Effective suppression of tumour cells by oligoclonal HER2-targeted delivery of liposomal doxorubicin

Synergistic effect of combined antibodies targeting distinct epitopes of a particular tumour antigen has encouraged some clinical trial studies and is now considered as an effective platform for cancer therapy. Providing several advantages over conventional antibodies, variable domain of heavy chain of heavy chain antibodies (VHH) is now major tools in diagnostic and therapeutic applications. Active targeting of liposomal drugs is a promising strategy, resulting in enhanced binding and improved cytotoxicity of tumour cells. In the present study, we produced four anti-HER2 recombinant VHHs and purified them via native and refolding method. ELISA and flow cytometry analysis confirmed almost identical function of VHHs in refolded and native states. Using a mixture of four purified VHHs, PEGylated liposomal doxorubicin was targeted against HER2-overexpressing cells. The drug release was analyzed at pH 7.4, 6.4 and 5.5 and dynamic light-scattering detector and TEM micrograph was applied to characterize...