SURG-101. A pilot study of laser interstitial thermal therapy (LITT) followed by hypofractionated radiation therapy (hypoRT) for patients with recurrent gliomas

BACKGROUND Patients with recurrent glioma have substantial morbidity and mortality. Salvage radiotherapy (RT) is commonly utilized for recurrent gliomas, with salvage hypofractionation (hypoRT) offering acceptable safety and accelerated schedule. Laser interstitial thermal therapy (LITT) feasibly allows for tumor thermoablation, with particular utility in recurrent tumors and symptomatic radiation necrosis. Given that LITT can be provided pre-RT, offers concurrent opportunity for stereotactic biopsy (with tissue-based diagnosis of recurrence versus radionecrosis, preventing the latter patient from receiving further RT), and could thermally sensitize tissue to subsequent RT, therefore, a rationale exists for combining LITT followed by hypoRT (LITT+hypoRT) for recurrent glioma. METHODS A pre-registered (NCT04181684), single-arm, pilot study was conducted for adult patients, aged ≥18 years, with WHO 2016 Grade II-IV glioma with radiographic recurrence, who had received once-prior RT (≥8-week interval, but no more than 1 irradiation); KPS ≥60 at enrolment; and were LITT candidates. Following MR-guided LITT, patients received hypoRT (35Gy/10 fractions, per NRG/RTOG-1205) only after LITT-biopsy confirmed recurrence. HypoRT simulation was performed within 10 days of LITT, and treatment delivered using either photon (IMRT) or proton beam, as appropriate. Primary endpoint was safety, hypothesized that <40% of patients completing full LITT+hypoRT regimen will have Grade ≥3 neurologic treatment-related toxicity (CTCAEv5.0). Secondary endpoints were median progression-free survival (PFS), median overall survival (OS), 6-month PFS, 1-year OS, 2-year OS, overall response (RANO), and quality of life. RESULTS Trial enrolment began in 03/2020 and concluded in 06/2025, with 24 patients having completed protocol-defined LITT+hypoRT regimen so far (one additional patient undergoing further treatments and expected to finish protocol shortly to complete final evaluable cohort). Median age was 62 years (range 29-75), with all non-Hispanic ethnicity patients. Median KPS was 80 (range 60-100). Median LITT-associated hospital length-of-stay was 2 days. Median hypoRT delivery time was 13 days. Pending completion of protocol-defined treatments, final endpoint data will be presented at conference. CONCLUSIONS LITT+hypoRT could be feasible approach for recurrent glioma.