Long-term outcomes to neoadjuvant pembrolizumab based on pathological response for patients with resectable stage III/IV cutaneous melanoma

While neoadjuvant immunotherapy for melanoma has shown promising results, the data have been limited by a relatively short follow-up time, with most studies reporting 2-year outcomes. The goal of this study was to determine long-term outcomes for stage III/IV melanoma patients treated with neoadjuvant and adjuvant programmed cell death receptor 1 (PD-1) inhibition. This is a follow-up study of a previously published phase Ib clinical trial of 30 patients with resectable stage III/IV cutaneous melanoma who received one dose of 200 mg IV neoadjuvant pembrolizumab 3 weeks before surgical resection, followed by 1 year of adjuvant pembrolizumab. The primary outcomes were 5-year overall survival (OS), 5-year recurrence-free survival (RFS), and recurrence patterns. We report updated results at 5 years of follow-up with a median follow-up of 61.9 months. No deaths occurred in patients with a major pathological response (MPR, 10% viable tumor remaining, 8 of 22 patients (36%) had a recurrence. Additionally, the median time to recurrence was 3.9 years for patients with ≤10% viable tumor and 0.6 years for patients with >10% viable tumor (P = 0.044). The 5-year results from this trial represent the longest follow-up of a single-agent neoadjuvant PD-1 trial to date. Response to neoadjuvant therapy continues to be an important prognosticator with regard to OS and RFS. Additionally, recurrences in patients with pCR occur later and are salvageable, with a 5-year OS of 100%. These results demonstrate the long-term efficacy of single-agent neoadjuvant/adjuvant PD-1 blockade in patients with a pCR and the importance of long-term follow-up for these patients. Clinicaltrials.gov, NCT02434354 •This represents the longest follow-up of a neoadjuvant trial of single-agent PD-1 blockade for cutaneous melanoma to date.•Pathologic response to treatment remains prognostic, as patients with ≤10% viable tumor remaining had a 5-year OS of 100%.•Patients with ≤10% viable tumor who had a recurrence do so after 3 years of follow-up and have salvageable recurrences.