Page 1

Phathom PHARMACEUTICALS TM Phathom Pharmaceuticals Reports First Quarter 2021 Results and Provides Recent Business Updates May 11 , 2021 • Positive Phase 3 trial of vonoprazan in Helicobacter pylori ( H. pylori ) infection ; New Drug Applications ( NDAs ) targeted for the fourth quarter of 2021 • U.S. Food and Drug Administration ( FDA ) grants additional qualified infectious disease product ( QIDP ) designations to vonoprazan - based regimens with amoxicillin capsules ; FDA had previously designated vonoprazan - based regimens with amoxicillin tablets as QIDP • Initiated Phase 2 trial evaluating vonoprazan on - demand in non - erosive reflux disease ( NERD ) – disease with large unmet need impacting an estimated more than 40 million people in the U.S. • Pivotal Phase 3 PHALCON - EE trial topline results expected in the fourth quarter of 2021 FLORHAM PARK , N.J. , May 11 , 2021 ( GLOBE NEWSWIRE ) -- Phathom Pharmaceuticals , Inc. ( Nasdaq : PHAT ) , a late clinical - stage biopharmaceutical company focused on developing and commercializing novel treatments for gastrointestinal diseases , today reported financial results for the first quarter of 2021 and provided an update on its recent clinical and organizational progress . " With both the impressive results from our pivotal Phase 3 PHALCON - HP trial and the initiation of our NERD development program , Phathom marks a strong start to 2021 having accomplished two of our key strategic imperatives for the year , " said Terrie Curran , Phathom's President and Chief Executive Officer . " We are well - positioned to further build on this positive momentum as we anticipate several other significant catalysts in 2021 - including the expected readout from our pivotal Phase 3 trial in erosive esophagitis and the planned NDA submissions for vonoprazan - based regimens in the treatment of H. pylori infection . " PHALCON - HP Clinical Development and Regulatory Updates : • On April 29 , 2021 , the company announced PHALCON - HP , a pivotal Phase 3 trial of vonoprazan in H. pylori infection , met all primary and secondary endpoints . • The PHALCON - HP study met the FDA required primary endpoints of noninferiority for vonoprazan in combination with amoxicillin and clarithromycin ( " vonoprazan triple therapy " ) and vonoprazan in combination with amoxicillin ( " vonoprazan dual therapy " ) compared to lansoprazole in combination with amoxicillin and clarithromycin ( " lansoprazole triple therapy " ) in clarithromycin sensitive patient population . • The PHALCON - HP study also demonstrated vonoprazan triple therapy and vonoprazan dual therapy were superior in the eradication of H. pylori compared to lansoprazole triple therapy in all patients and patients with clarithromycin resistant strains of H. pylori . • Based on these positive results , Phathom remains on track to submit NDAs for both vonoprazan - based regimens in the fourth quarter of 2021 . • In May 2021 , the FDA granted additional QIDP designations to vonoprazan triple therapy and vonoprazan dual therapy , each containing amoxicillin capsules , for the treatment of H. pylori infection . The FDA had previously granted QIDP designations to vonoprazan - based H. pylori regimens containing amoxicillin tablets . Other Clinical and Business Updates : • In April 2021 , the company commenced its NERD program by initiating PHALCON - NERD on - demand , a Phase 2 trial evaluating various doses of vonoprazan as an on - demand therapy for patients with NERD . The company expects to complete patient enrollment in the fourth quarter of 2021 and share topline results in the first half of 2022. NERD is a major subcategory of gastroesophageal reflux disease ( GERD ) and is characterized by reflux - related symptoms in the absence of esophageal erosions . There are estimated to be over 40 million people with NERD in the U.S. • The PHALCON - EE pivotal Phase 3 trial evaluating vonoprazan for both the healing and maintenance of healing of erosive esophagitis , as well as the relief of heartburn , remains on track with topline results expected in the fourth quarter of 2021 . • Phathom will have a significant presence at the Digestive Disease WeekⓇ ( DDW ) Virtual Meeting scheduled for May 21-23 , 2021. A vonoprazan - focused poster presentation , The Effect of Food on the Pharmacokinetics of the Potassium- competitive Acid Blocker Vonoprazan , has received recognition as a poster of distinction and will be presented in a virtual session . The poster will be presented live by Prof. Colin W. Howden , MD , FRCP , FACP , AGAF , FACG , on May 22 , 2021 at 12:15 pm ET . More information about Phathom's DDW abstracts will be made available on www.phathompharma.com following the conference .