Data from Activity of dasatinib against L576P KIT mutant melanoma: Molecular, cellular, and clinical correlates

Authors:
  • SWScott E. Woodman
    Scott E. Woodman
  • JTJonathan C. Trent
    Jonathan C. Trent
  • KSKatherine Stemke-Hale
    Katherine Stemke-Hale
  • ALAlexander J. Lazar
    Alexander J. Lazar
  • SPSabrina Pricl
    Sabrina Pricl
  • GPGiovanni M. Pavan
    Giovanni M. Pavan
  • MFMaurizio Fermeglia
    Maurizio Fermeglia
  • YGY.N. Vashisht Gopal
    Y.N. Vashisht Gopal
  • DYDan Yang
    Dan Yang
  • DPDonald A. Podoloff
    Donald A. Podoloff
  • DIDoina Ivan
    Doina Ivan
  • KKKevin B. Kim
    Kevin B. Kim
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Abstract
Point mutations in the KIT receptor tyrosine kinase gene have recently been identified in mucosal, acral lentiginous, and chronically sun-damaged melanomas. We have identified the first human melanoma cell line with an endogenous L576P mutation, the most common KIT mutation in melanoma (∼30-40%). In vitro testing showed that the cell viability of the L576P mutant cell line was not reduced by imatinib, nilotinib, or sorafenib small molecule KIT inhibitors effective in nonmelanoma cells with other KIT mutations. However, the viability of the mutant cells was reduced by dasatinib at concentrations as low as 10 nM (P = 0.004). Molecular modeling studies found that the L576P mutation induces structural changes in KIT that reduce the affinity for imatinib (ΔΔGbind = −2.52 kcal/mol) but not for dasatinib (ΔΔGbind = +0.32 kcal/mol). Two metastatic melanoma patients with the L576P KIT mutation were treated with dasatinib, including one patient previously treated with imatinib. Both patients had marked reduction (>50%) and elimination of tumor F18-fluorodeoxyglucose (FDG)-avidity by positron emission tomography (PET) imaging after dasatinib treatment. These data support the selective inhibitory effect of dasatinib against cells harboring the most common KIT mutation in melanoma, and thus has therapeutic implications for acrallentiginous, chronic sun-damaged, and mucosal melanomas. [Mol Cancer Ther 2009;8(8):2079–85]