This trial is the first large, placebo-controlled clinical trial of an acid suppression treatment in EoE
Topline results for the double-blind 12-week treatment portion of the study are expected in Q4 of 2026

FLORHAM PARK, N.J., June 23, 2026 (GLOBE NEWSWIRE) -- Phathom Pharmaceuticals, Inc. (Nasdaq: PHAT), a biopharmaceutical company focused on developing and commercializing novel treatments for gastrointestinal (GI) diseases, today announced it has completed enrollment in its Phase 2 pHalcon-EoE-201 clinical trial evaluating VOQUEZNA^® (vonoprazan) tablets as an investigational treatment for eosinophilic esophagitis (EoE) in adults. The study has enrolled 95 patients at 41 U.S. sites. Topline results are anticipated in the fourth quarter 2026.

"The pHalcon-EoE-201 study reflects our commitment to advancing care for people living with GI diseases,” said Steve Basta, President and Chief Executive Officer at Phathom. “For many years, acid suppression with proton pump inhibitors (PPIs) has played an important role in the treatment of EoE. As the first large, placebo-controlled study of acid suppression therapy in EoE, the pHalcon-EoE-201 study is designed to evaluate whether vonoprazan may offer a new, oral, non-steroidal treatment option for patients with EoE and, if successful, could help inform our future development strategy in this growing indication.”

"EoE remains a difficult disease to manage, with few approved therapies and a significant portion of patients relying on PPIs which are not FDA-approved for this indication," said Evan S. Dellon, MD, MPH, Professor of Medicine in the Division of Gastroenterology and Hepatology, and Director of the Center for Esophageal Diseases and Swallowing at the University of North Carolina School of Medicine, Chapel Hill, and principal investigator of the pHalcon-EoE-201 study. "Completing enrollment in this first large, placebo-controlled trial of an acid suppression treatment in EoE brings us closer to better understanding whether vonoprazan could offer a meaningful new option for patients."

The pHalcon-EoE-201 study is a two-part, randomized, double-blind, placebo-controlled Phase 2 study. In Part 1, 95 adults with endoscopically confirmed EoE and dysphagia have been randomized evenly to receive VOQUEZNA 20 mg or placebo once daily for 12 weeks. Patients who complete Part 1 are eligible to enter Part 2, a 12-week extension phase in which all participants receive VOQUEZNA 20 mg once daily. If the Phase 2 pHalcon-EoE-201 study generates positive results, Phathom expects to discuss with FDA potential future development plans in EoE, including pediatric evaluation that could potentially support an extension of regulatory exclusivity.

For more information about the pHalcon-EoE-201 study (NCT06851559), visit ClinicalTrials.gov.

About Eosinophilic Esophagitis
Eosinophilic esophagitis (EoE) is a chronic immune condition of the esophagus where white blood cells called eosinophils build up in the lining, causing inflammation and potential difficulty or painful swallowing, choking, or food impaction. Additional symptoms may include chest pain, heartburn, regurgitation, and vomiting. Although the exact cause is unknown, EoE is believed to be triggered by a variety of stimuli, including certain foods and environmental allergens. Identifying EoE can be complex and delayed diagnosis is common among patients. If left untreated, inflammation of EoE can worsen and narrow the esophagus, further exacerbating symptoms. Proton pump inhibitor (PPI) acid suppression therapies are commonly used as a first-line therapy for treatment of EoE although none are FDA approved for this use.

INDICATIONS AND USAGE

VOQUEZNA^® (vonoprazan) is a potassium-competitive acid blocker (PCAB) indicated in adults:

for the healing of all grades of Erosive Esophagitis (Erosive Gastroesophageal Reflux Disease or Erosive GERD) and relief of heartburn associated with Erosive GERD.
to maintain healing of all grades of Erosive GERD and relief of heartburn associated with Erosive GERD.
for the relief of heartburn associated with Non-Erosive GERD.
in combination with amoxicillin and clarithromycin for the treatment of Helicobacter pylori (H. pylori) infection.
in combination with amoxicillin for the treatment of H. pylori infection.

