Anti-IL-1RAP scFv-mSA-S19-TAT fusion carrier as a multifunctional platform for versatile delivery of biotinylated payloads to myeloid leukemia cells

Acute myeloid leukemia (AML) is an aggressive blood cancer with frequently poor clinical outcomes. This heterogeneous malignancy encompasses genetically, molecularly, and even clinically different subgroups. This makes it difficult to develop therapeutic agents that are effective for all subtypes of the disease. Therefore, a selective, universal, and adaptable delivery platform capable of carrying various types of anti-neoplastic agents is an unmet requirement in this area. Two multifunctional fusion proteins were designed for the delivery of biotinylated cargoes to human myeloid leukemia cells by fusing an anti-IL-1RAP single-chain antibody with streptavidin (tetramer or monomer), a cell-penetrating peptide (CPP), and an endosomolytic peptide in a single biomacromolecule. The designed fusions were analyzed primarily in silico, and the biofunctionality of the selected fusion was fully characterized via several binding assays, hemolysis assay, confocal microscopy and cell cytotoxicity assay after production via the Escherichia coli (E. coli) system. The refolded protein exhibited desirable binding activity to leukemic cells, pure antigen and biotinylated BSA. Further analyses revealed efficient cellular uptake, endosomolytic activity, and nuclear penetration without any detectable cytotoxicity toward normal epithelial cells. The described platform seems to have great potential for targeted delivery of different therapeutics to malignant myeloid cells.