The gain-of-function PIK3CA mutation in UWG02CTC is suitable for the targeted small molecule inhibitors shown in Figure 1A. We therefore investigated the molecular and functional cellular consequences of these inhibitors against UWG02CTCs and the gastric adenocarcinoma cell line AGS, which also harbours PIK3CA and a KRAS mutation (Figure 1A, Supplementary Table S1), as a non-CTC but an mGAC cell line comparator. Here, KRAS is linked to gastric adenocarcinoma.