Amyloid Fibril-Specific Chimeric Antigen Receptor Macrophages (CAR-M) Based Immunotherapy for Amyloid Clearance in Light Chain Amyloidosis

This proposal is focused on the development of a novel immunotherapy using amyloid fibril specific chimeric antigen receptor engineered macrophages (CAR-M) to treat amyloid light-chain (AL) amyloidosis. AL amyloidosis remains incurable with the lack of effective therapy to clear the insoluble amyloid fibrils. Inspired by the revolutionary advances of using synthetic transmembrane CAR receptors to reprogram T cells towards antibody directed killing of cancer cells, and given the fact that macrophage dependent phagocytosis is the key mechanism in amyloid fibril clearance, we hereby designed a novel AL amyloid fibril specific CAR engineered macrophage therapy to target the insoluble amyloid deposits and achieve effective fibril clearance through phagocytosis. Our initial effort showed that transduction and expansion of the primary mouse macrophages are technically impractical to generate enough cells for the proposed in vivo study. Therefore, we developed and optimized the production protocol of generating primary human CAR macrophages. The AL amyloid phagocytosis activity of the human CAR macrophages was validated by in vitro phagocytosis assay. Next, the in vivo activity of the human CAR macrophages was tested on a novel animal model to enable the real-time in vivo monitoring of amyloid targeting and clearance by CAR macrophages. Patient derived AL amyloid fibril extract was conjugated by Dylight fluorescence dye and then s.c. injected into NSG-SGM3 mice, which support the human macrophages expansion in mice. Our result showed that AL amyloid burden could be quantitatively monitored by this novel model. Our results also suggested that CAR macrophages inoculation route needs to be further explored to facilitate their targeting to the subcutaneously injected amyloidoma.