A multivalent DNA aptamer specific for the B-cell receptor on human lymphoma and leukemia

Abstract

Long-term survival still eludes most patients with leukemia and non-Hodgkin’s lymphoma. No approved therapies target the hallmark of the B cell, its mIgM, also known as the B-cell receptor (BCR). Aptamers are small oligonucleotides that can specifically bind to a wide range of target molecules and offer some advantages over antibodies as therapeutic agents. Here, we report the rational engineering of aptamer TD05 into multimeric forms reactive with the BCR that may be useful in biomedical applications. Systematic truncation of TD05 coupled with modification with locked nucleic acids (LNA) increased conformational stability and nuclease resistance. Trimeric and tetrameric versions with optimized polyethyleneglycol (PEG) linker lengths exhibited high avidity at physiological temperatures both in vitro and in vivo. Competition and protease studies showed that the multimeric, optimized aptamer bound to membrane-associated human mIgM, but not with soluble IgM in plasma, allowing the possibility of targeting leukemias and lymphomas in vivo. The B-cell specificity of the multivalent aptamer was confirmed on lymphoma cell lines and fresh clinical leukemia samples. The chemically engineered aptamers, with significantly improved kinetic and biochemical features, unique specificity and desirable pharmacological properties, may be useful in biomedical applications.

Use of a conformational switching aptamer for rapid and specific ex vivo identification of central nervous system lymphoma in a xenograft model

“…Aptamer TD05, which binds to the heavy mu chain of membrane bound immunoglobulin in CD20-positive Burkitt's lymphoma cells, has been reported previously [14,19]. In this study, a single stranded DNA linker is added to the existing TD05 aptamer sequence to create the switchable probe "Q-TD05."…”

Aptamer-Facilitated Protection of Oncolytic Virus From Neutralizing Antibodies

“…For these plaque forming assays, nondiluted serum was used in order to mimic the effect of aptamers interacting with other components present in serum and undergoing degradation by nucleases. 32 We have also shown that these multivalent structures decrease the aggregation of the VSV, which may contribute to increasing its infectivity (manuscript in preparation). Furthermore, our degradation experiments showed that the dimeric and tetrameric forms of the aptamers are more stable in serum (Supplementary Figure S6).…”

Ligand-Guided Selection of Target-Specific Aptamers: A Screening Technology for Identifying Specific Aptamers Against Cell-Surface Proteins

“…Therefore, a partially evolved SELEX pool might contain sequences with lower to moderate affinities. However, the affinity of these aptamers could be further enhanced given their high specificity by post-SELEX modification followed by linear multimerization approaches, as described earlier [17]. We are currently investigating the effect of the degree of enrichment of an SELEX pool against whole cells on LIGS to improve LIGS technique.…”

“…We and others have shown that aptamers selected using cell-SELEX compete with the cognate antibody for binding to its target epitope. For example, the aptamer TD05, selected using the cell-SELEX method targeting Burkitt's lymphoma, binds to the heavy chain of membranebound IgM (mIgM) and competes with the anti-IgM antibody, permitting the bound aptamer from the target to be eluted into the solution [17]. Similarly, an RNA aptamer selected against CD71-expressing cells using the hybrid-SELEX method competes with the anti-transferrin antibody [19].…”