IMPORTANT SAFETY INFORMATION

CONTRAINDICATIONS

VOQUEZNA is contraindicated in patients with a known hypersensitivity to vonoprazan or any component of VOQUEZNA, or in patients receiving rilpivirine-containing products.

For information about contraindications of antibacterial agents (clarithromycin and amoxicillin) indicated in combination with VOQUEZNA, refer to the Contraindications section of the corresponding prescribing information.

WARNINGS AND PRECAUTIONS

Presence of Gastric Malignancy: In adults, symptomatic response to therapy with VOQUEZNA does not preclude the presence of gastric malignancy. Consider additional follow-up and diagnostic testing in patients who have a suboptimal response or an early symptomatic relapse after completing treatment with VOQUEZNA. In older patients, also consider endoscopy.

Acute Tubulointerstitial Nephritis: Acute tubulointerstitial nephritis (TIN) has been reported with VOQUEZNA. If suspected, discontinue VOQUEZNA and evaluate patients with suspected acute TIN.

Clostridioides difficile-Associated Diarrhea: Published observational studies suggest that proton pump inhibitors (PPIs) may be associated with an increased risk of Clostridioides difficile-associated diarrhea (CDAD), especially in hospitalized patients. VOQUEZNA may also increase the risk of CDAD. Consider CDAD in patients with diarrhea that does not improve. Use the shortest duration of VOQUEZNA appropriate to the condition being treated.

CDAD has been reported with use of nearly all antibacterial agents. For more information specific to antibacterial agents (clarithromycin and amoxicillin) indicated for use in combination with VOQUEZNA, refer to Warnings and Precautions section of the corresponding prescribing information.

Bone Fracture: Several published observational studies suggest that PPI therapy may be associated with an increased risk for osteoporosis-related fractures of the hip, wrist, or spine, especially in patients receiving high dose (multiple daily doses) and long-term therapy (a year or longer). Bone fracture, including osteoporosis-related fracture, has also been reported with vonoprazan. Use the shortest duration of VOQUEZNA appropriate to the condition being treated. Patients at risk for osteoporosis-related fractures should be managed according to the established treatment guidelines.

Severe Cutaneous Adverse Reactions (SCAR): Severe cutaneous adverse reactions, including Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN) have been reported with VOQUEZNA. Discontinue VOQUEZNA at the first signs or symptoms of SCAR or other signs of hypersensitivity and consider further evaluation.

Vitamin B12 (Cobalamin) Deficiency: Long-term use of acid-suppressing drugs can lead to malabsorption of Vitamin B12 caused by hypo- or achlorhydria. Vitamin B12 deficiency has been reported postmarketing with vonoprazan. If clinical symptoms consistent with vitamin B12 deficiency are observed in patients treated with VOQUEZNA, consider further workup.

Hypomagnesemia and Mineral Metabolism: Hypomagnesemia has been reported postmarketing with vonoprazan. Hypomagnesemia may lead to hypocalcemia and/or hypokalemia and may exacerbate underlying hypocalcemia in at-risk patients.

Consider monitoring magnesium levels prior to initiation of VOQUEZNA and periodically in patients expected to be on prolonged treatment, in patients taking drugs that may have increased toxicity in the presence of hypomagnesemia or drugs that may cause hypomagnesemia. Treatment of hypomagnesemia may require magnesium replacement and discontinuation of VOQUEZNA.

Consider monitoring magnesium and calcium levels prior to initiation of VOQUEZNA and periodically while on treatment in patients with a preexisting risk of hypocalcemia. Supplement with magnesium and/or calcium, as necessary. If hypocalcemia is refractory to treatment, consider discontinuing VOQUEZNA.

