Precision targeting of CXCR4⁺ leukemia cells by a humanized MMAE-nanoconjugate in an AML mouse model

Acute myeloid leukemia (AML) presents major clinical challenges due to chemoresistance and high relapse rates, primarily driven by therapy-resistant leukemic stem cells (LSCs) within the bone marrow. To address this issue, we developed T22-HSNBT-H6-MMAE, a novel humanized nanoconjugate designed to target CXCR4^⁺ cells while delivering the cytotoxic payload monomethyl auristatin E (MMAE). CXCR4 signaling pathway plays a critical role in LSC survival by preserving stem-like properties and activating protective mechanisms that promote treatment resistance. Moreover, CXCR4 is overexpressed in approximately 50 % of AML patients and is associated with poor prognosis and high relapse rates. We evaluated the therapeutic potential of T22-HSNBT-H6-MMAE using in vitro assays with AML cell lines and primary patient samples, as well as in vivo studies in a disseminated AML mouse model. Our results demonstrated that T22-HSNBT-H6-MMAE exerts a CXCR4-dependent cytotoxic effect through mitotic catastrophe and apoptosis induction in CXCR4^⁺ AML cell lines. In vivo evaluation in a disseminated CXCR4^⁺ AML mouse model showed potent antineoplastic activity, with complete suppression of leukemic dissemination and significantly prolonged survival, all without systemic toxicity. Notably, the nanoconjugate remained effective even in models with extensive bone marrow involvement and exhibited activity against diverse patient-derived CXCR4^⁺ AML blasts, while sparing healthy donor bone marrow and peripheral blood mononuclear cells (PBMCs) from significant toxicity. Collectively, these findings highlight T22-HSNBT-H6-MMAE as a promising therapeutic candidate for a broad range of AML patients, offering selective antineoplastic activity against CXCR4^⁺ leukemic cells.