Correlation of CTNNB1 Mutation Status with Progression Arrest Rate in RECIST Progressive Desmoid-Type Fibromatosis Treated with Imatinib: Translational Research Results from a Phase 2 Study of the German Interdisciplinary Sarcoma Group (GISG-01)

Ann Surg Oncol. 2016 Jun;23(6):1924-7. doi: 10.1245/s10434-016-5132-4. Epub 2016 Feb 9.


Background: CTNNB1 gene mutations are the molecular key events in the majority of sporadic desmoid-type fibromatosis (DF). The specific S45F mutation has been reported to be associated with a more aggressive clinical course in DF. For the current study, the CTNNB1 mutation status was analyzed in DF samples from the prospective German Interdisciplinary Sarcoma Group (GISG) phase 2 study evaluating imatinib to induce progression arrest in DF Response Evaluation Criteria In Solid Tumors (RECIST) progressive patients.

Methods: Thirty-seven patients were treated with a planned dose of imatinib 800 mg daily over 2 years (NCT01137916). The progression arrest rate (PAR) after 6 months of treatment was the primary endpoint of the study. CTNNB1 exon 3 mutation status was analyzed using Sanger sequencing.

Results: Thirty-three (97 %) of 34 patients reaching the primary endpoint were evaluable for CTNNB1 mutation exon 3 status. T41A mutations accounted for 30.3 % of the study samples and S45 mutations for 48.5 %, whereas CTNNB1 wild-type status was found in 21.2 %. The respective PAR at 6 months was 70, 81, and 43 %. Patients harboring CTNNB1 mutations demonstrated a higher PAR compared to wild-type DF. There was a statistically significant difference comparing patients with S45F mutations (85 % PAR) versus wild-type status (p = 0.05).

Conclusions: Mutations at position S45 were overrepresented in the GISG-01 trial recruiting RECIST progressive patients only. The positive correlation of CTNNB1 mutation status with the progression arrest rate after imatinib therapy supports the idea of a potential predictive impact of the mutation status on DF treatment decision making.

Publication types

  • Clinical Trial, Phase II

MeSH terms

  • Antineoplastic Agents / therapeutic use
  • Biomarkers, Tumor / genetics*
  • Disease Progression
  • Fibromatosis, Aggressive / drug therapy
  • Fibromatosis, Aggressive / genetics*
  • Follow-Up Studies
  • Humans
  • Imatinib Mesylate / therapeutic use*
  • Mutation*
  • Prognosis
  • Prospective Studies
  • Response Evaluation Criteria in Solid Tumors
  • Survival Rate
  • Translational Research, Biomedical*
  • beta Catenin / genetics*


  • Antineoplastic Agents
  • Biomarkers, Tumor
  • CTNNB1 protein, human
  • beta Catenin
  • Imatinib Mesylate

Associated data