Successful examples of this include the co-development (and co-approval) of the BRAF inhibitor vemurafenib and its companion diagnostic BRAF V600E mutation assay for BRAF-mutant metastatic melanoma[1], and the ALK inhibitor crizotinib and its companion diagnostic ALK fusion gene test in advanced ALK-fusion positive non-small cell lung cancer (NSCLC) patients.[2], [3], [4]. The gene discussed is ALK; the disease is non-small cell lung carcinoma.