Unit of Oncogenomics and Epigenetics, IRCCS Regina Elena National Cancer Institute, Rome, Italy.
Department of Pathology, IRCCS Regina Elena National Cancer Institute, Rome, Italy.
J Hepatol. 2021 Aug;75(2):351-362. doi: 10.1016/j.jhep.2021.02.032. Epub 2021 Mar 17.
BACKGROUND & AIMS: About 15% of intrahepatic cholangiocarcinomas (iCCAs) express fibroblast growth factor receptor 2 (FGFR2) fusion proteins (FFs), usually alongside mutational inactivation of TP53, CDKN2A or BAP1. In FFs, FGFR2 residues 1-768 fuse to sequences encoded by a diverse array of partner genes (>60) causing oncogenic FF activation. While FGFR-specific tyrosine kinase inhibitors (F-TKI) provide clinical benefit in FF iCCA, responses are partial and/or limited by resistance mechanisms, such as the V565F substitution in the FGFR2 gatekeeper residue. Improving on FF targeting in iCCA therefore remains a critical unmet need. Herein, we aimed to generate a murine model of FF-driven iCCA and use this to uncover actionable FF-associated dependencies.
Four iCCA FFs carrying different fusion sequences were expressed in Tp53 mouse liver organoids. Tumorigenic properties of genetically modified liver organoids were assessed by transplantation into immuno-deficient mice. Cellular models derived from neoplastic lesions were exploited for pre-clinical studies.
Transplantation of FF-expressing liver organoids yielded tumors diagnosed as CCA based on histological, phenotypic and transcriptomic analyses. The penetrance of this tumorigenic phenotype was influenced by FF identity. Tumor organoids and 2D cell lines derived from CCA lesions were addicted to FF signaling via Ras-Erk, regardless of FF identity or V565F mutation. Dual blockade of FF and the Ras-Erk pathway by concomitant pharmacological inhibition of FFs and Mek1/2 provided greater therapeutic efficacy than single agent F-TKI in vitro and in vivo.
FF-driven iCCA pathogenesis was successfully modeled on a Tp53 murine background, revealing biological heterogeneity among structurally different FFs. Double blockade of FF-ERK signaling deserves consideration for precision-based approaches against human FF iCCA.
Intrahepatic cholangiocarcinoma (iCCA) is a rare cancer that is difficult to treat. A subtype of iCCA is caused by genomic alterations that generate oncogenic drivers known as FGFR2 fusions. Patients with FGFR2 fusions respond to FGFR inhibitors, but clinical responses are often of modest duration. We used animal and cellular models to show that FGFR2 fusions require the activity of a downstream effector named Mek1/2. We found that dual blockade of FGFR2 fusions and Mek1/2 was more effective than isolated inhibition of FGFR2 fusions, pointing to the potential clinical utility of dual FGFR2-MEK1/2 blockade in patients with iCCA.
约 15%的肝内胆管癌（iCCA）表达成纤维细胞生长因子受体 2（FGFR2）融合蛋白（FFs），通常伴随着 TP53、CDKN2A 或 BAP1 的突变失活。在 FFs 中，FGFR2 残基 1-768 与由 60 多种不同的伙伴基因编码的序列融合，导致致癌 FF 激活。虽然 FGFR 特异性酪氨酸激酶抑制剂（F-TKI）在 FF iCCA 中提供了临床获益，但反应是部分的和/或受到耐药机制的限制，例如 FGFR2 门控残基中的 V565F 取代。因此，改善 iCCA 中的 FF 靶向仍然是一个关键的未满足的需求。在此，我们旨在建立一个 FF 驱动的 iCCA 小鼠模型，并利用该模型揭示可操作的 FF 相关依赖性。
在 Tp53 小鼠肝类器官中表达了携带不同融合序列的四种 iCCA FFs。通过将遗传修饰的肝类器官移植到免疫缺陷小鼠中，评估其致瘤特性。利用来源于肿瘤病变的细胞模型进行临床前研究。
表达 FF 的肝类器官移植产生了根据组织学、表型和转录组分析诊断为 CCA 的肿瘤。这种致瘤表型的易感性受 FF 身份的影响。CCA 病变衍生的肿瘤类器官和 2D 细胞系依赖于 FF 信号通过 Ras-Erk，无论 FF 身份或 V565F 突变如何。同时抑制 FF 和 Mek1/2（通过药理学抑制 FFs 和 Mek1/2）对 FF-ERK 通路的双重阻断比单独使用 F-TKI 在体外和体内都具有更高的治疗效果。
在 Tp53 小鼠背景下成功地模拟了 FF 驱动的 iCCA 发病机制，揭示了结构不同的 FFs 之间存在生物学异质性。FF-ERK 信号的双重阻断值得考虑用于针对人类 FF iCCA 的基于精准医学的方法。
肝内胆管癌（iCCA）是一种难以治疗的罕见癌症。iCCA 的一个亚型是由产生致癌驱动因子的基因组改变引起的，这些驱动因子被称为 FGFR2 融合。FGFR2 融合的患者对 FGFR 抑制剂有反应，但临床反应通常持续时间较短。我们使用动物和细胞模型表明，FGFR2 融合需要一种下游效应因子 Mek1/2 的活性。我们发现，双重阻断 FGFR2 融合和 Mek1/2 比单独抑制 FGFR2 融合更有效，这表明在 iCCA 患者中双重 FGFR2-MEK1/2 阻断具有潜在的临床应用价值。
