Phathom Pharmaceuticals, Inc. announced that the U.S. Food and Drug Administration (FDA) has notified the Company that no action will be taken on the Company's new drug application (NDA) for vonoprazan, a novel potassium-competitive acid blocker (PCAB), under review as a treatment for erosive esophagitis, on or prior to the current Prescription Drug User Fee Act (PDUFA) target action date of January 11, 2023. On August 2, 2022, the Company announced that it had detected trace levels of a nitrosamine impurity, N-nitroso- vonoprazan (NVP) in commercial batches and was working closely with the FDA to obtain approval of a proposed acceptable daily intake limit, test method, and controls to address this impurity prior to releasing vonoprazan-based products to the market. While an acceptable daily intake limit for NVP has now been established by the FDA at 96 ng/day, the FDA has requested additional stability data demonstrating that levels of NVP remain below that limit throughout the proposed shelf life of the product.

The Company is actively in the process of both generating additional stability data and discussing with the FDA the nature and extent of such requested data. As a result, Phathom no longer expects product launches for H. pylori or erosive esophagitis in the first quarter of 2023.