PROTAGONIST THERAPEUTICS,INC. (NASDAQ:PTGX) Files An 8-K Other Events

PROTAGONIST THERAPEUTICS,INC. (NASDAQ:PTGX) Files An 8-K Other EventsItem 8.01. Other Events.

On October11, 2017, Protagonist Therapeutics,Inc. (“Protagonist” or “the Company”) entered into an underwriting agreement, or the Underwriting Agreement, with Leerink Partners LLC and Barclays Capital Inc., as representatives of the several underwriters named therein, collectively, the Underwriters, relating to the public offering, issuance and sale of 3,530,000 shares of the Company’s common stock, par value $0.00001 per share, or the Common Stock. The price to the public in this offering is $17.00 per share, and the Underwriters have agreed to purchase the shares from the Company to the Underwriting Agreement at a price of $15.98 per share. Under the terms of the Underwriting Agreement, Protagonist also granted the Underwriters an option exercisable for 30 days to purchase up to an additional 529,500 shares of Common Stock at the public offering price, less underwriting discounts and commissions. The gross proceeds to the Company from this offering are expected to be approximately $60.0 million, before deducting underwriting discounts and commissions and other estimated offering expenses payable by the Company, or $69.0 million if the Underwriters exercise in full their option to purchase additional shares of Common Stock. The offering is expected to close on October16, 2017, subject to customary closing conditions.

The Underwriting Agreement contains customary representations, warranties and agreements by the Company, customary conditions to closing, indemnification obligations of the Company and the Underwriters, including for liabilities under the Securities Act of 1933, as amended, other obligations of the parties and termination provisions. The representations, warranties and covenants contained in the Underwriting Agreement were made only for purposes of such agreement and as of specific dates, were solely for the benefit of the parties to such agreement, and may be subject to limitations agreed upon by the contracting parties, including being qualified by confidential disclosures exchanged between the parties in connection with the execution of the Underwriting Agreement.

The offering is being made to the Company’s effective registration statement on FormS-3 and an accompanying prospectus (Registration Statement No.333-220314) previously filed with the SEC and a preliminary and final prospectus supplement thereunder. The Underwriting Agreement is filed as Exhibit1.1 to this report, and the description of the material terms of the Underwriting Agreement is qualified in its entirety by reference to such exhibit. A copy of the opinion of Cooley LLP relating to the legality of the issuance and sale of the shares in the offering is attached as Exhibit5.1 hereto.

Additionally, the Company is filing information for the purpose of updating the risk factor disclosure contained in its prior public filings, including those discussed under the heading “Item 1A. Risk Factors” in its Quarterly Report on Form10-Q for the quarter ended June30, 2017, filed with the SEC on August8, 2017. The updated Company disclosures are filed herewith as Exhibit99.1 and are incorporated herein by reference.

Item 8.01. Financial Statements and Exhibits.

(d)Exhibits.