FDA Approves Precigen’s Immunotherapy to Treat Recurrent Respiratory Papillomatosis

FDA has approved a first-of-its-kind non-replicating adenoviral vector-based immunotherapy, zopapogene imadenovec-drba, for the treatment of adult patients with recurrent respiratory papillomatosis (RRP) (1). The treatment is marketed by Precigen under the brand name Papzimeos. There are currently no therapies that have been approved to treat RRP that eliminate the need for repeated surgeries.

Rare disease caused by HPV

According to FDA, RRP is a rare and chronic disease, the cause of which is persistent human papillomavirus (HPV) 6 or 11 infection (1). A primary symptom is the growth of tumors in the respiratory tract, especially in the larynx; although the tumors are commonly benign, significant morbidity may result because the tumors can cause voice changes, breathing difficulties, and airway obstruction.

FDA characterizes RRP as a rare disease with a significant unmet medical need, as there are approximately 1000 new cases diagnosed annually in the United States (1).

Officials contextualize the impact

“This approval has the potential to transform the treatment landscape for RRP and offer lasting relief for patients who previously faced repeated surgeries to control symptoms of their disease,” said Vijay Kumar, MD, acting director of the Office of Therapeutic Products in FDA’s Center for Biologics Evaluation and Research, in an FDA press release (1).

“Randomized trials are not always needed to approve medical products, and this approval is proof of that philosophy,” said CBER Director Vinay Prasad, MD, in the release (1). “FDA will always demand the correct clinical study for the specific medical product and disease. Our requirements for products given to tens of millions of healthy people will be different than products given to at most hundreds or thousands of patients with unique diseases.”

The approval is one of the first Prasad has had the opportunity to comment on following his sudden return to the directorship of CBER on Aug. 9, 2025, less than two weeks after a just-as-abrupt departure from the agency on July 29 (2,3).

Precigen weighs in

Precigen said it would begin promoting Papzimeos immediately, expanding on the data FDA provided by saying that there are approximately 27,000 adult RRP patients in the US based on an internal analysis of claims data and electronic health records (4). The company said patients with no other course of effective treatment may undergo hundreds of surgeries in their lifetimes.

"This long-awaited FDA approval represents a momentous milestone for the RRP community," said Kim McClellan, president of the Recurrent Respiratory Papillomatosis Foundation, in a Precigen press release (4). "For the first time, adult patients with RRP have access to an FDA-approved therapy that offers the potential to reduce—or even eliminate—endless repeated surgeries. This breakthrough brings long-overdue hope to patients and families who have endured so much."

Encouraging trial results

Precigen’s zopapogene imadenovec-drba treatment is administered subcutaneously, with adult patients with RRP who required three or more surgeries a year receiving four injections over a 12-week period in a single-arm, open-label trial (1). Of the 35 patients who progressed to the pivotal portion of the study, 18 of them—one better than half, 51.4%—achieved a “complete response,” or having no further need for surgical intervention in the 12 months following treatment. Follow-up data showed most patients maintained durable responses for two years.

FDA based its approval on results from this trial, having previously granted zopapogene imadenovec-drba priority review as well as both orphan drug and breakthrough therapy designations (1).

References

1. FDA. FDA Approves First Immunotherapy for Recurrent Respiratory Papillomatosis. Press Release. Aug. 14, 2025.
2. Cole, C. Prasad Returns to Head FDA’s CBER. BioPharmInternational.com, Aug. 11, 2025.
3. Cole, C. FDA Shake-Up: Vinay Prasad Exits Amid Tumult in Biologics Oversight. BioPharmInternational.com, July 30, 2025.
4. Precigen. Precigen Announces Full FDA Approval of Papzimeos (zopapogene imadenovec-drba), the First and Only Approved Therapy for the Treatment of Adults with Recurrent Respiratory Papillomatosis. Press Release. Aug. 15, 2025.