id_926. IMMUNOTHERAPY OF GLIOBLASTOMA – THERAPEUTIC POTENTIAL OF ELIMINATING TUMOR-ASSOCIATED MACROPHAGES
Olga Malik1,2, Natalia Mikołajczuk1,2, Małgorzata Bajor1, Magdalena Winiarska1, Julia Maroszek3,4, Christopher Forcados5,6, Sébastien Wälchli5, Maciej Szydłowski3, Marta Kłopotowska1
1 Department of Immunology, Mossakowski Medical Research Institute, Polish Academy of Sciences, Warsaw, Poland
2 Immunooncology Students' Science Association, Medical University of Warsaw, Warsaw, Poland
3 Department of Experimental Hematology, Institute of Hematology and Transfusion Medicine, Warsaw
4 Centre of Postgraduate Medical Education, Doctoral School, Warsaw, Poland
5 Translational Research Unit, Section of Cellular Therapy, Department of Oncology, Oslo University Hospital, Oslo, Norway
6 Institute of Clinical Medicine, Faculty of Medicine, University of Oslo, Oslo
INTRODUCTION: Immunotherapies in treatment of Glioblastoma (GBM) are an attractive strategy, but they face numerous challenges, including highly immunosuppressive tumour microenvironment (TME). Among the many factors in the TME, tumour-associated macrophages (TAM) play a key role in tumour progression and resistance to therapies. Targeting TAMs appears to be an attractive approach to improve therapeutic strategies in GBM. In our studies, we identified a marker specific for TAMs, representing a novel potential target for TAMs depletion. We designed CAR-T cell construct directed against it and evaluated its efficacy in eliminating macrophages in vitro.
AIM(S): Overall objective of the project is to verify therapeutic potential of eliminating TAMs in GBM with CAR T cell strategy.
METHOD(S): Macrophages were generated either from human monocytic cell line THP1 or from primary human monocytes isolated from buffy coats, and differentiated with PMA and M-CSF, respectively. Macrophages were polarized towards TAMs with IL-4, IL-10 or by coculture with GBM cells (U251, U87, DK-MG) in a transwell system or with conditioned medium collected from GBM cultures. Surface antigens and induction of CAR-T target protein on macrophages were evaluated with flow cytometry and Western blotting.
RESULTS: We established a research model to study the interaction between GBM, TAMs and immune cells, mimicking the natural TME. In this model we confirmed changes in macrophages towards M2-like phenotype with increased level of CD206 antigen after co-culture with supernatants from U87 cells. In this group, we also observed the induction of protein-of-interest recognized by our CAR-T cell.
CONCLUSIONS: We confirmed induction of mentioned CAR T cell target on macrophages conditioned with GBM line which is a rationale for testing the CAR-T therapy directed against this antigen. We aim to expand our research model to test patient derived GBM cell lines exhibiting a stem cell phenotype and evaluate a panel of CAR constructs for their anti-TAM effectiveness.
FINANCIAL SUPPORT: The research was conducted as part of a grant Opus NCN 2022/45/B/NZ6/02588.