European Neuroendocrine Tumor Society (ENETS) 2024 guidance paper for the management of well-differentiated small intestine neuroendocrine tumours.

Both the incidence and prevalence of well-differentiated neuroendocrine tumours from the small intestine (Si-NET) are gradually increasing. Most patients have non-functioning tumours with subtle GI symptoms and tumours are often discovered incidentally by endoscopy or at advanced disease stages by imaging depicting mesenteric lymph node and /or liver metastases while around 30% of the patients present with symptoms of the carcinoid syndrome. Adequate biochemical assessment and staging including functional imaging is crucial for treatment-related decision-making that should take place in an expert multidisciplinary team setting. Preferably, patients should be referred to specialised ENETS Centres of Excellence or centres of high expertise in the field. This guidance paper provides the current evidence and best knowledge for the management of Si-NET grade (G) 1-3 following 10 key questions of practical relevance for the diagnostic and therapeutic decision making.

Immunotherapy in Neuroendocrine Neoplasms: A Diamond to Cut.

A raise in the incidence of NENs is expected. Therefore, the identification of new therapeutic strategies, such as immunotherapy, remains crucial. To date, immune checkpoint inhibitors as monotherapy have shown modest activity in unselected NENs. Although immunotherapy combos (plus another immune agents or chemotherapy, among others) are potentially more active than single agents, this has not been uniformly confirmed, even in high-grade NENs. Other immunotherapeutic strategies under development include bispecific antibodies, targeting specific tumor antigens like DLL3, and cell therapy. Currently, no predictive immune biomarkers are available to guide clinical decisions. A comprehensive tumor molecular profiling approach needs to be developed for the selection of patients with NEN who could potentially benefit from immunotherapy. Ideally, clinical trials should incorporate this tumor molecular profiling to identify predictive biomarkers and improve efficacy. Achieving this goal requires an international collaborative effort.

Comparative analysis of international guidelines on the management of advanced non-functioning well-differentiated pancreatic neuroendocrine tumors.

This review presents a comprehensive comparative analysis of international guidelines for managing advanced, non-functioning, well-differentiated pancreatic neuroendocrine tumors (panNETs). PanNETs, which represent a significant proportion of pancreatic neuroendocrine neoplasms, exhibit diverse clinical behaviors and prognoses based on differentiation, grading, and other molecular markers. The varying therapeutic strategies proposed by different guidelines reflect their distinct emphases and regional considerations, such as the ESMO guideline's focus on advanced disease management and the ENETS guidance paper's multidisciplinary approach. This review examines the most recent guidelines from ESMO, NCCN, ASCO, ENETS, and NANETS, analyzing the recommendations for first-line therapies and subsequent treatment pathways in different clinical scenarios. Significant variations are observed in the recommendations, particularly concerning the choice and sequence of systemic therapies, the role of tumor grading and the Ki-67 index in therapeutic decisions, and the integration of regional regulatory and clinical practices. The analysis highlights the need for a tailored approach to managing advanced NF panNETs, advocating for flexibility in applying guidelines to account for individual patient circumstances and the evolving evidence base. This work underscores the complexities of managing this patient population and the critical role of a multidisciplinary team in optimizing treatment outcomes.

Comparing Survival of Perihilar Cholangiocarcinoma After R1 Resection Versus Palliative Chemotherapy for Unresected Localized Disease.

BACKGROUND: Resection of perihilar cholangiocarcinoma (pCCA) is a complex procedure with a high risk of postoperative mortality and early disease recurrence. The objective of this study was to compare patient characteristics and overall survival (OS) between pCCA patients who underwent an R1 resection and patients with localized pCCA who received palliative systemic chemotherapy. METHODS: Patients with a diagnosis of pCCA between 1997-2021 were identified from the European Network for the Study of Cholangiocarcinoma (ENS-CCA) registry. pCCA patients who underwent an R1 resection were compared with patients with localized pCCA (i.e., nonmetastatic) who were ineligible for surgical resection and received palliative systemic chemotherapy. The primary outcome was OS. RESULTS: Overall, 146 patients in the R1 resection group and 92 patients in the palliative chemotherapy group were included. The palliative chemotherapy group more often underwent biliary drainage (95% vs. 66%, p < 0.001) and had more vascular encasement on imaging (70% vs. 49%, p = 0.012) and CA 19.9 was more frequently >200 IU/L (64 vs. 45%, p = 0.046). Median OS was comparable between both groups (17.1 vs. 16 months, p = 0.06). Overall survival at 5 years after diagnosis was 20.0% with R1 resection and 2.2% with chemotherapy. Type of treatment (i.e., R1 resection or palliative chemotherapy) was not an independent predictor of OS (hazard ratio 0.76, 95% confidence interval 0.55-1.07). CONCLUSIONS: Palliative systemic chemotherapy should be considered instead of resection in patients with a high risk of both R1 resection and postoperative mortality.

