Antibody-nucleic acid conjugates - linking siRNAs to antibody

2014 Fiscal Year Research-status Report

• Project/Area Number: 26860075
• Research Institution: Hokkaido University
• Principal Investigator: セレスタ アジャヤラム 北海道大学, 薬学研究科(研究院), その他 (10626500)
• Project Period (FY): 2014-04-01 – 2016-03-31
• Keywords: monoclonal antibody / Antibody Drug Conjugate / Dendrimer / siRNA

Outline of Annual Research Achievements

This research is intended to develop a promising delivery system for siRNA and/or oligonucleotides using monoclonal antibody (mAb) for target specificity. The aim for this year was to explore a potential linker for oligonucleotides to be conjugated with antibody. Because of the high nucleic acid loading capacity of dendrimer through electrostatic complexation, it has been chosen as the linker between antibody and siRNAs. Dendrimers can release ‘payloads’ from the endosome through the phenomenon of ‘proton sponge effect’. The antibodies for the research viz, Herceptin (Transtuzumab) and Human IgG1-kappa were obtained from Gene Techno Science Co. Ltd. For a successful conjugation between antibody and dendrimer, their surfaces were appropriately modified and various cross-linking approaches were examined. Furthermore, antibody-fragments were also considered for the conjugation. In spite of many favorable properties of antibody-fragments over full antibody, a key limitation of their systemic use is their short half-life in circulation. This limitation can be overcome by pegylation. Monofunctional polyethylene glycols of various lengths were appropriately modified to load into the dendrimer. The modifications of the dendrimer and the synthesis of antibody-dendrimer conjugate are successfully accomplished, however further considerations are required to improve the synthetic yield and to control the number of dendrimers per antibody.

Current Status of Research Progress

2: Research has progressed on the whole more than it was originally planned.

Reason

The synthesis of antibody-dendrimer conjugate is accomplished as scheduled. The modification of dendrimer for the introduction of cross-linkers and imaging agents was achieved with good synthetic control. The required siRNAs ‘payload’ were either synthesized or purchased. With all the required components of the designed nanoparticle in hand, the research can be proceeded to in vitro experiments.

Strategy for Future Research Activity

An electrostatic complexation between the antibody-dendrimer conjugate and siRNA is planned for the preliminary in vitro experiment to check the cell delivery efficiency of the conjugate. The cell internalization of the conjugate can be monitored by fluorescent markers. The in vitro experiment will be conducted by a collaboration with Gene Techno Science Co. Ltd which has a well-equipped laboratory for the purpose. Further improvement of the antibody-dendrimer conjugate will be carried out according to the results. Furthermore, synthetic methods will be optimized to control the number of dendrimers per antibody and number of siRNAs per antibody-dendrimer conjugate.

Causes of Carryover

平成26年度中に全額使用済みであるが、
年度末に購入した物品の支払いが本報告書の
作成時点で反映されていないため。

Expenditure Plan for Carryover Budget

上記のとおり、平成26年度中に全て使用済みである。