FBXW7 mutations in patients with advanced cancers: clinical and molecular characteristics and outcomes with mTOR inhibitors

PLoS One. 2014 Feb 19;9(2):e89388. doi: 10.1371/journal.pone.0089388. eCollection 2014.

Abstract

Purpose: FBXW7 is a tumor suppressor gene responsible for the degradation of several proto-oncogenes. Preclinical data suggest that FBXW7 mutations sensitize cells to mTOR inhibitors. Clinicopathologic characteristics of cancer patients with FBXW7 mutations and their responses to mTOR inhibitors remain unknown.

Methods: Using multiplex gene panels we evaluated how the FBXW7 mutation affected the cancer phenotype of patients referred to a phase I clinic starting January 2012. Whenever possible patients positive for FBXW7 mutation were treated with regimens containing an mTOR inhibitors and their outcomes were reviewed.

Results: FBXW7 mutations were detected in 17 of 418 patients (4.0%). Among tumor types with more than 10 patients tested, FBXW7 mutations occurred in colorectal cancer (7/49; 14.3%), squamous cell cancer of head and neck (2/18; 11.1%), liver (1/13; 7.7%), and ovarian cancers (1/40; 2.5%). No one clinical, pathological or demographic feature was characteristic of the FBXW7-mutated patient population. The mutation occurred in isolation in only 2/17 (12%) patients, and KRAS was frequently found as a concomitant mutation, especially in patients with colorectal cancer (6/7; 86%). Ten patients were treated on a protocol containing an mTOR inhibitor, with a median time to treatment failure of 2.8 months (range, 1.3-6.8). One patient with liver cancer (fibrolamellar subtype) continues to have a prolonged stable disease for 6.8+ months.

Conclusion: In patients with advanced cancers, somatic mutations in FBXW7 usually occur with other simultaneous molecular aberrations, which can contribute to limited therapeutic efficacy of mTOR inhibitors.

MeSH terms

  • Cell Cycle Proteins / genetics*
  • DNA Mutational Analysis
  • F-Box Proteins / genetics*
  • F-Box-WD Repeat-Containing Protein 7
  • Humans
  • Mutation / genetics*
  • Neoplasms / genetics*
  • Neoplasms / pathology
  • Phenotype*
  • TOR Serine-Threonine Kinases / antagonists & inhibitors*
  • Texas
  • Ubiquitin-Protein Ligases / genetics*

Substances

  • Cell Cycle Proteins
  • F-Box Proteins
  • F-Box-WD Repeat-Containing Protein 7
  • FBXW7 protein, human
  • Ubiquitin-Protein Ligases
  • MTOR protein, human
  • TOR Serine-Threonine Kinases