Dose- and schedule-dependent inhibition of the mammalian target of rapamycin pathway with everolimus: a phase I tumor pharmacodynamic study in patients with advanced solid tumors

J Clin Oncol. 2008 Apr 1;26(10):1603-10. doi: 10.1200/JCO.2007.14.5482. Epub 2008 Mar 10.


Purpose: Everolimus is a selective mammalian target of rapamycin (mTOR) inhibitor with promising anticancer activity. In order to identify a rationally based dose and schedule for cancer treatment, we have conducted a tumor pharmacodynamic phase I study in patients with advanced solid tumors.

Patients and methods: Fifty-five patients were treated with everolimus in cohorts of 20, 50, and 70 mg weekly or 5 and 10 mg daily. Dose escalation depended on dose limiting toxicity (DLT) rate during the first 4-week period. Pre- and on-treatment steady-state tumor and skin biopsies were evaluated for total and phosphorylated (p) protein S6 kinase 1, eukaryotic initiation factor 4E (elF-4E) binding protein 1 (4E-BP1), eukaryotic initiation factor 4G (eIF-4G), AKT, and Ki-67 expression. Plasma trough levels of everolimus were determined on a weekly basis before dosing during the first 4 weeks.

Results: We observed a dose- and schedule-dependent inhibition of the mTOR pathway with a near complete inhibition of pS6 and peIF-4G at 10 mg/d and >or= 50 mg/wk. In addition, pAKT was upregulated in 50% of the treated tumors. In the daily schedule, there was a correlation between everolimus plasma trough concentrations and inhibition of peIF4G and p4E-BP1. There was good concordance of mTOR pathway inhibition between skin and tumor. Clinical benefit was observed in four patients including one patient with advanced colorectal cancer achieving a partial response. DLTs occurred in five patients: one patient at 10 mg/d (grade 3 stomatitis) and four patients at 70 mg/wk (two with grade 3 stomatitis, one with grade 3 neutropenia, and one with grade 3 hyperglycemia).

Conclusion: Everolimus achieved mTOR signaling inhibition at doses below the DLT. A dosage of 10 mg/d or 50 mg/wk is recommended for further development.

Publication types

  • Clinical Trial, Phase I
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aged
  • Aged, 80 and over
  • Antineoplastic Agents / administration & dosage*
  • Antineoplastic Agents / adverse effects
  • Antineoplastic Agents / pharmacokinetics
  • Dose-Response Relationship, Drug
  • Everolimus
  • Female
  • Humans
  • Male
  • Maximum Tolerated Dose
  • Middle Aged
  • Neoplasms / drug therapy*
  • Protein Kinases / drug effects*
  • Sirolimus / administration & dosage
  • Sirolimus / adverse effects
  • Sirolimus / analogs & derivatives*
  • Sirolimus / pharmacokinetics
  • TOR Serine-Threonine Kinases


  • Antineoplastic Agents
  • Everolimus
  • Protein Kinases
  • MTOR protein, human
  • TOR Serine-Threonine Kinases
  • Sirolimus