A preparation of natural killer T (NKT) cells engineered to express a chimeric antigen receptor (CAR) specific for roundabout homolog 1 (ROBO1, Robo1), with potential immunostimulating and antineoplastic activities. Upon administration, the ROBO1-targeted BiCAR-NK/T cells target and bind to ROBO1 expressed on the surface of tumor cells. This induces selective toxicity in ROBO1-expressing tumor cells. ROBO1, a member of the axon guidance receptor family, is often overexpressed in a variety of tumor types. It is involved in axon guidance, cell proliferation, cell motility and angiogenesis.