Clinical response to a lapatinib-based therapy of a Li-Fraumeni Syndrome patient with a novel HER2-V659E mutation 2 U# J2 d2 V" f8 |% g8 ?3 ~! b, @Genomic characterization of recurrent breast and lung tumors developed over the course of 10 years in a 29-year-old patient with a germline p53 mutation (Li-Fraumeni Syndrome) identified oncogenic alterations in the HER2 and EGFR genes across all tumors, including HER2 amplifications, an EGFR-exon 20 insertion, and the first-in-human HER2-V659E mutation showing a phenotypic convergent evolution towards HER2 and EGFR alterations. Following the identification of HER2-activating events in the most recent lung carcinoma and in circulating tumor cells, we treated the reminiscent metastatic lesions with a lapatinib-based therapy. A clinical response both symptomatic and radiologic was achieved. HER2-V659E sensitivity to lapatinib was confirmed in the laboratory.