Recently presented clinical trials with MM121 and tyrosine kinase inhibitors and chemotherapeutic drugs show the mRNA expression of neuregulin (NRG; HER3 ligand which binds to and activates HER3) [134] is associated with poor response to platinum-resistant ovarian cancer, ER/PR+ HER2− breast cancer and EGFR wild-type non-small cell lung cancer [135]. Here, ERBB3 is linked to breast cancer.