Singular Immune has developed an innovative recombinant protein-based platform for in vivo cell engineering. This platform enables the modification of various cells to create therapeutic interventions for cancer, autoimmune diseases, inflammatory diseases, and heart diseases. Utilizing this platform, we have successfully demonstrated the feasibility of generating Chimeric Antigen Receptor-Natural Killer (CAR-NK) cells in vivo through systemic infusion of the in vivo CAR (iCAR) protein. The iCAR technology offers an immediate and cell-free CAR therapy option for patients with hematologic or solid organ malignancies, eliminating the need for costly and time-consuming ex vivo expansion of CAR-immune cells.