This is a Phase 2, multicenter, open-label study of lifileucel (tumor-infiltrating lymphocytes [TIL]) in participants with previously treated advanced melanoma

This is a Phase 2 study of the lifileucel treatment regimen in participants who previously received treatment for unresectable or metastatic (advanced) melanoma with 1 prior line of an anti-programmed cell death protein-1 (PD-1) or anti-programmed death ligand 1 (PD-L1) agent or whose melanoma progressed during and/or within ≤ 12 weeks after adjuvant anti-PD-(L)1 treatment (early relapse). Participants who have BRAF V600 mutation positive melanoma may have received or refused 1 additional prior line treatment with a BRAF inhibitor

± a MEK inhibitor

Inclusion Criteria:

• Participant has a histologically or pathologically confirmed diagnosis of Stage IIIC, IIID, or IV unresectable or metastatic melanoma.
• The participant has an ECOG performance status of 0 or 1 and an estimated life expectancy of > 6 months.
• The participant must have experienced radiographic disease progression on: 1 prior line of an anti-PD-(L)1 treatment (as a monotherapy or as part of a combination) for advanced melanoma and/or during or within ≤ 12 weeks after adjuvant anti-PD-(L)1 treatment (as a monotherapy or as part of a combination). Participants who have BRAF V600 mutation positive melanoma may have received 1 additional prior line of treatment with a BRAF inhibitor ± a MEK inhibitor.
• 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.
• Participants who are > 70 years of age may be allowed to enroll after the investigator discusses with the medical monitor.
• Participants of childbearing potential or those with partners of childbearing potential must be willing to practice an approved method of highly effective birth control.
• Participants must have adequate organ function.
• Participant is willing to receive optimal supportive care, including intensive care, from enrollment until the first post-treatment tumor assessment.

Exclusion Criteria:

• Participant has melanoma of uveal/ocular origin.
• Participant has symptomatic untreated brain metastases.
• Participant has active uveitis that requires active treatment.
• Participant has an active medical illness(es) that, in the opinion of the investigator, would pose increased risks for study participation, such as systemic infections; seizure disorders; coagulation disorders; or other active major medical illnesses of the cardiovascular, respiratory, or immune systems.
• Participant has any form of primary or acquired immunodeficiency (eg, SCID or AIDS).
• Participant had another primary malignancy within the previous 3 years (except for those that do not require treatment or were curatively treated >1 year ago, and in the judgment of the investigator do not pose a significant risk of recurrence.)
• Participant has a history of allogeneic cell or organ transplant.
• Concurrent enrollment in another clinical study, unless it is an observational (non-interventional) clinical study or during the follow-up period of an interventional study.

Other protocol defined inclusion/exclusion criteria could apply.