Studies with ZD1839 in preclinical models.

ZD1839 (Iressa; AstraZeneca Pharmaceuticals LP, Wilmington, DE) is an orally active, selective inhibitor of epidermal growth factor receptor-tyrosine kinase (EGFR-TK) that blocks signaling pathways responsible for driving proliferation, invasion, and survival of cancer cells. In preclinical studies of cell lines and human tumor xenografts, ZD1839 as single-agent therapy produced growth inhibition in a wide variety of common solid tumor types including lung, prostate, breast, colon, and ovarian cancers. In these models, ZD1839 inhibited growth of tumor xenografts with high, moderate, and low expression of EGFR. The A431 vulvar carcinoma model, which expresses abnormally high levels of EGFR, was particularly sensitive to ZD1839 treatment, leading to tumor regression. When ZD1839 was coadministered with cytotoxic chemotherapy agents or radiotherapy, additive or even synergistic antitumor activity was achieved. The inhibition observed with ZD1839 treatment was not restricted to advanced metastatic tumors, but also extended to early lesions such as breast xenografts of human ductal carcinoma in situ. Inhibition of EGFR-TK has also been shown to delay the onset of tumor development in a transgenic animal model. The diverse and profound antitumor activities attained with ZD1839 treatment in tumor cells and in xenograft tumor models provided the rationale for clinical development of ZD1839. Ongoing preclinical studies continue to support the importance of EGFR-TK activity in the biology of solid tumors. Copyright 2003, Elsevier Science (USA)