Pfizer Inc announced the discontinuation of the SUN 1094 phase-3 study that evaluated Sutent (sunitinib malate) plus paclitaxel versus bevacizumab plus paclitaxel for the first line treatment of patients with advanced breast cancer. The independent Data Monitoring Committee (DMC) found that treatment with sunitinib in combination with paclitaxel would be unable to meet the primary endpoint of superior progression-free survival (PFS) compared to the combination of bevacizumab and paclitaxel. No new safety issues were identified.

"While we are disappointed that this trial did not meet its primary endpoint, we are continuing to study sunitinib in different breast cancer populations and with different regimens," said Dr Mace Rothenberg, senior vice president of Clinical Development and Medical Affairs for Pfizer's Oncology Business Unit. "Pfizer remains committed to evaluating sunitinib in advanced breast cancer through its two other phase-3 clinical trials investigating the effectiveness of Sutent in combination with standard of care chemotherapies."

One phase-3 trial (SUN 1064) is a comparison of Sutent plus docetaxel vs. docetaxel for the first line treatment of patients with advanced breast cancer, and the second (SUN 1099) is a phase-3 trial of Sutent plus capecitabine vs. capecitabine for the second line treatment of patients with advanced breast cancer. These trials are ongoing with an analysis expected by the end of the year or early next year.

Pfizer has notified clinical trial investigators involved in the study and regulatory agencies of these findings.

These results do not affect the approved indications with sunitinib as monotherapy. Sunitinib is currently approved for both gastrointestinal stromal tumour (GIST) after disease progression on or intolerance to imatinib mesylate, and advanced / metastatic renal cell carcinoma (RCC) based on efficacy and safety data from large, randomized phase-3 clinical trials. Sunitinib has played an important role in reshaping the treatment landscape for these two difficult-to-treat cancers. To date, more than approximately 58,000 patients globally have been treated with sunitinib.

Sutent is an oral multi-kinase inhibitor approved for the treatment of GIST after disease progression on or intolerance to imatinib mesylate and advanced / metastatic RCC.