Identification of a Novel EHBP1‐MET Fusion in an Intrahepatic Cholangiocarcinoma Responding to Crizotinib

Abstract

As an aggressive tumor, intrahepatic cholangiocarcinoma (ICC) originates in the epithelium of the bile duct and has a poor prognosis. The therapeutic options for ICC are challenging and limited because of poor response to chemotherapy and the lack of targeted therapy. Here we report on a 41‐year‐old female patient with ICC with EHBP1‐MET fusion and multiple intrahepatic metastases responding to crizotinib. Next‐generation sequencing–based tumor mutation profiling was performed on the tumor biopsy and circulating tumor DNA from plasma. A novel EHBP1‐MET fusion was identified and confirmed by Sanger sequencing. Immunohistochemistry of biopsy sample also revealed c‐MET positivity. Subsequently, the patient started treatment with MET inhibitor crizotinib. Magnetic resonance imaging scan demonstrated a partial response for 8 months. To the best of our knowledge, this is the first clinical case report of a patient with MET‐rearranged ICC successfully treated with crizotinib. This case suggests that crizotinib may be a promising treatment option for patients with ICC with MET fusion, warranting further clinical investigation.

Key Points

• To the authors' knowledge, this is the first reported case of EHBP1‐MET fusion.

• This is also the first clinical case report of clinical benefit from crizotinib treatment in an intrahepatic cholangiocarcinoma (ICC) with MET fusion.

• MET fusion is rare in ICC, and inhibition of MET could be a viable option for ICC that warrants further clinical investigation.

Short abstract

This case report describes a patient with intrahepatic cholangiocarcinoma with EHBP1‐MET fusion successfully treated with crizotinib.

Patient Story

In April 2019, a 41‐year‐old woman presented to our hospital with upper abdominal pain and poor appetite that had persisted for nearly a month. She had neither familial history of bile duct disease nor history of working at a printing company. The positron emission tomography–computed tomography scan revealed a tumor mass at the left lobe of the liver with multiple intrahepatic metastases, enlarged lymph nodes at right cardiophrenic angle and porta hepatis, and accumulation of [18F]‐fluorodeoxyglucose. The levels of tumor marker carcinoembryonic antigen (CEA), carbohydrase antigen (CA) 19‐9, and CA125 were increased (42 ng/L, 443.9 U/mL, and 101.5 U/mL, respectively) (Fig. 1A). Liver function test was abnormal with markedly elevated bilirubin (total bilirubin was 123.5 μmol/L). Combined enhanced magnetic resonance imaging (MRI), diffusion‐weighted imaging (DWI), and magnetic resonance cholangiopancreatography (MRCP) showed mass at the junction of the left and right lobe of the liver, involving the porta hepatis bile duct and the left internal branch of the portal vein (Fig. 1B). Combined MRI, DWI, and MRCP scans also revealed multiple intrahepatic metastases and dilatation of the intrahepatic bile duct.

Figure 1.

Levels of tumor markers and magnetic resonance imaging (MRI) during the course of crizotinib treatment. (A): Change of tumor markers during crizotinib treatment. (B): Basal MRI evaluation. (C): MRI evaluation after 1 month of crizotinib treatment showed shrunken tumor mass. (D): MRI evaluation after 3 months of crizotinib treatment revealed a significant dimensional regression of liver lesions. MRI evaluation after 6 months (E) and 8 months (F) of crizotinib treatment showed continuous response.Abbreviations: CA125, carbohydrase antigen 125; CA199, carbohydrase antigen 19‐9; CEA, carcinoembryonic antigen.

