Armoring of CAR-Ts with TIM-3 decoy can bypass Galectin-9 (Gal-9) inhibition of T-cell antitumor responses in B-ALL. (1) B-ALL expresses Gal-9, which targets TIM-3 expression on CAR-Ts inducing T-cell apoptosis and suppressing the immune response. (2) Armored CAR-Ts secreting a TIM-3 decoy can avoid this inhibition. TIM-3 decoy binds to Gal-9, neutralizing its effect on CAR-Ts, which are now able to survive the hostile tumor microenvironment and eliminate the B-ALL tumor cells.