P12.18.a Ttfields and Radiosurgery Guided by Early Tyrosine-Pet (Ttarget) in Recurrent Glioblastoma: A Prospective, Single-Arm, Externally-Controlled Trial

BACKGROUND Treatment options for recurrent glioblastoma (rGBM) are limited. MATERIAL AND METHODS Here we performed a prospective, single-arm trial to evaluate the efficacy and safety of combined tumor treating fields (TTFields) and stereotactic radiosurgery (SRS) guided by tyrosine-PET in 40 patients with rGBM. The primary outcome was one-year overall survival (OS) compared to two sets of historical propensity-matched controls from EF-11 [cohort 1 (n=40) and 2 (n=13)]. RESULTS The one-year survival rate was 67.5% (95%CI 50.7-79.7) for patients treated with SRS and TTFields compared with 43.6% (95%CI 27.9-58.3) for cohort 1 and 30.8% (95%CI 9.5-55.4) for cohort 2. 87.5% of patients showed stabilization or reduced tumor enhancement in T1-GAD images. The ORR was 10% in the TTaRGeT population. Radiation necrosis was grade >1 in only 1 case, and there was no treatment-related mortality. CONCLUSION Combining TTFields with tyrosine-PET-guided SRS significantly improves survival and tumor control in rGBM patients. ClinicalTrials.gov NCT04671459.