Finally, we confirmed that IL1RL1 was up-regulated in eight pediatric AML PDX models regardless of MLL oncofusion and that in vivo treatment with anti-hIL1RL1 T-BsAb BC282 reduced leukemia to undetectable levels within 5 weeks as opposed to no treatment, human T cells, and T cells with control T-BsAb BC283 therapies. Here, KMT2A is linked to leukemia.