Two conventional CS PDX models, CS-347 and CS-281, grade 2 and grade 3, respectively, have been established in the study of Giordano et al. [85], which showed in both CS PDXs and in the CS-281 PDX-derived cell line a high expression of Ephrin type A receptor 2 (EphA2) and an in vitro dose-dependent growth inhibition by the EphA2 inhibitor ALW II-41-27, suggesting a new possible targeted therapy for CS. The gene discussed is EPHA2; the disease is Cowden syndrome 1.