Cholangiocarcinoma (CCA) is a heterogeneous group of malignancies arising from the epithelial cells of the bile ducts. It is classified anatomically into intrahepatic (iCCA), perihilar (pCCA), and distal (dCCA) subtypes. Risk factors include primary sclerosing cholangitis, liver fluke infection, hepatolithiasis, and chronic biliary inflammation, though approximately 50% of Western cases lack identifiable risk factors. CCA is characterized by a dense desmoplastic stroma, frequent actionable molecular alterations (IDH1/2 mutations, FGFR2 fusions, BRAF mutations, HER2 amplification), and an immunosuppressive tumor microenvironment. Gemcitabine-cisplatin plus durvalumab or pembrolizumab is the current first-line standard, with targeted therapies for molecularly defined subsets.
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name: Cholangiocarcinoma
creation_date: "2026-04-08T00:00:00Z"
description: >-
Cholangiocarcinoma (CCA) is a heterogeneous group of malignancies arising from the
epithelial cells of the bile ducts. It is classified anatomically into intrahepatic (iCCA),
perihilar (pCCA), and distal (dCCA) subtypes. Risk factors include primary sclerosing
cholangitis, liver fluke infection, hepatolithiasis, and chronic biliary inflammation,
though approximately 50% of Western cases lack identifiable risk factors. CCA is
characterized by a dense desmoplastic stroma, frequent actionable molecular alterations
(IDH1/2 mutations, FGFR2 fusions, BRAF mutations, HER2 amplification), and an
immunosuppressive tumor microenvironment. Gemcitabine-cisplatin plus durvalumab or
pembrolizumab is the current first-line standard, with targeted therapies for
molecularly defined subsets.
categories:
- Gastrointestinal Cancer
- Hepatobiliary Cancer
disease_term:
preferred_term: cholangiocarcinoma
term:
id: MONDO:0019087
label: cholangiocarcinoma
classifications:
icdo_morphology:
classification_value: Adenocarcinoma
notes: >-
Derived from this entry's disease term MONDO:0019087 (cholangiocarcinoma),
which carries the cross-reference ICDO:8160/3 and whose NCIT
cross-reference NCIT:C4436 (Cholangiocarcinoma) is a descendant of
NCIT:C2852 (Adenocarcinoma), the term this enum value is bound to.
evidence:
- reference: PMID:32129902
reference_title: "Global trends in intrahepatic and extrahepatic cholangiocarcinoma incidence from 1993 to 2012."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "Cholangiocarcinomas (CCAs) are rare tumors that originate from cholangiocytes in the bile ducts"
explanation: >-
Cholangiocytes are the glandular epithelial lining of the bile ducts, the
cell of origin underlying the adenocarcinoma morphology assignment.
harrisons_chapter:
- classification_value: ONCOLOGY_HEMATOLOGY
notes: >-
Cholangiocarcinoma is managed as a hepatobiliary solid-tumor oncology
problem (resection, cytotoxic chemotherapy, FGFR2/IDH1-targeted therapy).
parents:
- adenocarcinoma of gallbladder and extrahepatic biliary tract
has_subtypes:
- name: Intrahepatic
display_name: Intrahepatic Cholangiocarcinoma (iCCA)
subtype_term:
preferred_term: intrahepatic cholangiocarcinoma
term:
id: MONDO:0003210
label: intrahepatic cholangiocarcinoma
description: >-
Arises from the intrahepatic bile ducts, proximal to the second-order bile ducts.
Most common site for FGFR2 fusions and IDH1/2 mutations. Increasing in incidence
worldwide. Can be further subtyped into small duct and large duct types with
distinct molecular profiles.
- name: Perihilar
display_name: Perihilar Cholangiocarcinoma (pCCA, Klatskin tumor)
subtype_term:
preferred_term: hilar cholangiocarcinoma
term:
id: MONDO:0003345
label: hilar cholangiocarcinoma
description: >-
Arises at the confluence of the right and left hepatic ducts. The most common
anatomic subtype. Often presents with obstructive jaundice. Strongly associated
with primary sclerosing cholangitis.
- name: Distal
display_name: Distal Cholangiocarcinoma (dCCA)
description: >-
Arises from the extrahepatic bile duct below the cystic duct insertion. Clinically
resembles pancreatic head cancer. Treated with pancreaticoduodenectomy when resectable.
Note: No exact MONDO term for distal cholangiocarcinoma exists; see monarch-initiative/mondo issue.
pathophysiology:
- name: Chronic Biliary Inflammation and Cholestasis
description: >-
Chronic inflammation of the biliary epithelium from conditions such as primary
sclerosing cholangitis, hepatolithiasis, or liver fluke infection leads to repeated
cycles of injury and repair. Persistent cholestasis and bile acid exposure cause
oxidative stress and DNA damage in cholangiocytes, promoting malignant transformation.
In Western countries about 50% of cases are diagnosed without any identifiable risk
factor.
evidence:
- reference: PMID:30851228
reference_title: "Cholangiocarcinoma: Epidemiology and risk factors."
supports: SUPPORT
snippet: >-
in Western countries about 50% of cases are still diagnosed without any
identifiable risk factor
explanation: >-
Confirms that many CCA cases lack identifiable risk factors, but chronic biliary
inflammation remains a key driver in cases with known etiology.
- reference: PMID:32129902
reference_title: "Global trends in intrahepatic and extrahepatic cholangiocarcinoma incidence from 1993 to 2012."
supports: SUPPORT
snippet: >-
Between 1993 and 2012, incidence rates of both ICC and ECC increased in most
countries.
explanation: >-
Documents rising global CCA incidence, consistent with increasing exposure to
risk factors including metabolic syndrome and chronic liver disease.
cell_types:
- preferred_term: cholangiocyte
term:
id: CL:1000488
label: cholangiocyte
biological_processes:
- preferred_term: inflammatory response
modifier: INCREASED
term:
id: GO:0006954
label: inflammatory response
- preferred_term: response to oxidative stress
modifier: INCREASED
term:
id: GO:0006979
label: response to oxidative stress
locations:
- preferred_term: bile duct
term:
id: UBERON:0002394
label: bile duct
downstream:
- target: Desmoplastic Stromal Reaction
description: Chronic inflammation activates periductal fibroblasts and stellate cells
- target: Accumulation of Oncogenic Mutations
description: Repeated injury-repair cycles promote somatic mutation accumulation
- name: Accumulation of Oncogenic Mutations
description: >-
CCA harbors a diverse mutational landscape. Common alterations include IDH1/2 mutations
(10-20% of iCCA), FGFR2 fusions/rearrangements (10-16% of iCCA), TP53 mutations,
KRAS mutations, ARID1A mutations, BAP1 loss, and PBRM1 mutations. The mutational
profile differs by anatomic and pathologic subtype, with IDH and FGFR alterations
enriched in small duct iCCA and KRAS mutations more common in large duct and
extrahepatic subtypes.
evidence:
- reference: PMID:36528236
reference_title: "Charting co-mutation patterns associated with actionable drivers in intrahepatic cholangiocarcinoma."
supports: SUPPORT
snippet: >-
We provide a highly representative cartography of the genomic landscape of iCCA
and outline the co-mutational spectra of seven therapeutically relevant oncogenic
driver genes: IDH1/2, FGFR2, ERBB2, BRAF, MDM2, BRCA1/2, MET and KRASG12C.
explanation: >-
Comprehensive genomic profiling of iCCA confirming the diverse mutational
landscape with multiple actionable driver genes.
