P858 An open-label, multi-center trial of INO-5401 and INO-9012 delivered by electroporation (EP) in combination with cemiplimab in subjects with newly-diagnosed glioblastoma (GBM)

Background GBM is one of the most deadly cancers and treatment is surgery, followed by radiation (RT) and temozolomide (TMZ) daily during RT followed by cycles of TMZ for select patients.1 New immunotherapies, such as checkpoint inhibition, may benefit patients with GBM. T cell-enabling therapies, in combination with checkpoint inhibition, may improve overall survival (OS). In this study, a novel antigen-specific T cell-generating therapy, INO-5401 (synthetic DNA plasmids encoding for human telomerase [hTERT], Wilms Tumor-1 [WT-1] and prostate specific membrane antigen [PSMA]), plus INO-9012 (synthetic DNA plasmid encoding for IL-12), with the PD-1 checkpoint inhibitor, cemiplimab, was given to patients with newly-diagnosed GBM to evaluate tolerability, immunogenicity and clinical efficacy of the combination. Methods Phase I/II, single arm, two cohort study (A: MGMT Promoter Unmethylated, B: MGMT Promoter Methylated). The primary objective is to evaluate the safety of INO-5401 and INO-9012 followed by EP with CELLECTRA® 2000 in combination with cemiplimab. Secondary objectives include the evaluation of preliminary clinical efficacy and immunogenicity. Treatment is with 9 mg INO-5401 with 1 mg INO-9012 every three weeks (Q3W) for four doses, then Q9W; and cemiplimab (350 mg IV Q3W). RT is given as 40 Gy over three weeks; TMZ is given concurrent with radiation (Cohorts A and B), followed by maintenance TMZ (Cohort B). Results 52 patients were enrolled onto this study; 32 in Cohort A and 20 in Cohort B. 18 were women (35%) and 47 were white (90%). The median age was 60 years (range 19-78 years). The most common Grade ≥3 adverse events were elevations in alanine or aspartate aminotransferase (ALT/AST; 5 patients), and tumor inflammation/edema (5 patients); there was one Grade 5 unrelated event of urosepsis. The only related SAE reported in more than one patient was pyrexia. 22 patients (42%) reported immune-related AEs, with the most common being elevations in ALT or AST (8 patients), and were reported most commonly within the first nine weeks of treatment. The safety profile was consistent with that of patients with GBM and of checkpoint inhibitors. ELISpot assessments performed to date demonstrated the majority of patients have T cell responses to INO-5401. PFS6 was 75% (95% CI 56.6, 88.5) in Cohort A (preliminary; Cohort B pending). Conclusions INO-5401 + INO-9012 with cemiplimab has an acceptable safety profile, is immunogenic and is potentially efficacious in patients with newly-diagnosed GBM. This combination is promising; survival results will be updated next year. Trial Registration NCT03491683. Ethics Approval This study was approved by New York University institution’s Ethics Board; approval number i17-00764. References Stupp R, et al. (2009). Lancet Oncology 10(5): 459–466.