Combinatorial Checkpoint Blockade and Laser Interstitial Thermal Therapy: A Single Center Study

INTRODUCTION: Immune checkpoint blockade (ICB) has gained acceptance as a life-extending therapy in a variety of solid tumor types. For patients with brain metastases, combination stereotactic radiosurgery (SRS) and ICB remains an area of clinical equipoise. Similarly, for recurrent or difficult-to-access intracranial lesions, safety and synergy of laser interstitial thermal therapy (LITT) and ICB has yet to be explored. METHODS: In accordance with an IRB-approved protocol, all patients undergoing LITT at a tertiary center from 2015-2022 were retrospectively reviewed. Patients who received ICB within 6 weeks of LITT were included in the LITT + ICB cohort. Demographic, clinical, and survival data were collected. RESULTS: Combination LITT and ICB occurred in 25 patients with clinically recurrent tumors. The median cohort age was 62 (40-78) and 12 (48%) were female. The median KPS was 80 (50-100). The most common primary pathology was non-small cell lung cancer (NSCLC) in 15 patients (60%), followed by melanoma in 3 (12%); two high-grade gliomas were additionally treated. The majority of the cohort (24 patients, 96%) recieved single agent ICB in combination with LITT, with pembrolizumab (12, 48%) and nivolumab (6, 24%) most common. Median duration between ICB dosing and LITT was 2.85 (0.85-5.84) weeks. Ten patients (40%) had evidence of immune-related adverse events attributable to ICB, with only 1 event > grade 3 according to Common Terminology Criteria; 17 (68%) had a pre-LITT steroid requirement. Intracranial adverse events related to LITT were rare, with median overall survival for the cohort of 8.6 months (1.4-26.4 months). CONCLUSIONS: Combination LITT and ICB appears safe and feasible. No prospective studies have compared cytoreduction with LITT to LITT + ICB; construction of a matched NSCLC cohort is ongoing. Exploration of the immune consequences of LITT + ICB is needed.