CTNI-20. FEASIBILITY OF SINGLE-PASS STEREOTACTIC NEEDLE BIOPSY IN RECURRENT GLIOBLASTOMA PATIENTS TO SUPPORT CLIA-CERTIFIED TUMOR PHARMACODYNAMICS FOR A PHASE 0/2 CLINICAL TRIAL

Abstract

Abstract BACKGROUND In neuro-oncology clinical trials, pharmacodynamic (PD) analysis of tumor tissue before and after experimental therapy is challenging. Today, Phase 0 studies in brain tumor patients typically employ archival tissue from a prior resection as the baseline PD comparator. However, the time-interval between tissue acquisitions can be months to years and often includes confounding exposure to other therapies. Here, we demonstrate the feasibility of a pre-treatment, single-pass stereotactic needle biopsy to support CLIA-certified genetic screening and tumor PD analysis in a Phase 0/2 clinical trial. METHODS In support of an ongoing Phase 0/2 ‘trigger’ trial testing CDK4/6 plus ERK1/2 inhibition in recurrent glioblastoma (GBM), a single-pass stereotactic biopsy was completed in select patients prior to enrollment. Each biopsy yields six tissue cores for immunohistochemistry (IHC) and genetic characterization. Using CLIA-certified protocols, genomic DNA (gDNA) was extracted from two cores, followed by library preparation and next-generation sequencing of a customized panel of 37 genes (IvySeq). In the four remaining cores, IHC staining was performed for RB, pRB, pERK, pS6, CDKN2A, MIB-1, ClCas-3 and pH2AX. RESULTS Single-pass stereotactic needle biopsies were collected from five recurrent GBM patients. No intraoperative, perioperative, or radiographic evidence of morbidity was observed. 800-2400ng of gDNA was isolated from each stereotactic biopsy. IvySeq analysis detected CDKN2A deletion, ATRX loss, and mutations in IDH, PTEN and TP53 genes. Based on IHC and genetic analyses of the biopsied samples, three patients were enrolled into the Phase 0/2 clinical trial and baseline value were used for PD analysis. CONCLUSION Single-pass stereotactic needle biopsy is a feasible and safe strategy to collect pre-treatment tissue in support of a Phase 0 clinical trial, enabling CLIA-certified genetic analysis for trial screening and tumor PD analysis.