Our study also showed that HER2-mutant lung cancers had a similar PFS of pemetrexed-based chemotherapy with KRAS-mutant lung cancers (5.0 months), which was inferior compared with EGFR-mutant(6.5 months) and ALK/ROS1-rearranged (9.2 months), indicating that HER2 mutation might predict a poor efficacy of pemetrexed-based chemotherapy, just like KRAS mutation. The gene discussed is ROS1; the disease is lung cancer.