Pfizer Inc. announced that two phase-3 studies of Sutent (sunitinib malate) in advanced breast cancer did not meet their primary endpoints. The SUN 1064 phase 3 study of sunitinib in combination with docetaxel for the first-line treatment of patients with advanced HER-2 negative breast cancer did not show a statistically significant improvement in progression-free survival compared with docetaxel alone. In addition, the SUN 1099 phase 3 study of sunitinib plus capecitabine, in previously-treated advanced breast cancer patients, did not show a statistically significant improvement in progression-free survival compared with capecitabine alone.

"Sunitinib has been thoroughly evaluated in advanced HER-2 negative breast cancer, and while we are disappointed in the results, these trials have helped us define the limits and opportunities for the compound and better understand the complex biology of this disease," said Dr. Mace Rothenberg, senior vice president of Clinical Development and Medical Affairs for Pfizer's Oncology Business Unit. "Pfizer Oncology is committed to the rigorous evaluation of investigational therapies in breast cancer, which despite recent advancements, continues to claim far too many lives each year."

There were more adverse events, including serious adverse events, in the investigational arm than in the comparator arm of each study. A continuing analysis of efficacy and safety data will be completed and presented at a medical meeting in the near future.

Sutent 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. Sutent has played a significant role in advancing the treatment landscape and remains standard of care in its approved indications. To date, more than 82,000 patients globally have been treated with sunitinib in the clinical setting and in trials across multiple tumours.

Pfizer remains committed to the development program for sunitinib and is continuing to study its potential role in the treatment of other solid tumours including advanced non-small cell lung cancer, advanced castration-resistant prostate cancer, advanced hepatocellular carcinoma, and as adjuvant therapy for renal cell carcinoma, in phase 3 trials.

Pfizer Oncology is dedicated to further understanding and developing agents to better match specific patients with treatments and increase benefits from selected therapies.

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.

Sutent works by blocking multiple molecular targets implicated in the growth, proliferation and spread of cancer. Two important Sutent targets, vascular endothelial growth factor receptor (VEGFR) and platelet-derived growth factor receptor (PDGFR), are expressed by many types of solid tumours and are thought to play a crucial role in angiogenesis, the process by which tumours acquire blood vessels, oxygen and nutrients needed for growth. Sutent also inhibits other targets important to tumour growth, including KIT, FLT3 and RET.