Dive Brief:

• The Food and Drug Administration has declined to approve Ultragenyx Pharmaceutical’s experimental gene therapy for a rare neurodegenerative disorder, citing manufacturing concerns in a complete response letter issued weeks ahead of its August 18 decision deadline.
• Ultragenyx said on Friday that the FDA had requested additional information regarding manufacturing processes at its facility. The company said the agency’s observations are “not directly related to the quality of the product,” and it believes the issues are “readily addressable.”
• Ultragenyx plans to resubmit its drug once the issues are resolved, which would start a new six-month review clock once completed. In a client note Friday, Leerink Partners analyst Joseph Schwartz wrote that, while the news is disappointing, “it looks like this is a speed bump to approval, rather than a roadblock.” Shares for the company fell about 5% Friday, but traded up nearly 1% to open Monday trading.

Dive Insight:

The complete response letter is another hit to Ultragenyx, which just announced a disappointing interim update from a closely watched clinical trial of a drug it is developing with partner Mereo BioPharma.

The rejected therapy, known as UX111, is designed to treat people with Sanfilippo syndrome Type A, a rare lysosomal storage disorder that can cause a range of progressive neurological symptoms and lead to early death.

A one-time infusion, Ultragenyx’s gene therapy is meant to deliver a functional copy of a gene called SGSH. Cells with the corrected gene can then produce the enzyme that gene encodes, which is deficient in people with Sanfilippo Type A. Ultragenyx licensed the therapy from Abeona Therapeutics in a 2022 deal.

Ultragenyx said the FDA did not cite any issues with the clinical data submitted in its application, although the agency did ask for updated results from current study participants to be included in any resubmission. The company will work with the FDA over the next few months to resolve the manufacturing issues observed.

Kristen Kluska, an analyst at Cantor Fitzgerald, also described the rejection as a disappointment, as UX111 could have been a “near-term revenue and [priority review voucher] sale opportunity,” she wrote in a client note, referring to the transferable fast passes granted by the FDA upon certain drug approvals.

Still, Kluska noted how most manufacturing-related complete response letters are resolved and she expects UX111 to ultimately get approved.