Trogocytosis contributes tumor escape and limits tumoricidal activity in hPSCs-derived CAR macrophages

Pluripotent stem cells (PSCs) derived chimeric antigen receptor macrophages (iCAR-Ms) hold great potential for immunotherapy, particularly against T-cell malignancies which are challenging in CAR-T therapy. Here, we generate human iCAR-Ms targeting CD5 for treating T-cell malignancies. iCAR-Ms display tumoricidal activities against various T- malignant cells expressing CD5 such as Jurkat, SUP-T1 and primary tumor cells. However, The iCAR-M tumoricidal activities are largely dependent on CD5 density on tumor cells. The escaped tumor cells show reversible CD5 loss without changes on its mRNA level. Meanwhile, the retrieved iCAR-Ms show little reduced tumoricidal activities against new tumor cells expressing CD5. Based on time lapse imaging and transcriptional analysis, we show that iCAR-Ms mainly medicate trogocytosis while less phagocytosis when approach tumor cells. Our data reveal trogocytosis as an important limitation factor in iCAR-M tumoricidal activities and tumor escape, providing a rational to develop enhanced CAR-M for immunotherapies.