Neoadjuvant Pembrolizumab and High-Dose IFNα-2b in Resectable Regionally Advanced Melanoma

Neoadjuvant immunotherapy may improve the clinical outcome of regionally advanced operable melanoma and allows for rapid clinical and pathologic assessment of response. We examined neoadjuvant pembrolizumab and high-dose IFNα-2b (HDI) therapy in patients with resectable advanced melanoma.

Patients with resectable stage III/IV melanoma were treated with concurrent pembrolizumab 200 mg i.v. every 3 weeks and HDI 20 MU/m²/day i.v., 5 days per week for 4 weeks, then 10 MU/m²/day subcutaneously 3 days per week for 2 weeks. Definitive surgery followed, as did adjuvant combination immunotherapy, completing a year of treatment. Primary endpoint was safety of the combination. Secondary endpoints included overall response rate (ORR), pathologic complete response (pCR), recurrence-free survival (RFS), and overall survival (OS). Blood samples for correlative studies were collected throughout. Tumor tissue was assessed by IHC and flow cytometry at baseline and at surgery.

A total of 31 patients were enrolled, and 30 were evaluable. At data cutoff (October 2, 2019), median follow-up for OS was 37.87 months (range, 33.2-43.47). Median OS and RFS were not reached. Radiographic ORR was 73.3% [95% confidence interval (CI): 55.5-85.8], with a 43% (95% CI: 27.3-60.1) pCR rate. None of the patients with a pCR have had a recurrence. HDI and pembrolizumab were discontinued in 73% and 43% of patients, respectively. Correlative analyses suggested that intratumoral PD-1/PD-L1 interaction and HLA-DR expression are associated with pCR (P = 0.002 and P = 0.008, respectively).

Neoadjuvant concurrent HDI and pembrolizumab demonstrated promising clinical activity despite high rates of treatment discontinuation. pCR is a prognostic indicator.See related commentary by Menzies et al., p. 4133.