This is a Phase 3, multicenter, open-label, randomized, parallel group, treatment study to assess the efficacy and safety of lifileucel in combination with pembrolizumab compared with pembrolizumab alone in participants with untreated, unresectable or metastatic melanoma. Participants randomized to the pembrolizumab monotherapy arm who subsequently have a blinded independent central review- verified confirmed progressive disease (PD) will be offered lifileucel monotherapy in an optional crossover period.
Participant has a histologically or pathologically confirmed diagnosis of Stage IIIC, IIID, or IV unresectable or metastatic melanoma.
In the investigator's assessment, the participant has an Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1 and an estimated life expectancy of > 6 months.
Participant is assessed as having at least one resectable lesion (or aggregate lesions) for lifileucel generation.
Participant must have at least one measurable disease as defined by RECIST 1.1 following tumor resection.
Participant has melanoma of uveal/ocular origin.
Participant has symptomatic untreated brain metastases.
Participant received more than 1 prior line of therapy.
Participant received prior therapy for metastatic disease