Sequential somatic mutations upon secondary anti-HER2 treatment resistance in metastatic ERBB2S310F mutated extramammary Paget's disease.

We report of a patient with metastatic penoscrotal extramammary Paget's disease, with an ERBB2S310F mutation, in which near complete response was achieved upon treatment with trastuzumab and carboplatin. However, after 10 cycles of trastuzumab and carboplatin, widespread metastasis re-occurred. Analysis of a newly developing metastasis revealed additional genomic alterations including ERBB3A232V and PIK3CAG106V point mutations as well as MET and CDK6 amplification, providing a potential mechanism of acquired treatment resistance. Therefore, ERBB family inhibitor afatinib was initiated. Unfortunately, the patient succumbed to disease-related complications shortly after treatment initiation. This is the first report of ERBB2S310F mutated, metastatic extramammary Paget's disease with secondary resistance to trastuzumab / carboplatin, potentially due to additional acquired genomic alterations. This case contributes to the growing evidence of HER2 in the pathogenesis of metastatic extramammary Paget's disease and emphasizes the importance of repetitive, genomic analysis in rare diseases. PMID: 31803359 [PubMed]
Source: Oncotarget - Category: Cancer & Oncology Tags: Oncotarget Source Type: research