Ultrasound‐guided fine needle aspiration of the liver lesion was performed, and pathologic examination confirmed poorly differentiated adenocarcinoma (Fig. 2A). The tumor was positive for CK7, CK19, Ki‐67 (index: 40%), HNF‐1β, CDX2 (weak), HER‐2 (index: 80%), SATB2, Muc‐2, S100p, MSH2, MSH6, PMS2, and MOC‐31 but negative for PD‐1, PD‐L1, IDH1, CK20, and SMAD4. Combined with the immunohistochemical results, cholangiocarcinoma was considered. The possibility of gastrointestinal tumor was excluded by using gastrointestinal endoscopy. Finally, the patient was diagnosed with intrahepatic cholangiocarcinoma (ICC).

Figure 2.

Pathological examinations. (A): Hematoxylin and eosin staining revealed poorly differentiated adenocarcinoma. (B): Immunohistochemical staining of c‐MET.

Molecular Tumor Board

Genotyping Results and Interpretation of the Molecular Results

Considering the markedly elevated bilirubin level, this patient was not suitable for chemotherapy and other antitumor treatment. To seek other treatments, the patient was referred for genetic testing (OrigiMed, Shanghai, China). The biopsy sample and circulating tumor DNA (ctDNA) sample from plasma of this patient were subjected to next‐generation sequencing using the YuanSu 578 gene panel and QiYuan 329 gene panel, respectively. Genomic DNA extraction and DNA targeted sequencing have been previously described [1, 2]. Genomic alterations, including copy number variants, single base substitution, short and long insertions/deletions (indels), and gene rearrangement and fusions were analyzed. The tumor mutational burden was estimated by analyzing somatic mutations including coding base substitution and indels per megabase of the panel sequences examined. A proprietary algorithm of OrigiMed was used for the molecular and clinical interpretation of these diagnostic results. Both the tissue and ctDNA samples harbored the novel EHBP1‐MET fusion, ATM mutation, KMT2D mutation, and SMARCA4 mutation. The EHBP1‐MET fusion was generated from the fusion of exons 1 to 21 of EHBP1 to exons 15 to 21 of MET, retaining the intact kinase domain of MET (Fig. 3A). The breakpoints of EHBP1 and MET are located on introns 21 and 14, respectively. This fusion was confirmed by Sanger sequencing (Fig. 3B). Immunohistochemistry also revealed a strong positive signal of c‐MET in in the tumor cells, suggesting elevated expression of c‐MET (Fig. 2B).

Figure 3.

EHBP1‐MET fusion. (A): Schematic representation of EHBP1‐MET fusion of the patient. (B): Sanger sequencing confirmed the EHBP1‐MET fusion.

Functional and Clinical Significance of the Specific Mutation in the Particular Cancer

EH domain binding protein 1 (EHBP1) was first identified in 3T3‐L1 adipocytes, containing a calponin homology domain and five NPF motifs [3]. EHBP1 acts as a novel EH domain protein 2–interacting protein and regulates actin rearrangement and endocytosis [4]. Elevated EHBP1 level is associated with the short survival of patients with colorectal cancer [5]. EHBP1 also mediates the anti‐invasive effect of atorvastatin in PTEN‐expressing prostate cancer cells [6].

MET, encoding the proto‐oncogene tyrosine kinase c‐MET, is the receptor for hepatocyte growth factor (HGF) [7, 8]. c‐MET is mainly expressed in epithelial cells, and its ligand HGF is expressed and released by surrounding mesenchymal cells [9]. Under normal physiological conditions, the c‐MET signaling pathway regulates multiple cellular responses, including growth, morphogenesis, apoptosis, and motility, which is very important in the control of tissue homeostasis [8, 9, 10]. Of note, MET signaling activation can stimulate some proangiogenic factors and induce angiogenesis, leading to the initiation of cancer progression [11]. Mutation or amplification of the MET gene in a variety of human malignancies continues to activate c‐MET signaling and promotes uncontrolled cell proliferation and tumor metastasis [9].

