Phase II trial of temsirolimus in patients with metastatic breast cancer

Gini F. Fleming, Cynthia X. Ma, Dezheng Huo, Husain Sattar, Maria Tretiakova, L. Lin, Olwen M. Hahn, F. O. Olopade, R. Nanda, Philip C. Hoffman, M. J. Naughton, Timothy Pluard, Suzanne D. Conzen, Matthew J. Ellis

Research output: Contribution to journalArticlepeer-review

56 Scopus citations


Preclinical models suggested that activating mutations of the PIK3CA gene are associated with sensitivity to inhibitors of the mammalian target of rapamycin (mTOR). In breast cancers, PIK3CA mutations are associated with estrogen receptor (ER) positivity. We therefore performed an open-label single arm phase II study of the rapamycin analog, temsirolimus, at a dose of 25 mg weekly, in women with pretreated breast cancers that were positive for ER, PR, or HER2. Archived formalin-fixed paraffin embedded tumor was collected for immunohistochemical evaluation of components of the PI3K/Akt/mTOR pathway and PIK3CA mutation analysis. Thirty-one patients were enrolled. There were no major objective responses; however, three patients had stable disease for over 24 weeks. Twenty-three tumor samples were available for mutational analysis. There were five tumors with PIK3CA mutations; no association was found between prolonged stable disease and PIK3CA mutation or any immunohistochemical marker. There was a trend toward improved progression free survival (PFS) for patients with positive nuclear staining for phospho-Akt308. One patient remains on study four and a half years after starting therapy; her tumor did not have a PIK3CA mutation. We conclude that single agent temsirolimus has minimal activity in a population of women with heavily pretreated breast cancer. We found no evidence that either absence of immunohistochemical staining for PTEN or mutations in the hotspot domains of PIK3CA in the primary tumor were associated with clinical benefit.

Original languageEnglish
Pages (from-to)355-363
Number of pages9
JournalBreast Cancer Research and Treatment
Issue number2
StatePublished - Nov 2012


  • Breast cancer
  • PIK3CA
  • PTEN
  • Rapamycin
  • Temsirolimus
  • Treatment


Dive into the research topics of 'Phase II trial of temsirolimus in patients with metastatic breast cancer'. Together they form a unique fingerprint.

Cite this