[Ponatinib inhibits growth of patient-derived xenograft of cholangiocarcinoma expressing FGFR2-CCDC6 fusion protein in nude mice].

OBJECTIVE To investigate the antitumor effect of ponatinib on the growth of cholangiocarcinoma xenograft derived from a clinical patient in a mouse model expressing FGFR2-CCDC6 fusion protein. METHODS Lung metastatic tumor tissue was collected from a patient with advanced intrahepatic cholangiocarcinoma and implanted subcutaneously a NOD/SCID/ Il2rg-knockout (NSG) mouse. The tumor tissues were harvested and transplanted in nude mice to establish mouse models bearing patient-derived xenograft (PDX) of cholangiocarcinoma expressing FGFR2-CCDC6 fusion protein. The PDX mouse models were divided into 4 groups for treatment with citrate buffer (control group), intragastric administration of 20 mg/kg ponatinib dissolved in citrate buffer (ponatinib group), weekly intraperitoneal injections of 50 mg/kg gemcitabine and 2.5 mg/ kg cisplatin (gemcitabine group), or ponatinib combined with gemcitabine and cisplatin at the same doses (10 mice in each group, and 9 mice were evaluated in ponatinib group). The expressions of p-FGFR, p-FRS2, p-AKT, p-ERK, CD31, and Ki-67 in the xenografts were evaluated with immunohistochemistry, and cell apoptosis was analyzed with cleaved caspase-3 (CC3) staining and TUNEL staining. Western blotting was used to detect the expressions of FGFR2, p-FGFR, AKT, p-AKT, ERK, p-ERK, FRS2 and p-FRS2 in the tumor tissues. RESULTS Compared with those in the control group, the mice in ponatinib group showed a significantly reduced tumor volume (P < 0.0001) and suppressed tumor cell proliferation with significantly increased cell apoptosis. Western blotting and immunohistochemistry revealed obviously lowered phosphorylation level of FGFR and its downstream signal markers FRS2, AKT and ERK in the xenografts from ponatinib-treated mice. Gemcitabine treatment combined with cisplatin more effectively inhibited tumor growth than ponatinib alone (P < 0.0001) but did not further decrease the phosphorylation levels of FGFR or its downstream signaling molecules FRS2, AKT and ERK. CONCLUSIONS Ponatinib can regulate FGFR signaling to inhibit the proliferation and induce apoptosis of tumor cells in mice bearing patient-derived cholangiocarcinoma xenograft with FGFR2 fusion. FGFR inhibitor can serve as a treatment option for patients with cholangiocarcinoma with FGFR2 fusion.