442 Repurposing FDA-approved PI3K/Akt Inhibitors to Improve Anti-Cancer Drug Brain Uptake in Glioblastoma Resection Models

Abstract

OBJECTIVES/GOALS: We have shown that glioblastoma upregulates blood-brain barrier drug efflux transporters via a mechanism that likely involves TNFα and PI3K/Akt. Our goal is to repurpose FDA-approved PI3K/Akt inhibitors to increase anticancer drug brain concentrations, which holds the potential for translation into the neuro-oncology clinic. METHODS/STUDY POPULATION: GL261 Red-FLuc and MBR525-1 Red-FLuc cells (2μl; 2.5K cells/μl; 1μl/min) were injected into the right hemisphere of 8-week old female J:NU mice (coordinates relative to bregma: AP -2 mm, ML -2 mm, DV -3 mm). Tumor burden was assessed weekly with IVIS® Spectrum in vivo imaging; tumor volume and invasiveness were measured by MRI and histopathology, respectively. On day 14 post-injection, mice received 5-ALA (200 mg/kg ip), and tumors were resected with a 2 mm punch biopsy tool and surgical fluorescence microscope (ex/em: 405/635nm). Drug efflux transporter expression and activity in isolated brain capillaries were determined by Western blot and substrate fluorescence assays, respectively. Cytotoxicity was assessed after 48-hour drug incubation using CyQuant MTT Cell Proliferation Assay kits. RESULTS/ANTICIPATED RESULTS: IC50 values of temozolomide, lapatinib, alpelisib, and miltefosine were N/A, 32, 20, and 190 μM for GL261 Red-FLuc cells and N/A, 49, 36, and 148 μM for MBR525-1 Red-FLuc cells, respectively. Median survival of GL261 Red-FLuc mice was 26.5d and significantly increased to 34d with resection (p=0.116). In GBM mice, drug efflux transporter expression and activity levels in brain capillaries isolated from the contralateral hemisphere were significantly upregulated compared to sham controls. Furthermore, treatment with FDA-approved PI3K/Akt inhibitors, alpelisib and miltefosine, significantly reduced drug efflux transporter expression and activity to control levels. In PK and survival studies, we expect that PI3K/Akt inhibition will increase brain uptake of anticancer drugs and prolong GBM mouse survival. DISCUSSION/SIGNIFICANCE: We have previously shown that PI3K/Akt inhibition reduces P-gp/BCRP levels in brain capillaries. Here, we vertically extend this strategy by repurposing the FDA-approved PI3K/Akt inhibitors alpelisib/miltefosine to improve brain uptake of anticancer drugs in GBM resection models.