Gefitinib therapy helps shrink breast tumors

Alone or in combination with anastrozole, gefitinib is an effective, well-tolerated treatment for reducing the size of breast tumors, according to a report in the May 17th online issue of The Lancet Oncology.

The study was funded by drugmaker AstraZeneca, which markets gefitinib as Iressa. The commercial prospects for Iressa as a lung cancer treatment suffered a major blow in December when trial results showed it was no better than placebo at improving survival (see Reuters report December 17, 2004).Some estrogen receptor (ER) positive breast cancers have been shown to express epidermal growth factor receptor (EGFR). However, it was unclear if treatment with an anti-EGFR agent, such as gefitinib, offered any therapeutic benefits. To investigate, Dr. R. Charles Coombes, from Imperial College in London, and colleagues assessed the outcomes of 56 postmenopausal women with EGFR-positive breast cancer who were randomized to receive gefitinib with or without the aromatase inhibitor anastrozole starting about 1 month before surgical resection.Both regimens inhibited tumor cell proliferation, but the effect was more pronounced when both gefitinib and anastrozole were given (p = 0.054), the researchers point out. Approximately half of the patients in each group experienced a reduction in tumor size of at least 30%. Likewise, the reduction in levels of ER phosphorylation was comparable in each group.Nearly all of the patients in each group experienced an adverse event, but most were mild and tolerable, the authors note. “Our study suggests that gefitinib has a role in the adjuvant setting, and that a strategy of EGFR inhibition could have been applicable to 114 of 348 (33%) of postmenopausal patients screened,” Dr. Coombes’ team concludes. Still, further studies are needed to clarify the clinical benefits, they add. (Source: Lancet Oncol 2005: Reuters Health: Oncolink: May 2005.)