The U.S. Food and Drug Administration (FDA) has delayed the review of two medicines selected under its recently launched Commissioner’s National Priority Voucher Program, after regulators raised concerns related to safety and clinical effectiveness.

One of the affected products is an experimental therapy from Disc Medicine for a rare blood disorder. The agency extended the review timeline after questioning aspects of the clinical data, including durability of response and potential misuse risks. The decision date has been pushed back by around two weeks.

The FDA has also postponed its review of Sanofi’s Tzield, which is being evaluated for an expanded indication in late-stage type 1 diabetes. The delay follows reports of serious adverse events observed during trials, including seizures, a clotting incident and a reported treatment-related death. The revised action date has been moved by more than a month.

The National Priority Voucher Program, introduced in 2025, is designed to significantly shorten drug review timelines for therapies considered important to public health or national priorities. Under the scheme, selected drugs are targeted for review decisions within one to two months, compared with standard regulatory timelines.

However, the latest delays highlight that even under accelerated pathways, the FDA maintains flexibility to extend reviews when additional scrutiny is required. Internal regulatory updates also indicate that review dates for other medicines in the voucher program have been adjusted, including candidates from Boehringer Ingelheim and Eli Lilly.

Industry observers note that the actions reinforce the agency’s commitment to maintaining regulatory rigor, signalling that speed will not override safety and efficacy standards. To date, only one medicine has received approval through the voucher pathway, with several others still under review.

The developments suggest that while the priority voucher initiative aims to transform review timelines, regulatory oversight remains firmly anchored in data quality and patient safety.