96P Long-term outcomes after initial disease progression with anti-PD-1 in melanoma

Long-term melanoma survival is now attainable with anti-PD-1 regimens. Notably, a subset of patients experience disease progression (PD) during their immunotherapy treatment but still survive >5 years. Factors that contribute to this prolonged despite initial PD are great interest for prognostication and selection. We conducted retrospective study who survived years from advanced non-uveal at two centers. Overall (OS) was calculated 5-years post treatment. Time second the date on progression. Of 298 treated least 5 years, 102 experienced Median patient age 62 (range 22-90); 30 had unresectable stage III, 64 M1a, 75 M1b, 98 M1c, 31 M1d disease. Patients received anti-PD(L)1 monotherapy (176) or nivolumab + ipilimumab (122). The best overall response complete (150), partial (92), stable (30), (26). follow-up among survivors (274) 79 months 60-143). OS year 6 (1-year 5-year landmark) 94.9% (95% CI: 91.4-97.0%). 24 died after anti-PD-1, 10 due melanoma. In those without failure, probability remaining failure-free an additional 2 96.5% 93.4-99.6%). Among progressed 56 existing sites, 28 new 18 both. yrs. Probability free 67.8% 62.2-72.8%) 64.4% 58.2-69.8%), respectively. 69 progression; median time 36 21-58) mos. progress anti-PD-1-based regimens 5+ have promising low rates These data help guide survivorship planning in go respond later lines therapy.