Background: While immunotherapies including checkpoint inhibitors and targeted therapies (BRAF/MEK inhibitors) are options for patients with metastatic melanoma, many patients still develop progressive disease. These patients have few treatment options available including high dose IL-2 and chemotherapy with reported second line response rates of 4-10%. Adoptive cell therapy utilizing tumor-infiltrating lymphocytes (TIL) is recognized as an effective treatment in metastatic melanoma, able to elicit durable and complete responses in even heavily pretreated patients. We provide preliminary data for lifileucel TIL (LN-144) in heavily pre-treated metastatic melanoma patients who progressed on multiple checkpoint and BRAF/MEK inhibitors. Methods: C-144-01 is an ongoing global Phase 2, open-label, multicenter study of efficacy and safety of lifileucel in patients with unresectable metastatic melanoma. We report on Cohort 2 (N = 47) patients who received cryopreserved lifileucel. Tumors resected at local institutions were processed at central GMP facilities in a 22-day manufacturing process. The final product was cryopreserved and shipped to sites. Patients received a one week cyclophosphamide/fludarabine preconditioning lymphodepletion regimen, a single lifileucel infusion, followed by up to 6 doses of iv IL-2 (600,000 IU/kg). Results: Patients with Stage IIIC/IV melanoma had 3.3 mean prior therapies (range: 1-9) and high baseline tumor burden, reflected by a mean sum of diameters of target lesions of 112 mm. Preliminary efficacy results: ORR = 38% (1 CR, 13 PR, 4 uPR), DCR = 77%, and median DOR 6.4 mo (range: 1.3 to 13.7) with median follow-up 6.0 mo. Longer follow-up led to improved responses in some patients including the CR. Frequency of AEs decreased over time, a potentially important benefit of one-time TIL treatment. Conclusions: Preliminary data support lifileucel TIL as an efficacious and well-tolerated therapeutic option for patients with metastatic melanoma who have failed multiple lines of prior therapies including checkpoint inhibitors and BRAF/MEK inhibitors. Clinical trial information: NCT02360579