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 30, 2020

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 30, 2020, Phathom Pharmaceuticals, Inc. (the “Company”) announced that it has completed patient enrollment in PHALCON-EE, the Company’s pivotal Phase 3 clinical trial of vonoprazan for both the healing and maintenance of healing of erosive esophagitis (“EE”) as well as the relief of heartburn. The Company exceeded the patient enrollment target of 1,000 patients. The Company continues to expect topline results from the PHALCON-EE trial in the second half of 2021.

PHALCON-EE is a randomized, double-blind, two-phase, multicenter Phase 3 trial that has enrolled over 1,000 patients with EE in the U.S. and Europe. The first phase of the trial is evaluating the efficacy and safety of vonoprazan 20 mg administered once-daily (“QD”) compared to lansoprazole 30 mg QD for the healing of EE for up to eight weeks. The second phase of the trial is evaluating the efficacy and safety of vonoprazan 10 mg QD and 20 mg QD compared to lansoprazole 15 mg QD for the maintenance of healing of EE for 24 weeks. Both phases will also evaluate relief of heartburn symptoms.

PHALCON-EE is one of two Phase 3 trials evaluating vonoprazan in gastrointestinal diseases. The second trial, PHALCON-HP, is a randomized, multicenter trial evaluating vonoprazan in combination with antibiotics for the successful eradication of Helicobacter pylori (H. pylori) infection. The Company expects to complete patient enrollment in PHALCON-HP in the first quarter of 2021 with topline results expected in the second quarter of 2021.

Forward Looking Statements

The Company cautions you that statements contained in this report regarding matters that are not historical facts are forward-looking statements. These statements are based on the Company’s current beliefs and expectations. Such forward-looking statements include, but are not limited to, statements regarding when the Company expects to achieve targeted enrollment of patients in its PHALCON-HP Phase 3 clinical trial; and the expected availability of topline results from the PHALCON-EE and PHALCON-HP Phase 3 clinical trials. The inclusion of forward-looking statements should not be regarded as a representation by the Company that any of its plans will be achieved. Actual results may differ from those set forth in this report due to the risks and uncertainties inherent in the Company’s business, including, without limitation: the rate of patient enrollment in PHALCON-HP due to the COVID-19 pandemic is highly uncertain due to factors outside the Company’s control; potential additional delays in the commencement, enrollment and completion of clinical trials; patients already enrolled in PHALCON-EE and PHALCON-HP may not complete the clinical trials or public health conditions and governmental restrictions may lead the Company to stopping such trials all together, which may adversely impact the Company’s trial results and development plans; the Company’s dependence on third parties in connection with product manufacturing, research and preclinical and clinical testing; regulatory developments in the United States and foreign countries; unexpected adverse side effects or inadequate efficacy of vonoprazan that may limit its development, regulatory approval and/or commercialization, or may result in recalls or product liability claims; the Company’s ability to obtain and maintain intellectual property protection for vonoprazan; the Company’s ability to comply with its license agreement with Takeda; the Company’s ability to maintain undisrupted business operations due to the ongoing spread of the COVID-19 coronavirus, including delaying or otherwise disrupting its clinical trials, manufacturing and supply chain, and other risks described in the Company’s prior filings with the Securities and Exchange Commission (SEC), including under the heading “Risk Factors” in the Company’s 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 the Company undertakes no obligation to update such statements to reflect events that occur or circumstances that exist 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.