- reference: PMID:41850925
reference_title: "Comprehensive molecular-clinical profiling of cholangiocarcinoma according to pathologic subtypes."
supports: SUPPORT
snippet: >-
KRAS and PIK3CA mutations were more frequent in the large duct type, while IDH1/2
mutations and FGFR2 fusions were more common in the small duct type.
explanation: >-
Confirms that mutational profiles differ by pathologic subtype, with IDH1/2 and
FGFR2 enriched in small duct type and KRAS enriched in large duct type.
- reference: PMID:41682001
reference_title: "FGFR2-Rearranged Biliary Tract Cancer: Biology, Resistance Mechanisms, and Emerging Therapeutic Strategies."
supports: SUPPORT
snippet: >-
Approximately 10-16% of iCCA cases harbor FGFR2 fusions or rearrangements,
defining a distinct molecular subtype characterized by sensitivity to
FGFR-targeted therapies.
explanation: >-
Confirms prevalence of FGFR2 fusions in iCCA and their therapeutic relevance.
biological_processes:
- preferred_term: regulation of cell population proliferation
modifier: INCREASED
term:
id: GO:0042127
label: regulation of cell population proliferation
downstream:
- target: Epigenetic Dysregulation
description: IDH mutations produce oncometabolite 2-HG causing epigenetic changes
- target: Enhanced Cell Proliferation and Survival
description: KRAS and FGFR alterations drive proliferative signaling
- name: Epigenetic Dysregulation
description: >-
IDH1/2 mutations produce the oncometabolite 2-hydroxyglutarate (2-HG), which inhibits
alpha-ketoglutarate-dependent dioxygenases including TET2 and histone demethylases.
This leads to DNA and histone hypermethylation, blocking cholangiocyte differentiation
and promoting a progenitor-like state. EZH2 overexpression further drives epigenetic
silencing of tumor suppressors. vCAF-derived IL-6 induces epigenetic alterations
in CCA cells, particularly upregulating EZH2.
evidence:
- reference: PMID:36528236
reference_title: "Charting co-mutation patterns associated with actionable drivers in intrahepatic cholangiocarcinoma."
supports: SUPPORT
snippet: >-
We observed a negative selection of RTK/RAS/ERK pathway co-alterations, and an
enrichment of epigenetic modifiers such as ARID1A and BAP1 in patients with IDH1/2
and FGFR2 alterations.
explanation: >-
Shows that IDH1/2 and FGFR2-altered tumors co-occur with mutations in epigenetic
modifiers, supporting epigenetic dysregulation as a key mechanism.
- reference: PMID:32505533
reference_title: "Single-cell transcriptomic architecture and intercellular crosstalk of human intrahepatic cholangiocarcinoma."
supports: SUPPORT
evidence_source: IN_VITRO
snippet: >-
IL-6 secreted by vCAFs induced significant epigenetic alterations in ICC cells,
particularly upregulating enhancer of zeste homolog 2 (EZH2) and thereby enhancing
malignancy.
explanation: >-
Single-cell analysis demonstrating that vCAF-derived IL-6 drives EZH2-mediated
epigenetic reprogramming in iCCA cells.
biological_processes:
- preferred_term: chromatin organization
modifier: ABNORMAL
term:
id: GO:0006325
label: chromatin organization
- preferred_term: epigenetic regulation of gene expression
modifier: ABNORMAL
term:
id: GO:0040029
label: epigenetic regulation of gene expression
- name: Desmoplastic Stromal Reaction
description: >-
CCA is characterized by a prominent desmoplastic stroma comprising cancer-associated
fibroblasts (CAFs), extracellular matrix proteins, and inflammatory cells. Single-cell
analysis identified six distinct fibroblast subsets, with vascular CAFs (vCAFs)
dominant and expressing high levels of IL-6. Matricellular glycoproteins including
periostin, osteopontin, and tenascin-C promote proliferation, invasion, EMT, and
immune evasion. The dense stroma limits immune cell infiltration and drug delivery.
evidence:
- reference: PMID:35961702
reference_title: "Matricellular proteins in intrahepatic cholangiocarcinoma."
supports: SUPPORT
snippet: >-
Intrahepatic cholangiocarcinoma (iCCA) is typically characterized by a prominent
desmoplastic stroma that is often the most dominant feature of the tumor.
explanation: >-
Establishes the desmoplastic stroma as the most dominant feature of iCCA.
- reference: PMID:35961702
reference_title: "Matricellular proteins in intrahepatic cholangiocarcinoma."
supports: SUPPORT
snippet: >-
the interplay between cholangiocarcinoma cells, CAFs, and TAMs in particular play
a critical role in promoting cholangiocarcinoma progression, therapeutic resistance,
and immune evasion
explanation: >-
Confirms that CAF-TAM-cancer cell crosstalk drives CCA progression, drug
resistance, and immune evasion.
- reference: PMID:32505533
reference_title: "Single-cell transcriptomic architecture and intercellular crosstalk of human intrahepatic cholangiocarcinoma."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
We identified 6 distinct fibroblast subsets, of which the majority were
CD146-positive vascular cancer-associated fibroblasts (vCAFs), with highly
expressed microvasculature signatures and high levels of interleukin (IL)-6.
explanation: >-
Single-cell RNA-seq on human ICC surgical specimens revealing six fibroblast
subsets in iCCA, with vCAFs as the dominant subset secreting high IL-6 levels.
cell_types:
- preferred_term: cancer-associated fibroblast
term:
id: CL:0000057
label: fibroblast
biological_processes:
- preferred_term: extracellular matrix organization
modifier: INCREASED
term:
id: GO:0030198
label: extracellular matrix organization
downstream:
- target: Immunosuppressive Tumor Microenvironment
description: Dense stroma and CAF-derived factors create immune-excluded phenotype
- target: Enhanced Cell Proliferation and Survival
description: CAF-secreted growth factors promote tumor cell proliferation
- name: Immunosuppressive Tumor Microenvironment
description: >-
The CCA microenvironment is enriched with tumor-associated macrophages, myeloid-derived
suppressor cells, and regulatory T cells with highly immunosuppressive characteristics.
PD-L1 expression is variable. The dense desmoplastic stroma acts as a physical barrier
to T cell infiltration. Tumor-infiltrating B cells are scarce, immature, and
immunosuppressive.
evidence:
- reference: PMID:32505533
reference_title: "Single-cell transcriptomic architecture and intercellular crosstalk of human intrahepatic cholangiocarcinoma."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
tumor-infiltrating CD4 regulatory T cells exhibited highly immunosuppressive
characteristics
explanation: >-
Single-cell analysis of human ICC surgical specimens confirming immunosuppressive
Treg infiltration in the iCCA tumor microenvironment.
- reference: PMID:39570809
reference_title: "Mapping of the T-cell Landscape of Biliary Tract Cancer Unravels Anatomic Subtype-Specific Heterogeneity."
supports: SUPPORT
snippet: >-
ICC displayed an inflamed immunophenotype with an enrichment of IFN-related
pathways and high expression of LGALS1 in activated regulatory T cells
explanation: >-
T cell landscape mapping showing LGALS1-expressing Tregs contribute to
immunosuppression in iCCA.
cell_types:
- preferred_term: tumor-associated macrophage
term:
id: CL:0000235
label: macrophage
biological_processes:
- preferred_term: immune response
modifier: DECREASED
term:
id: GO:0006955
label: immune response
- name: Enhanced Cell Proliferation and Survival
description: >-
Multiple oncogenic pathways converge to drive CCA proliferation and survival.
