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J Clin Oncol. 2013 Sep 10;31(26):3182-90. doi: 10.1200/JCO.2012.47.7836. Epub 2013 Jun 17.

Imatinib for melanomas harboring mutationally activated or amplified KIT arising on mucosal, acral, and chronically sun-damaged skin.

Author information

1
F. Stephen Hodi, Anita Giobbie-Hurder, Philip Friedlander, Jason J. Luke, Katherine A. Zukotynski, Jeffrey T. Yap, Annick D. Van den Abbeele, and George D. Demetri, Dana-Farber Cancer Institute; Jonathan A. Fletcher, Meijun Zhu, and Adrian Marino-Enriquez, Brigham and Women's Hospital; Donald Lawrence, Keith T. Flaherty, and David E. Fisher, Massachusetts General Hospital, Boston, MA; Christopher L. Corless, Michael C. Heinrich, and Carol Beadling, Portland Veterans Administration Medical Center and Oregon Health & Science University, Portland, OR; Philip Friedlander, Mount Sinai Medical Center, New York, NY; Rene Gonzalez, University of Colorado Cancer Center, Aurora, CO; Jeffrey S. Weber, H. Lee Moffitt Cancer Center and Research Institute, Tampa, FL; Thomas F. Gajewski, University of Chicago, Chicago, IL; Steven J. O'Day, Beverly Hills Cancer Center, Beverly Hills, CA; Kevin B. Kim, The University of Texas MD Anderson Cancer Center, Houston, TX; Frances A. Collichio, The University of North Carolina at Chapel Hill, Chapel Hill, NC; and Marc S. Ernstoff, Geisel School of Medicine and Norris Cotton Cancer Center, Hanover, NH.

Abstract

PURPOSE:

Amplifications and mutations in the KIT proto-oncogene in subsets of melanomas provide therapeutic opportunities.

PATIENTS AND METHODS:

We conducted a multicenter phase II trial of imatinib in metastatic mucosal, acral, or chronically sun-damaged (CSD) melanoma with KIT amplifications and/or mutations. Patients received imatinib 400 mg once per day or 400 mg twice per day if there was no initial response. Dose reductions were permitted for treatment-related toxicities. Additional oncogene mutation screening was performed by mass spectroscopy.

RESULTS:

Twenty-five patients were enrolled (24 evaluable). Eight patients (33%) had tumors with KIT mutations, 11 (46%) with KIT amplifications, and five (21%) with both. Median follow-up was 10.6 months (range, 3.7 to 27.1 months). Best overall response rate (BORR) was 29% (21% excluding nonconfirmed responses) with a two-stage 95% CI of 13% to 51%. BORR was significantly greater than the hypothesized null of 5% and statistically significantly different by mutation status (7 of 13 or 54% KIT mutated v 0% KIT amplified only). There were no statistical differences in rates of progression or survival by mutation status or by melanoma site. The overall disease control rate was 50% but varied significantly by KIT mutation status (77% mutated v 18% amplified). Four patients harbored pretreatment NRAS mutations, and one patient acquired increased KIT amplification after treatment.

CONCLUSION:

Melanomas that arise on mucosal, acral, or CSD skin should be assessed for KIT mutations. Imatinib can be effective when tumors harbor KIT mutations, but not if KIT is amplified only. NRAS mutations and KIT copy number gain may be mechanisms of therapeutic resistance to imatinib.

TRIAL REGISTRATION:

ClinicalTrials.gov NCT00424515.

PMID:
23775962
PMCID:
PMC4878082
DOI:
10.1200/JCO.2012.47.7836
[Indexed for MEDLINE]
Free PMC Article

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