Low-level clonal FGFR2 amplification defines a unique molecular subtype of intrahepatic cholangiocarcinoma in a Chinese population

Intrahepatic cholangiocarcinoma with FGFR alterations: A series of Chinese cases with an emphasis on their clinicopathologic and genetic features

Intrahepatic Cholangiocarcinoma (iCCA) with FGFR alterations is relatively rare, and its identification is important in the era of targeted therapy. We collected a large series of FGFR-altered cases in the Chinese population and characterized their clinicopathological and genetic features. Among the 18 FGFR-altered cases out of 260 iCCAs, 10 were males and 8 were females, ranging in age from 35 to 74 years (mean, 57.3 years; median, 58 years). Pathologically, they include 9 cases of large duct (LD, 50 %) and small duct (SD, 50 %) types each. All of them (100 %, 18/18) showed microsatellite stable (MSS) and low tumor mutation burden (TMB). Genetically, FGFR alterations involved FGFR1 (20 %), FGFR2 (70 %), and FGFR3 (10 %), with FGFR2 rearrangement accounting for the most (11/18). The most frequently altered genes/biological processes were development/proliferation-related pathways (44 %), chromatin organization (20 %), and tumor suppressors (32 %). Our study further revealed the clinicopathological and genetic features of FGFR-altered iCCA and demonstrated that its occurrence may show regional or ethnic variability and is less common in the Chinese population. A significant number of LD-type iCCA cases also have FGFR alterations rather than the SD type.

Pemigatinib in previously treated Chinese patients with locally advanced or metastatic cholangiocarcinoma carrying FGFR2 fusions or rearrangements: A phase II study

OBJECTIVE

This study evaluated the antitumor activity and safety of pemigatinib in previously treated Chinese patients with advanced cholangiocarcinoma and fibroblast growth factor receptor 2 (FGFR2) fusions or rearrangements.

BACKGROUND

Pemigatinib provided clinical benefits for previously treated patients with cholangiocarcinoma carrying FGFR2 fusions or rearrangements and was approved for this indication in multiple countries.

METHODS

In this ongoing, multicenter, single-arm, phase II study, adult patients with locally advanced or metastatic cholangiocarcinoma carrying centrally confirmed FGFR2 fusions or rearrangements who had progressed on ≥1 systemic therapy received 13.5 mg oral pemigatinib once daily (3-week cycle; 2 weeks on, 1 week off) until disease progression, unacceptable toxicity, or consent withdrawal. The primary endpoint was objective response rate (ORR) assessed by an independent radiology review committee.

RESULTS

As of January 29, 2021, 31 patients were enrolled. The median follow-up was 5.1 months (range, 1.5-9.3). Among 30 patients with FGFR2 fusions or rearrangements evaluated for efficacy, 15 patients achieved partial response (ORR, 50.0%; 95% confidence interval [CI], 31.3-68.7); 15 achieved stable disease, contributing to a disease control rate of 100% (95% CI, 88.4-100). The median time to response was 1.4 months (95% CI, 1.3-1.4), the median duration of response was not reached, and the median progression-free survival was 6.3 months (95% CI, 4.9-not estimable [NE]). Eight (25.8%) of 31 patients had ≥grade 3 treatment-emergent adverse events. Hyperphosphatemia, hypophosphatasemia, nail toxicities, and ocular disorders were mostly <grade 3, except for 2 events ≥grade 3.

CONCLUSIONS

The encouraging antitumor activity and favorable safety profile support the use of pemigatinib as a treatment in previously treated Chinese patients with cholangiocarcinoma and FGFR2 rearrangements.

FGFR Inhibitors in Cholangiocarcinoma-A Novel Yet Primary Approach: Where Do We Stand Now and Where to Head Next in Targeting This Axis?

Cholangiocarcinomas (CCAs) are rare but aggressive tumours with poor diagnosis and limited treatment options. Molecular targeted therapies became a promising proposal for patients after progression under first-line chemical treatment. In light of an escalating prevalence of CCA, it is crucial to fully comprehend its pathophysiology, aetiology, and possible targets in therapy. Such knowledge would play a pivotal role in searching for new therapeutic approaches concerning diseases' symptoms and their underlying causes. Growing evidence showed that fibroblast growth factor/fibroblast growth factor receptor (FGF/FGFR) pathway dysregulation is involved in a variety of processes during embryonic development and homeostasis as well as tumorigenesis. CCA is known for its close correlation with the FGF/FGFR pathway and targeting this axis has been proposed in treatment guidelines. Bearing in mind the significance of molecular targeted therapies in different neoplasms, it seems most reasonable to move towards intensive research and testing on these in the case of CCA. However, there is still a need for more data covering this topic. Although positive results of many pre-clinical and clinical studies are discussed in this review, many difficulties lie ahead. Furthermore, this review presents up-to-date literature regarding the outcomes of the latest clinical data and discussion over future directions of FGFR-directed therapies in patients with CCA.

