On August 15, 2025, the U.S. Food and Drug Administration (FDA) approved Papzimeos (zopapogene imadenovec-drba), the first therapy ever approved for recurrent respiratory papillomatosis (RRP)—a rare, debilitating, and sometimes life-threatening respiratory disease caused by human papillomavirus (HPV) types 6 and 11.
This milestone marks not only a paradigm shift for RRP patients, who have long depended on repeated surgeries to manage the disease, but also an important moment in regulatory history, as the FDA granted full approval without requiring confirmatory randomized trials.
For Precigen, the biotechnology firm behind Papzimeos, the approval represents a commercial breakthrough and a major validation of its adenoviral vector-based immunotherapy platform. For the broader medical and surgical community, this decision provides hope that rare, underserved diseases can benefit from innovative therapies with accelerated pathways to approval.
What Is Recurrent Respiratory Papillomatosis (RRP)?
RRP is a rare, chronic condition in which wart-like tumors grow in the airway (larynx, vocal cords, trachea, and sometimes the lungs), caused by persistent HPV infection. The disease affects an estimated 27,000 adults in the U.S., and thousands more worldwide.
Key challenges include:
• Frequent Surgeries: Patients often undergo multiple surgeries per year, sometimes over 100 surgeries in a lifetime, to physically remove tumors and keep the airway open.
• No Prior Therapies: Until now, no disease-modifying therapy existed. Surgery was the only option to restore airway function, but recurrence rates were high.
• Quality of Life Impact: Patients face hoarseness, breathing difficulties, and repeated hospitalizations, along with the psychological toll of living with a chronic, recurring illness.
Papzimeos is a non-replicating adenoviral vector-based immunotherapy.
• It delivers a genetic sequence that trains the immune system to recognize and attack HPV-infected cells (HPV 6 and 11).
• By targeting the root cause of RRP, Papzimeos reduces tumor regrowth and, in many patients, eliminates the need for further surgeries.
• The therapy is administered by subcutaneous injection rather than surgery, representing a fundamental shift in how the disease is managed.
This disease-modifying approach is the first of its kind for RRP.
Clinical Data Behind Approval
The FDA’s decision was based on an open-label clinical trial of 35 adult patients with severe, surgery-dependent RRP.
Key findings:
• Complete Response Rate: 51% of patients (18 of 35) achieved a complete response, meaning they required no surgery for 12 months after treatment.
• Durability: Of those responders, 15 patients remained disease-free for 24 months, demonstrating long-term control.
• Safety: The therapy was generally well tolerated, with most adverse events being mild injection site reactions or flu-like symptoms.
The results were considered so compelling that the FDA granted full approval without requiring a randomized controlled trial (RCT)—a rare but significant decision for a rare disease.
Share Price Surge: Following the approval, Precigen’s shares surged 81%, reflecting investor confidence in Papzimeos’ commercial potential.
Revenue Projections: Analysts estimate peak U.S. sales could range between $250 million and $1.1 billion annually by the early 2030s.
Rare Disease Pipeline Momentum: The approval reinforces the attractiveness of rare disease immunotherapies for both biotech investors and large pharmaceutical companies looking for acquisition targets.
Why This Approval Matters
1. First-Ever Therapy for RRP
This is the first treatment approved specifically for RRP, ending decades of reliance solely on surgery.
2. Shift Toward Disease Modification
Instead of managing symptoms, Papzimeos targets the viral cause, potentially offering long-term control and even functional cure in some cases.
3. Regulatory Flexibility
The FDA’s willingness to approve based on smaller, open-label trials may set precedent for future rare disease therapies, particularly where large-scale RCTs are impractical.
4. Patient Relief
For patients who have undergone dozens or even hundreds of surgeries, this approval represents the possibility of ending a lifelong surgical cycle.
• Dr. Vinay Prasad, FDA’s Center for Biologics Evaluation and Research:
“Randomized trials are not always needed to approve medical products, and this approval is proof of that philosophy.”
• Kim McClellan, RRP Foundation President and long-time patient advocate:
“I’ve had more than 250 surgeries. For the first time, we may be able to say ‘no more surgery.’ This approval is life-changing.”
• Dr. Helen Green, ENT surgeon and trial investigator:
“Papzimeos has the potential to change the natural history of RRP. Instead of preparing patients for years of surgery, we can now discuss a therapy that addresses the disease itself.”
Next Steps and Implementation
1. Commercial Rollout
Precigen will launch Papzimeos in the U.S. under its new patient assistance initiative “Papzimeos SUPPORT” to help patients navigate insurance coverage.
2. Clinical Integration
ENT surgeons, pulmonologists, and infectious disease specialists will need training on therapy administration and monitoring protocols.
3. Global Expansion
Approval in the U.S. is expected to accelerate regulatory filings in Europe and Asia, where RRP burden is also significant.
4. Guideline Updates
RRP management guidelines from ENT and oncology societies will likely be updated to include Papzimeos as a first-line option for adults.