Facts and Hopes in the Systemic Therapy of Biliary Tract Carcinomas.

Biliary tract cancers (BTC) are a heterogeneous group of cancers that continue to present a particularly poor prognosis. BTC treatment is rapidly evolving yet facing many challenges to improve patient outcomes and maximize benefit from treatment. Only a minority of patients are diagnosed with early-stage disease and are suitable for curative resection. Current surgical strategies are limited by a high relapse rate, and despite extensive efforts focused on adjuvant strategies, the development of more effective adjuvant strategies remains a challenge. In addition, the role of locoregional strategies, liver transplant, and neoadjuvant treatment remains unclear. Systemic treatment in the advanced setting is based on three main pillars: first, cytotoxic chemotherapy options; second, the addition of immunotherapy to chemotherapy; and third, targeted therapies. The role of targeted therapies is oriented by many promising targets, including IDH1 mutations, FGFR2 fusions, BRAF-V600E mutations, and HER2 amplifications. The aim of this review is to provide an overview of current facts and future hopes in the management of BTC, including an overview of the unmet need, and particularly focus on systemic therapies.

Somatostatin Receptor Imaging with [18F]FET-ßAG-TOCA PET/CT and [68Ga]Ga-DOTA-Peptide PET/CT in Patients with Neuroendocrine Tumors: A Prospective, Phase 2 Comparative Study.

There is a clinical need for 18F-labeled somatostatin analogs for the imaging of neuroendocrine tumors (NET), given the limitations of using [68Ga]Ga-DOTA-peptides, particularly with regard to widespread accessibility. We have shown that [18F]fluoroethyl-triazole-[Tyr3]-octreotate ([18F]FET-ßAG-TOCA) has favorable dosimetry and biodistribution. As a step toward clinical implementation, we conducted a prospective, noninferiority study of [18F]FET-ßAG-TOCA PET/CT compared with [68Ga]Ga-DOTA- peptide PET/CT in patients with NET. Methods: Forty-five patients with histologically confirmed NET, grades 1 and 2, underwent PET/CT imaging with both [18F]FET-ßAG-TOCA and [68Ga]Ga-peptide performed within a 6-mo window (median, 77 d; range, 6-180 d). Whole-body PET/CT was conducted 50 min after injection of 165 MBq of [18F]FET-ßAG-TOCA. Tracer uptake was evaluated by comparing SUVmax and tumor-to-background ratios at both lesion and regional levels by 2 unblinded, experienced readers. A randomized, blinded reading of both scans was also then undertaken by 3 experienced readers, and consensus was assessed at a regional level. The ability of both tracers to visualize liver metastases was also assessed. Results: A total of 285 lesions were detected on both imaging modalities. An additional 13 tumor deposits were seen in 8 patients on [18F]FET-ßAG-TOCA PET/CT, and [68Ga]Ga-DOTA-peptide PET/CT detected an additional 7 lesions in 5 patients. Excellent correlation in SUVmax was observed between both tracers (r = 0.91; P < 0.001). No difference was observed between median SUVmax across regions, except in the liver, where the median tumor-to-background ratio of [18F]FET-ßAG-TOCA was significantly lower than that of [68Ga]Ga-DOTA-peptide (2.5 ± 1.9 vs. 3.5 ± 2.3; P < 0.001). Conclusion: [18F]FET-ßAG-TOCA was not inferior to [68Ga]Ga-DOTA-peptide in visualizing NET and may be considered in routine clinical practice given the longer half-life and availability of the cyclotron-produced fluorine radioisotope.

