A Study of V503 (A Multivalent Human Papillomavirus [HPV] L1 Virus-Like Particle [VLP] Vaccine) in Preadolescents and Adolescents (V503-002)

This study will evaluate the immunogenicity and tolerability of V503 (a multivalent human papillomavirus \[HPV\] L1 virus-like particle \[VLP\] vaccine) in preadolescent and adolescent participants between 9 and 15 years old and demonstrate the consistency of the manufactured vaccine through assessment of 3 different final manufacturing process lots of V503. The primary hypotheses are as follows: 1. The 9-valent HPV L1 VLP vaccine when administered to preadolescent and adolescent boys and girls 9 to 15 years of age and young women 16 to 26 years of age is generally well-tolerated. 2. 9-valent HPV L1 VLP vaccine induces non-inferior immune responses in preadolescent and adolescent girls 9 to 15 years of age who are seronegative at Day 1 to the relevant HPV type compared to young women 16 to 26 years of age who are seronegative at Day 1 and polymerase chain reaction (PCR)-negative Day 1 through Month 7 to the relevant HPV type, as measured by anti-HPV 6, 11, 16, 18, 31, 33, 45, 52, and 58 geometric mean titers (GMTs) at 4 weeks post-dose 3. 3. The 9-valent HPV L1 VLP vaccine induces non-inferior immune responses in preadolescent and adolescent boys 9 to 15 years of age who are seronegative at Day 1 to the relevant HPV type compared to young women 16 to 26 years of age who are seronegative at Day 1 and PCR-negative Day 1 through Month 7 to the relevant HPV type, as measured by anti-HPV 6, 11, 16, 18, 31, 33, 45, 52, and 58 GMTs at 4 weeks post-dose 3. 4. Three separate final manufacturing process (FMP) lots of the 9-valent HPV L1 VLP vaccine induce similar immune responses, as measured by anti-HPV types 6, 11, 16, 18, 31, 33, 45, 52, and 58 GMTs at 4 weeks post-dose 3.

The base study V503-002 was a 12-month study that collected immunogenicity data through Month 7 and safety data through Month 12. An optional extension study (V503-002 EXT1) collected safety and immunogenicity information through Month 36. Participants enrolled in the 16- to 26-year-old cohort in the base study were not included in EXT1. Per protocol, EXT1 included immunogenicity data from a subset of 9- to 15-year-old females and safety data from all 9- to 15-year-old females regardless of lot administered. An optional second extension study (V503-002 EXT2) collected long-term safety and immunogenicity information through approximately Month 126. No study vaccine was administered in the extension studies. Participants enrolled in the 16- to 26-year-old cohort in the base study were not included in EXT2. Per protocol, EXT2 included immunogenicity data from a subset of 9- to 15-year-old females and effectiveness and safety data from all 9- to 15-year-old females regardless of lot administered.