Abstract A021: Vaccination with autologous, nonattenuated, live glioblastoma cells induces potent peripheral and intratumoral anti-tumoral responses: A first-in-human study

Abstract

Abstract Glioblastoma (GBM), which grows uninhibited in the brain, almost never metastasizes outside of it. The rare occurrence (<0.5%) of overt GBM extracranial metastasis is paradoxically associated with significantly enhanced patient survival. We previously reported that the highly malignant F98 Fischer-rat GBM model, which grows aggressively in the brain, spontaneously regresses when injected subcutaneously as live unattenuated cells. The peripheral growth and regression of live glioma cells markedly enhanced the survival of all rats, and cured (survival >9 months) approximately 50% of rats challenged with F98 cells intracranially. The results in the F98 model were corroborated in the CNS1 astrocytoma model in Lewis rats. The fraction of cured rats in both models were the highest reported in published literature. We found that the spontaneous rejection of live glioma cells inoculated in peripheral sites was immune-mediated. This location-biased immune response was termed “Split Immunity”—a tumor that thrives in an immune-privileged site (e.g., the brain) may be inhibited by injecting live unmodified tumor cells in a site that is not privileged, generating protective immunity that spreads back to the privileged site.To evaluate the applicability of the “Split Immunity” approach in humans, we ran a first-in-human (FIH) study on two recurrent GBM patients. The patients were vaccinated subcutaneously, initially with autologous irradiated tumor cells, and then with autologous, non-attenuated, live tumor cells. The treatment caused no serious adverse events. The injected live tumor cells did not grow at the inoculation site, nor did they spread metastatically, as evaluated by choline 18F PET-CT. Standard biochemical and hematologic blood tests showed no treatment-related adverse effects. Both patients’ quality of life (QoL) questionnaires demonstrated subjective improvements in self-evaluated “global health status.” The treatment had demonstrated several signs indicative of efficacy. MRI evaluation using “treatment response assessment maps” (TRAM) demonstrated strong increases in the “treatment-response” component following live-cell vaccination, compatible with “pseudo-progression-like” responses in both patients. Using elaborate 8-color flow cytometric panels, we detected potent tumor-cell specific polyfunctional activation in 2.5% and 5% of peripheral cytotoxic T-cell (CTL) and T helper cells (Th), respectively, 3 days following live-cell vaccination. Flow cytometric immune mapping of all intratumoral immune cell subsets showed major changes from baseline that had occurred shortly after live-cell vaccinations. We observed major increases (8 to 200 fold) in both patients of all monitored intratumoral dendritic cell (DC) subsets (CD1c+ and CD141+ myeloid DC, CD123+ plasmacytoid DC). Patient-1 showed the highest frequency of intratumoral CD56brt natural killer (NK) cells from all previously fully mapped brain tumor patients. Patient-2’s intratumoral CTL and Th were increase by 6- and 17-fold, respectively. Patient-2’s CD141+ and CD1c+ myeloid DC had exhibited upregulated CD86 maturation marker following treatment. Overall, the immune infiltrate following treatment in Patient-2 exceeded the immune infiltrates found in 42 previously fully-mapped brain tumor patients. The flow cytometric results were corroborated by the patients’ immunohistochemistry data. Patient-2, who had been treated by a tighter vaccination protocol than Patient-1, had survived 19 months after GBM recurrence, which is considerably longer than the median 6- to 8-month survival of recurrent GBM patients. Taken together, the accumulated FIH results are suggestive of safety and efficacy of the “Split Immunity” approach. Based on the these results, we have recently received an ethical approval for a phase IIa clinical trial on 8 recurrent- and 4 newly-diagnosed GBM patients. Citation Format: Ilan Volovitz, Nati Shapira, Rachel Grossman, Zvi Ram. Vaccination with autologous, nonattenuated, live glioblastoma cells induces potent peripheral and intratumoral anti-tumoral responses: A first-in-human study [abstract]. In: Proceedings of the Fourth CRI-CIMT-EATI-AACR International Cancer Immunotherapy Conference: Translating Science into Survival; Sept 30-Oct 3, 2018; New York, NY. Philadelphia (PA): AACR; Cancer Immunol Res 2019;7(2 Suppl):Abstract nr A021.