Phase 1 study of GT101 as an autologous tumor infiltrating lymphocyte (TIL) therapy in advanced solid tumors.

2548 Background: Adoptive cell therapy utilizing autologous TIL has demonstrated efficacy and durable long-term responses in patients with certain advanced solid tumors progressed after conventional therapies. We present data from 14 patients enrolled in the study of GT101, a Phase 1, open-label, single-arm, multicenter trial (NCT05430373) of autologous TIL therapy, aiming to investigate the safety profile, efficiency trend and the duration of response. Methods: The trial was designed with the primary endpoint on evaluating DLT and characterizing the safety profile of GT101 in solid tumor patients measured by the incidence of Grade ≥ 3 treatment-emergent adverse events (TEAEs). The secondary endpoints were to assess efficacy parameters including overall response rate (ORR), disease control rate (DCR), progression-free survival (PFS), duration of response (DOR), and overall survival (OS) according to RECIST v1.1. Results: As of November 10, 2023, a cohort of 14 patients received treatment with a median age of 46.9 and a median of 2.6 lines of prior therapies. Following a standard FC-based lymphodepletion, patients underwent GT101 infusion at doses ≥ 5x10 9 cells with median dose of 3.7x10 10 cells, followed by high-dose IL-2 administration. Most of observed Grade ≥ 3 AEs were related to the FC conditioning regimen and IL-2, including decreased lymphocyte count, decreased white blood cell count, decreased neutrophil count, anemia, pyrexia and decreased platelet count. The majority of these AEs were recovered within 14 days, while a few were downgraded to ≤ Grade 2 within 4 weeks. Among 14 enrolled patients across various indications (small-cell-lung cancer, melanoma, cervical cancer), the ORR was 35.7%. Specifically, 4 pts (28.6%) had a confirmed partial response (PR), 1 pt (7.1 %) achieved complete response (CR), and 8 pts (57.1 %) had stable disease (SD) as their best response. One pt had unconfirmed disease progression (PD). Notably, among 11/14 patients with cervical cancer, the ORR was 45.5% (5/11) with 4 pts (36.4%) achieving PR and 1 pt (9.1 %) achieving CR. Disease control was observed in 10/11 pts (90.9%), and the median PFS was 4.2 months for this cohort. The CR patient underwent a long-term follow-up and the duration of CR and PFS (estimated by Kaplan-Meier) was 24 weeks and 36 weeks, respectively. Post GT101 infusion, T cell expanded robustly in the peripheral blood of all patients with median Tmax 6.83 days and average 15.9 days. Conclusions: In the GT101 Phase 1 study, no treatment-related SAEs and DLT were observed. In patients with heavily pretreated advanced or metastatic solid tumors, GT101 exhibited a manageable safety profile under the treatment protocol of lymphodepletion and high-dose IL-2 and a favorable clinical profile, particularly in cervical cancer, with an encouraging ORR and sustained response duration. Clinical trial information: NCT05430373 .