(166h) Antibody Drug Nanoparticle Induces Synergistic Therapeutic Outcome in Breast Cancer

We explore a combination therapeutic approach of chemo and immunotherapy in exploiting the specificity of antibody conjugated drug nanoparticles for breast cancer therapy. The goal of this work is to engineer antibody-drug nanoparticles (ADNs) comprising of pure anti-cancer drug nanorods (NRs) in the core with a therapeutic monoclonal antibody on the surface of the nanoparticles for specific targeting and synergistic treatments of cancer cells. The ADNs were designed by first synthesizing ~95 nm diameter × ~500 nm long paclitaxel (PTX) NRs using nano precipitation method (Figure 1a,1b). The surface of PTXNRs were functionalized at 2'OH nucleophilic site using carbonyl diimidazole and conjugated to Trastuzumab (TTZ) through the lysine group interaction forming PTXNR-TTZ conjugates. The optimum conjugation efficiency was >95% with the combination of 5 mg/ml PTXNR and 0.5 mg/ml TTZ. The drug NRs along with the antibody conjugated PTXNR-TTZ showed substantial colloidal stability. In vitro cytotoxicity analysis showed PTXNR-TTZ inhibited the HER2-positive breast cancer cells more efficiently than the individual treatment with PTXNR and TTZ . PTXNR-TTZ inhibited >80% of the HER2-positive breast cancer cells whereas in case of HER2-negative breast cancer the inhibition was roughly 50%. In both the cell lines conventional Paclitaxel solution showed resistance with increasing dosage. Whereas, PTXNR monotherapy or PTXNR-TTZ combination treatment had increased toxicity with increasing dosage. PTXNR-TTZ showed a synergistic effect on HER2-positive breast carcinoma. Cell cycle analysis showed PTXNR-TTZ arrested more than 80% of the cancer cells in G2/M phase (Figure 1c). In western blot analysis protein expressions show that the combination treatment with PTXNR-TTZ drug nanoparticle inducing prolonged cell cycle arrest in G2/M phase resulted in apoptosis in HER2-positive breast cancer cells in the intrinsic caspase dependent pathway (Figure 1d).