Gene mutations in small-cell lung cancer (SCLC): Results of a panel of 6 genes in a cohort of Italian patients

• We investigated the presence of mutations in a panel of 6 genes in 113 SCLCs.
• We could identify only 7 mutations, 2 in EGFR and 5 in c-MET gene.
• EGFR mutations seem to be related to female gender and low tobacco exposure.
• c-MET mutations do not show any correlation with specific features.
• Studies with c-MET and EGFR-directed therapies are warranted also in SCLC.

BackgroundNo target therapies are presently available in the treatment of small-cell lung cancer (SCLC). We investigated the presence of potentially drugable mutations in the EGFR, c-MET, BRAF, KRAS, PDGFRa and c-KIT genes in a retrospective series of SCLC from 2 Italian Institutions. Correlations with immunohistochemical, clinical and outcome features were evaluated.Materials and methodsGenes were studied by direct sequencing of DNA extracted from formalin-fixed paraffin-embedded tissues. Immunohistochemical expression of TTF-1, p63, chromogranin, synaptophysin, CD56 and bcl-2 was assessed.ResultsSamples from 113 SCLC patients were analyzed. All cases were wild-type for BRAF, KRAS, PDGFRa and c-KIT (data available for 82 patients). Two (1.8%) patients were EGFR-mutated (exon 19 delE746-A750 and exon 21 L858R); both were females, non-smoker and had limited disease. Overall survival of EGFR-mutated patients was 21 months as compared to 11 months in wild-type. Five (4.4%) patients were c-MET-mutated (4 on exon 14: 2 R988C, 1 D990N, 1 D102Y; 1 on exon 17 R1166Q); all were smokers, 3 were males and 4 had extensive disease. Their OS was comparable to wild-type cases (12 vs. 11 months). EGFR and c-MET mutations were mutually exclusive. Gene mutations did not correlate with immunophenotype.ConclusionsTargetable mutations are uncommon in SCLC. EGFR-mutated patients tended to be female and non-smoker and experienced a prolonged OS suggesting a possible positive prognostic effect. c-MET mutations did not affect survival. Target therapy might be considered in EGFR and c-MET-mutated patients.