Dose-related efficacy and safety of oral DP2 receptor antagonists fevipiprant (QAW039), timapriprant (OC000459), and BI 671800 have been tested in patients with allergic asthma and COPD, and PGD2 has shown anticancer effects in NSCLC (non-small cell lung carcinoma), kidney and lung fibrosis, and gastric cancer (Bateman Guerreros et al., 2017; Jandl and Heinemann, 2017; Pearson et al., 2017; Sandham et al., 2017a,b; Murillo et al., 2018; Brightling et al., 2020). This evidence concerns the gene PTGDS and gastric cancer.