Phathom Pharmaceuticals Inc — Current Report (Form 8-K)

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): November 4, 2025

PHATHOM PHARMACEUTICALS, INC.

(Exact name of registrant as specified in its charter)

100 Campus Drive, Suite 102

Florham Park, New Jersey 07932

(Address of principal executive offices) (Zip Code)

(877) 742-8466

(Registrant’s telephone number, include area code)

N/A

(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. ☐

Item 8.01 Other Events.

On November 4, 2025, Phathom Pharmaceuticals, Inc. (“Phathom” or the “Company”) announced the first patient has been dosed in its Phase 2 pHalcon EoE-201 clinical trial evaluating VOQUEZNA^® (vonoprazan) tablets as an investigational treatment for eosinophilic esophagitis (“EoE”) in adults.

Phathom’s Phase 2 EoE study is a two-part, randomized, double-blind, placebo-controlled study. The first part will enroll 80 adults with endoscopic-confirmed EoE and dysphagia, or trouble swallowing, to be randomized evenly to receive VOQUEZNA 20 mg or placebo, once daily for 12 weeks. Patients who complete the initial 12-week treatment period will be eligible to enter Part 2, a 12-week extension phase, where all subjects will receive VOQUEZNA 20 mg for the remainder of the study.

Topline primary and secondary results are anticipated to be available in 2027.

Forward Looking Statements

This report contains forward-looking statements. All statements other than statements of historical facts contained in this report, including statements regarding: Phathom’s plans, expectations, and goals for development of VOQUEZNA in eosinophilic esophagitis (“EoE”); potential timelines for the pHalcon-EoE-201 study (the “Study”), including timelines for reporting of topline results; the potential for the Study to support discussions on a pediatric program that could extend regulatory exclusivity; the unmet need for additional options in the treatment of EoE and the potential of VOQUEZNA as a treatment option; and Phathom’s plans, expectations and strategies with respect to our business, goals, mission and vision; and as to future performance, results and likelihood of success, are forward-looking statements. In some cases, you can identify forward-looking statements by terms such as “may,” “will,” “should,” “expect,” “plan,” “anticipate,” “could,” “intend,” “target,” “project,” “contemplates,” “believes,” “estimates,” “predicts,” “potential”, “guidance”, or “continue” or the negative of these terms or other similar expressions. These statements involve known and unknown risks, uncertainties and other important factors that may cause our actual results, performance or achievements to be materially different from any future results, performance or achievements expressed or implied by the forward-looking statements, including the risk that: Phathom may encounter issues with conduct of the Study that delay its timelines, including slower than expected enrollment or issues with conduct of the study or data analysis; Phathom may receive negative or mixed results from the Study that are not sufficient to advance the program; even if the results of the Study are positive, Phathom may decide not to advance the EoE program and Phathom may decide not to conduct a pediatric program in EoE; if Phathom decides to conduct a pediatric program in EoE, the studies its conduct may not meet the requirements or timelines for receiving an extension of our regulatory exclusivity for VOQUEZNA; the data from the Study or any future studies Phathom may conduct in EoE may not support the potential for VOQUEZNA as a treatment option in this indication; the success of the EoE program may be impacted by potential safety or tolerability issues, competition from other therapies or treatment approaches, or technical issues; future cash needs may cause Phathom to change its plans; and any of the foregoing or other factors may negatively impact our ability to achieve our plans, goals, mission, vision and potential. For additional discussion of these and other risks, see the risk disclosure in our filings with the Securities and Exchange Commission (“SEC”), including our Annual Report on Form 10-K and any subsequent filings with the SEC. You are cautioned not to place undue reliance on these forward-looking statements, which speak only as of the date hereof, and Phathom undertakes no obligation to revise or update this report to reflect events or circumstances after the date hereof. All forward-looking statements are qualified in their entirety by this cautionary statement, which is made under the safe harbor provisions of the Private Securities Litigation Reform Act of 1995.

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.