Abstract
PurposeConjugation of nanocarriers with antibodies that bind to specific membrane receptors that are overexpressed in cancer cells enables targeted delivery. In the present study, we developed and synthesised two PAMAM dendrimer-trastuzumab conjugates that carried docetaxel or paclitaxel, specifically targeted to cells which overexpressed HER-2.MethodsThe 1H NMR, 13C NMR, FTIR and RP-HPLC were used to analyse the characteristics of the products and assess their purity. The toxicity of PAMAM-trastuzumab, PAMAM-doc-trastuzumab and PAMAM-ptx-trastuzumab conjugates was determined using MTT assay and compared with free trastuzumab, docetaxel and paclitaxel toward HER-2-positive (SKBR-3) and negative (MCF-7) human breast cancer cell lines. The cellular uptake and internal localisation were studied using flow cytometry and confocal microscopy, respectively.ResultsThe PAMAM-drug-trastuzumab conjugates in particular showed extremely high toxicity toward the HER-2-positive SKBR-3 cells and very low toxicity towards to HER-2-negative MCF-7 cells. As expected, the HER-2-positive SKBR-3 cell line accumulated trastuzumab from both conjugates rapidly; but surprisingly, although a large amount of PAMAM-ptx-trastuzumab conjugate was observed in the HER-2-negative MCF-7 cells. Confocal microscopy confirmed the intracellular localisation of analysed compounds. The key result of fluorescent imaging was the identification of strong selective binding of the PAMAM-doc-trastuzumab conjugate with HER-2-positive SKBR-3 cells only.ConclusionsOur results confirm the high selectivity of PAMAM-doc-trastuzumab and PAMAM-ptx-trastuzumab conjugates for HER-2-positive cells, and demonstrate the utility of trastuzumab as a targeting agent. Therefore, the analysed conjugates present an promising approach for the improvement of efficacy of targeted delivery of anticancer drugs such as docetaxel or paclitaxel.
Highlights
Since their development, researchers have recognised the potential of nanocarriers as drug delivery systems
In human epidermal growth factor receptor-2 (HER-2)-positive metastatic breast cancer (MBC) patients, three doses peer week of docetaxel (100 mg/m2) given in combination with trastuzumab resulted in a high overall response rate (ORR), overall survival (OS), response duration, time to progression and time to treatment failure (TTF), and the toxicity of the drug combination was only slightly increased compared with docetaxel alone [3]
Trastuzumab provides specificity against human epidermal growth factor receptor 2 (HER-2), which is overexpressesed in various cancers including breast cancer; taxanes provide cytotoxic effects and the PAMAM dendrimer protects the whole conjugate in the circulatory system and provides specific drug release in the tumour environment when linked with an anticancer drug via a pH-sensitive linker
Summary
Researchers have recognised the potential of nanocarriers as drug delivery systems. ; paclitaxel, which is the preferred single chemotherapeutic agent for recurrent or metastatic breast cancer according to National Comprehensive Cancer Network (NCCN) guidelines [4], resulted in improved progression-free survival (PFS) of HER-2positive patients when administrated at a dosage of 80 mg/m2 weekly in combination with a trastuzumab monoclonal antibody at 4 mg/kg (loading dose, followed by weekly administration of 2 mg/kg), compared with paclitaxel alone [5]. To introduce thiol groups into G4 dendrimer surface, the primary amine groups were reacted with a 10:1 mol excess of Traut’s reagent in 0.1 M PBS buffer, at room temperature under N2 for 1 h pH 8.0. The final stoichiometric ratio for PAMAM-drug-trastuzumab conjugate was 1:1:1
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