MET fusions have been identified in several tumor types, such as lung cancer, glioblastoma, salivary secretory carcinoma, and spindle cell sarcoma [12, 13, 14, 15]. The reported MET fusion partners include KIF5B, ETV6, TGF, CLIP2, TRIM4, ZKSCAN1, ATXN7L1, and others [12, 13, 14, 15, 16, 17]. These fusion proteins often lead to kinase domain activation and are involved in tumorigenesis and progression. Here we identified a novel EHBP1‐MET fusion never previously reported. Moreover, this case is unique because of the rare presentation of MET fusion in ICC.

Potential Strategies to Target the Pathway and Implications for Clinical Practice

This fusion‐driven activation of MET is likely to be an actionable target for crizotinib. Crizotinib is a small‐molecule tyrosine kinase inhibitor that actively inhibits MET, ALK, and ROS1. Crizotinib was approved by the U.S. Food and Drug Administration for ALK‐ or ROS1‐positive advanced non‐small cell lung cancer (NSCLC). Response to the MET inhibitors crizotinib has been documented in case reports of patients with lung adenocarcinoma (LADC). Patients with LADC harboring KIF5B‐MET fusion exhibited a clinical benefit from crizotinib treatment for 8 to 10 months [12]. A 62‐year‐old woman with LADC with STARD3NL‐MET gene fusion achieved a partial response (PR) (69% reduction) of the primary tumor to crizotinib treatment before metastasis [18]. A 74‐year‐old woman with LADC with HLA‐DRB1‐MET fusion achieved complete response to crizotinib [19]. These case reports indicate that crizotinib is a promising drug for MET‐rearranged NSCLC. Moreover, a child with a PTPRZ1‐MET fusion–driven pediatric glioblastoma achieved a relief of symptoms over a period of 2 months and substantial tumor shrinkage after crizotinib treatment [13]. However, there has been no report so far of crizotinib in the treatment of patients with ICC.

Patient Update

After communicating with the patient and her family, crizotinib monotherapy (200 mg twice a day) was initiated on April 23, 2019. Significant improvement in the patient's jaundice and liver function was observed. In May 2019, abdominal MRI showed shrunken tumor mass, involving the porta hepatis bile duct and the left internal branch of the portal vein, with dilatation of the intrahepatic bile duct, which was evaluated as PR (Fig. 1C). At the meantime, the levels of tumor markers CEA (32.9 μg/L), CA19‐9 (311 μg/L), and CA125 (63.3 μg/L) markedly decreased (Fig. 1A). In July 2019, MRI revealed a significant dimensional regression of liver lesions (50% reduction as assessed by RECIST evaluation criteria) (Fig. 1D), which was evaluated as PR. Meanwhile, significant decrease of CEA, CA19‐9, and CA125 were observed, and this tendency has been seen continuously (Fig. 1A). In October and December, MRI showed a continuous response (Fig. 1E, 1F). Because of the continuous and significant response and lack of any significant side effects, the patient had been on crizotinib monotherapy for 8 months until the latest follow‐up. To the best of our knowledge, this is the first report of a patient with MET‐rearranged ICC successfully treated with crizotinib. This case suggests that crizotinib may be a new treatment option for patients with ICC with MET fusion. However, the response seen in this patient, though hopeful, requires large clinical trials to confirm.

Author Contributions

Conception/design: Yiyi Yu

Provision of study material or patients: Yiyi Yu, Qing Liu, Wei Li

Collection and/or assembly of data: Qing Liu, Wei Li, Yueting Qu, Yihong Zhang

Data analysis and interpretation: Yueting Qu, Yihong Zhang, Tianshu Liu

Manuscript writing: Yiyi Yu

Final approval of manuscript: Yiyi Yu, Qing Liu, Wei Li, Yueting Qu, Yihong Zhang, Tianshu Liu

Disclosures

Yueting Qu: OrigiMed (E); Yihong Zhang: OrigiMed (E). The other authors indicated no financial relationships.

(C/A) Consulting/advisory relationship; (RF) Research funding; (E) Employment; (ET) Expert testimony; (H) Honoraria received; (OI) Ownership interests; (IP) Intellectual property rights/inventor/patent holder; (SAB) Scientific advisory board