CTNI-28. FINAL RESULTS OF A PILOT STUDY TO EVALUATE INFUSION RATE ESCALATION TO MAXIMIZE VOLUME OF DISTRIBUTION DURING CONVECTION ENHANCED DELIVERY TO CONTRAST-ENHANCING GLIOBLASTOMA

Abstract

Abstract BACKGROUND Volume of distribution (Vd) during convection enhanced delivery is impacted by the characteristics of the tissue being treated. For Glioblastoma (GBM), Vd is substantially higher in non-contrast enhancing tumor than in contrast enhancing tumor due to higher infusate efflux in enhancing tumor. We hypothesized that increasing the infusion rate could overcome the infusate efflux rate in enhancing tumor to improve the Vd to volume of infusion (Vi) ratio and provide better tumor coverage. METHODS A single center, IRB-approved pilot study was conducted under an IND (held by MAV) to perform rate escalated delivery of Topotecan with Gadolinium-DTPA to contrast-enhancing recurrent GBM (rGBM). A single Cleveland Multiport Catheter was surgically placed into enhancing tumor and then a 4-hour infusion was performed with real-time MRI visualization. Intra- and inter-patient rate escalation was performed. RESULTS 3 patients with rGBM were enrolled and treated. The initial infusion rate for patient 1 was 5 microliters/minute per microcatheter (4 total) and the final infusion rate for the third patient was 20 microliters/minute per microcatheter. We observed partial backflow at this rate and so did not escalate higher. There was coverage of both enhancing and non-enhancing tumor in all cases, and the Vd/Vi ratio ranged from 0.7 to 1.3. Patients tolerated the treatments well; there were no CTCAE Grade 3 or higher treatment related adverse events. CONCLUSIONS The higher efflux rate associate with contrast-enhancing tumor tissue can be overcome with sufficient infusion rate escalation.