Zopa Retreatment and Vector Shedding in Adults With RRP

Key Inclusion Criteria: * Age 18 years and older. * Clinical diagnosis of recurrent respiratory papillomatosis with histological confirmation of papilloma. * Cohort 1: Treatment-naïve with respect to Zopa. * Cohort 2: Received a minimum of four administrations of Zopa at 5 × 10\^11 PU per injection and require clinically indicated debulking procedures. * Presence of laryngotracheal papillomas accessible for endoscopic cleanout. * ECOG performance status 0 or 1. * Sexually active participants of reproductive potential must agree to use contraception during treatment and for 120 days for males and 6 months for females after last dose. * Ability to understand and sign informed consent. Key Exclusion Criteria: * Conditions or therapies that increase risk or interfere with participation per investigator judgment. * Systemic corticosteroids \>10 mg prednisone equivalent or other immunosuppressive medications within 14 days prior to dosing. * Other systemic RRP treatments or investigational agents within 30 days. * History of heparin-induced thrombocytopenia or vaccine-induced thrombotic thrombocytopenia. * Active uncontrolled HIV, hepatitis B, or hepatitis C infection. * Pregnant or nursing women. * Known allergy to any study drug component.