Supplementary Material for: Identification of a novel NRG1 fusion with targeted therapeutic implications in locally advanced pediatric cholangiocarcinoma: A case report

Locally advanced cholangiocarcinoma has a poor prognosis, with long-term survival only for patients where complete surgical resection is achieved. Median overall survival with chemotherapy alone is less than one year. Novel strategies combining conventional chemotherapy and radiotherapy followed by targeted agents can lead to durable treatment responses and are applicable to cholangiocarcinoma management. Pediatric cholangiocarcinoma is exceedingly rare, with an estimated 15-22 cases reported in the last 40 years. As such, no standard therapeutic regimen exists. We present a case of a 17-year-old previously healthy patient with unresectable cholangiocarcinoma whose tumor genetic sequencing revealed a novel, actionable NRG1 (neuregulin 1) gene translocation. The patient underwent standard systemic chemotherapy with gemcitabine and cisplatin followed by hypofractionated proton radiation therapy for local control. The patient then started an oral pan-ERBB (erythroblastic B receptor tyrosine kinases including ErbB1/EGFR, ErbB2/HER2, ErbB3/HER3, ErbB4/HER4) family inhibitor as a maintenance medication, remaining with stable disease and excellent quality of life for over two years. This case highlights a novel NRG1 fusion in a rare clinical entity that provided an opportunity to utilize a multimodal therapeutic strategy in the pediatric setting.