Abstract CT569: Combination of reovirus (pelareorep) and granulocyte-macrophage colony-stimulating factor (GM-CSF) alongside standard chemoradiotherapy and adjuvant chemotherapy (temozolomide) for patients with glioblastoma multiforme (GBM): Long term follow up results of the ReoGlio phase Ib trial

Abstract

Abstract Background: Oncolytic viruses are of increasing interest as an immunologic approach to treating glioma. We previously reported safety data from a phase Ib, open-label study of intravenous pelareorep with GM-CSF alongside standard chemoradiotherapy in newly diagnosed glioblastoma and confirmed that the combination is tolerable. Following agreement from the relevant ethics authorities we have now completed long term follow up data on all patients treated in the study to investigate whether there is a signal of impact on survival. METHODS: 15 patients with newly diagnosed GBM were treated with GM-CSF 50μg subcutaneously on days 1-3 and pelareorep on days 4-5 in weeks 1 and 4 of chemoradiotherapy, and subsequently in week 1 of each adjuvant temozolomide course: 7 patients received 1x1010TCID50 (dose level 1); 8 received 3x1010TCID50 (dose level 2). The primary objective was to determine the maximum tolerated dose of pelareorep and GM-CSF with standard chemoradiotherapy. Following end of study patients were followed up as per institutional practice. Ethical approval was granted to collect survival data in all patients who survived beyond study closure up to June 2021. Results: We showed that using intravenous pelareorep with GM-CSF alongside standard chemoradiotherapy in patients with GBM was tolerable with 87% of patients completing treatment as planned. Survival data analysis showed that median OS was 12.6 months for patients in dose level 1 and 16.1 months in dose level 2, giving median OS for all patients 13.1 months. It was notable however that a small number of patients survived beyond 24 months. The 24-month survival estimate for all patients was 33%, 16.7% for dose level 1 and 50% for dose level 2. One patient in dose level 2 remains alive at 42 months. Conclusion: We previously reported that intravenous delivery of pelareorep with standard chemoradiotherapy is tolerable in newly diagnosed GBM. Although based on small numbers, these long-term follow up data suggest that this may be an active combination in a subset of GBM patients and further randomized studies are warranted. Citation Format: Susan C. Short, Jessica Kendall, Anthony Chalmers, Catherine McBain, Alan Melcher, Adel Samson, Rachel Phillip, Sarah Brown. Combination of reovirus (pelareorep) and granulocyte-macrophage colony-stimulating factor (GM-CSF) alongside standard chemoradiotherapy and adjuvant chemotherapy (temozolomide) for patients with glioblastoma multiforme (GBM): Long term follow up results of the ReoGlio phase Ib trial [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr CT569.