RAS-MAPK and PI3K-AKT-mTOR pathways are frequently activated by KRAS mutations,
FGFR alterations, or growth factor receptor amplifications. MAPK pathway activation
serves as a convergent resistance mechanism across targeted therapies.
evidence:
- reference: PMID:41460204
reference_title: "MAPK Pathway Mutations Emerge in Mutant IDH1 Inhibitor-Resistant Cholangiocarcinoma and Attenuate the IFN Response."
supports: SUPPORT
snippet: >-
MAPK pathway alterations represent a recurrent mechanism of resistance to mIDH1
inhibition in ICC
explanation: >-
Demonstrates that MAPK activation is a convergent resistance mechanism in CCA,
emerging during IDH1 inhibitor therapy.
- reference: PMID:41682001
reference_title: "FGFR2-Rearranged Biliary Tract Cancer: Biology, Resistance Mechanisms, and Emerging Therapeutic Strategies."
supports: SUPPORT
snippet: >-
the development of acquired resistance-most commonly driven by secondary
kinase-domain mutations and activation of bypass signaling pathways-remains a
major limitation to sustained therapeutic benefit
explanation: >-
Confirms bypass signaling including MAPK activation as a key resistance mechanism
to FGFR inhibitors in CCA.
biological_processes:
- preferred_term: cell population proliferation
modifier: INCREASED
term:
id: GO:0008283
label: cell population proliferation
phenotypes:
- category: Clinical
name: Obstructive Jaundice
description: >-
Painless jaundice due to biliary obstruction, particularly common in perihilar
and distal CCA. Results from tumor growth causing mechanical obstruction of bile flow.
phenotype_term:
preferred_term: Obstructive jaundice
term:
id: HP:0012334
label: Extrahepatic cholestasis
- category: Clinical
name: Abdominal Pain
description: >-
Right upper quadrant or epigastric pain, more common in intrahepatic CCA.
May present as a dull ache related to hepatic capsule distension.
phenotype_term:
preferred_term: Abdominal pain
term:
id: HP:0002027
label: Abdominal pain
- category: Clinical
name: Unintentional Weight Loss
description: >-
Weight loss is a common presenting symptom, particularly in advanced disease.
Results from cancer cachexia and reduced caloric intake due to biliary obstruction.
phenotype_term:
preferred_term: Weight loss
term:
id: HP:0001824
label: Weight loss
evidence:
- reference: PMID:41429598
reference_title: "Systemic Therapy for Advanced Biliary Tract Cancers in 2026: Current Standard of Care and Emerging Therapeutic Strategies."
supports: SUPPORT
snippet: >-
the majority present with advanced disease, and palliative systemic therapy is
the mainstay of treatment
explanation: >-
Confirms most CCA patients present with advanced disease where weight loss is a
common symptom; snippet is indirect as it does not specifically mention weight loss.
- category: Clinical
name: Pruritus
description: >-
Generalized itching resulting from cholestasis and bile salt deposition in the skin.
Often accompanies obstructive jaundice.
phenotype_term:
preferred_term: Pruritus
term:
id: HP:0000989
label: Pruritus
- category: Clinical
name: Hepatomegaly
description: >-
Liver enlargement, particularly seen in intrahepatic CCA with large tumor masses
or in the setting of biliary obstruction.
phenotype_term:
preferred_term: Hepatomegaly
term:
id: HP:0002240
label: Hepatomegaly
treatments:
- name: Gemcitabine-Cisplatin Plus Immune Checkpoint Inhibitor
description: >-
Current first-line standard of care for advanced CCA. TOPAZ-1 and KEYNOTE-966
established GemCis plus durvalumab or pembrolizumab as the standard. Real-world
data report median OS of 16 months, median PFS of 5 months.
evidence:
- reference: PMID:41429598
reference_title: "Systemic Therapy for Advanced Biliary Tract Cancers in 2026: Current Standard of Care and Emerging Therapeutic Strategies."
supports: SUPPORT
snippet: >-
In the first-line setting, gemcitabine plus cisplatin (GemCis) chemotherapy
served as the long-standing standard of care; subsequently, TOPAZ-1 and
KEYNOTE-966 established GemCis plus durvalumab or pembrolizumab as the current
standard.
explanation: >-
Establishes GemCis+ICI as the current first-line standard of care for advanced
biliary tract cancer.
- reference: PMID:40533571
reference_title: "Treatment with gemcitabine/cisplatin and durvalumab for advanced biliary tract cancer - real-world data from a multicenter German patient population."
supports: SUPPORT
snippet: >-
The median overall survival (mOS) was 16 months, and the median
progression-free survival (mPFS) was 5 months.
explanation: >-
Real-world data validating GemCis+durvalumab efficacy in advanced BTC.
treatment_term:
preferred_term: chemotherapy with immunotherapy
term:
id: NCIT:C15632
label: Chemotherapy
- name: Surgical Resection
description: >-
Surgical resection is the only potentially curative treatment for CCA. Procedure
type depends on anatomic location: hepatectomy for iCCA, hilar resection with
hepatectomy for pCCA, and pancreaticoduodenectomy for dCCA. R0 resection is the
most important prognostic factor.
therapeutic_modality: SURGERY
treatment_term:
preferred_term: surgical resection
term:
id: NCIT:C154430
label: Definitive Surgical Resection
- name: Adjuvant Capecitabine
description: >-
Standard adjuvant therapy after curative resection of CCA. The BILCAP trial
demonstrated improved median OS of 49.6 months with capecitabine versus 36.1 months
with observation alone.
evidence:
- reference: PMID:35316080
reference_title: "Long-Term Outcomes and Exploratory Analyses of the Randomized Phase III BILCAP Study."
supports: SUPPORT
snippet: >-
the median OS was 49.6 months (95% CI, 35.1 to 59.1) in the capecitabine group
compared with 36.1 months (95% CI, 29.7 to 44.2) in the observation group
explanation: >-
Long-term BILCAP data confirming capecitabine survival benefit in resected BTC.
treatment_term:
preferred_term: adjuvant chemotherapy
term:
id: NCIT:C15632
label: Chemotherapy
- name: Targeted Therapy for Molecular Subtypes
description: >-
FDA-approved targeted therapies include ivosidenib for IDH1-mutant CCA, pemigatinib
and futibatinib for FGFR2-altered CCA. Comprehensive genomic profiling is recommended
to identify actionable alterations. MAPK pathway activation is a convergent resistance
mechanism across these agents.
evidence:
- reference: PMID:39730074
reference_title: "Cholangiocarcinoma Targeted Therapies: Mechanisms of Action and Resistance."
supports: SUPPORT
snippet: >-
Hotspot IDH1 mutations and activating fibroblast growth factor receptor 2 fusions
occur frequently, and small-molecule inhibitors against these alterations are US
Food and Drug Administration approved.
explanation: >-
Confirms FDA approval of targeted therapies for IDH1 and FGFR2 alterations in CCA.
- reference: PMID:41460204
reference_title: "MAPK Pathway Mutations Emerge in Mutant IDH1 Inhibitor-Resistant Cholangiocarcinoma and Attenuate the IFN Response."
supports: SUPPORT
snippet: >-
Acquired mutations in mitogen-activated protein kinase (MAPK) pathway genes
(KRAS, NRAS, MAP2K1, NF1) were identified in five cases, with instances of
concurrent alterations and/or high variant allele fractions (VAF).
explanation: >-
Identifies MAPK pathway mutations as acquired resistance mechanism to ivosidenib,
highlighting need for combination strategies.
treatment_term:
preferred_term: targeted molecular therapy
term:
id: NCIT:C15986
label: Pharmacotherapy
- name: Immune Checkpoint Inhibitor Therapy
description: >-
Durvalumab combined with gemcitabine-cisplatin is now a standard first-line option
based on the TOPAZ-1 trial. Pembrolizumab is approved for MSI-high/dMMR tumors.
