In the HERACLES cohort B, a single-arm phase II trial, the combination of pertuzumab and the antibody-drug conjugate trastuzumab emtansine was investigated in patients with histologically confirmed RAS/BRAF wild-type HER2-positive metastatic colorectal cancer (mCRC) refractory to standard treatments. Here, ERBB2 is linked to metastatic colorectal cancer.