Persistent response to combination therapy of pemigatinib and chemotherapy in a child of combined hepatocellular-cholangiocarcinoma with FGFR2 fusion.

Combined hepatocellular-cholangiocarcinoma (cHCC-CCA), an extremely rare and underinvestigated subtype of primary liver cancer in children, generally has a poor prognosis and greater aggressiveness. Histological diagnosis of cHCC-CCA is difficult because of its diverse components, including hepatocellular carcinoma (HCC) and cholangiocarcinoma (CCA). cHCC-CCA shares some genetic alterations with HCC and CCA. However, only a few studies on genetic alterations in fibroblast growth factor receptor 2 (FGFR2) in cHCC-CCAs have been reported in adults. Therapeutic strategies for cHCC-CCAs are limited, and surgical resection is the only standard of care. No standard systemic treatment has been established for unresectable cHCC-CCAs. Herein, we report a rare case of a 14-year-old female patient diagnosed with unresectable cHCC-CCA with multiple liver masses and metastases to the lungs, lymph nodes and peritoneum. Next-generation sequencing (NGS) has identified an FGFR2-PRDM16 fusion, which has not been previously reported as a common FGFR2 fusion. The blood tumour markers alpha-fetoprotein (AFP) and carbohydrate antigen 19 - 9 (CA19 - 9) were both elevated. The patient was treated with pemigatinib (a selective FGFR inhibitor) in combination with Gemcitabine and Cisplatin at our hospital. After three cycles of the combination therapy, the patient achieved a partial response and normalization of tumor markers. After seven cycles of combination therapy, the patient achieved stable disease with the best response. Subsequently, the patient was administered received pemigatinib and gemcitabine. As of the last follow-up date, the patient has survived for 26 months. To the best of our knowledge, this is the first reported rare case of unresectable cHCC-CCA with FGFR2-PRDM16 fusion in a child successfully treated with a combination of pemigatinib and chemotherapy as a first-line regimen. This treatment combination may be effective and safe for patients with unresectable cHCC-CCAs.