A Study of Lifileucel (Tumor-infiltrating Lymphocytes) in Adults With Advanced Soft Tissue Sarcoma

Inclusion Criteria: * Participant must be ≥ 16 years of age at the time of signing the informed consent and assent. * Participants who are \> 70 years of age may be allowed to enroll after the investigator discusses with the medical monitor. * Participant must have a confirmed diagnosis of histologically confirmed unresectable or metastatic UPS (Cohort 1) or DDLPS (Cohort 2), with or without a well-differentiated component, who have received ≥ 1 and a maximum of 3 prior systemic therapies, including ≥ 1 anthracycline-based regimen. * Participant has demonstrated progressive disease on or after the last line of therapy. * Participant is assessed as having at least one resectable lesion (or aggregate lesions) with an estimated minimum diameter of 1.5 cm (short axis) for lifileucel generation. * Following tumor resection for lifileucel generation, the participant will have at least one measurable lesion, as defined by RECIST v1.1 at Baseline. * Participant is expected to achieve washout from investigational or anticancer therapy(ies). * If the participant has preplanned surgical procedure(s), the procedure will take place at least 14 days (for major operative procedures) prior to the tumor resection. Wound healing will have occurred, and all complications will have resolved at the time of tumor resection. * Participant has recovered from all prior anticancer treatment-related AEs to Grade ≤ 1(per NCI-CTCAE), except for peripheral neuropathy, alopecia, or vitiligo. * Participant…