We also observed a significant association between the methylation status of the BRCA1meth models and the PDX tumor source: the majority of models with complete methylation of the BRCA1 promoter were treatment-naïve (n = 9/11, 81.8%), whereas all of those with partial methylation (5/5) had been established from post-treatment tumors (P = 0.005, Fig. 3C). This evidence concerns the gene BRCA1 and neoplasm.