Abstract
INTRODUCTION: Recurrent GBM is a diffuse disease and resection (R) alone does not routinely provide durable local control (LC) or prolonged overall survival (OS). We hypothesized R plus immediate radiation (RT) utilizing a novel brachytherapy device might achieve more durable LC and thereby secondarily improve OS. METHODS: From 2/2013-2/2018, locally recurrent GBM were treated in a single arm trial (ClinicalTrials.gov, NCT#03088579) of R plus immediate implantation of a surgically targeted radiation therapy (STaRT) device utilizing Cs-131 in bioresorbable collagen tiles (GammaTile, GT Medical Technologies, Tempe AZ USA). RESULTS: 28 patients (pts) were treated, 20 at first recurrence (range 1-3). Median age 58 (range 21-80), KPS 80 (60-100), female:male ratio 10:18. Median OS was 10.7 mo., radiographic LC 8.8 mo., and no first failure was local. MGMT, KPS, and sex were non-predictive. Post hoc analysis disclosed after R+STaRT, 17 pts (54%) received > 1 cycle of Sys (“Sys+”) and 13 (46%) did not (“Sys- “). Sys was given as adjuvant, salvage, or both, either alone or in combination. 15 pts received bevacizumab (BEV), 12 temozolomide (TMZ) and 8 lomustine (CCNU). Median OS (mo.) for Sys+ vs. Sys- was 15.1/6.5 (hazard ratio (HR) .38, p=.017); OS for BEV+ vs. BEV- was 16.7/4.5 (HR .38, p=.017), TMZ+ vs. TMZ- 17.5/6.7 (HR .40, p=.025) and for CCNU+ vs. CCNU- 17.5/7.9 (HR .61, p=.25), respectively. LC was 11.4 mo. for Sys+ vs. 2.1 mo. for Sys- (HR .44; p=.16). Three attributed AE occurred, 1 wound infection requiring surgery and 2 radiation brain effects, managed medically. CONCLUSION: Post hoc analysis suggests R+STaRT+Sys may have the potential to impact OS in locally recurrent GBM, possibly by allowing sufficient time for effective but biologically slower treatments to have an impact. FDA clearance was received in 2018 for recurrent intracranial neoplasms and in 2020 for newly-diagnosed malignant brain tumors.