Neurofibromatosis type 1-associated wild-type gastrointestinal stromal tumor treated with anti-IGF-1R monoclonal antibody

Gastrointestinal stromal tumors lacking mutations in KIT or PDGFRα are known as wild type (WT) and are less responsive to imatinib. These WT tumors are hypothesized to be dependent on signaling through the insulin-like growth factor 1 receptor (IGF-1R). We report the case of a 29-year-old woman with neurofibromatosis type 1-associated WT GIST treated with an anti-IGF-1R monoclonal antibody. Treatment was ineffective, and the potential basis for lack of response is discussed in the context of IGF-1R expression levels measured within this patients' primary tumor. We suggest that future clinical trials of anti-IGF-1R therapies prospectively determine tumor IGF-1R expression levels for correlation with response to treatment.