TRTH-23. FEASIBILITY AND SAFETY OF SURGICAL BIOPSY FOR PATIENTS WITH DIPG: PRELIMINARY RESULTS FROM DIPG-BATS

Abstract

INTRODUCTION: The DIPG Biology and Treatment Study (DIPG-BATS) incorporated a surgical biopsy at presentation and stratified patients to receive FDA-approved agents chosen on the basis of specific biologic targets. METHODS: Subjects were enrolled in the DIPG-BATS trial if the imaging appearance of the tumors had typical features of a DIPG. Surgical biopsies were performed after enrollment and prior to definitive treatment. Subjects were all treated with conventional fractionated external radiotherapy, and bevacizumab. Subjects were stratified to receive erlotinib or temozolomide, both agents, or neither agent. Whole-genome sequencing (WGS) and RNA-sequencing were performed on tumor samples but not used for treatment planning. RESULTS: Fifty-three patients were enrolled at 23 participating institutions, of which 50 underwent biopsy. The median age was 6.4 years, with a male to female ratio of 24::29. Surgical biopsies were performed using standard stereotactic techniques with a transcerebellar approach. There were no deaths attributed to the surgical procedure. Two patients experienced grade 3 toxicities during the procedure (one patient with apnea and one with hypertension). One patient experienced a neurologic deficit (left hemiparesis) that did not recover. Of the 50 patients biopsied, 46 provided sufficient tissue to perform the assays (92%, two-stage exact binomial 90% confidence interval 83–97%). CONCLUSIONS: Surgical biopsy of DIPGs is technically feasible, associated with acceptable risks, and can provide biologic data that informs treatment decision making.