Immunological correlates from phase I study of CARv3-TEAM-E in patients with recurrent glioblastoma (GBM): INCIPIENT trial.

2008 Background: Chimeric Antigen Receptor (CAR) T cells for glioblastoma (GBM) have been limited by the challenge of targeting a single tumor antigen in a heterogeneous disease. To address this barrier, we generated a novel engineered T-cell product (CARv3-TEAM-E) that targets the EGFRvIII antigen while also secreting T-cell-Engaging Antibody Molecules (TEAMs) against wild-type EGFR. Methods: The INCIPIENT clinical trial is a first-in-human study of CARv3-TEAM-E in patients with recurrent GBM (NCT05660369). Patients were treated with intraventricular CARv3-TEAM-E T cells (10E6 cells per infusion). A subset of patients were conditioned with lymphodepleting chemotherapy (LDC) consisting of cyclophosphamide and fludarabine. Immune cells were profiled in the cerebrospinal fluid (CSF) and peripheral blood of patients by flow cytometry. Results: CAR T cells were detected in the CSF of all patients for an average of 33.6 days ( SD = 10.33). Granulocytes, NK cells, B cells, and monocytes appeared in the CSF immediately after infusion, decreasing to low levels over the course of several weeks. TEAM-positive T cells persisted in CSF until (median) day 33.6 ( SD = 10.8) with a range of 21-56 days. CAR T cells were transiently detected in the peripheral blood of 9/10 patients at an average of 14 days ( SD = 3.5) after infusion. Prior to infusion, CAR T cells were predominantly CD4-positive and remained as such in the CSF over time. Those in the periphery exhibited CD4-to-CD8 polarization. Of patients who received multiple infusions, 3 out of 6 had CAR-positive T cells in the CSF after a second infusion, although their persistence was short-lived and was not detected in the periphery following repeat infusions. LDC increased engraftment of CAR T cells in CSF but not in peripheral blood. Patients with poor CAR persistence demonstrated the development of anti-CARv3-TEAM-E antibodies in the CSF and serum, which increased with reinfusion. Conclusions: Following initial infusion, intraventricularly delivered CARv3-TEAM-E T cells were detected in the CSF and peripheral blood in patients with recurrent GBM. Reduced persistence was observed with subsequent infusions. This corresponded with the emergence of anti-CARv3-TEAM-E antibodies in treated patients. Clinical trial information: NCT05660369 .