Metformin decreases the dose of chemotherapy for prolonging tumor remission in mouse xenografts involving multiple cancer cell types

Cancer Res. 2011 May 1;71(9):3196-201. doi: 10.1158/0008-5472.CAN-10-3471. Epub 2011 Mar 17.


Metformin, the first-line drug for treating diabetes, selectively kills the chemotherapy resistant subpopulation of cancer stem cells (CSC) in genetically distinct types of breast cancer cell lines. In mouse xenografts, injection of metformin and the chemotherapeutic drug doxorubicin near the tumor is more effective than either drug alone in blocking tumor growth and preventing relapse. Here, we show that metformin is equally effective when given orally together with paclitaxel, carboplatin, and doxorubicin, indicating that metformin works together with a variety of standard chemotherapeutic agents. In addition, metformin has comparable effects on tumor regression and preventing relapse when combined with a four-fold reduced dose of doxorubicin that is not effective as a monotherapy. Finally, the combination of metformin and doxorubicin prevents relapse in xenografts generated with prostate and lung cancer cell lines. These observations provide further evidence for the CSC hypothesis for cancer relapse, an experimental rationale for using metformin as part of combinatorial therapy in a variety of clinical settings, and for reducing the chemotherapy dose in cancer patients.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Administration, Oral
  • Animals
  • Antineoplastic Combined Chemotherapy Protocols / pharmacology*
  • Breast Neoplasms / drug therapy
  • Carboplatin / administration & dosage
  • Carcinoma, Ductal, Breast / drug therapy
  • Cell Line, Tumor
  • Dose-Response Relationship, Drug
  • Doxorubicin / administration & dosage
  • Drug Synergism
  • Female
  • Humans
  • Injections, Intraperitoneal
  • Lung Neoplasms / drug therapy
  • Male
  • Metformin / administration & dosage
  • Metformin / pharmacology*
  • Mice
  • Mice, Nude
  • Neoplasms / drug therapy*
  • Paclitaxel / administration & dosage
  • Prostatic Neoplasms / drug therapy
  • Xenograft Model Antitumor Assays


  • Doxorubicin
  • Metformin
  • Carboplatin
  • Paclitaxel