CSF1R-CAR T cells induce CSF1R signaling and promote target cell growth

ABSTRACT: Chimeric antigen receptor (CAR) T cells have revolutionized the landscape of cancer therapy, demonstrating unprecedented success in treating relapsed or refractory blood cancers. Previous studies of the mechanisms underlying the interactions and responses of CAR T cells and their targets have focused on the activation of CAR T cells and attempted to optimize CAR design to increase efficacy, while ignoring tumors and their responses to CAR ligation. We evaluated the signaling of a second-generation, ligand-based CAR built from the colony-stimulating factor 1 (CSF1) ligand to target the CSF1 receptor (CSF1R) on CSF1R-expressing target cells, and compared it to a conventional single-chain variable fragment (scFv)–based CAR against the B-cell antigen CD19 using stable isotope labeling by amino acids in cell culture (SILAC) co-culture with phosphotyrosine (pY) enrichment and liquid chromatography–tandem mass spectrometry (LC–MS/MS).. We showed that ligation of CSF1R-expressing THP-1 cells with CSF1R-CAR T cells stimulated CSF1R-like signaling in the THP-1 cells, whereas no target cell signaling response was observed after the ligation of CD19-CAR T cells with target Raji cells. In experiments with small-molecule inhibitors of the tyrosine kinase Lck, actin polymerization, and CSF1R, we found that CAR-induced CSF1R signaling in THP-1 cells depended exclusively on the kinase activity of CSF1R with no participation from T cell activation. Consistently, CSF1R-CAR T cells promoted THP-1 cell growth at low effector-to-target (E:T) ratios but prevented THP-1 cell growth at high E:T ratios. Our data provide evidence for an unintended consequence of CARs: CAR-induced signaling in cancer cells. These data may have broad implications for the choice of CAR antigen for optimal clinical efficacy.

INSTRUMENT(S):

ORGANISM(S): Homo Sapiens (human)

TISSUE(S): T Cell

DISEASE(S): Acute Leukemia

SUBMITTER: Arthur Salomon  

LAB HEAD: Arthur Robert

PROVIDER: PXD058576 | Pride | 2025-11-21

REPOSITORIES: Pride