KLRK1 and malignant pleural mesothelioma: Regarding the targets chosen to treat solid tumors (Figure 4D), the distribution for international trials is between mesothelin (34), MUC1 (27), and GPC3 (27), whereas European trials have chosen other targets, such as NKG2D (4 studies in colorectal cancer and liver cancer), GD2 (2 studies in neuroblastoma), FAP (one study in malignant pleural mesothelioma) and T4 (one study in thyroid tumor) as innovative targets.