Tertiary lymphoid structure status may predict immunotherapy response.
evidence:
- reference: PMID:39870490
reference_title: "Comparative impact of tertiary lymphoid structures and tumor-infiltrating lymphocytes in cholangiocarcinoma."
supports: SUPPORT
snippet: >-
TLS-positive (N=7) patients demonstrated significantly better immunotherapy
outcomes compared with TLS-negative (N=9) patients, including higher objective
response rates (71% vs 0%)
explanation: >-
Demonstrates that tertiary lymphoid structures predict dramatically better
immunotherapy response in CCA.
treatment_term:
preferred_term: immune checkpoint inhibitor therapy
term:
id: NCIT:C15986
label: Pharmacotherapy
infectious_agent:
- name: Opisthorchis viverrini
description: >-
Liver fluke endemic in Southeast Asia (Thailand, Laos, Vietnam, Cambodia).
Chronic infection causes biliary inflammation and epithelial damage, leading
to cholangiocarcinoma. Classified as a Group 1 carcinogen by IARC.
infectious_agent_term:
preferred_term: Opisthorchis viverrini
term:
id: NCBITaxon:6198
label: Opisthorchis viverrini
evidence:
- reference: PMID:32129902
reference_title: "Global trends in intrahepatic and extrahepatic cholangiocarcinoma incidence from 1993 to 2012."
supports: SUPPORT
snippet: >-
The highest rates of ICC and ECC were in Asia, specifically South Korea (ASR for
ICC, 2.80; ASR for ECC, 2.24), Thailand (ASR for ICC, 2.19; ASR for ECC, 0.71)
explanation: >-
Highest CCA rates in regions endemic for liver fluke infection.
- name: Clonorchis sinensis
description: >-
Liver fluke endemic in East Asia (China, South Korea, Russia). Chronic infection
causes periductal inflammation and cholangiocarcinoma. Classified as a Group 1
carcinogen by IARC.
infectious_agent_term:
preferred_term: Clonorchis sinensis
term:
id: NCBITaxon:79923
label: Clonorchis sinensis
environmental:
- name: Liver Fluke Infection
influences_mechanisms:
- target: Chronic Biliary Inflammation and Cholestasis
environmental_effect: TRIGGERS
causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
description: >-
The best-evidenced link in this tranche, and the only one where the
intervening step is quoted rather than assumed: the flukes cause chronic
irritation and increased cellular turnover in the bile ducts, which is
the inflammation this node holds. Deliberately down to one item. Two
further sentences were fetched from the same review, a four to fivefold
risk figure and the ingestion route, and both were moved to the
exposure's own evidence where they characterise the exposure rather
than this edge into the node. The sentence that was already on the
exposure reports incidence rates by country and never mentions flukes at
all, so it names neither the exposure nor any relation to this node and
stays where it is.
evidence:
- reference: PMID:32129902
reference_title: "Global trends in intrahepatic and extrahepatic cholangiocarcinoma incidence from 1993 to 2012."
supports: SUPPORT
snippet: "These flukes cause chronic irritation and increased cellular turnover, which can increase the susceptibility of cholangiocytes to endogenous and exogenous carcinogens"
explanation: >-
Names the mechanism this edge asserts: chronic irritation and cellular
turnover in the bile ducts, which is this node's content, and then the
carcinogen susceptibility that follows from it.
description: >-
Infection with Opisthorchis viverrini or Clonorchis sinensis, endemic in Southeast
Asia, is a major risk factor for CCA, particularly in Thailand and Laos. Chronic
fluke infection causes biliary inflammation and epithelial damage.
evidence:
- reference: PMID:32129902
reference_title: "Global trends in intrahepatic and extrahepatic cholangiocarcinoma incidence from 1993 to 2012."
supports: SUPPORT
snippet: "Risk of CCA has been estimated to increase 4-5-fold with liver fluke infection in places such as South Korea (Clonorchis sinensis) and Thailand (Opisthorchis viverrini)"
explanation: >-
Quantifies the exposure at a four to fivefold increase in disease risk
and names both species. It sizes the exposure rather than arguing for
any particular step inside the mechanism, which is why it sits here
rather than on the link.
- reference: PMID:32129902
reference_title: "Global trends in intrahepatic and extrahepatic cholangiocarcinoma incidence from 1993 to 2012."
supports: SUPPORT
snippet: "Liver flukes are parasitic trematodes that, when ingested via raw, pickled, or undercooked fish, can live in the host biliary system for decades"
explanation: >-
Establishes the route and the duration, which is what makes this an
environmental exposure rather than a host state: the organism is eaten,
and it then occupies the bile ducts long enough for chronic
inflammation to matter.
- reference: PMID:32129902
reference_title: "Global trends in intrahepatic and extrahepatic cholangiocarcinoma incidence from 1993 to 2012."
supports: SUPPORT
snippet: >-
The highest rates of ICC and ECC were in Asia, specifically South Korea (ASR for
ICC, 2.80; ASR for ECC, 2.24), Thailand (ASR for ICC, 2.19; ASR for ECC, 0.71)
explanation: >-
Highest CCA rates in regions endemic for liver fluke infection (Thailand,
South Korea).
- name: Primary Sclerosing Cholangitis
description: >-
Chronic autoimmune biliary disease causing progressive biliary fibrosis and
stricturing. Confers a lifetime CCA risk of 10-20%, representing the strongest
identifiable risk factor in Western populations.
evidence:
- reference: PMID:30725866
reference_title: "Primary Sclerosing Cholangitis."
supports: SUPPORT
snippet: >-
PSC also carries substantial risk for hepatobiliary malignancies, especially
cholangiocarcinoma, with a lifetime incidence of 10% to 20% and an annual risk
of 1% to 2%
explanation: >-
Directly quantifies PSC-associated CCA lifetime risk at 10-20% with 1-2%
annual incidence.
datasets:
- accession: ega:EGAS00001000375
title: Exome sequencing of paired tumor/normal DNA samples from the eight intrahepatic cholangiocarcinoma patients
description: Intrahepatic cholangiocarcinoma (ICC) is the second most common primary liver malignancy after hepatocellular carcinoma, with increasing incidence worldwide. To gain new insight into the genetic basis of ICC, we performed whole-exome sequencing of paired tumor/normal DNA samples from the 8 ICC patients. The patients underwent surgical resection at the Liver Cancer Institute, Zhongshan Hospital of Fudan University. The study was approved by the Zhongshan Hospital Ethics Committee, and informed consent was obtained from each patients under Institutional Review Board protocols. Tumor tissue was analyzed by frozen section to assess neoplastic cellularity (above 80%).
organism:
preferred_term: human
term:
id: NCBITaxon:9606
label: Homo sapiens
data_type: WES
notes: 'European Genome-phenome Archive study, matched because the disease is named in the study''s own title ("Cholangiocarcinoma"); description-level mentions were not accepted. EGA study_type: Exome Sequencing. Controlled access -- data require a Data Access Agreement. EGA metadata retrieved 2026-08-01.'
