Amryt Pharmaceuticals, Inc. – FDA CRL

The U.S. Food and Drug Administration (FDA) issued a Complete Response Letter (CRL) on February 26, 2022, to Amryt Pharmaceuticals DAC regarding their New Drug Application (NDA 215064) for Filsuvez (birch triterpenes) gel. Submitted under Section 505(b) of the Federal Food, Drug, and Cosmetic Act, the application sought approval for treating wounds associated with inherited epidermolysis bullosa (EB).

The FDA determined that the application could not be approved due to insufficient evidence of effectiveness. While a primary clinical study met its endpoint, secondary endpoints showed limited support for a substantial benefit compared to the control gel, with similar treatment trajectories over time. Additionally, supportive open-label studies were deemed unsuitable for providing confirmatory evidence, and there was inadequate data to support the drug's mechanism of action in EB, with results from other wound types not considered extrapolatable.

To address these issues, Amryt Pharmaceuticals must submit additional confirmatory evidence demonstrating Filsuvez's effectiveness for EB or specific patient subsets. The company is also required to provide a comprehensive safety update, incorporating all new nonclinical and clinical data, detailing any changes in the safety profile, and updating all related safety analyses and documentation, including worldwide experience. Comments on proposed labeling and the proprietary name are deferred until the clinical deficiencies are resolved.