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.