Brightline-2: a phase IIa/IIb trial of brigimadlin (BI 907828) in advanced biliary tract cancer, pancreatic ductal adenocarcinoma or other solid tumors.

Mouse double minute 2 homolog (MDM2) is a key negative regulator of the tumor suppressor p53. Blocking the MDM2-p53 interaction, and restoring p53 function, is therefore a potential therapeutic strategy in MDM2-amplified, TP53 wild-type tumors. MDM2 is amplified in several tumor types, including biliary tract cancer (BTC), pancreatic ductal adenocarcinoma (PDAC), lung adenocarcinoma and bladder cancer, all of which have limited treatment options and poor patient outcomes. Brigimadlin (BI 907828) is a highly potent MDM2-p53 antagonist that has shown promising activity in preclinical and early-phase clinical studies. This manuscript describes the rationale and design of an ongoing phase IIa/IIb Brightline-2 trial evaluating brigimadlin as second-line treatment for patients with advanced/metastatic BTC, PDAC, lung adenocarcinoma, or bladder cancer.

Brightline-2: a phase IIa/IIb trial of brigimadlin (BI 907828) in advanced BTC, PDAC, or other solid tumorsIn some types of cancer, including cancers of the bile duct, pancreas, bladder and lung, the number of copies of a gene called MDM2 is abnormally increased (MDM2 amplification). MDM2 usually regulates p53, a protein that stops cancer cells from growing uncontrollably. When MDM2 is amplified, the cell makes too much of the MDM2 protein, which prevents p53 from stopping cancer growth. Blocking the interaction between MDM2 and p53 may allow p53 to do its job again and stop cancer cells from growing.Brightline-2 is a clinical trial that is currently in progress. This trial is assessing the efficacy and safety of an investigational drug, brigimadlin (or BI 907828), in patients with selected advanced or metastatic cancers. To be included, patients must have advanced biliary tract cancer, pancreatic ductal adenocarcinoma, bladder cancer, or lung adenocarcinoma. The tumor must show amplification of MDM2 when tested by a laboratory. Patients will take a 45 mg tablet of brigimadlin by mouth, once every 3 weeks. In this trial, researchers are investigating the ability of the drug to shrink tumors, the side effects of the drug, and the impact of the drug on a patients' quality of life.The goal of this trial is to assess the potential of brigimadlin as a new treatment option for patients with advanced biliary tract cancer, pancreatic ductal adenocarcinoma, bladder cancer, or lung adenocarcinoma.Clinical Trial Registration: NCT05512377 (ClinicalTrials.gov).

Revolutionizing anti-HER2 therapies for extrahepatic cholangiocarcinoma and gallbladder cancer: Current advancements and future perspectives.

Biliary tract cancers (BTCs) encompass a heterogeneous group of rare tumors, including intrahepatic cholangiocarcinoma (iCCA), extrahepatic cholangiocarcinoma (eCCA), gallbladder cancer (GBC) and ampullary cancer (AC). The present first-line palliative treatment regimen comprises gemcitabine and cisplatin in combination with immunotherapy based on two randomized controlled studies. Despite the thorough investigation of these palliative treatments, long-term survival remains low. Moving beyond conventional chemotherapies and immunotherapies, the realm of precision medicine has demonstrated remarkable efficacy in malignancies such as breast and gastric cancers, characterized by notable HER2 overexpression rates. In the context of biliary tract cancer, significant HER2 alterations are observed, particularly within eCCA and GBC, heightening the interest in precision medicine. Various anti-HER2 therapies, including trastuzumab, pertuzumab, trastuzumab-deruxtecan, zanidatamab and neratinib, have undergone investigation. The objective of this review is to summarize the current evidence and outline future directions of targeted HER2 treatment therapy in patients with biliary tract tumors, specially extrahepatic cholangiocarcinoma and gallbladder cancer.

Chemotherapy with or without selective internal radiation therapy for intrahepatic cholangiocarcinoma: Data from clinical trials.

