Phathom Pharmaceuticals Reports Third Quarter 2019 Financial Results and Provides Corporate Update

Phathom Pharmaceuticals Reports Third Quarter 2019

Financial Results and Provides Corporate Update

BUFFALO GROVE, Ill., November 25, 2019 Phathom Pharmaceuticals, Inc. (Nasdaq: PHAT), a late clinical-stage biopharmaceutical

company focused on developing and commercializing novel treatments for gastrointestinal diseases, announced today its results for the third quarter ended September 30, 2019 and provided an update on recent corporate developments.

Phathom has made tremendous progress in the six months since licensing the rights to vonoprazan, our foundational product candidate for the treatment of

acid-related disorders, said David Socks, President and CEO of Phathom. In that time, we met with and received positive feedback from the FDA and EMA, received IND clearance as well as QIDP and Fast Track status from the FDA, and

completed our IPO with gross proceeds of $209.0 million. We also remain on track to initiate PHALCON-EE, our Phase 3 clinical trial of vonoprazan for both the healing and maintenance of healing of erosive

esophagitis as well as the relief of heartburn, and PHALCON-HP, our Phase 3 clinical trial of vonoprazan in combination with antibiotics for the treatment of H. pylori infection, before year end.

Third-Quarter 2019 Business Highlights:

Recent Developments:

Third Quarter and Year-to-Date

2019 Financial Results:

Vonoprazan is an oral small molecule potassium competitive acid blocker

(P-CAB). P-CABs are a novel class of medicines that block acid secretion in the stomach. Vonoprazan has shown rapid, potent, and durable anti-secretory effects

and has demonstrated clinical benefits over standard of care treatments as a single agent in the treatment of gastroesophageal reflux disease (GERD) and in combination with antibiotics for the treatment of Helicobacter pylori (H.

pylori) infection. Phathom in-licensed the U.S., European, and Canadian rights to vonoprazan from Takeda, which completed 17 Phase 3 trials for vonorpazan and received marketing approval in

Japan and eight other countries in Asia and Latin America.

Phathom Pharmaceuticals is a biopharmaceutical company focused on the development and commercialization of novel treatments for gastrointestinal diseases and

disorders. Phathom has licensed the exclusive rights in the United States, Europe, and Canada to vonoprazan, a novel potassium competitive acid blocker (P-CAB) in late-stage development for the treatment of

acid-related disorders. For more information about Phathom, visit the company s website at www.phathompharma.com.

Phathom cautions you that statements contained in this press release 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 the expected timing of the initiation of Phase 3 clinical trials of

vonoprazan before the end of 2019; and the potential to receive regulatory and exclusivity benefits as a result of QIDP and Fast Track designations. The inclusion of forward-looking statements should not be regarded as a representation by Phathom

that any of its plans will be achieved. Actual results may differ from those set forth in this press release due to the risks and uncertainties inherent in Phathom s business, including, without limitation: potential delays in the commencement,

enrollment and completion of clinical trials; our dependence on third parties in connection with product manufacturing, research and preclinical and clinical testing; the success of our clinical trials of vonoprazan, and the results of prior

other investigator-initiated clinical trials of vonoprazan are not necessarily predictive of our future results and the FDA and comparable foreign regulatory authorities may not accept the data

from such prior trials to support approval; 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; QIDP and Fast Track designations may not actually lead to a faster development or regulatory review or extended exclusivity, and would not assure FDA approval of vonoprazan;

our ability to obtain and maintain intellectual property protection for vonoprazan; our ability to comply with our license agreement with Takeda; and other risks described in the company s prior press releases and the Company s filings

with the Securities and Exchange Commission (SEC), including under the heading Risk Factors in the Company s Registration Statement on Form S-1 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 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.

Sam Brown Inc. Healthcare Communications

PHATHOM PHARMACEUTICALS, INC.

Combined Statements of Operations and Comprehensive Loss

thousands, except per share data)

PHATHOM PHARMACEUTICALS, INC.

Combined Balance Sheets