A number of studies have reported on the presence of ALK-translocated CTCs in blood taken from NSCLC patients [12,14,15,17,21,22,23] with recent findings from Pailler et al., 2019, sequencing single CTCs that revealed the heterogeneity and resistance mutations in ALK-rearranged patients. The gene discussed is ALK; the disease is non-small cell lung carcinoma.