Final data from the phase 2a single-arm trial of SurVaxM for newly diagnosed glioblastoma.

Abstract

2037 Background: Newly diagnosed glioblastoma (nGBM) routinely treated with surgery, radiation, and temozolomide (TMZ), still result in early progression and near-universal lethality within 5 years. Tumor associated “survivin” is expressed in >95% of nGBM and targetable by SurVaxM immunotherapy. Results from the recently completed multi-center phase 2a trial of SurVaxM in nGBM are presented. Methods: nGBM patients (pts) were enrolled at 5 trial sites. Eligibility criteria included: age ≥ 18, Karnofsky performance status ≥70, IHC confirmation of survivin expression, expression of HLA-A*02, A*03, A*11 or A*24 MHC-I alleles and residual contrast enhancement of ≤1 cm3 by MRI within 72h post-resection. Pts received standard TMZ chemoradiation followed by initiation of 4 priming doses of SurVaxM (500 mcg in emulsion with Montanide ISA 51, every 2 weeks) with 100 mcg sargramostim. Maintenance doses of SurVaxM-Montanide plus sargramostim were thereafter administered every 12 weeks. Adjuvant TMZ was administered for at least 6 cycles, after at least the first dose of SurVaxM and beginning no sooner than 28 days after completion of chemoradiation. Pts were monitored by MRI every 8 weeks, and progression was assessed using modified RANO criteria. The primary endpoint was 70% progression free survival (PFS) at 6 mos. Primary analyses of median PFS (mPFS) and median overall survival (OS) were measured from first immunization. Safety, tolerability, and immune responsiveness were also determined. Results: 63 pts with nGBM were enrolled, comprised of 38 males and 25 females with a median age of 60 years. The cohort was consistent with the 4 commonly observed primary molecular GBM subtypes (classical, mesenchymal, neural and proneural). SurVaxM was well tolerated, with no serious adverse events. A strong positive correlation, accounting for censoring, was observed between PFS and OS of all pts (r = 0.79; 95% CI (0.66,0.87)). SurVaxM was immunogenic and produced survivin-specific CD8+ T-cells and antibody (IgG) titers in both methylated and unmethylated MGMT pts and both groups showed clinical benefit. Conclusions: SurVaxM appeared to be safe and well-tolerated in pts with nGBM. SurVaxM was effective at stimulating survivin-specific immune responses and the primary endpoint was met. SurVaxM represents a promising therapy for nGBM, including for those pts with unmethylated MGMT genes. For pts treated with SurVaxM, PFS may be an acceptable surrogate for OS. Clinical trial information: NCT02455557. [Table: see text]