A number of trials of sunitinib for breast cacner provided dissapointing results. 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.There were more adverse events, including serious adverse events, in the investigational arm than in the comparator arm of each study. Pfizer disconitued the SUN sstudy for this reason. An independent Data Monitoring Committee (DMC) found that even if the trial had been allowed to continue, treatment with single-agent sunitinib would be unable to demonstrate a statistically significant improvement in the primary endpoint of progression-free survival (PFS) compared to single-agent capecitabine in the study population.

For HER+ breast cancer, there are phase II trials suggesting effectiveness. It is difficult to know what to make of it in light of the SUN trial, albeit that it was in HER negative patients. A phase III trial is eagerly awaited,

Bergh J1, Bondarenko IM, Lichinitser MR, Liljegren A, Greil R, Voytko NL, Makhson AN, Cortes J, Lortholary A, Bischoff J, Chan A, Delaloge S, Huang X, Kern KA, Giorgetti C.First-line treatment of advanced breast cancer with sunitinib in combination with docetaxel versus docetaxel alone: results of a prospective, randomized phase III study.J Clin Oncol. 2012 Mar 20;30(9):921-9.

http://press.pfizer.com/press-release/pfizer-discontinues-one-sunitinib-phase-3-trial-advanced-breast-cancer-other-advanced-