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Open Access Research article

Impact of KIT exon 10 M541L allelic variant on the response to imatinib in aggressive fibromatosis: analysis of the desminib series by competitive allele specific Taqman PCR technology

Armelle Dufresne12*, Laurent Alberti1, Mehdi Brahmi1, Sarah Kabani1, Héloïse Philippon1, David Pérol3 and Jean Yves Blay12

Author Affiliations

1 Cancer Research Center of Lyon, INSERM UMR 1052, CNRS UMR 5286, Centre Leon Berard, 28 rue Laënnec, Lyon, France

2 Medical Oncology Department, Lyon, France

3 Biostatistics unit Anticancer Center Leon Berard, Lyon, France

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BMC Cancer 2014, 14:632  doi:10.1186/1471-2407-14-632

Published: 29 August 2014

Abstract

Background

Aggressive fibromatosis (AF) is a rare fibroblastic proliferative disease with a locally aggressive behavior and no distant metastasis, characterized by driver mutations in CTNNB1 or the APC gene. When progressive and/or symptomatic AF is not amenable to local management, a variety of medical treatments may be efficient, including imatinib mesylate. The phase II “Desminib trial” included 40 patients with AF to evaluate the toxicity and efficacy of imatinib resulting in a 65% tumor control rate at 1 year. We investigated a potential predictive value of KIT exon 10 M541L variant (KITL541) on this prospective series.

Methods

DNA was extracted in sufficient quantity from 33 patients included in the Desminib trial. The detection of KITL541 was performed by Competitive Allele-Specific Taqman® PCR technology. Chi-2 analyses were performed to search for a correlation between KIT status and tumor response. Progression free (PFS) and overall survival (OS) were compared by log-rank test after Kaplan-Meier analysis.

Results

In 6 out of 33 cases (18%), the technique failed to determine the mutational status; 5 patients (19%) harboured KITL541 and 22 patients (81%) were classified as KIT wild type. Compared with total cohort, KITL541 frequency did not distinguish between different clinical characteristics. In the KITL541 and the KITWT subgroups, the tumor control rate at 1 year was 100% and 68%, respectively (p = 0.316). The median PFS of patients harboring KITL541 or not is 29.9 and 24.5 months, respectively (p = 0.616), and the median OS is not reached, in any of the groups.

Conclusion

Our results do not support a predictive effect of KITL541 on the efficacy of imatinib for patients with AF.

Keywords:
Aggressive fibromatosis; KIT exon 10 M541L allelic variant; Imatinib