Laser interstitial thermotherapy (LITT) for newly diagnosed and recurrent glioblastoma: Safety, effectiveness and association between time to initiation of chemotherapy postprocedure and outcome (P4.155)

Objective: We investigated LITT safety, effectiveness and if time to initiation of chemotherapy post-LITT was associated with progression free survival (PFS) and overall survival (OS). Background: LITT is used for cytoreduction of unresectable glioblastoma and is associated with blood brain barrier disruption with an increased permeability peak at 2 weeks Design/Methods: Records of glioblastoma patients who underwent LITT at our institution between 2013–2017 were reviewed. Patients with inadequate follow-up or no further treatment after LITT were excluded. A time-to-event analysis was performed to investigate the association between PFS, OS and the time to initiation of chemotherapy after LITT. Results: The study included 21 patients; 17 recurrent glioblastoma (rGBM) (6 secondary glioblastoma), 4 newly diagnosed glioblastoma (nGBM). Median age was 53.6 (19.8–64.9) years. Three patients (14%) had isocitrate dehydrogenase (IDH)-1 mutation by immunohistrochemistry and two patients had unknown IDH status. Pre- and post-operative median KPS were 90 (60–100) and 80 (40–100) respectively. Eleven patients had difficulty weaning steroids (4 patients initiated steroids peri-operetively, 7 patients prior to surgery). For rGBM post-LITT median PFS was 3.36 months (95% CI (0.21, 0.51)) and median OS was 18.48 months (95% CI (0.66, NA)) with 5 deaths. Median PFS and OS for nGBM has not been reached. Eighteen patients (86%) received post-LITT chemotherapy of which eight initiated treatment >3 weeks post-LITT due to poor functionality (6), pregnancy (1), and patient choice (1). Among the patients receiving chemotherapy, time to initiation of chemotherapy was not associated with PFS or OS. Chemotherapy in rGBM cohort included lomustine (6), temozolomide (5), bevacizumab (3), bevacizumab + lomustine (1), lapatinib (1), and Novo-TTF (1). Median time to initiation ofi bevacizumab (4 patients) after LITT was 30.5 (17–45) days, without complications. Conclusions: LITT may be an effective cytoreductive treatment for glioblastoma. Timing of onset of chemotherapy after LITT for glioblastoma is not associated with PFS or OS. Disclosure: Dr. Maraka has nothing to disclose. Dr. Bastos has nothing to disclose. Dr. O9Brien has received personal compensation for consulting, serving on a scientific advisory board, speaking, or other activities with Yes, Advisory Board/Consultant with AbbVie Inc. Dr. Liu has nothing to disclose. Dr. Starostina has nothing to disclose. Dr. Alfaro-Munoz has received personal compensation for consulting, serving on a scientific advisory board, speaking, or other activities with AbbVie. Dr. Ganesh has nothing to disclose. Dr. De Groot has received personal compensation for consulting, serving on a scientific advisory board, speaking, or other activities with Celldex (rindopepimit); Deciphera Pharmaceuticals (see above), AbbVie (ABT-414), FivePrime Therapeutics, Inc. (cabiralizumab),Genentech (bevacizumab); Celldex (see above); Foundation Medicine, Inc. (diagnostics, genomic testing platform); Novogen (GDC-008. Dr. De Groot has received royalty, license fees, or contractual rights payments from DSMB: VBL Therapeutics (VB111); Novella (ICT-107). Dr. De Groot holds stock and/or stock options in Ziopharm Oncology, Gilead. Dr. De Groot has received research support from Sanofi-Aventis (XL765); Astrazeneca (AZD 0156); EMD-Serono (M2698, Pimasertib); Eli Lilly (numerous durgs); Novartis (numerous durgs); Deciphera Pharmaceuticals DCC2618, altiratinib), Mundipharma (EDO-S101). Dr. Prabhu has nothing to disclose.