- accession: ega:EGAS00001001653
title: Whole-Genome and Epigenomic Landscapes of Etiologically Distinct Subtypes of Cholangiocarcinoma
description: Cholangiocarcinoma (CCA) is a hepatobiliary malignancy exhibiting high incidence in countries with endemic liver-fluke infection. We analyzed 489 CCAs from 10 countries, combining whole-genome (71 cases), targeted/exome, copy-number, gene expression, and DNA methylation information. Integrative clustering defined 4 CCA clusters-fluke-positive CCAs (clusters 1/2) are enriched in ERBB2 amplifications and TP53 mutations; conversely, fluke-negative CCAs (clusters 3/4) exhibit high copy-number alterations and PD-1/PD-L2 expression, or epigenetic mutations (IDH1/2, BAP1) and FGFR/PRKA-related gene rearrangements.
organism:
preferred_term: human
term:
id: NCBITaxon:9606
label: Homo sapiens
publication: PMID:28667006
notes: 'European Genome-phenome Archive study, matched because the disease is named in the study''s own title ("Cholangiocarcinoma"); description-level mentions were not accepted. EGA study_type: Other. Controlled access -- data require a Data Access Agreement. EGA metadata retrieved 2026-08-01.'
- accession: ega:EGAS00001002547
title: Clonal evolution study of Intrahepatic cholangiocarcinoma in Zhongshan Hospital
description: Clonal evolution study of Intrahepatic cholangiocarcinoma
organism:
preferred_term: human
term:
id: NCBITaxon:9606
label: Homo sapiens
notes: 'European Genome-phenome Archive study, matched because the disease is named in the study''s own title ("Cholangiocarcinoma"); description-level mentions were not accepted. EGA study_type: Other. Controlled access -- data require a Data Access Agreement. EGA metadata retrieved 2026-08-01.'
- accession: metabolomics_workbench:ST000230
title: Comprehensive analysis of transcriptome and metabolome in Intrahepatic Cholangiocarcinoma and Hepatocellular Carcinoma
notes: Located via OmicsDI, which aggregates across omics repositories; this record comes from metabolomics_workbench. Only repositories with no other discovery route in this project and with a working accession resolver are curated from OmicsDI -- GEO, ArrayExpress, PRIDE, MetaboLights and EGA hits are excluded as duplicates of dedicated passes. Matched because the disease is named in the dataset's own title ("Cholangiocarcinoma"). Retrieved 2026-08-02.
- accession: metabolomics_workbench:ST000231
title: Comprehensive analysis of transcriptome and metabolome in Intrahepatic Cholangiocarcinoma and Hepatocellular Carcinoma (part II)
notes: Located via OmicsDI, which aggregates across omics repositories; this record comes from metabolomics_workbench. Only repositories with no other discovery route in this project and with a working accession resolver are curated from OmicsDI -- GEO, ArrayExpress, PRIDE, MetaboLights and EGA hits are excluded as duplicates of dedicated passes. Matched because the disease is named in the dataset's own title ("Cholangiocarcinoma"). Retrieved 2026-08-02.
- accession: massive:MSV000084273
title: TWEAK/Fn14 signalling promotes cholangiocarcinoma niche formation and progression
description: Cholangiocarcinoma is a cancer of the hepatic bile ducts that is typically detected at a stage too advanced for resection. Additionally, chemotherapy is of limited efficacy, hence, novel therapeutic approaches are urgently required, including targeting of the cancer stroma. A macrophage-derived signal, tumour necrosis factor-like weak inducer of apoptosis (TWEAK), binds to cell-surface fibroblast growth factor-inducible 14 (Fn14), on cholangiocarcinoma cells to induce cytokine and chemokine expression and secretion.
notes: Located via OmicsDI, which aggregates across omics repositories; this record comes from massive. Only repositories with no other discovery route in this project and with a working accession resolver are curated from OmicsDI -- GEO, ArrayExpress, PRIDE, MetaboLights and EGA hits are excluded as duplicates of dedicated passes. Matched because the disease is named in the dataset's own title ("Cholangiocarcinoma"). Retrieved 2026-08-02.
Cholangiocarcinoma (CCA) is a heterogeneous group of biliary tract malignancies with rising global incidence, distinct molecular subtypes dictating therapeutic eligibility, and a rapidly evolving treatment landscape. This comprehensive review, synthesized from 82 peer-reviewed publications, reveals that CCA is not a single disease but a collection of molecularly and anatomically distinct entities: intrahepatic CCA (iCCA) harbors actionable FGFR2 fusions (~13%) and IDH1/2 mutations (~20%), while extrahepatic/perihilar CCA (eCCA/pCCA) is enriched for KRAS (~25%) and TP53 (~35%) mutations. Within iCCA itself, further stratification into small duct and large duct types — and more recently into five intratumor heterogeneity (ITH)-insensitive transcriptomic subtypes — carries direct implications for prognosis and therapy selection.
The treatment paradigm has undergone a transformative shift since 2020. First-line therapy has advanced from gemcitabine/cisplatin (GemCis) alone (median overall survival [mOS] ~11.6 months) to GemCis plus immune checkpoint inhibitors (durvalumab or pembrolizumab), established by the TOPAZ-1 and KEYNOTE-966 trials (real-world mOS ~16 months). For biomarker-selected patients, FDA-approved targeted agents — pemigatinib, futibatinib, and infigratinib for FGFR2 fusions; ivosidenib for IDH1 mutations — offer meaningful clinical benefit. In the adjuvant setting, capecitabine remains the only chemotherapy with proven survival benefit after resection (mOS 49.6 vs. 36.1 months).
A critical mechanistic insight emerging from this investigation is that MAPK pathway activation serves as a convergent resistance mechanism across both FGFR2 and IDH1 inhibitors, suggesting that combined targeted therapy plus MEK/ERK inhibition represents a rational next-generation strategy. Additionally, the desmoplastic tumor microenvironment (TME) — dominated by cancer-associated fibroblasts (CAFs) and tumor-associated macrophages (TAMs) — drives immune evasion across all CCA subtypes, but novel stroma-targeting approaches (photothermal therapy, PARG inhibition, SUMOylation inhibition) can reprogram the TME from immune-cold to immune-hot, synergizing with checkpoint immunotherapy.
CCA encompasses anatomically and molecularly distinct subtypes with divergent clinical behavior and therapeutic vulnerabilities. Intrahepatic CCA harbors IDH1/2 mutations (~20%), FGFR2 fusions (~13%), and BAP1 mutations (~12%), while extrahepatic/perihilar CCA is enriched for KRAS mutations (~25%), TP53 mutations (~35%), and PIK3CA mutations. This molecular dichotomy was confirmed by large-scale genomic profiling: a comprehensive cartography of iCCA outlined co-mutational spectra of seven therapeutically relevant oncogenic driver genes (IDH1/2, FGFR2, ERBB2, BRAF, MDM2, BRCA1/2, MET, and KRAS) (PMID: 36528236). Pathological subtyping further distinguishes large duct type iCCA — with worse survival, higher N1 stage rates, and enrichment in inflammation/AKT/KRAS pathways — from small duct type, which is enriched for IDH1/2 mutations and FGFR2 fusions (PMID: 41850925).
A landmark 2026 study by Lin et al. integrated multi-omics data from multi-region, single-region, and single-cell RNA sequencing to define five robust iCCA subgroups that overcome the problem of intratumor heterogeneity: inflammatory (SI), metabolic (SII), atypical (SIII-1), immune-silent (SIII-2), and neurodegenerative (SIII-3). Existing subtyping systems misclassify a median 27.8% of tumors due to ITH driven by immune/stromal components (PMID: 41916296). Critically, this new classification identifies subtype-specific therapeutic strategies: HSP90 inhibition synergizes with anti-PD1 in inflammatory iCCA, whereas combined anti-PD1 and anti-TIM3 suppresses neurodegenerative iCCA. GPRC5A and VTCN1 serve as practical IHC biomarkers for clinical implementation.
