Recently, therapies targeting signaling pathways involved in the pathogenesis of different tumors have been developed. Studies have shown that the tyrosine kinase inhibitor STI-571 (Gleevec) is used successfully against tumors expressing the c-kit oncogene, such as gastrointestinal stromal tumors (GISTs). A recent in vitro study also demonstrated an antiproliferative effect of STI-571 on small-cell lung cancer (SCLC) cell lines. To determine the expression of c-kit in SCLC, we retrospectively analyzed presence of c-kit by immunohistochemistry in biopsy samples from patients with SCLCs. Formalin-fixed, paraffin-embedded archival tissue samples from 30 SCLCs were stained with an antibody directed against c-kit (CD117) by immunohistochemistry. Thirty cases of SCLCs, including 17 males (age 44 to 89) and 13 females (age 21 to 85), were examined. Sixteen of 30 (53.3%) SCLCs showed c-kit expression. Kaplan-Meier survival analysis with a log-rank test revealed that patients with c-kit expression had a tendency toward lower survival than c-kit-negative patients (median survival, 6 months versus 31 months, P =.062). Based on previously established anti-c-kit effects of STI-571 on SCLC cell lines and our findings, clinical trials may be considered for selected SCLC patients with c-kit expression. Furthermore, determination of c-kit in SCLC may have a prognostic value in SCLC patients.
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