Pegvaliase dosing in adults with PKU: Requisite dose for efficacy decreases over time.

Novel pharmaceutical therapies such as pegvaliase, phenylalanine ammonia lyase (PAL), have enhanced disease control for many individuals with phenylketonuria (PKU). We present a retrospective chart review to assess pegvaliase doses over time in individuals followed at the Boston Children's Hospital PAL Clinic, including those who started pegvaliase in a clinical trial ("trial patients") and those who started after drug came to market ("post-market patients"). Trial patients were on pegvaliase an average of 4.8 years longer, and their mean current pegvaliase dose was 126 ± 92 compared to 223 ± 147 mg/week for post-market patients (p = 0.0155), suggesting that the pegvaliase dose for target efficacy may decrease over time in adults with PKU. In post-market patients, we demonstrated a significant, inverse correlation with dose change and number of weeks from response (r = -0.46, p = 0.046). The entire cohort showed significant variability in terms of time to achieve a therapeutic response, response dose, and current dose. Our data suggest that patients tolerate a reduction in pegvaliase dose over time while maintaining efficacy. This is a clinically meaningful finding as it indicates that patients may reduce number of weekly injections over time on pegvaliase.