IFNA1 and acral lentiginous melanoma: Subgroup analysis on the impact of prior PEG-IFN-α treatment on RFSPem showed a trend towards better clinical response to adjuvant pembrolizumab for patients with acral melanoma who received prior PEG-IFN-α therapy (median RFSPem 8.5 months vs. 5.4 months, Figure S3A).