For Immediate Release: August 14, 2025

Today, the U.S. Food and Drug Administration approved Papzimeos (zopapogene imadenovec-drba), a first-of-its-kind non-replicating adenoviral vector-based immunotherapy for the treatment of adult patients with recurrent respiratory papillomatosis (RRP).

RRP is a rare, chronic disease caused by persistent human papillomavirus (HPV) 6 or 11 infection, leading to the growth of benign tumors in the respiratory tract, most commonly the larynx. The disease is associated with significant morbidity, including voice changes, breathing difficulties, and airway obstruction. There are currently no approved medical therapies that eliminate the need for repeated surgical procedures.

“Randomized trials are not always needed to approve medical products and this approval is proof of that philosophy,” said Vinay Prasad, M.D., M.P.H., Director of the FDA’s Center for Biologics Evaluation and Research (CBER). “The 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.”

With an estimated 1,000 new cases diagnosed annually in the U.S., RRP represents a rare disease with significant unmet medical need. Until today, no therapies have been approved for RRP. Papzimeos is administered via subcutaneous injection and is designed to stimulate an immune response against cells infected with HPV types 6 and 11—the causative agents in RRP. The therapy offers a novel mechanism of action distinct from traditional treatments, which have relied primarily on repeated surgical interventions.

“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, M.D., Acting Director of the Office of Therapeutic Products in CBER.

Data Supporting Papzimeos

The approval is based on results from a single-arm, open-label trial evaluating Papzimeos in adult patients with RRP who required three or more surgeries per year. Patients received four subcutaneous injections of Papzimeos over 12 weeks following surgical debulking (reduction) procedures.

In the pivotal portion of the study, 51.4% of patients (18/35) achieved a complete response—defined as no need for surgical intervention in the 12 months following treatment. Follow-up data showed that durable responses were maintained in most patients through two years, with a strong correlation between clinical benefit and the induction of HPV 6/11-specific T cells.

The safety profile was favorable, with most treatment-emergent adverse events being mild to moderate. No dose-limiting toxicities were observed, and no treatment-related serious adverse events were reported.

This approval was completed under Priority Review and the product received both Orphan Drug designation and Breakthrough Therapy designation.

The FDA granted approval of Papzimeos to Precigen, Inc.

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The FDA, an agency within the U.S. Department of Health and Human Services, protects the public health by assuring the safety, effectiveness, and security of human and veterinary drugs, vaccines and other biological products for human use, and medical devices. The agency also is responsible for the safety and security of our nation’s food supply, cosmetics, dietary supplements, radiation-emitting electronic products, and for regulating tobacco products.