Interactions with Diagnostic Investigations for Neuroendocrine Tumors: Serum chromogranin A (CgA) levels increase secondary to drug-induced decreases in gastric acidity. The increased CgA level may cause false positive results in diagnostic investigations for neuroendocrine tumors. Temporarily discontinue VOQUEZNA treatment at least 4 weeks before assessing CgA levels and consider repeating the test if initial CgA levels are high.

Fundic Gland Polyps: Use of VOQUEZNA is associated with a risk of fundic gland polyps that increases with long-term use, especially beyond one year. Fundic gland polyps have been reported with vonoprazan in clinical trials and during postmarketing use with PPIs. Most patients who developed fundic gland polyps were asymptomatic and fundic gland polyps were identified incidentally on endoscopy. Use the shortest duration of VOQUEZNA appropriate to the condition being treated.

ADVERSE REACTIONS:

Healing of Erosive GERD: The most common adverse reactions (≥2% of patients in the VOQUEZNA arm) include gastritis (3%), diarrhea (2%), abdominal distention (2%), abdominal pain (2%), and nausea (2%).

Maintenance of Healed Erosive GERD: The most common adverse reactions (≥3% of patients in the VOQUEZNA arm) include gastritis (6%), abdominal pain (4%), dyspepsia (4%), hypertension (3%), and urinary tract infection (3%).

Relief of Heartburn Associated with Non-Erosive GERD: The most common adverse reactions (≥2% of patients in the VOQUEZNA arm) include abdominal pain (2%), constipation (2%), diarrhea (2%), nausea (2%), and urinary tract infection (2%).

Treatment of H. Pylori Infection (VOQUEZNA and Amoxicillin): The most common adverse reactions (≥2% in any treatment arm) include diarrhea (5%), abdominal pain (3%), vulvovaginal candidiasis (2%), nasopharyngitis (2%), dysgeusia (1%), headache (1%), and hypertension (1%).

Treatment of H. Pylori Infection (VOQUEZNA, Amoxicillin and Clarithromycin): The most common adverse reactions (≥2% in any treatment arm) include dysgeusia (5%), diarrhea (4%), vulvovaginal candidiasis (3%), headache (3%), abdominal pain (2%), hypertension (2%), and nasopharyngitis (<1%).

For more information on adverse reactions and laboratory changes with amoxicillin or clarithromycin, refer to Adverse Reactions section of the corresponding prescribing information.

DRUG INTERACTIONS

VOQUEZNA has the potential for clinically important drug interactions, including interactions with drugs dependent on gastric pH for absorption, drugs that are substrates for certain CYP enzymes, and some diagnostic tests. Avoid concomitant use of VOQUEZNA with atazanavir or nelfinavir. See full Prescribing Information for more details about important drug interactions. Consult the labeling of concomitantly used drugs to obtain further information about interactions with vonoprazan.

For information about drug interactions, contraindications, and warnings and precautions of antibacterial agents (amoxicillin or clarithromycin) indicated in combination with VOQUEZNA, refer to their corresponding prescribing information.

USE IN SPECIFIC POPULATIONS

Pregnancy: There is a pregnancy exposure registry that monitors pregnancy outcomes in women exposed to VOQUEZNA during pregnancy. Healthcare providers are encouraged to register patients by calling 1-866-609-1612 or visiting https://voqueznapregnancyregistry.com/.

Lactation: There are no data on the effects of vonoprazan on the breastfed child or the effects on milk production. The developmental and health benefits of breastfeeding should be considered along with the mother’s clinical need for VOQUEZNA and any potential adverse effects on the breastfed child from VOQUEZNA or from the underlying maternal condition.

Renal Impairment: For the healing of Erosive GERD, dosage reduction is recommended in patients with severe renal impairment (eGFR < 30 mL/min). Use of VOQUEZNA is not recommended for the treatment of H. pylori infection in patients with severe renal impairment.

