Characteristics and probability of survival for patients with advanced melanoma who live five or more years after initial treatment with immune checkpoint blockade (ICB).
Authors: Loo Kimberly , Goldman Debra A. , Panageas Katherine , Callahan Margaret K. , Chapman Paul B. , Momtaz Parisa , Shoushtari Alexander Noor , Wolchok Jedd D. , Postow Michael A. , Betof Warner Allison 
Published: June 2021

9534 Background: A subset of melanoma patients treated with ICB (ipilimumab [ipi], nivolumab [nivo], pembrolizumab [pembro] or nivo+ipi) will experience durable responses. While five-year survival rates have been reported for patients treated with ICB on clinical trials, little is known about the clinical characteristics, survival past five years, and patterns of late relapse of long-term survivors. Methods: We retrospectively reviewed all patients treated at Memorial Sloan Kettering for unresectable stage III/IV melanoma who survived at least five years following their first dose of ICB (N = 151). Demographics, disease characteristics, and nature of progression were examined. Overall survival (OS) was calculated from 5 years post-ICB. Time to Treatment failure (TTF) was calculated conditionally from 5 years out until next therapy, progression, or death. Results: Of the 151 long-term survivors, median age at first ICB treatment was 62 years (range 22-83), with 101 (66.9%) male and 50 (33.1%) female patients. Stage at first ICB treatment was unresectable stage III (26, 17.2%), M1a (21,13.9%), M1b (39, 25.8%), M1c (52, 34.4%), M1d (13, 8.6%). Melanoma subtype was cutaneous (122, 80.8%), unknown primary (24, 15.9%), mucosal (3, 2%), and acral (2, 1.3%). First ICB was ipi (108, 71.5%), PD-1 (nivo or pembro) (5, 3.3%), and nivo+ipi (37, 24.5%). The best overall response to first ICB was CR (76, 50.3%), PR (27, 17.9%), SD (16, 10.6%) and PD (32, 21.2%). Of the patients who progressed after initial ICB, 38 received subsequent systemic treatment as follows: PD-(L)1 in 20 (53%), BRAF ± MEK in 9 (23.7%), ipi in 7 (18.4%), and chemotherapy in 2 (5.3%). Median duration of follow-up among survivors (N = 138) was 93 months (range 60-192). From 5 years post-ICB, 85% (95% CI: 73-92%) survived an additional 5 years. In those who made it to 5 years without treatment failure (N = 72), the probability of remaining failure-free was 92% (95% CI: 86-99%) at 7 years. Of the 151 patients, only 4 patients (2.6%) experienced disease progression after 5 years. Three patients had radiographic or pathologic disease progression in the lymph nodes and one in the subcutaneous tissue. No patients progressed in the lungs, visceral organs, or CNS after 5 years. At time of analysis, 13 (8.6%) patients died after 5 years post ICB, none died of progressive melanoma. 6 patients died of unknown causes, 2 died of other causes, and 5 died of other non-melanoma cancer-related causes. Conclusions: Patients who survive five years after their initial immunotherapy have excellent overall survival and treatment failure-free survival. Given the anxiety surrounding survivorship and late progression, long-term survivors should be reassured of their excellent prognosis. These data suggest that aggressive follow-up schedules and imaging of melanoma patients after 5 years of survival may not be required.