Five of the cases are patients with lung cancer, including two patients with invasive mucinous adenocarcinoma and three patients with nonmucinous adenocarcinoma….NRG1 fusion partners for the patients with lung cancer were either CD74 or SDC4….Two patients received afatinib as first- or second-line therapy, three patients received the drug as third- to fifth-line therapy, and one patient received afatinib as fifteenth-line therapy. Best response with afatinib was stable disease in two patients (duration up to 16 months when combined with local therapies) and partial response (PR) of >18 months in three patients, including one with ongoing PR after 27 months.