In contrast to in vitro studies using conventional HER2+ cell lines, in the HCI-12 PDX, paclitaxel was significantly more effective than sabizabulin to repress tumor growth over time (Figure 5A) and at study endpoint (Figure 5B,C), suggesting that HCI-12 PDX model is not paclitaxel-refractory. This evidence concerns the gene ERBB2 and neoplasm.