Interestingly, statistically significant differences were also present in the tumor volume between the group treated with AZD5438 combined with trastuzumab and those treated with AZD5438 or trastuzumab alone in ERBB2 and CCNE1 co-amplified PDX models, but the results were not observed in CCNE1 non-amplified PDX models (Fig. 5i–k). This evidence concerns the gene CCNE1 and neoplasm.