Based on the unanimous recommendation of an Independent Data Monitoring Committee (IDMC), GlaxoSmithKline (GSK) has halted enrolment in its phase III clinical trial evaluating the combination of Tykerb (lapatinib ditosylate) and capecitabine (Xeloda) versus capecitabine alone. The trial evaluated women with refractory advanced or metastatic breast cancer who have documented ErbB2 (HER2) over expression and whose disease progressed following treatment with trastuzumab (Herceptinâ) as well as other cancer therapies. A pre-planned interim analysis of 321 patients in the study yielded statistically significant results, exceeding the primary endpoint, a GSK release said.

According to the study protocol, the pre-planned interim analysis was reviewed by the IDMC, which is comprised of medical oncology experts and a statistician. The IDMC unanimously recommended halting enrolment in the study because it exceeded its primary endpoint of time to disease progression, or TTP, for women receiving the combination of Tykerb and capecitabine.

The IDMC made their recommendation based on pre-specified stopping rules outlined in their charter. All women currently enrolled in the trial will continue to be followed and those who are receiving capecitabine alone will be offered the option of switching to the combination therapy of capecitabine and Tykerb in consultation with their physician.

"We are extremely encouraged by these data which suggest that Tykerb may offer significant benefit as an oral medication in combination with chemotherapy for patients with advanced or metastatic ErbB2 positive breast cancer, and whose disease has progressed on previous treatment regimens, including Herceptin," Paolo Paoletti, senior vice president of the Oncology Medicine Development Center, at GSK said adding, "On the basis of this and other data we now plan to file in the US and Europe during the second half of 2006."

The phase III trial (EGF100151) is an international, multicentre, randomised, open-label study to evaluate and compare TTP in patients with documented ErbB2 (HER2) over expressing refractory advanced or metastatic breast cancer treated with Tykerb in combination with capecitabine versus capecitabine alone. The primary endpoint of the study was to detect a 50 per cent increase in TTP in the combination arm compared with the capecitabine alone arm. 392 patients have been enrolled in the study of which 321 were included in the analysis (160 in the combination arm and 161 in the monotherapy arm). The most common drug-related adverse events in the combination arm of the study were diarrhea and nausea.

The World Health Organization reports that just over one million cases of breast cancer are diagnosed annually. Breast cancer is the most common non-cutaneous malignancy in women and one of the leading causes of cancer death.