Predictive, Diagnostic, Oncogenic, Functional evidence:
Predictive: The study provides evidence that somatic mutations in the EGFR gene's TK domain are associated with sensitivity to gefitinib and erlotinib, as indicated by the significant differences in mutation presence between gefitinib-sensitive and refractory tumors. This correlation suggests that the presence of these mutations can predict the response to these specific therapies.
Diagnostic: The abstract mentions that most mutation-positive tumors were adenocarcinomas from never smokers, indicating that these mutations can be used to classify a specific subtype of lung cancer. This association supports the use of EGFR mutations as a diagnostic marker for identifying a distinct subset of lung cancers.
Oncogenic: The presence of somatic mutations in the EGFR TK domain is implicated in the development of lung cancer, as the study discusses the mutations found in tumors and their association with sensitivity to targeted therapies. This suggests that these mutations contribute to tumor development or progression in the context of lung cancer.
Functional: The study describes how specific mutations in the EGFR TK domain alter the molecular function of the protein, as evidenced by the differences in phosphotyrosine levels and drug sensitivity in the mutant forms compared to the wild-type. This indicates that the mutations have a direct impact on the biochemical activity of the EGFR protein.