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 20, 2025

PROTAGONIST THERAPEUTICS, INC.

(Exact name of registrant as specified in its charter)

Protagonist Therapeutics, Inc. 

7707 Gateway Blvd., Suite 140

Newark, California 94560-1160

(Address of principal executive offices, including zip code)

(510) 474-0170

(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:

Securities registered pursuant to Section 12(b) of the Act:

Indicate by check mark whether the registrant is an emerging growth company 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. ¨

On June 20, 2025, Protagonist Therapeutics, Inc., a Delaware corporation (the “Company”), held its 2025 Annual Meeting of Stockholders (the “Annual Meeting”). As of the close of business on April 23, 2025, the record date for the Annual Meeting, there were 61,957,230 shares of common stock, par value $0.00001 per share (the “Common Stock”), entitled to vote at the meeting.

At the Annual Meeting, the stockholders voted on the three proposals listed below. The proposals are described in detail in the Company’s definitive proxy statement for the Annual Meeting, which was filed with the Securities and Exchange Commission on April 29, 2025. The results of the proposals voted upon at the Annual Meeting were:

Proposal 1 — To elect the two Class III director nominees to hold office until the 2028 Annual Meeting of Stockholders and until their successors are duly elected and qualified. Each of the two nominees was so elected, with the votes thereon as follows:

Proposal 2 — To approve, on a non-binding, advisory basis, the compensation of the Company’s named executive officers. This proposal was approved by the requisite vote, with the votes thereon as follows:

Proposal 3 — To ratify the selection of Ernst & Young LLP as the Company’s independent registered public accounting firm for its fiscal year ending December 31, 2025. This proposal was approved by the requisite vote, with the votes thereon as follows:

No other matters were submitted for stockholder action.

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.