RDTA-20 BRAIN-DIRECTED RADIOTHERAPY IN THE MANAGEMENT OF PATIENTS WITH MELANOMA BRAIN METASTASES TREATED WITH TUMOR-INFILTRATING LYMPHOCYTE (TIL) THERAPY

Abstract PURPOSE Tumor-infiltrating lymphocyte (TIL) therapy is an emerging option for treatment-refractory melanoma. Studies for TIL therapy approval excluded patients with uncontrolled melanoma brain metastases (MBMs). Given the timeline from TIL harvest to infusion and use of lymphodepletion there are concerns about intralesional hemorrhage, intracranial progression and toxicity. There are limited data on management of MBMs during the peri-TIL therapy window and the safety/efficacy of integrating radiotherapy (RT). METHODS We performed a retrospective analysis of patients with advanced melanoma that underwent TIL harvest at a single institution from May to December 2024 with attention to clinical outcomes, RT parameters and adverse events (CTCAEv5.0) related to TIL therapy or RT. Patients with MBMs were stratified by receipt of RT and timing of development of MBMs relative to TIL harvest. RESULTS 9 patients with MBMs and undergoing TIL harvest were identified. Median time from TIL harvest to infusion was 2.1mo and median follow-up post-harvest was 4.4mo. Two patients had known MBMs and underwent RT >3mo prior to TIL harvest. 55% (5 of 9) of patients developed new MBMs during the window from TIL harvest to infusion. 67% (6 of 9 patients) underwent brain-directed RT. Of note, 50% of patients that underwent RT had evidence of possible intralesional bleed noted on brain MRI prior to RT. RT-related toxicity was minimal with grade 1-2 fatigue, grade 1 headaches and no radiographic or symptomatic radiation necrosis. There were no intracranial bleeding events after TIL harvest. Extracranial, regional brain and irradiated/local control was 44%, 67%, 83%, respectively. CONCLUSION Our experience suggests that treatment of MBMs with RT in patients undergoing TIL therapy is feasible and safe. Given the risk of intracranial progression or development of new MBMs between TIL harvest and infusion, RT is an option as a consolidative ‘bridging’ therapy for intracranial disease control.