Authors
Claire Victoria Ong, Sabina Kaczanowska, Harrish Ganesh, Emily San Andres Montalvan, Wei Ju, Jim Cronk, Sneha Ramakrishna, Rosandra Kaplan
Introduction
Chimeric antigen receptor T cells (CAR-Ts) are an emerging immunotherapy that have remarkable efficacy against leukemias and lymphomas but limited success against solid tumors. We conducted a phase I clinical trial (NCT 02107963) of GD2 CAR-T (GD2-CAR.OX40.28.z.ICD9) administration to children and young adults with neuroblastoma and, for the first time, osteosarcoma. While all patients progressed and were switched to alternative therapy, we observed a significant association between good CAR-T expanders and expression of C-X-C Motif Chemokine receptor 3 (CXCR3) on monocytes detected in pretreatment apheresis. This study seeks to uncover the possible interactions between CXCR3 and CAR-Ts that may alter CAR-T function and ultimately lead to better CAR-T expansion. We hypothesize that CXCR3+ monocytes induce functional change in CAR-Ts resulting in improved expansion.
Methods
To recapitulate the interaction between tumor, CAR-Ts and monocytes, we took 143Bs (osteosarcoma cell line) and GD2 CAR-Ts and co cultured them with THP-1s (a monocytic leukemia cell line) that were either untransduced (UTD) or transduced via lentivirus to express CXCR3 (CXCR3+). The ratio of UTD or CXCR3+ THP-1s to CAR-Ts and 143Bs was varied between co cultures. Enzyme-linked immunoassay (ELISA) for interferon gamma (IFNy) expression was run as a proxy measurement for CAR-T cell activity. Flow cytometry was used to assess for expression of activation and exhaustion markers. Differences between UTD and CXCR3+ co cultures were evaluated for statistical significance via unpaired t-test.
Results
We observed that CXCR3 was elevated on GD2 CAR-Ts co cultured with CXCR3+ monocytes. This pattern was seen most prominently in CD4+ CAR-Ts, but also subtly in CD8+ T-cells. Exhaustion markers CD39 and LAG3 were elevated in CAR-Ts co cultured with CXCR3+ monocytes. Additionally, CAR-Ts co cultured with CXCR3+ monocytes displayed greater activity via elevated IFNy expression.
Conclusion
We conclude that GD-2 CAR-T cells co cultured with CXCR3+ monocytes express elevated exhaustion markers due to possible increased activity when in the presence of CXCR3+ monocytes. Additionally, we suspect that elevated CXCR3 expression on CAR-Ts co cultured with CXCR3+ monocytes may be helping CAR-Ts better target tumor cells, thus leading to improved expansion. If CXCR3 can improve CAR-T cell function, this could lead to better optimization of CAR-Ts against solid tumors and create a viable treatment option for neuroblastoma and osteosarcoma patients.
References
N/A
Want to have your abstract featured here? ACP will begin accepting submissions for the 2025 Competitions on or about October 1, 2024. Find out more at ACP Online.
Back to the August 2024 issue of ACP IMpact