(M1430-01-04) Implementing siRNA Therapy Targeted at MLL-AF4 in Acute Lymphoblastic Leukemia

Purpose: The therapeutic promise of short-interfering RNAs (siRNAs) in addressing genetic diseases is immense but is currently hindered by delivery challenges, notably their transport across cell membranes [1]. This issue is particularly pronounced in lymphocytes, where the minimal surface area and limited cytoplasm complicate siRNA delivery due to their negative charge and size [2].

Methods: To overcome these hurdles, we engineered a novel lipopolymer-based delivery system incorporating lipid-tethered polyethyleneimine (PEI). By modifying low molecular weight PEI (1.2 kDa) with aliphatic lipids, we formulated a platform of lipopolymer that yields nanocomplexes with siRNA, namely lipopolymer nanoparticle (LPNP), to facilitate efficient siRNA uptake into lymphocytes. This method utilizes the positive charge of PEI to bind with the negatively charged siRNA, enhancing cellular uptake through lipid-mediated mechanisms. We tested the delivery system's efficacy in targeting a fusion oncogene MLL-AF4 in acute lymphoblastic leukemia (ALL) cell lines RS4;11 and SEM through in vitro and in vivo experiments.

Results: The MLL-AF4 LPNP demonstrated significant therapeutic potential, achieving efficient siRNA delivery into both ALL cell lines, RS4;11 and SEM; significant target gene silencing including induction of apoptosis. These effects led to a marked reduction in colony formation in vitro and a substantial decrease in leukemia burden in vivo. Additionally, further evaluation of LPNP revealed significant leukemia suppression and improved survival outcomes in the RS4;11 xenograft model.

Conclusion: This research introduces a promising lipopolymer-based system for siRNA delivery as a potential strategy for developing alternative therapy for ALL.

References: (1) Ansari, A. S.; K.C., R.; Morales, L. C.; Nasrullah, M.; Meenakshi Sundaram, D. N.; Kucharski, C.; Jiang, X.; Brandwein, J.; Uludağ, H. Lipopolymer Mediated SiRNA Delivery Targeting Aberrant Oncogenes for Effective Therapy of Myeloid Leukemia in Preclinical Animal Models. Journal of Controlled Release 2024, 367, 821–836. https://doi.org/10.1016/J.JCONREL.2024.02.018.
(2) Nasrullah, M.; Kc, R.; Nickel, K.; Parent, K.; Kucharski, C.; Meenakshi Sundaram, D. N.; Rajendran, A. P.; Jiang, X.; Brandwein, J.; Uludağ, H. Lipopolymer/SiRNA Nanoparticles Targeting the Signal Transducer and Activator of Transcription 5A Disrupts Proliferation of Acute Lymphoblastic Leukemia. ACS Pharmacol Transl Sci 2024. https://doi.org/10.1021/ACSPTSCI.4C00336

Acknowledgements: Financial support is provided by the Canadian Institute of Health Research, Alex’s Lemonade Stand Foundation, Canadian Cancer Society, Rachel Mandel Scholarship in Lymphoma and Other Blood Cancers, and RJH Biosciences (Edmonton, AB)/MITACS. RKC and HU declare a conflict of interest due to ownership in RJH Biosciences.