Harnessing genetically engineered hematopoietic progenitor cells to redirect the tumor immune microenvironment against glioblastoma (TEM-GBM Study).

2040 Background: Immunotherapies represent powerful tools that are transforming the treatment of many cancers. However, immune dysfunction in cancer is multifactorial requiring multiple points of action, especially in immunologically-cold tumors. Methods: We have developed a genetically modified, autologous hematopoietic stem cell-based platform designed to deliver Interferon-alpha (IFNa) specifically into the tumor microenvironment through Tie-2 expressing monocytes (Temferon), in order to activate the immune system in an agnostic way against the tumor and re-establish immunosurveillance. Results: As of Jan 2022, 3 escalating doses of Temferon (from 0.5 to 2.0x10 6 /kg) were tested across 15 patients assigned to 5 cohorts affected by newly diagnosed, unmethylated MGMT glioblastoma (GBM). The follow-up range from surgery is 5 – 27 mo (3 – 24 mo after Temferon). In all patients, we observed rapid engraftment of gene modified progenitors and fast recovery from sub-myeloablative conditioning (median engraftment across all the cohorts: Neu D+13, PLT D+14). Temferon-derived differentiated cells, as determined by the presence of vector genomes in the DNA, were found at increasing proportions in blood and bone marrow, reaching up to 30% at 1 mo for the highest dose cohorts tested and persisting up to 18 mo, albeit at lower levels. Despite the significant proportion of engineered cells, only very low median concentrations of IFNα were detected in the plasma (D+30, 5.9; D+90, 8.8pg/mL) and in the CSF (D+30, 1.5; D+90, 2.4pg/mL), indicating tight regulation of vector expression. SAEs were mostly attributed to conditioning chemotherapy (e.g. infections) or disease progression (e.g. seizures). 1 SUSAR (persistent GGT elevation) has occurred. Median OS is 14 mo from surgery (10 mo post Temferon). A patient from cohort 3, had at D+120 disease progression with two distant enhancing lesions, and increased tumor necrosis. One year following Temferon, with no 2nd line therapy added, there was approximately 40% reduction in enhancing tumor volume compared to D+180. Four pts from the low dose cohorts underwent 2nd surgery. Vector genomes were detectable in tumor biopsies. Single cell RNA seq performed on CD45+ cells purified from the GBM TME highlighted the presence of an Interferon gene signature in all patients, resulting in macrophage repolarization in some of them. Conclusions: Our interim results show that Temferon is well tolerated, with no dose limiting toxicities identified to date. The results provide initial evidence of Temferon’s potential to modulate the TME of GBM patients. Clinical trial information: NCT03866109.