Hepatic Impairment: For the healing of Erosive GERD, dosage reduction is recommended in patients with moderate to severe hepatic impairment (Child-Pugh Class B and C). Use of VOQUEZNA is not recommended for the treatment of H. pylori infection in patients with moderate to severe hepatic impairment.

You are encouraged to report suspected adverse reactions by contacting Phathom Pharmaceuticals at 1-888-775-PHAT (7428) or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch.

Please click here for full Prescribing Information for VOQUEZNA.

About VOQUEZNA^®
VOQUEZNA^® (vonoprazan) tablets contain vonoprazan, an oral small molecule potassium-competitive acid blocker (PCAB). PCABs are a novel class of medicines that block acid secretion in the stomach. VOQUEZNA is approved in the U.S. for the treatment of adults with Erosive Esophagitis, also known as Erosive GERD, the relief of heartburn associated with Erosive GERD, the relief of heartburn associated with Non-Erosive GERD, and for the treatment of H. pylori infection in combination with either amoxicillin or amoxicillin and clarithromycin. Phathom in-licensed the rights to vonoprazan for the U.S., Europe and Canada from Takeda, which markets the product in Japan and numerous other countries in Asia and Latin America.

About Phathom Pharmaceuticals, Inc.
Phathom Pharmaceuticals is a biopharmaceutical company focused on the commercialization and development of novel treatments for gastrointestinal diseases. Phathom has in-licensed the exclusive rights to vonoprazan, a first-in-class potassium-competitive acid blocker (PCAB), for the U.S., Europe and Canada. Phathom currently markets vonoprazan in the United States as VOQUEZNA^® (vonoprazan) tablets for the relief of heartburn associated with Non-Erosive GERD in adults, the healing and maintenance of healing of Erosive GERD in adults and relief of associated heartburn, and as part of VOQUEZNA^® TRIPLE PAK^® (vonoprazan tablets, amoxicillin capsules, clarithromycin tablets) and VOQUEZNA^® DUAL PAK^® (vonoprazan tablets, amoxicillin capsules) for the treatment of H. pylori infection in adults. For more information about Phathom, visit the company's website at www.phathompharma.com and follow on LinkedIn and X.

Forward-Looking Statements
This press release contains forward-looking statements, including statements regarding: our plans, expectations, and goals for development of VOQUEZNA in eosinophilic esophagitis (EoE); the potential timeline for reporting top-line results from the pHalcon-EoE-201 study (the "Study"); the potential for the Study to generate positive results and to inform our future development strategy in EoE; the potential for the Study to support future discussions with the FDA on a pediatric program and the potential for such a pediatric program to extend regulatory exclusivity; the unmet need for additional options in the treatment of EoE and the potential of vonoprazan as a future treatment option; our business strategies, goals, mission and vision; and our expectations, forecasts and predictions as to future performance, results and likelihood of success. 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: we may encounter issues with conduct of the Study or analysis of results that delay our timeline for reporting results; we 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, we may decide not to advance the EoE program or we may not agree with the FDA on a pediatric program or may decide not to conduct a pediatric program in EoE; if we decide to conduct a pediatric program in EoE, the studies we conduct may not meet the requirements or timeline for receiving an extension of our regulatory exclusivity for VOQUEZNA; the data from the Study or any future studies we 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; even if the Study and future studies are successful, regulatory authorities may not approve VOQUEZNA for EoE; future cash needs may cause us to change our 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 we undertake no obligation to revise or update this press release 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.

MEDIA CONTACT
Nick Benedetto
1-877-742-8466
media@phathompharma.com

INVESTOR CONTACT
Eric Sciorilli
1-877-742-8466
ir@phathompharma.com

6/26 US-VPZ-26-0177

Phathom Pharmaceuticals Completes Patient Enrollment Ahead of Schedule in Phase 2 pHalcon-EoE-201 Study of VOQUEZNA® (vonoprazan) in Eosinophilic Esophagitis (EoE)