IL1RAP antibody-drug conjugates potently target primary and metastatic disease in multiple oncofusion-driven cancers

Gene fusions generated by chromosomal rearrangements function as oncogenic drivers in human cancers. We previously showed that EWSR1-ETS oncofusions of Ewing sarcoma (EwS) directly induce surface expression of IL1 receptor accessory protein (IL1RAP), which along with limited expression in healthy tissues except placenta nominate IL1RAP as a promising EwS immunotherapy target. We therefore engineered antibody-drug conjugates (ADCs) with different cytotoxic payloads to target IL1RAP. ADCs potently blocked tumor growth and induced durable regression of EwS xenografts in mice, and diminished metastatic dissemination in vivo. Moreover, we show that other oncofusions also induce IL1RAP expression in diverse cancers, including NPM-ALK in anaplastic large cell lymphoma (ALCL), and ETV6-NTRK3 in multiple tumor types. IL1RAP expression rendered these malignancies similarly vulnerable to IL1RAP-targeting ADCs, which effectively blocked growth of ALCL xenografts and syngeneic ETV6-NTRK3+ sarcomas. Lack of detectable normal tissue toxicity, including in non-human primates, support the further clinical translation of IL1RAP-targeting ADCs.