BioMarin’s Palynziq Pregnancy Study: What the Latest Update Means for Investors

Biomarin Pharmaceutical Inc. (BMRN) announced an update on their ongoing clinical study.

BioMarin’s latest clinical update centers on a global, multicenter Phase 4 observational study titled “A Global, Multicenter Study to Assess Maternal, Fetal and Infant Outcomes of Exposure to Palynziq® (Pegvaliase) During Pregnancy and Breastfeeding.” The goal is to understand how Palynziq, a treatment for women with maternal phenylketonuria (PKU), affects both mothers and their babies during pregnancy and breastfeeding. This work matters because real‑world safety data in pregnancy can shape treatment guidelines, support label changes, and influence how widely the drug is used.

The intervention in focus is Palynziq (pegvaliase), a drug used to lower phenylalanine levels in adults with PKU. This study does not introduce a new drug or change the dosing. Instead, it tracks pregnant women who are already being treated with pegvaliase from just before conception or at any time during pregnancy and breastfeeding, and then follows outcomes in both mothers and infants.

The study is observational, not a randomized trial. All enrolled women have PKU and are receiving pegvaliase, so there is no control arm or blinded comparison group. Researchers will prospectively follow this cohort over time, collecting data on pregnancy outcomes, newborn health, and early infant development. The primary purpose is to monitor safety and outcomes in real‑world use rather than to test how well the drug works.

The study was first submitted in October 2022, marking the start of formal tracking of these pregnancies. It is currently listed as recruiting, meaning enrollment is ongoing and data are still being collected. The last update was submitted on November 24, 2025, signaling that the protocol or status has been recently reviewed and refreshed. Primary completion and final completion dates have not yet been reported, so key outcome readouts are still in the future and will likely be released in stages as more pregnancies and infant follow‑ups are completed.

For investors, this update reinforces BioMarin’s commitment to building long‑term safety data around Palynziq, a key asset in its rare disease portfolio. Positive pregnancy and breastfeeding safety findings would reduce a major barrier to use in women of childbearing age, potentially expanding the addressable PKU market and supporting steadier revenue over time. Conversely, any safety concerns could tighten prescribing, weigh on sentiment, and prompt closer regulatory review. The PKU space has limited direct drug competitors, and real‑world pregnancy data can become a differentiator against dietary therapies and emerging treatments. The recent update suggests the study is active and progressing, which should be seen as a modest long‑term positive for BioMarin’s profile in rare metabolic diseases.

The study is ongoing and recently updated, with more detailed information available on the ClinicalTrials portal.

To learn more about BMRN’s potential, visit the Biomarin Pharmaceutical Inc. drug pipeline page.