Study to Investigate Lifileucel Regimen Plus Pembrolizumab Compared With Pembrolizumab Alone in Participants With Untreated Advanced Melanoma.

The study will enroll participants with unresectable or metastatic melanoma (Stage IIIC, IIID, or IV per the American Joint Committee on Cancer \[AJCC\] staging system) who have had no prior therapy for metastatic disease. Previous adjuvant/neoadjuvant therapy with a single line of protooncogene B-Raf (BRAF) inhibitor with or without a mitogen-activated protein kinase (MEK) inhibitor, PD-1 inhibitor, or cytotoxic T-lymphocyte-associated antigen-4 \[CTLA-4\] inhibitor is allowed, provided such treatment was completed ≥6 months before progression to metastatic disease.