The US Food and Drug Administration (FDA) has approved the first treatment for recurrent respiratory papillomatosis (RRP), a rare respiratory tract disease caused by human papillomavirus (HPV) that requires patients to undergo multiple surgeries every year.
The approval of Precigen’s Papzimeos (zopapogene imadenovec-drba) by the FDA in adults with RRP means the need for repeated procedures to remove benign tumours caused by the disease could be reduced or eliminated.
Papzimeos is a non-replicating adenoviral vector-based immunotherapy designed to help the immune system fight HPV types 6 and 11 – the two that cause RRP. The drug is administered as four subcutaneous injections over three months.
According to Precigen, the immunotherapy targets the underlying pathology of RRP, meaning the benign tumours, also known as warts, that usually disturb the voice box and airway never develop.
This was the case with Megan, a 23-year-old patient in the US with RRP, who required surgeries every eight months, as per a Recurrent Respiratory Papillomatosis Foundation (RRPF) patient story. Megan is just one of around 27,000 cases estimated in the US, many of whom rely on repeated surgeries to control the disease.
RRPF president Kim McClellan said: "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.”
Precigen CEO Helen Sabzevari said: “All adult RRP patients are now eligible for access to the first and only approved therapy that targets the root cause of the disease."
The FDA approval, which came in ahead of schedule of the agency's Prescription Drug User Fee Act (PDUFA) date, represents a growing number of drugs approved with lower clinical data ceilings when intended for rare disease populations.
Precigen completed submission of the rolling biologics licence application (BLA) in December 2024 under an accelerated approval pathway; however, the FDA granted Papzimeos full approval, which does not require a confirmatory clinical trial.
The marketing decision was based on results from a single-arm, open-label pivotal trial (NCT04724980) conducted by clinicians at the National Institutes of Health (NIH). The trial evaluated Papzimeos in adult patients with RRP who required three or more surgeries per year. In patients who received Papzimeos over 12 weeks following surgical debulking procedures, 51.4% achieved a complete response – defined as not needing surgical intervention in the 12 months following treatment.
Papzimeos showed a long-lasting effect, with follow-up data demonstrating responses were maintained in most patients through two years. Most treatment-emergent adverse events (AEs) were mild to moderate with no dose-limiting toxicities observed, and no reported treatment-related serious AEs.
FDA’s Center for Biologics Evaluation and Research (CBER) director Vinay Prasad said: “Randomised trials are not always needed to approve medical products, and this approval is proof of that philosophy.
“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 from products given to at most hundreds or thousands of patients with unique diseases.”
The FDA approval validates Precigen’s decision to prioritise the drug in 2024. The strategic move involved cutting 20% of its workforce and pausing several other clinical programmes to target commercialisation of Papzimeos, formerly known as PRGN-2012.