The TOPAZ-1 and KEYNOTE-966 trials established GemCis plus durvalumab or pembrolizumab as the current first-line standard of care for advanced biliary tract cancer (PMID: 41429598). Real-world data from a German multicenter cohort (n=90) reported mOS of 16 months, mPFS of 5 months, ORR of 11.1%, and DCR of 41.1% with GemCis plus durvalumab (PMID: 40533571). A meta-analysis of 17 RCTs (n=4,584) confirmed that pooled mOS for GemCis alone was 11.6 months, with ICIs providing incremental but significant benefit (PMID: 39980751).
For biomarker-selected patients in later lines, the therapeutic landscape includes:
| Target | Agent(s) | Key Efficacy | Approval Status |
|---|---|---|---|
| FGFR2 fusions | Pemigatinib, futibatinib, infigratinib | mOS ~20–21 months | FDA-approved |
| IDH1 mutations | Ivosidenib | mOS 10.8 months (adjusted) | FDA-approved |
| HER2 amplification | Trastuzumab deruxtecan (T-DXd) | mOS 12.4 months | Under investigation |
| BRAF V600E | Dabrafenib + trametinib | Tumor-agnostic approval | FDA-approved |
These targeted agents are available for patients whose tumors harbor specific molecular alterations, underscoring the importance of comprehensive genomic profiling (PMID: 39730074).
iCCA is characterized by a prominent desmoplastic stroma comprising dense fibro-collagenous extracellular matrix (ECM), cancer-associated fibroblasts (CAFs), and tumor-associated macrophages (TAMs). The interplay between CCA cells, CAFs, and TAMs plays a critical role in promoting CCA progression, therapeutic resistance, and immune evasion (PMID: 35961702). Matricellular glycoproteins — periostin, osteopontin, tenascin-C, thrombospondin-1, and mesothelin — are overexpressed and regulate proliferation, invasion, epithelial–mesenchymal transition (EMT), ECM remodeling, and immune evasion. Single-cell RNA sequencing of 56,871 cells from iCCA identified six distinct fibroblast subsets, with vascular CAFs (vCAFs) expressing high levels of IL-6 that drive epigenetic alterations in tumor cells (PMID: 32505533).
Global analysis of cancer registry data from 38 countries (1993–2012) found that ICC and ECC incidence increased in the majority of countries (PMID: 32129902). Highest rates are observed in Asia (South Korea ICC ASR 2.80, Thailand ICC ASR 2.19). Mortality from ICC increased in all 32 countries studied, with the highest rates of 1.5–2.5/100,000 in men. Critically, in Western countries, approximately 50% of CCA cases are diagnosed without any identifiable risk factor (PMID: 30851228), highlighting the large proportion of idiopathic disease and the need for improved understanding of pathogenesis.
Resistance to targeted therapies in CCA involves polyclonal genomic escape mechanisms. For FGFR2 inhibitors, resistance involves gatekeeper mutations (e.g., V565F), kinase domain mutations, and bypass signaling via the RAS/MAPK pathway. Cell-free DNA (cfDNA) analysis of 1,671 advanced BTC patients revealed that FGFR2 fusions, IDH1 mutations, and BRAF V600E are clonal in the majority of cases, affirming these as early driver events (PMID: 36089135). Notably, cfDNA analysis uncovered novel putative resistance mechanisms, including mutation of the cysteine residue (FGFR2 C492F) to which covalent FGFR inhibitors bind. IDH1 tissue–cfDNA concordance is 87% and BRAF V600E is 100%, but FGFR2 fusions are only 18% concordant, highlighting limitations of liquid biopsy for fusion detection.
Longitudinal ctDNA analysis of 18 ivosidenib-treated patients from the ClarIDHy phase III trial revealed acquired MAPK pathway mutations (KRAS, NRAS, MAP2K1, NF1) in 5/18 cases (28%), with instances of concurrent alterations and/or high variant allele fractions (PMID: 41460204). Functional studies demonstrated that MAPK activation blunted gene expression induced by ivosidenib plus IFNγ, a key therapeutic output of mIDH1 inhibition. Baseline ctDNA profiling of 81 patients showed that ARID1A mutations and elevated mIDH1 VAF were associated with reduced clinical benefit. This parallels the RAS/MAPK bypass signaling seen with FGFR2 inhibitor resistance (PMID: 41682001), establishing MAPK activation as a convergent escape route across CCA targeted therapies.
Wang et al. (2026) demonstrated that IDH1 mutations alone correlate with favorable outcomes in mouse models, but MYC overexpression drives malignant phenotypic manifestation of IDH1 mutations, reversing this phenotype (PMID: 41800252). Mechanistically, IDH1-mutant ICC reprograms glutamine metabolism to regulate MYC expression. ICC with concurrent IDH1 mutations and MYC amplification exhibited sensitivity to the BET inhibitor (+)-JQ1, but remained resistant to ivosidenib (AG-120). This finding has immediate clinical implications: IDH1-mutant patients with MYC co-amplification may benefit from BET inhibitor therapy rather than standard IDH1 inhibition.
In a phase II trial of nivolumab plus modified gemcitabine/S-1 in CCA, TLS-positive patients (n=7) demonstrated dramatically better outcomes compared with TLS-negative patients (n=9): ORR 71% vs. 0%, DCR 100% vs. 67%, with significantly improved PFS (p=0.03) (PMID: 39870490). TLS presence correlated with "inflamed" tumors exhibiting substantial T and B cell infiltration and upregulation of B cell-related genes with higher memory B cell properties. This positions TLS status as a potentially powerful biomarker for immunotherapy patient selection in CCA.
VEGF blockade combined with anti-CTLA4 and anti-PD-L1 in CCA potentiated a BAFF-dependent proinflammatory B cell response and IL-12-dependent expansion/rewiring of Tregs toward an anti-tumor Th1-like fragile state (PMID: 40088889). Separately, tumor-infiltrating B cells in iCCA were found to be scarce, immature, and immunosuppressive, with coculture with tumour cells or CAFs impairing B-cell differentiation and function, including downregulation of BAFFR (PMID: 40889886). Dual blockade of IL-6 and TGF-β restored B cell activation, suggesting multi-target immunomodulatory strategies.
Single-cell RNA-seq and TCR-seq analysis across 36 samples from 16 BTC patients revealed that ECC has a unique profile of T cell exhaustion with elevated CXCL13, more mature TLS, and fewer desert immunophenotypes, while ICC displayed an inflamed immunophenotype with enrichment of IFN-related pathways and high LGALS1 expression in activated Tregs associated with immunosuppression (PMID: 39570809). Inhibition of LGALS1 reduced tumor growth and Treg prevalence in ICC mouse models, identifying it as a novel therapeutic target.
Multiple preclinical strategies demonstrate the feasibility of converting immune-cold CCA tumors to immune-hot:
| Strategy | Mechanism | Key Result |
|---|---|---|
| Photothermal therapy (gold-iron oxide NPs) + anti-PD1 | Reduces ECM stiffness, reprograms CAF subsets | Enhanced cytotoxic T-cell infiltration (PMID: 41037683) |
| PARG inhibition | Halts CCA via Hippo pathway, alleviates desmoplasia | Significantly greater tumor burden reduction with GemCis + anti-PD1 (PMID: 41016443) |
| SUMOylation inhibition (ML792, SAM) | Reduces CAFs, recruits anti-tumor immune cells | Suppressed tumorigenesis in subcutaneous/oncogene-driven models (PMID: 39932259) |
| NEDDylation inhibition (pevonedistat) | Disrupts tumor–stroma crosstalk | Halted cholangiocarcinogenesis (PMID: 35217064) |
CCA exhibits multi-layered epigenetic dysregulation. EZH2 (PRC2 component) overexpression predicts poor prognosis, and PRC2 inhibition restores SFRP1 via DNA hypomethylation at bivalent promoters (PMID: 38050190). The dual G9a/DNMT1 inhibitor CM272 is effective in CCA cells, patient-derived tumoroids, xenografts, and mouse models (PMID: 33222246). O. viverrini-associated CCA shows a predominant hypermethylation phenotype. These epigenetic layers interact with IDH1-driven 2-HG production, which competitively inhibits α-KG-dependent dioxygenases causing DNA/histone hypermethylation — linking metabolic and epigenetic oncogenic programs.
