zibotentan and Breast-Neoplasms

Recent advances in the understanding of prostate cancer biology and its progression to bone metastasis have led to the development of drugs directed against precise molecular alterations in the prostate tumor cell and host cells in the normal bone environment such as osteoclasts and osteoblasts. Endothelins (ETs) and their receptors have emerged as a potential target in prostate cancer bone metastasis. By activating the ETA receptor, ET-1 is pathogenically involved in facilitating several aspects of prostate cancer progression, including proliferation, escape from apoptosis, invasion, and new bone formation, processes that are general to many malignancies. Notwithstanding, there are a number of features specifically driven by the ET axis in prostate cancer, such as creating and perpetuating a unique interaction between the metastatic prostate cancer cell and the bone microenvironment (osteoblast, osteoclast, and stroma) or altering the equilibrium in pain modulation. These features have led to the preferential clinical evaluation of atrasentan (ABT-627) as a biological therapy in prostate carcinoma, first in hormone-refractory prostate cancer. Biological activity of atrasentan in patients with prostate cancer has been shown by the suppression of biochemical markers of prostate cancer progression in bone, and clinical activity is evidenced by a consistent trend demonstrating a delay in time to disease progression when compared with placebo, especially in patients with bone metastases. Further studies of atrasentan and other selective ET-1 antagonists (ZD4054) are ongoing.

Topics: Antineoplastic Agents; Atrasentan; Bone Neoplasms; Breast Neoplasms; Clinical Trials as Topic; Endothelin Receptor Antagonists; Female; Humans; Male; Prostatic Neoplasms; Pyrrolidines

Endothelin-1 (ET-1) and endothelin A receptor (ETAR) contribute to the development and progression of breast carcinomas by modulating cell proliferation, angiogenesis, and anti-apoptosis. We investigated antitumoral effects of the specific ETAR antagonist ZD4054 in breast cancer cells and xenografts, and assessed antitumoral efficacy of the combinations of ZD4054 with aromatase inhibitors and fulvestrant. Gene expression changes were assessed by quantitative real-time PCR. Cell proliferation was measured using alamarBlue; migration and invasion assays were performed using modified Boyden chambers. Evaluating the antitumoral efficacy of ZD4054 in vivo, different breast cancer models were employed using nude mice xenografts. ZD4054 reduced ET-1 and ETAR expression in MCF-7, MDA-MB-231, and MDA-MB-468 breast cancer cells in a concentration-dependent manner. ZD4054 inhibited invasion by up to 37.1% (P = 0.022). Combinations of ZD4054 with either anastrozole or letrozole produced significant reductions in migration of aromatase-overexpressing MCF-7aro cells (P < 0.05). Combination of ZD4054 with fulvestrant reduced MCF-7 cell migration and invasion by 36.0% (P = 0.027) and 56.7% (P < 0.001), respectively, with effects significantly exceeding those seen with either compound alone. Regarding tumor volume reduction in vivo, ZD4054 (10 mg/kg) was equipotent to fulvestrant (200 mg/kg) and exhibited additive effects with anastrozole (0.5 mg/kg). These data are the first indicating that selective ETAR antagonism by ZD4054 displays antitumoral activity on breast cancer cells in vitro and in vivo. Our data strongly support a rationale for the clinical use of ZD4054 in combination with endocrine therapies.

Topics: Anastrozole; Animals; Antineoplastic Combined Chemotherapy Protocols; Aromatase Inhibitors; Breast Neoplasms; Cell Line, Tumor; Cell Movement; Cell Proliferation; Dose-Response Relationship, Drug; Endothelin A Receptor Antagonists; Endothelin-1; Estradiol; Estrogen Antagonists; Female; Fulvestrant; Gene Expression Regulation, Neoplastic; Humans; Mice; Mice, Nude; Neoplasm Invasiveness; Nitriles; Pyrrolidines; Receptor, Endothelin A; Tamoxifen; Time Factors; Triazoles; Tumor Burden; Xenograft Model Antitumor Assays