Key Inclusion Criteria:  Histologically confirmed advanced (unresectable or metastatic) cutaneous melanoma. Cohort 1: Disease that is relapsed after or refractory to at least 1 prior line of systemic therapy that must include a PD-1 inhibitor and, if positive for proto- oncogene BRAF V600 activating mutation, targeted therapy. Cohort 2: Disease that is persistent after discontinuing PD-1 due to toxicity. Patients with a proto-oncogene BRAF V600 activating mutation must have progressed after targeted therapy. Cohort 3: Disease that is stable (SD) after at least 4 doses of a PD-1 inhibitor. Patients with a proto-oncogene BRAF V600 activating mutation must have progressed after targeted therapy. Medically suitable for surgical resection of tumor tissue Following tumor resection for TIL harvest, will have, at minimum, 1 remaining measurable lesion as identified by CT or MRI per Response Evaluation Criteria in Solid Tumors (RECIST) v1.1 Eastern Cooperative Oncology Group (ECOG) performance status 0 or 1 Adequate bone marrow and organ function  Key Exclusion Criteria:  History of another primary malignancy within the previous 3 years Melanoma of uveal, acral, or mucosal origin Previously received an allogeneic stem cell transplant or organ allograft Previously received TIL or engineered cell therapy ( eg, CAR T-cell) Significant cardiac disease Stroke or transient ischemic attack within 12 months of enrollment History of significant central nervous system (CNS) disorder Symptomatic and/or untreated CNS metastases History of significant autoimmune disease within 2 years prior to enrollment Known history of severe, immediate hypersensitivity reaction attributed to cyclophosphamide, fludarabine, or IL-2.