Meta-analysis of 4 RCTs (n=1,308; BILCAP, ASCOT, BCAT, PRODIGE-12) demonstrated that 5-FU-based adjuvant chemotherapy improved RFS (HR 0.80, 95% CI 0.68–0.95, p=0.012) and OS (HR 0.78, 95% CI 0.65–0.94, p=0.009), while gemcitabine-based chemotherapy provided no benefit (PMID: 40101432). BILCAP long-term follow-up (median 106 months) confirmed capecitabine mOS of 49.6 months vs. observation 36.1 months (PMID: 35316080). This establishes capecitabine as the standard adjuvant regimen for resected CCA.
The following model synthesizes findings into a unified framework of CCA biology, resistance, and therapeutic intervention:
┌─────────────────────────────────┐
│ RISK FACTORS / INITIATION │
│ Liver flukes, PSC, hepatolithia- │
│ sis, metabolic syndrome, viral │
│ hepatitis, idiopathic (~50%) │
└──────────────┬──────────────────┘
│
┌──────────────▼──────────────────┐
│ EARLY DRIVER MUTATIONS │
│ (Clonal, tissue-specific) │
├──────────────┬───────────────────┤
│ iCCA (small │ eCCA/pCCA │
│ duct type) │ │
│ • IDH1/2 │ • KRAS (~25%) │
│ • FGFR2 │ • TP53 (~35%) │
│ • BAP1 │ • PIK3CA │
└──────────────┴───────────────────┘
│
┌──────────────▼──────────────────┐
│ EPIGENETIC REPROGRAMMING │
│ • IDH1→2-HG→DNA/histone │
│ hypermethylation │
│ • EZH2/PRC2 overexpression │
│ • G9a/DNMT1 co-activation │
│ • MYC co-amplification reverses │
│ IDH1 favorable phenotype │
└──────────────┬──────────────────┘
│
┌──────────────▼──────────────────┐
│ DESMOPLASTIC TME FORMATION │
│ • CAFs (vCAFs secrete IL-6) │
│ • TAMs (immunosuppressive) │
│ • Dense ECM (matricellular │
│ glycoproteins) │
│ • B cell dysfunction (BAFFR↓) │
│ • Treg LGALS1↑ (iCCA) │
└──────────────┬──────────────────┘
│
┌────────────────────┼────────────────────┐
▼ ▼ ▼
┌─────────────────┐ ┌──────────────────┐ ┌──────────────────┐
│ IMMUNE EVASION │ │ TREATMENT │ │ RESISTANCE │
│ • T cell exhaust│ │ • GemCis+ICI │ │ MECHANISMS │
│ • Cold TME │ │ (1st line) │ │ • FGFR2: gate- │
│ • CXCL13 (ECC) │ │ • FGFR2i, IDH1i │ │ keeper mut + │
│ • IFN/LGALS1 │ │ (2nd line+) │ │ MAPK bypass │
│ (ICC) │ │ • Capecitabine │ │ • IDH1: MAPK │
│ │ │ (adjuvant) │ │ mut (28%) + │
│ BIOMARKERS: │ │ • Stroma-target │ │ 2° IDH1/IDH2 │
│ • TLS (ORR 71% │ │ (emerging) │ │ ───────────────│
│ vs 0%) │ │ │ │ CONVERGENT: │
│ • PD-L1, TMB │ │ │ │ MAPK activation │
└─────────────────┘ └──────────────────┘ └──────────────────┘
Central Insight: MAPK pathway activation is the dominant convergent resistance mechanism in CCA targeted therapy. Both FGFR2 inhibitor resistance (via bypass signaling) and IDH1 inhibitor resistance (via acquired KRAS/NRAS/MAP2K1/NF1 mutations) converge on MAPK pathway activation. This suggests a unified therapeutic strategy: combining targeted agents with MEK/ERK inhibitors to preempt or overcome resistance.
The molecular heterogeneity of CCA was established through comprehensive genomic profiling. The co-mutational cartography of iCCA (PMID: 36528236) provided "a highly representative cartography of the genomic landscape of iCCA" outlining seven therapeutically relevant driver genes. Molecular-clinical profiling according to pathologic subtypes confirmed that "KRAS and PIK3CA mutations were more frequent in the large duct type, while IDH1/2 mutations and FGFR2 fusions were more common in the small duct type" (PMID: 41850925). The ITH-resistant five-subtype classification (PMID: 41916296) represents the most advanced molecular taxonomy, revealing that "immune and stromal heterogeneity are primary drivers of ITH, leading to misclassification of a median 27.8% of tumors by existing subtyping systems."
The evolution from GemCis to GemCis+ICI was defined by the TOPAZ-1 and KEYNOTE-966 trials, which "established GemCis plus durvalumab or pembrolizumab as the current standard" (PMID: 41429598). Targeted therapy approval was supported by evidence that "hotspot IDH1 mutations and activating fibroblast growth factor receptor 2 fusions occur frequently, and small-molecule inhibitors against these alterations are US Food and Drug Administration approved" (PMID: 39730074). The adjuvant capecitabine benefit is supported by BILCAP long-term data showing "the median OS was 49.6 months (95% CI, 35.1 to 59.1) in the capecitabine group compared with 36.1 months (95% CI, 29.7 to 44.2) in the observation group" (PMID: 35316080), confirmed by meta-analysis demonstrating "adjuvant 5FU-based chemotherapy improved RFS [HR: 0.80] and OS [HR: 0.78]" (PMID: 40101432).
The identification of convergent MAPK resistance is supported by two independent lines of evidence. In IDH1-mutant CCA, "acquired mutations in mitogen-activated protein kinase (MAPK) pathway genes (KRAS, NRAS, MAP2K1, NF1) were identified in five cases" and "MAPK activation blunted gene expression induced by ivosidenib plus IFNγ" (PMID: 41460204). For FGFR2-rearranged CCA, "the development of acquired resistance—most commonly driven by secondary kinase-domain mutations and activation of bypass signaling pathways—remains a major limitation" (PMID: 41682001). cfDNA profiling confirmed that key targets are clonal early drivers and "uncovered novel putative mechanisms of resistance to targeted therapies, including mutation of the cysteine residue (FGFR2 C492F) to which covalent FGFR inhibitors bind" (PMID: 36089135). The MYC–IDH1 interaction demonstrated that "MYC overexpression drove the malignant phenotypic manifestation of Idh1 mutations" and that concurrent IDH1/MYC tumors "exhibited sensitivity to the MYC inhibitor (+)-JQ1, but remained resistant to the IDH1 mutation inhibitor AG120" (PMID: 41800252).
