Analysis of c-kit protein expression in small-cell lung carcinoma and its implication for prognosis.

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. Copyright 2002, Elsevier Science (USA). All rights reserved.