CD71-Targeted and ROS-Responsive Micelles for Homoharringtonine Delivery to Enhance Therapeutic Efficiency Against
Yuqian Tang1, Jiaxin Li2, Wu Ye3
1Department of Hematology, West China Hospital, Sichuan University, Chengdu, 610041, People's Republic of China.
Purpose:
The FMS-like tyrosine kinase 3- internal tandem duplication (FLT3-ITD) subtype of acute myeloid leukemia (AML) is associated with poor clinical outcomes. Homoharringtonine (HHT), a natural protein inhibitor, has shown strong activity against FLT3-ITD AML. However, its clinical use is limited by rapid clearance and systemic toxicity. To address these limitations, a CD71-targeted, ROS-responsive micelle (TDTP/HHT) was developed for precise and efficient HHT delivery.
Methods:
CD71 expression was assessed in AML patient samples and cell lines. TDTP/HHT was prepared by self-assembly using a D-peptide ligand (DT7) for CD71 targeting and a ROS-cleavable linker for stimuli-responsive drug release. Cellular uptake, cytotoxicity and signaling pathway inhibition were evaluated in vitro across AML cell lines with distinct FLT3 statuses. The therapeutic efficacy of TDTP/HHT was further validated in a disseminated AML xenograft mouse model.
Results:
Cytotoxicity analysis revealed that FLT3-ITD AML is intrinsically sensitive to HHT. Analysis of patient samples and cell lines revealed high CD71 expression and elevated ROS levels in AML, most predominantly in the FLT3-ITD subtype. The designed TDTP/HHT showed prolonged circulation time, ROS-responsive drug release, and stable targeting capacity. It did not compete with endogenous transferrin for binding sites but instead demonstrated transferrin-promoted cellular uptake. Both in vitro and in vivo studies confirmed that TDTP/HHT significantly inhibited the growth of FLT3-ITD AML cells. Mechanistically, TDTP/HHT suppressed multiple key downstream signaling proteins of FLT3-ITD. In addition, the system also remained active in CD71-high FLT3-WT AML cells, although higher HHT concentrations were required.
Conclusion:
This study presents a novel targeted nanodrug that exploits the intrinsic HHT sensitivity of FLT3-ITD AML cells and their characteristic high CD71 expression and elevated ROS levels. Therefore, this platform is particularly suited for the treatment of FLT3-ITD AML while potentially applicable to other AML subtypes with high CD71 expression. By enabling specific intracellular accumulation of HHT and multitarget inhibition of FLT3 signaling pathways, this system achieves enhanced anti-AML efficacy both in vitro and in vivo, offering strong potential for future clinical translation.