The role of the desmoplastic TME was characterized through analysis showing "the interplay between cholangiocarcinoma cells, CAFs, and TAMs in particular play a critical role in promoting cholangiocarcinoma progression, therapeutic resistance, and immune evasion" (PMID: 35961702). TLS as immunotherapy biomarker was established with "TLS-positive (N=7) patients demonstrated significantly better immunotherapy outcomes compared with TLS-negative (N=9) patients, including higher objective response rates (71% vs 0%)" (PMID: 39870490). The BAFF-dependent mechanism showed that "VEGF blockade in combination with anti-CTLA4 + anti-PD-L1 in cholangiocarcinoma potentiated a multimodal mechanism dependent on BAFF, leading to a proinflammatory B cell response" (PMID: 40088889). B cell dysfunction was further characterized: "coculture with tumour cells or CAFs impaired B-cell differentiation and function, including downregulation of BAFFR in peripheral B cells" (PMID: 40889886). T cell landscape mapping revealed that "ICC displayed an inflamed immunophenotype with an enrichment of IFN-related pathways and high expression of LGALS1 in activated regulatory T cells" and that "inhibition of LGALS1 reduced tumor growth and regulatory T-cell prevalence in ICC mouse models" (PMID: 39570809).
Novel stroma-targeting strategies demonstrated that "the combinatorial strategy effectively reduced ECM stiffness, reprogrammed CAF subsets, and enhanced cytotoxic T-cell infiltration" (PMID: 41037683), and "combining PD-1 blockade and gemcitabine/cisplatin with PARG inhibitors resulted in a significantly greater reduction in tumor burden, as well as a survival benefit" (PMID: 41016443). Epigenetic targeting was supported by evidence that "increased expression of EZH2 in CCA exhibited a significantly poorer prognosis" (PMID: 38050190) and that "dual targeting of G9a and DNMT1 with epigenetic small molecule inhibitors such as CM272 is a potential strategy to treat CCA" (PMID: 33222246).
Small sample sizes in biomarker studies: The TLS-immunotherapy correlation (n=16) and MAPK resistance findings (n=18) require validation in larger, prospective cohorts. These early signals are compelling but not yet practice-changing.
Subtype-specific trial data lacking: Most clinical trials enroll mixed BTC populations. Subtype-stratified efficacy data (e.g., iCCA vs. eCCA, small duct vs. large duct) are scarce, limiting precision of treatment recommendations for individual subtypes.
ITH-insensitive subtypes require prospective validation: The five-subtype classification by Lin et al. was derived from retrospective multi-omics data. Prospective clinical trials testing subtype-matched therapies (HSP90i + anti-PD1 for SI; anti-PD1 + anti-TIM3 for SIII-3) are needed before clinical adoption.
Stroma-targeting strategies are preclinical: While photothermal therapy, PARG inhibition, SUMOylation inhibition, and NEDDylation inhibition show promise in mouse models, none have entered randomized clinical trials in CCA patients. Translation remains uncertain.
Liquid biopsy limitations: cfDNA concordance for FGFR2 fusions is only 18%, limiting utility for fusion detection despite high concordance for IDH1 (87%) and BRAF V600E (100%). This gap affects real-time resistance monitoring.
Idiopathic CCA pathogenesis unclear: With approximately 50% of Western CCA cases lacking identifiable risk factors, the molecular pathogenesis of sporadic CCA remains poorly understood, hindering prevention strategies.
Resistance beyond MAPK: While MAPK is the dominant convergent resistance pathway, secondary IDH1/IDH2 mutations and other bypass mechanisms (PI3K/AKT/mTOR) require further characterization and therapeutic targeting.
Limited immunotherapy biomarkers: PD-L1, TMB, and MSI have shown inconsistent predictive value in CCA. TLS is promising but requires standardized assessment methods.
Prospective TLS-stratified immunotherapy trial: Design a phase II trial of GemCis + ICI in advanced CCA with mandatory pre-treatment biopsy for TLS assessment (IHC + gene expression panel). Primary endpoint: ORR stratified by TLS status. This would validate the dramatic ORR difference (71% vs. 0%) observed in the small initial cohort.
Targeted + MEK inhibitor combinations: Based on convergent MAPK resistance, initiate phase Ib/II trials combining:
Primary endpoints: safety, ORR, cfDNA MAPK mutation clearance
BET inhibitor trial in IDH1+MYC co-altered CCA: Screen IDH1-mutant iCCA patients for MYC amplification and enroll in a BET inhibitor (e.g., pelabresib) basket trial. This directly addresses the finding that these tumors are resistant to ivosidenib but sensitive to JQ1.
LGALS1 antagonist development for iCCA: Based on the identification of LGALS1 as a driver of Treg-mediated immunosuppression specifically in iCCA, develop and test anti-LGALS1 antibodies in combination with anti-PD1 in iCCA patient-derived xenograft models.
Retrospective validation of five ITH-insensitive subtypes: Apply GPRC5A/VTCN1 IHC to archival tissue from completed trials (TOPAZ-1, ClarIDHy, FIGHT-202) to retrospectively assess subtype-treatment response correlations without requiring new patient enrollment.
Anti-VEGF + ICI combination trial design: Based on the BAFF-dependent B cell activation mechanism, design a CCA-specific trial of bevacizumab + atezolizumab + GemCis, with correlative B cell phenotyping and BAFF/BAFFR measurement.
Longitudinal cfDNA monitoring protocol: Implement serial cfDNA profiling in ongoing targeted therapy trials to detect emergent MAPK mutations early and guide adaptive therapy switching before clinical progression.
Single-cell multi-omics of resistance evolution: Perform longitudinal single-cell RNA-seq + ATAC-seq on paired pre-treatment/progression biopsies from FGFR2i- and IDH1i-treated patients to map the cellular and epigenetic architecture of resistance at single-cell resolution.
CAF subtype-specific targeting: Develop strategies that selectively deplete tumor-promoting CAF subsets (e.g., vCAFs) while preserving tumor-restraining populations, informed by the single-cell CAF taxonomy identifying six distinct subsets.
Epigenetic combination strategies: Test CM272 (G9a/DNMT1 inhibitor) + EZH2 inhibitor combinations in CCA organoids and PDX models, especially in IDH1-mutant contexts where 2-HG-driven hypermethylation creates epigenetic vulnerability.
DIAGNOSIS: Advanced/Metastatic CCA
│
▼
Comprehensive Genomic Profiling (tissue + cfDNA)
│
├── FIRST LINE ──────────────────────────────────────┐
│ GemCis + Durvalumab (or Pembrolizumab) │
│ mOS ~16 months (real-world) │
│ │
├── SECOND LINE+ (biomarker-selected) ───────────────┤
│ • FGFR2 fusion → Pemigatinib/Futibatinib │
│ • IDH1 mutation → Ivosidenib │
│ • BRAF V600E → Dabrafenib + Trametinib │
│ • HER2 amp → T-DXd (investigational) │
│ • MSI-H/dMMR → Pembrolizumab │
│ • IDH1 + MYC amp → BET inhibitor (emerging) │
│ │
├── ADJUVANT (resected) ─────────────────────────────┤
│ Capecitabine × 8 cycles │
│ mOS 49.6 vs 36.1 months │
│ │
└── EMERGING STRATEGIES ─────────────────────────────┘
• Targeted + MEK inhibitor (resistance preemption)
• Stroma-targeting + ICI (TME reprogramming)
• TLS-guided immunotherapy selection
• Anti-VEGF + ICI combinations (BAFF activation)
• Epigenetic therapies (EZH2i, CM272)
Report generated from systematic analysis of 82 peer-reviewed publications across 5 investigative iterations. Fifteen confirmed findings with verified literature citations. All statistical evidence drawn from primary literature with validated abstracts.