Lapatinib in metastatic breast cancer

Emerging Biomarkers and Targeted Therapies in Feline Mammary Carcinoma

Feline mammary carcinoma (FMC) is a common aggressive malignancy with a low survival rate that lacks viable therapeutic options beyond mastectomy. Recently, increasing efforts have been made to understand the molecular mechanisms underlying FMC development, using the knowledge gained from studies on human breast cancer to discover new diagnostic and prognostic biomarkers, thus reinforcing the utility of the cat as a cancer model. In this article, we review the current knowledge on FMC pathogenesis, biomarkers, and prognosis factors and offer new insights into novel therapeutic options for HER2-positive and triple-negative FMC subtypes.

Tyrosine Kinase Inhibitors Are Promising Therapeutic Tools for Cats with HER2-Positive Mammary Carcinoma

Feline mammary carcinoma (FMC) is a common neoplasia in cat, being HER2-positive the most prevalent subtype. In woman’s breast cancer, tyrosine kinase inhibitors (TKi) are used as a therapeutic option, by blocking the phosphorylation of the HER2 tyrosine kinase domain. Moreover, clinical trials demonstrated that TKi produce synergistic antiproliferative effects in combination with mTOR inhibitors, overcoming resistance to therapy. Thus, to uncover new chemotherapeutic strategies for cats, the antiproliferative effects of two TKi (lapatinib and neratinib), and their combination with a mTOR inhibitor (rapamycin), were evaluated in FMC cell lines (CAT-M, FMCp and FMCm) and compared with a human breast cancer cell line (SkBR-3). Results revealed that both TKi induced antiproliferative effects in all feline cell lines, by blocking the phosphorylation of EGFR members and its downstream effectors. Furthermore, combined treatments with rapamycin presented synergetic antiproliferative effects. Additionally, the DNA sequence of the her2 TK domain (exons 18 to 20) was determined in 40 FMC tissue samples, and despite several mutations were found none of them were described as inducing resistance to therapy. Altogether, our results demonstrated that TKi and combined protocols may be useful in the treatment of cats with mammary carcinomas, and that TKi-resistant FMC are rare.

In vitro assessment of the photo(geno)toxicity associated with Lapatinib, a Tyrosine Kinase inhibitor

The epidermal growth factor receptors EGFR and HER2 are the main targets for tyrosine kinase inhibitors (TKIs). The quinazoline derivative lapatinib (LAP) is used since 2007 as dual TKI in the treatment of metastatic breast cancer and currently, it is used as an oral anticancer drug for the treatment of solid tumors such as breast and lung cancer. Although hepatotoxicity is its main side effect, it makes sense to investigate the ability of LAP to induce photosensitivity reactions bearing in mind that BRAF (serine/threonine-protein kinase B-Raf) inhibitors display a considerable phototoxic potential and that afloqualone, a quinazoline-marketed drug, causes photodermatosis. Metabolic bioactivation of LAP by CYP3A4 and CYP3A5 leads to chemically reactive N-dealkylated (N-LAP) and O-dealkylated (O-LAP) derivatives. In this context, the aim of the present work is to explore whether LAP and its N- and O-dealkylated metabolites can induce photosensitivity disorders by evaluating their photo(geno)toxicity through in vitro studies, including cell viability as well as photosensitized protein and DNA damage. As a matter of fact, our work has demonstrated that not only LAP, but also its metabolite N-LAP have a clear photosensitizing potential. They are both phototoxic and photogenotoxic to cells, as revealed by the 3T3 NRU assay and the comet assay, respectively. By contrast, the O-LAP does not display relevant photobiological properties. Remarkably, the parent drug LAP shows the highest activity in membrane phototoxicity and protein oxidation, whereas N-LAP is associated with the highest photogenotoxicity, through oxidation of purine bases, as revealed by detection of 8-Oxo-dG.

Nanoparticle albumin bound Paclitaxel in the treatment of human cancer: nanodelivery reaches prime-time?

Nanoparticle albumin bound paclitaxel (nab-paclitaxel) represents the first nanotechnology-based drug in cancer treatment. We discuss the development of this innovative compound and report the recent changing-practice results in breast and pancreatic cancer. A ground-breaking finding is the demonstration that nab-paclitaxel can not only enhance the activity and reduce the toxicity of chromophore-diluted compound, but also exert activity in diseases considered refractory to taxane-based treatment. This is the first clinical demonstration of major activity of nanotechnologically modified drugs in the treatment of human neoplasms.