FGFR2-IIIb Expression by Immunohistochemistry Has High Specificity in Cholangiocarcinoma with FGFR2 Genomic Alterations

BACKGROUND

FGFR2 genomic alterations are observed in 10-20% of cholangiocarcinoma (CCA). Although FGFR2 fusions are an important actionable target, FGFR2 protein expression has not been thoroughly characterized.

AIMS

To evaluate FGFR2 protein expression in cholangiocarcinoma harboring FGFR2 genomic alterations.

METHODS

FGFR2 protein expression was evaluated in 99 CCA cases with two different antibodies. FGFR2 genomic alterations were confirmed via next-generating sequencing (NGS) or FISH. Primary objective was to determine the specificity and sensitivity of FGFR2 immunohistochemistry staining for detecting FGFR2 genomic alterations. Secondary objectives included overall FGFR2 immunohistochemistry staining in CCA patients, and evaluation of whether FGFR2 expression correlates with clinical outcomes including overall survival (OS), progression-free survival (PFS), and time-to-tumor recurrence (TTR).

RESULTS

Immunohistochemistry staining with two antibodies against FGFR2, FPR2-D, and clone 98706 showed high accuracy (78.7% and 91.9%) and specificity (82.9% and 97.7%), and moderate sensitivity (53.9% and 57.1%), respectively, when compared with the standard methods for detecting FGFR2 genomic alterations. In a median follow-up of 72 months, there were no statistically significant differences in OS, PFS, and TTR, for patients with positive or negative FGFR2 staining.

CONCLUSION

FGFR2 protein expression by immunohistochemistry has high specificity and therefore could be used to imply the presence of FGFR2 genomic alterations in the context of a positive test. In the case of a negative test, NGS or FISH would be necessary to ascertain cases with FGFR2 genomic alterations.

Targeted genomic profiling revealed a unique clinical phenotype in intrahepatic cholangiocarcinoma with fibroblast growth factor receptor rearrangement

Genomic aberrations (GAs) in fibroblast growth factor receptors (FGFRs) are involved in the pathogenesis of intrahepatic cholangiocarcinoma (ICC), and clinical trials have shown efficacy of FGFR inhibitors in treating ICC patients with FGFR GAs such as FGFR2 rearrangement. To clarify the FGFRs GA profile and corresponding clinicopathological features in Chinese patients with ICC, a total of 257 cases were identified. Fourteen cases (5.45%) were positive for FGFR2 rearrangement. Further analysis on the 110 FGFR2 rearrangement negative cases showed that 13 patients present additional FGFRs GAs, including FGFR3 rearrangement (2.73%), and FGFRs mutations. When compared with patients without FGFRs GAs, those with FGFR2 or FGFR3 rearrangement presented more under the age of 58 years, female sex, HBsAb positivity, CD10 expression, and PD-L1 expression. The clinical characteristics between patients with FGFRs mutation and those without FGFRs GAs were similar, with the exception that cases with FGFRs mutation have more hepatolithiasis. We concluded that FGFR rearrangement is associated with unique clinical phenotypes in ICC.

Update on the association of hepatitis B with intrahepatic cholangiocarcinoma: Is there new evidence?

Intrahepatic cholangiocarcinoma (iCCA) is a subgroup of cholangiocarcinoma that accounts for about 10%-20% of the total cases. Infection with hepatitis B virus (HBV) is one of the most important predisposing factors leading to the formation of iCCA. It has been recently estimated based on abundant epidemiological data that the association between HBV infection and iCCA is strong with an odds ratio of about 4.5. The HBV-associated mechanisms that lead to iCCA are under intense investigation. The diagnosis of iCCA in the context of chronic liver disease is challenging and often requires histological confirmation to distinguish from hepatocellular carcinoma. It is currently unclear whether antiviral treatment for HBV can decrease the incidence of iCCA. In terms of management, surgical resection remains the mainstay of treatment. There is a need for effective treatment modalities beyond resection in both first- and second-line treatment. In this review, we summarize the epidemiological evidence that links the two entities, discuss the pathogenesis of HBV-associated iCCA, and present the available data on the diagnosis and management of this cancer.

Typing FGFR2 translocation determines the response to targeted therapy of intrahepatic cholangiocarcinomas

