Generation of chimeric antigen receptor macrophages from human pluripotent stem cells to target glioblastoma

Background

Glioblastoma (GBM) is an aggressive brain tumor giving a poor prognosis with the current treatment options. The advent of chimeric antigen receptor (CAR) T-cell therapy revolutionized the field of immunotherapy and has provided a new set of therapeutic options for refractory blood cancers. In an effort to apply this therapeutic approach to solid tumors, various immune cell types and CAR constructs are being studied. Notably, macrophages have recently emerged as potential candidates for targeting solid tumors, attributed to their inherent tumor-infiltrating capacity and abundant presence in the tumor microenvironment.

Materials and methods

In this study, we developed a chemically defined differentiation protocol to generate macrophages from human pluripotent stem cells (hPSCs). A GBM-specific CAR was genetically incorporated into hPSCs to generate CAR hPSC-derived macrophages.

Results

The CAR hPSC-derived macrophages exhibited potent anticancer activity against GBM cells in vitro.

Conclusion

Our findings demonstrate the feasibility of generating functional CAR-macrophages from hPSCs for adoptive immunotherapy, thereby opening new avenues for the treatment of solid tumors, particularly GBM.

Advancing cellular immunotherapy with macrophages

Cell-based immunotherapies have become an exciting avenue for cancer treatment, particularly CAR T cells, which have shown great success in treating hematological malignancies. However, the limited success of T cell-based approaches in treating solid tumors has sparked interest in alternative cell types that could be used for solid tumor immunotherapy. Recent research has pointed to macrophages as a potential solution, given their ability to infiltrate solid tumors, exhibit a strong anti-tumor response, and persist long-term in the tumor microenvironment. Although early attempts with ex-vivo activated macrophage-based therapies failed to translate into clinical success, the field has revolutionized with the recent development of chimeric antigen receptor-expressing macrophages (CAR-M). While CAR-M therapy has reached the clinical trial stage, several challenges still need to be overcome before the therapy can become a reality. Here we review the evolution of macrophage-based cell therapy and evaluate recent studies and developments, emphasizing the potential of macrophages as cellular therapeutics. Furthermore, we also discuss the challenges and opportunities associated with using macrophages as a basis for therapeutic interventions.