According to the results of a phase II clinical trial presented at the 2006 annual meeting of the American Society of Clinical Oncology, monotherapy with Tykerb® (lapatinib) produced a treatment response in 62% of women with heavily pre-treated, ErbB2-overexpressing inflammatory breast cancer.

Tykerb is an investigational, small-molecule, ErbB1 and ErbB2 tyrosine kinase inhibitor. Tykerb is administered orally, has rapid action, and has the potential to cross the blood-brain barrier. If Tykerb proves to be safe and effective in inflammatory breast cancer, it would provide an important new treatment option for women with this very aggressive type of cancer.

The effect of monotherapy with Tykerb was evaluated in a phase II clinical trial among women with heavily pre-treated inflammatory breast cancer. Seventy-nine percent of study participants had stage IV disease and 21% had stage IIIB disease. All patients were treated with 1500 mg/day of Tykerb. The study included women with ErbB2 overexpression, as well as women with ErbB1 but without ErbB2 overexpression.

Among the 24 women with ErbB2 overexpression, 62% experienced a partial response after treatment with Tykerb. The response rate among women without without ErbB2 overexpression was much lower.

Gstrointestinal and skin toxicity were the most common adverse effects of treatment. Most of these events were mild.

The researchers concluded that Tykerb monotherapy is well tolerated and clinically active in ErbB2-overexpressing, relapsed or refractory inflammatory breast cancer.

Reference: Spector NL, Blackwell K, Hurley J et al. EGF103009, a Phase II Trial of Lapatinib Monotherapy in Patients with Relapsed/Refractory Inflammatory Breast Cancer (IBC): Clinical Activity and Biologic Predictors of Response. Proceedings from the 42nd Annual Meeting of the American Society of Clinical Oncology. Atlanta, GA. 2006. Abstract # 502.