Exhibit 99.1 Phathom Pharmaceuticals Reports First Quarter 2024 Financial Results and Provides Business Update • Over 17,500 total prescriptions for VOQUEZNA® products have been dispensed, launch-to-date, a 361% increase since last quarterly report • Net revenues of $1.9 million reported for the first full quarter of launch • Cigna Healthcare recently added VOQUEZNA tablets to its formularies, broadening coverage to approximately 48% of all U.S. commercial lives • National direct-to-consumer campaign, “VOQU ...