Introduction: Topical clindamycin phosphate 1.2%/adapalene 0.15%/benzoyl peroxide 3.1% (CAB) gel is the first fixed-dose, triple-combination formulation approved for the treatment of acne. In three clinical studies of participants with moderate-to-severe acne, CAB gel demonstrated superior efficacy to vehicle and component dyads, with good safety/tolerability. As acne pathogenesis and treatment outcomes can vary with age, this post hoc analysis was performed to evaluate the efficacy and safety of CAB in pediatric and adolescent participants (aged 9-24 years) versus adult participants (≥25 years). This age cutoff was chosen as acne in patients aged 18-24 years is more similar to adolescents than adults, and age 25 is often used to define “adult acne”. Methods: In a phase 2 (NCT03170388) and two phase 3 (NCT04214652, NCT04214639) studies, participants aged ≥9 years with moderate-to-severe acne were randomized to once-daily CAB or vehicle gel. Endpoints included percentage of participants achieving treatment success (defined as ≥2-grade reduction from baseline in Evaluator’s Global Severity Score and clear/almost clear skin) and least-squares mean percent change from baseline in inflammatory/noninflammatory lesion counts at week 12. Treatment-emergent adverse events (TEAEs) were also assessed. Pooled data across all three studies were analyzed for participants aged 9-24 years (CAB: n=297; vehicle: n=218) or ≥25 years (n=91; n=51). Results: At week 12, approximately half of CAB-treated participants in both age groups achieved treatment success (9-24 years: 50.6%; ≥25: 49.0%) versus less than one-fourth with vehicle (15.7% and 20.6%; P<0.01, both). Treatment with CAB resulted in >70% reductions from baseline in inflammatory and noninflammatory lesions in both age groups, versus 45%-62% with vehicle (P≤0.001, all). There were no significant differences between CAB-treated participants in the two age groups across any of these efficacy endpoints (P=0.68-0.97). Most TEAEs with CAB were of mild-moderate severity, with no age-related trends in safety/tolerability. Conclusions: Fixed-dose, triple-combination CAB gel was efficacious and well tolerated in participants with moderate-to-severe acne, regardless of age. Approximately half of pediatric/adolescent and adult participants achieved clear/almost clear skin with CAB, and lesion count reductions of >70% were observed. Funding: Ortho Dermatologics