Impact of the new EGF receptor and ALK testing guideline on personalized lung cancer medicine.

Abstract

All advanced-stage lung adenocarcinoma patients should be tested for EGF receptor (EGFR) mutations and for EML4–ALK translocations as a guide for selecting them for tyrosine kinase inhibitor (TKI) therapy. The new EGFR and ALK guideline provides useful recommendations for appropriate testing [1]. Lung tumors are the leading cause of cancerrelated mortality worldwide [2]. Almost 80% of cases are non-small-cell lung cancer (NSCLC) and extensive disease is present at the time of diagnosis in the majority of patients. Systemic treatment with chemotherapy has reached a plateau of 10–20% response rates and 4–5 months of progression-free survival (PFS), and has not improved in more than a decade [3–5]. A first milestone in a new era of targeted therapy for this disease was reached with the discovery of a subset of tumors carrying activating mutations of EGFR, which can be selectively blocked with TKIs such as erlotinib and gefitinib. Numerous clinical studies have demonstrated the efficacy of these TKIs in the treatment of EGFR-mutated lung tumors, with 55–83% response rates and 9–13 month PFS [6,7]. A second milestone was the discovery, in 2007, of the EML4–ALK translocation in 6.7% of Japanese NSCLC patients [8]. The translocation was later found in 4–7% of Chinese [9], European [10] and US patients [11]. When treated with a novel ALK inhibitor, crizotinib, these patients showed response rates of 57% with a PFS greater than 6 months [12]. As a result of these new developments, many laboratories worldwide are currently testing lung tumor samples for EGFR mutations and EML4–ALK fusions. In an effort to standardize testing practices, the College of American Pathologists, the International Association for the Study of Lung Cancer and the Association for Molecular Pathology constituted writing and advisory panels, presided by three cochairs, to