Chromosomal translocations involving fibroblast growth factor receptor 2 (FGFR2) gene at the breakpoints are common genetic lesions in intrahepatic cholangiocarcinoma (ICC) and the resultant fusion protein products have emerged as promising druggable targets. However, predicting the sensitivity of FGFR2 fusions to FGFR kinase inhibitors is crucial to the prognosis of the ICC-targeted therapy. Here, we report identification of nine FGFR2 translocations out of 173 (5.2%) ICC tumors. Although clinicopathologically these FGFR2 translocation bearing ICC tumors are indistinguishable from the rest of the cohort, they are invariably of the mass-forming type originated from the small bile duct. We show that the protein products of FGFR2 fusions can be classified into three subtypes based on the breaking positions of the fusion partners: the classical fusions that retain the tyrosine kinase (TK) and the Immunoglobulin (Ig)-like domains (n = 6); the sub-classical fusions that retain only the TK domain without the Ig-like domain (n = 1); and the non-classical fusions that lack both the TK and Ig-like domains (n = 2). We demonstrate that cholangiocarcinoma cells engineered to express the classical and sub-classical fusions show sensitivity to FGFR-specific kinase inhibitors as evident by the suppression of MAPK/ERK and AKT/PI3K activities following the inhibitor treatment. Furthermore, the kinase-deficient mutant of the sub-classical fusion also lost its sensitivity to the FGFR-specific inhibitors. Taken together, our study suggests that it is essential to determine the breakpoint and type of FGFR2 fusions in the small bile duct subtype of ICC for the targeted treatment.

Inhibition of FGF-FGFR and VEGF-VEGFR signalling in cancer treatment

The sites of targeted therapy are limited and need to be expanded. The FGF‐FGFR signalling plays pivotal roles in the oncogenic process, and FGF/FGFR inhibitors are a promising method to treat FGFR‐altered tumours. The VEGF‐VEGFR signalling is the most crucial pathway to induce angiogenesis, and inhibiting this cascade has already got success in treating tumours. While both their efficacy and antitumour spectrum are limited, combining FGF/FGFR inhibitors with VEGF/VEGFR inhibitors are an excellent way to optimize the curative effect and expand the antitumour range because their combination can target both tumour cells and the tumour microenvironment. In addition, biomarkers need to be developed to predict the efficacy, and combination with immune checkpoint inhibitors is a promising direction in the future. The article will discuss the FGF‐FGFR signalling pathway, the VEGF‐VEGFR signalling pathway, the rationale of combining these two signalling pathways and recent small‐molecule FGFR/VEGFR inhibitors based on clinical trials.

Targeting the FGFR signaling pathway in cholangiocarcinoma: promise or delusion?

Cholangiocarcinoma (CCA) is a refractory cancer with limited treatment options and poorly understood molecular mechanisms underlying tumor development. The most effective treatment is surgical resection; however, patients are highly prone to recurrence. Moreover, considering that most patients are diagnosed in advanced stages, treatment options are restricted to palliative care, which results in poor prognosis. Due to the limited effect of chemotherapy and radiotherapy, targeted therapy is becoming a hot topic in the field of biliary cancer treatment. The fibroblast growth factor/fibroblast growth factor receptor (FGF/FGFR) signaling pathway involves a variety of key biological processes for cell survival, differentiation, and metabolism. Next-generation sequencing data mining has shown that high levels of FGF/FGFR expression are associated with reduced overall survival (OS) in CAA, which indicates that the FGF/FGFR pathway may be an effective target for CAA treatment. This paper reviews the effect of FGF/FGFR signaling on CCA from onset to treatment and highlights the promise of FGF/FGFR signaling pathway inhibitors for targeting CCA.

Target molecular treatment markers in Intrahepatic Cholangiocarcinoma based on Chinese population

BACKGROUND

As more and more molecular markers have been identified in Intrahepatic Cholangiocarcinoma (ICC), target treatments are promising all around the world. However, geographical and ethnic variations in the ICC epidemiology suggest different genetic variance prevalence in western and eastern countries.

METHODS

Six genetic variations in Chinese ICC populations were analyzed by fluorescent in situ hybridization (FISH) or Sanger sequencing, listed as IDH1/2 mutation, FGFR2 translocation, NTRK1 amplification, MDM2 amplification, HER2 amplification and MET amplification, all of which have corresponding target drugs; meanwhile, they were compared with these gene prevalence in Spanish population based on the cBioPortal database.

RESULTS

The incidences of IDH1/2 mutation, FGFR2 translocation, NTRK1 amplification, MDM2 amplification, HER2 amplification and MET amplification were 29.5 %, 12.9 %, 1.51 %, 2.27 %, 3.03 % and 0.75 %, respectively, in the Spanish population and 7.14 %, 5.71 %, 7.86 %, 5.71 %,4.29 % and 2.14 %, respectively, in the Chinese population. For the gene NTRK1, 11 samples showed signal apart companied amplified using FISH break-apart probes but none of them demonstrated genetic fusion by next-generation sequencing. As to clinicopathological characteristics, patients carrying IDH1/2 mutation showed longer overall survival in the Chinese population, while those carrying FGFR2 translocation tended to be younger in the Spanish population. For HER2, MDM2 and MET, gene amplification predicted protein high-expression, whereas FGFR2 translocation and NTRK1 amplification did not predict protein high-expression.

CONCLUSIONS

Although many target drugs have been speeded up for approval such as BGJ398 for FGFR2 fusion positive ICC patients in western countries, the beneficiary populations are very small in China. The regular target drug such as trastuzumab for HER2 amplification and Crizotinib for MET amplification may be potential candidates in target treatment based on the Chinese population.