To mimic the molecular specificity and cell selectivity of
monoclonal antibody (mAb) binding while decreasing size, nanomolecules (selective high-affinity
ligands; SHALs), based on in silico modeling, have been created to bind to
human leukocyte antigen-DR (HLA-DR10), a signaling receptor
protein upregulated on the malignant B-lymphocytes of
non-Hodgkin's lymphoma and
chronic lymphocytic leukemia. SHALs were synthesized with a
biotin or
DOTA chelate (1,4,7,10-tetraazacyclododecane-N,N',N'',N'''-tetraacetic acid), using a solid-phase
lysine-polyethyleneglycol backbone to link sets of
ligands shown previously to bind to
HLA-DR10. Using cell-binding and death assays and confocal microscopy, SHAL uptake, residualization, and cytocidal activity were evaluated in
HLA-DR10 expressing and nonexpressing live, human
lymphoma cell lines. All of the SHALs tested were selective for, and accumulated in, expressing cells. Reflecting binding to
HLA-DR10 inside the cells, SHALs having the Ct
ligand (3-(2-([3-chloro-5-trifluoromethyl)-2-pyridinyl]oxy)-anilino)-3-oxopropanionic
acid) residualized in expressing cells greater than 179 times more than accountable by cell-surface membrane HLA-DR10. Confocal microscopy confirmed the intracellular residualization of these SHALs. Importantly, SHALs with a Ct
ligand had direct cytocidal activity, similar in potency to that of Lym-1 mAb and
rituximab, selectively for HLA-DR10 expressing
lymphoma cells and xenografts. The results show that SHALs containing the Ct
ligand residualize intracellularly and have cytocidal effects mediated by HLA-DR10. These SHALs have extraordinary potential as novel molecules for the selective targeting of
lymphoma and
leukemia for molecular
therapy and imaging. Further, these SHALs can be used to transport and residualize
cytotoxic agents near critical sites inside these malignant cells.