BCMA-specific fibronectin type III (FN3) domains, BCMA-targeting chimeric antigen receptors (CARs) comprising the FN3 domains, and engineered BCMA-targeting immune cells expressing the CARs are described. Also described are nucleic acids and expression vectors encoding the FN3 domains and the CARs, recombinant cells containing the vectors, and compositions comprising the engineered immune cells. Methods of making the FN3 domains, CARs, and engineered immune cells, and methods of using the engineered immune cells to treat diseases including cancer are also described.
