On February 16, the U.S. Food and Drug Administration (FDA) granted accelerated approval to the tumor-derived T-cell immunotherapy lifileucel (Amtagvi) for adult patients with unresectable or metastatic melanoma who were previously treated with a PD-1 blocking antibody, or, if they have BRAF V600 mutation–positive disease, a BRAF inhibitor with or without a MEK inhibitor. The accelerated approval came after the safety and efficacy of lifileucel were evaluated in the C-144-01 trial (ClinicalTrials.gov identifier NCT02360579). Researchers administered lifileucel following a lymphodepleting regimen consisting of cyclophosphamide at 60 mg/kg per day with mesna for 2 days followed by fludarabine at 25 mg/m2 per day for 5 days. Three to 24 hours after infusion, patients received IL-2 (aldesleukin) at 600,000 IU/kg every 8 to 12 hours for up to six doses in order to support cell expansion in vivo. The median lifileucel dose was 21.1 x 109 viable cells, and the median number of interleukin-2 doses administered was six. Among the 89 patients who participated in the trial, 2 were excluded because the product did not meet specification and 5 were excluded because of product comparability. The median time to initial response to lifileucel was 1.5 months. The objective response rate among the 73 patients who received lifileucel within the recommended dosing range of 7.5 x 109 to 72 x 109 viable cells was 31.5% (95% confidence interval [CI] = 21.1%–43.4%) and the median duration of response was not reached (95% CI = 4.1 months to not reached). The most common adverse events included chills, pyrexia, fatigue, tachycardia, diarrhea, febrile neutropenia, edema, rash hypotension, alopecia, infection, hypoxia, and dyspnea. The prescribing information for lifileucel contains a Boxed Warning for treatment-related mortality, prolonged severe cytopenia, severe infection, and cardiopulmonary and renal impairment.