To test the efficacy of combining osimertinib and antibodies neutralizing EGFR and HER2 (cetuximab, Cx, and trastuzumab, Tz, respectively), we made use of two PDX models: The lung TP103 model (harboring two EGFR mutations: L858R and T790M) and the TM00219 (PDXJ2) model, which was derived from a metastatic tumor carrying delE746–A750 (along with T790M). The gene discussed is ERBB2; the disease is metastatic neoplasm.