CTIM-28. MDNA55, AN INTERLEUKIN-4 RECEPTOR TARGETED IMMUNOTHERAPY, FOR RECURRENT GBM DELIVERED BY CONVECTION ENHANCED DELIVERY (CED). (12th November 2021) - Sampson, John
Abstract: BACKGROUND: MDNA55 is an IL4R-targeted toxin in development for treatment of recurrent glioblastoma (rGBM). MDNA55 binds to IL4R expressed by tumor cells and non-malignant cells of the tumor microenvironment. METHOD: MDNA55-05 was an open-label, single-arm study of MDNA55 delivered by CED as a single treatment in patients with 1st or 2nd recurrence following de novo GBM, IDH wild type status and not indicated for resection at relapse. Dose volumes (up to 60mL) and concentration of MDNA55 (1.5 to 9.0 μg/mL) were studied. RESULTS: MDNA55 showed an acceptable safety profile at all doses tested. Median OS (mOS) amongst all subjects was 11.9 months, OS-24 was 20%, and PFS-12 was 27%. Among subjects expressing high levels of IL4R (irrespective of MDNA55 dose) and low levels of IL4R expression administered high dose (≥ 180μg) of MDNA55 (IL4R hi + IL4R lo/hd ), mOS further improved to 14.0 months with OS-24 of 20%. Unmethylated MGMT promoter status did not affect MDNA55 treatment outcomes. In the IL4R hi + IL4R lo/hd population (N=17), mOS was 14.9 months with OS-24 of 22%. Following treatment with high concentrations of MDNA55 (6.0 or 9.0 μg/mL), transient (median of 3 cycles) low dose Avastin (5mg/kg q2w or 7.5mg/kg q3w) was used for symptom control and steroid sparring. Among these subjects, mOS amongst all comers (N=9) and the IL4R hi + IL4R lo/hd group (N=8) increased to 21.8 and 18.6 months with OS-24 of 44% and 38%, respectively. CONCLUSIONS: MDNA55 shows potential to benefit all rGBM patients treated at high dose irrespective of IL4R expression. In the 1:1 randomized Phase 3 trial, the study will enrol two-thirds of subjects in the SOC arm from a matched external control arm. Unlike conventional RCTs, the hybrid design sets a new precedent for GBM trials, allowing robust OS analysis while significantly reducing the number of subjects randomized to SOC arm.