DDEL-19. DRUG-TUMOR RESIDENCE TIME DRIVES EFFICACY OF CONVECTION-ENHANCED DELIVERY IN H3 K27-ALTERED DIFFUSE MIDLINE GLIOMA

Abstract Advancements in understanding H3 K27-altered diffuse midline glioma (DMG) biology have not yet translated into effective therapies for these tumors likely due to delivery challenges across the blood-brain barrier (BBB) and variable tumor genetics. This study systematically probes convective-enhanced delivery (CED) as a means to administer small molecule drugs directly to DMG tumors, circumventing constraints imposed by the BBB. Our findings emphasize the necessity of strategic drug selection and pharmacokinetic analysis in refining CED approaches, advocating for precision medicine techniques specialized for DMG. We demonstrate that while most small molecule drugs are rapidly cleared from the brain following CED, their retention and effectiveness are substantially improved by co-administration of systemic efflux transporter (ET) inhibitors such as everolimus. The synergistic potential of combining everolimus with topotecan or ponatinib offers a novel therapeutic pathway, advocating for further investigation into this DMG management strategy.