Apomab, a fully human agonistic antibody to DR5, exhibits potent antitumor activity against primary and metastatic breast cancer.

Abstract

Apomab, a fully human agonistic DR5 monoclonal antibody, triggers apoptosis through activation of the extrinsic apoptotic signaling pathway. In this study, we assessed the cytotoxic effect of Apomab in vitro and evaluated its antitumor activity in murine models of breast cancer development and progression. MDA-MB-231-TXSA breast cancer cells were transplanted into the mammary fat pad or directly into the tibial marrow cavity of nude mice. Apomab was administered early, postcancer cell transplantation, or after tumors progressed to an advanced stage. Tumor burden was monitored progressively using bioluminescence imaging, and the development of breast cancer-induced osteolysis was measured using microcomputed tomography. In vitro, Apomab treatment induced apoptosis in a panel of breast cancer cell lines but was without effect on normal human primary osteoblasts, fibroblasts, or mammary epithelial cells. In vivo, Apomab exerted remarkable tumor suppressive activity leading to complete regression of well-advanced mammary tumors. All animals transplanted with breast cancer cells directly into their tibiae developed large osteolytic lesions that eroded the cortical bone. In contrast, treatment with Apomab following an early treatment protocol inhibited both intraosseous and extraosseous tumor growth and prevented breast cancer-induced osteolysis. In the delayed treatment protocol, Apomab treatment resulted in the complete regression of advanced tibial tumors with progressive restoration of both trabecular and cortical bone leading to full resolution of osteolytic lesions. Apomab represents a potent immunotherapeutic agent with strong activity against the development and progression of breast cancer and should be evaluated in patients with primary and metastatic disease.

• Authors: Irene Zinonos, Agatha Labrinidis, Michelle Lee, Vasilios Liapis, Shelley Hay, Vladimir Ponomarev, Peter Diamond, Andrew C W Zannettino, David M Findlay, Andreas Evdokiou
• Journal: Molecular cancer therapeutics (Mol Cancer Ther) Vol. 8 Issue 10 Pg. 2969-80 (Oct 2009) ISSN: 1538-8514 [Electronic] United States
• PMID: 19808976 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Antibodies, Monoclonal
• Antineoplastic Agents
• Receptors, Death Domain
• apomab

Topics

• Animals
• Antibodies, Monoclonal (pharmacology, therapeutic use)
• Antineoplastic Agents (pharmacology, therapeutic use)
• Apoptosis (drug effects)
• Breast Neoplasms (drug therapy, pathology)
• Cell Line, Tumor
• Cell Proliferation (drug effects)
• Female
• Humans
• Mice
• Neoplasm Metastasis
• Osteolysis (pathology)
• Receptors, Death Domain (agonists)
• Tumor Burden (drug effects)
• Xenograft Model Antitumor Assays