Abstract 3726: Design of personalised polymer based combination therapeutics for advanced stage breast cancer patients

Our objective is to engineer tumour-targeted polymer-based combination therapies specifically designed to treat metastatic breast cancer (BC) in a personalised manner. Our strategy is to develop novel multicomponent polymer conjugates and assess structure activity relationships in clinically relevant models to understand mechanisms of action. Furthermore, we are searching for novel drug combinations, including tumour-derived exosome release pathway inhibitors due to their association with metastasis and tumour drug resistance mechanisms. NCA polymerization techniques have allowed us to precisely control the synthesis of well-defined star-based (STP) and linear (LTP) polypeptidic architectures. After fluorescence labelling, we studied our systems in vitro demonstrating a much more rapid uptake for STP through clathrin-coated mediated endocytosis. pK and biodistribution in healthy mice revealed renal excretion profiles and greater terminal and accumulation half-lives for STP architectures when compared to the LTP. Remarkably, we also observed clear accumulation in immune system-related organs including the spleen and lymph nodes (LN) (up to 40% ID/g tissue accumulation in the LN after i.v. administration). This is possibly due to their inherent structural and morphological features, such as their size (≈100nm), highly negative z-potential values, and/or hydrophilic surfaces. These data highlight the great potential of our stabilized self-assemblies as carriers to target LN metastasis, cancer immunotherapy, or immune system-related approaches, such as vaccination. In parallel, we have performed a High Throughput Screening to select synergistic drug combinations to be used in polymer-based combination approaches through rationally designed linkers that confer adequate drug release kinetics. To perform this approach we selected four metastatic human BC cell lines representing clinical BC subtypes. All cell models have been fully characterized regarding their Cathepsin B activity, intracellular pH, as well as oestrogen, progesterone, Her2 receptors, GSH and exosomes levels; all representing patient-specific biomarkers. Cell viability and exosomes release modulation have been studied following treatments and several drug combinations have been selected for each specific BC subtype. With selected drug combinations different linking chemistry has been designed. We have studied a combination conjugate with the chemotherapeutic agent conjugated to PGA through two different length pH-labile hydrazone linkers. This provided different therapeutic outputs in cells and in a metastatic immunocompetent orthotopic breast cancer model, not only for the primary tumor but also for metastasis progression. The results obtained so far open up a wide range of opportunities for the currently unsuccessful clinical approaches to target LN metastasis and cancer immunotherapy. Citation Format: Ana Arminan, Zoraida Andreu, Juan J Arroyo-Crespo, David Charbonnier, Esther Masia, Fernanda Rodriguez-Otomin, Aroa Duro-Castano, Vicent J Nebot, Maria J Vicent. Design of personalised polymer based combination therapeutics for advanced stage breast cancer patients [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 3726.