AbstractIntroduction: Novel early-line therapies for advanced (unresectable or metastatic) melanoma are needed to improve the rate of deep and durable responses and increase the proportion of patients with long-term benefit. TILVANCE-301 will evaluate the efficacy and safety of lifileucel autologous TIL cell therapy plus pembrolizumab in patients with untreated advanced melanoma.Methods: TILVANCE-301 (NCT05727904) is a phase 3, multicenter, randomized, open-label, parallel group study that will randomize ~670 patients (1:1; Day 0) to Arm A: lifileucel plus pembrolizumab (Day 3: tumor tissue resection for TIL manufacturing; Day 5: pembrolizumab 200 mg; Day 26: pembrolizumab 400 mg; Day 28-29: cyclophosphamide 60 mg/kg; Day 28-32: fludarabine 25 mg/m2; Day 33: lifileucel; Day 34-37: ≤6 doses of high-dose IL-2; Week 10: pembrolizumab 400 mg Q6W) or Arm B: pembrolizumab alone (same pembrolizumab dosing as Arm A). Patients in Arm B with confirmed progressive disease verified by blinded independent review committee (BIRC) have the option to receive lifileucel monotherapy as immediate next treatment and may continue pembrolizumab until start of nonmyeloablative lymphodepletion. Eligible adults have histologically confirmed advanced melanoma, Eastern Cooperative Oncology Group performance status of 0-1, estimated life expectancy >6 months, ≥1 resectable lesion to generate lifileucel, and ≥1 remaining measurable lesion. Prior neoadjuvant or adjuvant treatment including immune checkpoint inhibitors may be allowed. Prior therapy for metastatic disease, symptomatic untreated brain metastases, organ allograft or prior cell therapy, uveal/ocular melanoma, and chronic systemic steroid therapy are not permitted. The dual primary efficacy endpoints are BIRC-assessed (RECIST v1.1) objective response rate (ORR) and progression-free survival (PFS). Key secondary efficacy endpoint is overall survival. Additional secondary efficacy endpoints include BIRC-assessed complete response (CR) rate, duration of response (DOR), and event-free survival (EFS); investigator-assessed ORR, PFS, CR rate, DOR, EFS, and PFS2; and safety as characterized by severity and seriousness of treatment-emergent adverse events and relationship to study drug. Exploratory endpoints include in vivo T-cell persistence (unique CDR3 sequences in peripheral blood mononuclear cell [PBMC] over time) and correlative biomarkers (eg, lifileucel phenotypic and functional characteristics; lifileucel, tumor, and PBMC gene expression profiles; tumor mutational landscape). The study will enroll globally, with initial sites in Europe, North America, and Australia.Trial registration: NCT05727904Citation Format: Sajeve Thomas, Young Ki Hong, Yazan Samhouri, James Larkin, David J. Olson, Gino K. In, Victoria Atkinson, Philip Lammers, Andrew J. Furness, Juan Martin-Liberal, Patrick Terheyden, Andrew S. Poklepovic, Ryan H. Nguyen, Idit Peretz, Marcus Butler, Adnan Khattak, Lavinia Spain, E.M. Gaughan, Melissa Wilson, John W. Dubay, Anja Williams, Stephanie Goff, Gary C. Doolittle, Jason Chesney, Friedrich Graf Finckenstein, Jeffrey Chou, Xiao Wu, Giri Sulur, Wen Shi, John Haanen. TILVANCE-301, a phase 3 study of lifileucel tumor-infiltrating lymphocyte (TIL) cell therapy in combination with pembrolizumab vs pembrolizumab alone in treatment-naive unresectable or metastatic melanoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(7_Suppl):Abstract nr CT286.