Tumor infiltrating lymphocytes (LM103 infusion) in solid tumors: A phase I trial evaluating clinical and immunological anti-tumor activity.

2537 Background: Tumor-infiltrating lymphocyte (TIL) therapy has shown clinical promise in melanoma, but its applicability across diverse solid tumors in Asian patients remains unclear, and exploring molecular targets to improve anti-tumor responses of TIL are needed. Methods: In the phase I investigator-initiated trial, we evaluated the safety, feasibility, and preliminary efficacy of autologous TIL therapy in twelve patients with advanced melanoma, cervical, lung, or head and neck cancers. Twelve patients who failed with standard treatments were successfully enrolled in the trail from August 2022 to December 2024. The patients received a lymphodepletion therapy which consisted of cyclophosphamide (30mg/kg) for 2 days, followed by fludarabine (25mg/m 2 ) for 5 days, approximately 24 hours before receiving the intravenous autologous TILs infusion, and then received high doses of IL-2 for 6-12 days with the purpose of maintaining T cell survival and proliferation. After a 28 days safety observation, tumor assessment according to RECIST 1.1 was conducted every 6 weeks until 6 months followed by every 12 weeks long-term follow-up. T cell receptor (TCR) sequencing was performed to explore TIL persistence in vivo after TIL infusion. Differential genes were identified via Bulk-RNA sequencing on TILs of responders and non-responders. Target gene knocking out of TIL using CRISPR/Cas9 technology was performed to enhance its anti-tumor function. Results: The most common adverse observed events were fever, anemia, nausea, hypertension, and hyponatremia. The objective response rate (ORR) was 33.3% (4/12), including one complete response (CR) and three partial responses (PR), and the disease control rate (DCR) reached 75% (9/12). Infused TILs persisted in peripheral blood and induced reversed peripheral CD4+T and CD8+T percentages. T cell receptor (TCR) sequencing revealed dynamic clonal remodeling in responders. Transcriptomic profiling of infused TILs identified ASS1 and CEP20 as genes negatively associated with therapeutic activity. CRISPR/Cas9-mediated knockout of these targets enhanced TIL memory phenotypes, cytokine production, and tumor cytotoxicity in vitro and in vivo . Conclusions: Autologous TIL monotherapy is feasible and safe. This study reveals effective TIL therapy in diverse solid tumors of Asian patients and potent anti-tumor activity of genetically enhanced ASS1 KO and CEP20 KO TILs, which offer mechanistic insights that may guide optimization of TIL therapy for broader clinical application. Trial registration number: NCT05366478. Clinical trial information: NCT05366478 .