Clint Allen, MD, Senior Investigator, and Scott Norberg, DO, Associate Research Physician at Center for Cancer Research at the National Cancer Institute, discuss results from a study testing the safety and efficacy of zopapogene imadenovec to treat patients with recurrent respiratory papillomatosis (RRP).
RRP is a rare viral disease where tumors grow in the respiratory tract. The tumors can cause a hoarse voice, chronic cough, and difficulty breathing. These tumors rarely become cancerous, but can cause long-term airway and voice complications. RRP is caused by two types of human papillomaviruses (HPV), HPV 6 and HPV 11. There are currently no systemic treatments for this condition.
A recent study published in The Lancet Respiratory Medicine aimed to assess the safety and clinical activity of zopapogene imadenovec (PRGN 2012) in adult patients with RRP. Zopapogene imadenovec is a gorilla adenovirus vector-based gene therapy that targets robust T-cell immunity specific to HPV 6 or 11.
The study was a single-center, single-arm, phase 1/2 trial (NCT04724980) enrolling 38 patients who received a 12-week treatment course. The primary outcome measure was complete response rate, defined as the percentage of patients who did not require an intervention to control RRP in 12 months following treatment.
Of the 35 patients treated at the recommended phase 2 dose (5×1011 particle units), 51% demonstrated a complete response with the median duration of complete response yet to be reached. Complete responses were durable in 83% of those who achieved complete response, requiring no interventions in 12 months following treatment with a median follow up of 22 months.
Additionally, five patients had a partial response, defined as a 50% or greater reduction in clinically indicated interventions after treatment compared with before treatment. The objective response rate was 66%. Adverse events were mild and included grades 1-2 injection site reaction, fatigue, chills, and fever.
Based on these positive results, the U.S. Food and Drug Administration (FDA) approved zopapogene imadenovec in August 2025.
To learn more about RRP and other rare lung conditions, visit https://checkrare.com/diseases/lung-diseases/