The effectiveness of current AML treatments is abysmal yielding only an overall 5-year survival rate of ~25%, and it has been hypothesized that the treatment may be more durable if leukemic stem cells (LSC) are eliminated. IL1RAP is a compelling target because it is expressed on LSC in majority of AML patients, but not on healthy hematopoietic stem cells. Also, suppressing IL1RAP expression in AML cells can greatly inhibit tumor cell growth/survival. From SBIR Phase I contract, the contractor developed various antibodies against IL1RAP having functional blocking properties, a higher affinity for membrane-bound IL1RAP relative to the secreted form, and tumor cell inhibition activities.