-5300

(Registrant’s telephone number, including area code)

Not Applicable

(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:

¨ Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)

¨ Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)

¨ Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))

¨ Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))

The following proposals were submitted to the stockholders at the 2016 Annual Meeting of Stockholders (the “Annual Meeting”) of Chiasma, Inc. (the “Company”) held on June 9, 2016:

(i) The election of three Class I directors, as nominated by the Board of Directors, to hold office until the 2019 Annual Meeting of Stockholders or until their successors are duly elected and qualified; and

(ii) The ratification of the appointment of Deloitte & Touche LLP as the independent registered public accounting firm of the Company for its fiscal year ending December 31, 2016.

The proposals are described in detail in the Company’s Proxy Statement filed with the Securities and Exchange Commission on April 25, 2016.

The number of shares of common stock entitled to vote at the Annual Meeting was 24,293,524. The number of shares of common stock present or represented by valid proxy at the Annual Meeting was 19,479,121. All matters submitted to a vote of the Company’s stockholders at the Annual Meeting were approved and all director nominees were elected.

The number of votes cast for and against and the number of abstentions and broker non-votes with respect to each matter voted upon are set forth below:

There were 2,570,005 broker non-votes regarding the election of directors.

Stockholders ratified the appointment of Deloitte & Touche LLP as the Company’s independent registered public accounting firm for the fiscal year ending December 31, 2016. The results of the voting included 19,337,709 votes for, 122,241 votes against and 19,171 votes abstained. There were no broker non-votes regarding this proposal.

SIGNATURES

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.