BACKGOUND AND AIMS: In advanced, liver-only intrahepatic cholangiocarcinoma (iCCA), selective internal radiation therapy (SIRT) has been suggested as promising in nonrandomized studies. We aimed to compare data from patients with advanced, liver-only iCCA treated in the first line in clinical trials with either chemotherapy alone or the combination with SIRT. APPROACH AND RESULTS: We collected individual patients' data from the ABC-01, ABC-02, ABC-03, BINGO, AMEBICA, and MISPHEC prospective trials. Data from patients with liver-only iCCA treated in chemotherapy-only arms of the first 5 trials were compared with data from patients treated with SIRT and chemotherapy in MISPHEC. Emulated target trial paradigm and Inverse Probability of Treatment Weighting (IPTW methods) using the propensity score were used to minimize biases. We compared 41 patients treated with the combination with 73 patients treated with chemotherapy alone, the main analysis being in 43 patients treated with cisplatin-gemcitabine or gemcitabine-oxaliplatin. After weighting, overall survival was significantly higher in patients treated with SIRT: median 21.7 months (95% CI: 14.1; not reached) versus 15.9 months(95% CI: 9.8; 18.9), HR = 0.59 (95% CI: 0.34; 0.99), p = 0.049. Progression-free survival was significantly improved: median 14.3 months (95% CI: 7.8; not reached) versus 8.4 months (95% CI: 5.9; 12.1), HR = 0.52 (95% CI: 0.31; 0.89), p < 0.001. Results were confirmed in most sensitivity analyses. CONCLUSIONS: This analysis derived from prospective clinical trials suggests that SIRT combined with chemotherapy might improve outcomes over chemotherapy alone in patients with advanced, liver-only iCCA. Randomized controlled evidence is needed to confirm these findings.

Molecular profiling in cholangiocarcinoma: A practical guide to next-generation sequencing.

Cholangiocarcinomas (CCA) are a heterogeneous group of tumors that are classified as intrahepatic, perihilar, or distal according to the anatomic location within the biliary tract. Each CCA subtype is associated with distinct genomic alterations, including single nucleotide variants, copy number variants, and chromosomal rearrangements or gene fusions, each of which can influence disease prognosis and/or treatment outcomes. Molecular profiling using next-generation sequencing (NGS) is a powerful technique for identifying unique gene variants carried by an individual tumor, which can facilitate their accurate diagnosis as well as promote the optimal selection of gene variant-matched targeted treatments. NGS is particularly useful in patients with CCA because between one-third and one-half of these patients have genomic alterations that can be targeted by drugs that are either approved or in clinical development. NGS can also provide information about disease evolution and secondary resistance alterations that can develop during targeted therapy, and thus facilitate assessment of prognosis and choice of alternative targeted treatments. Pathologists play a critical role in assessing the viability of biopsy samples for NGS, and advising treating clinicians whether NGS can be performed and which of the available platforms should be used to optimize testing outcomes. This review aims to provide clinical pathologists and other healthcare professionals with practical step-by-step guidance on the use of NGS for molecular profiling of patients with CCA, with respect to tumor biopsy techniques, pre-analytic sample preparation, selecting the appropriate NGS panel, and understanding and interpreting results of the NGS test.

Use and perceived utility of [18 F]FDG PET/CT in neuroendocrine neoplasms: A consensus report from the European Neuroendocrine Tumor Society (ENETS) Advisory Board Meeting 2022.

Somatostatin receptor (SST) PET/CT is the gold standard for well-differentiated neuroendocrine tumours (NET) imaging. Higher grades of neuroendocrine neoplasms (NEN) show preferential [18F]FDG (FDG) uptake, and even low-grade NET may de-differentiate over time. FDG PET/CT's prognostic role is widely accepted; however, its impact on clinical decision-making remains controversial and its use varies widely. A questionnaire-based survey on FDG PET/CT use and perceived decision-making utility in NEN was submitted to the ENETS Advisory Board Meeting attendees (November 2022, response rate = 70%). In 3/15 statements, agreement was higher than 75%: (i) FDG was considered useful in NET, irrespective of grade, in case of mis-matched lesions (detectable on diagnostic CT but negative/faintly positive on SST PET/CT), especially if PRRT is contemplated (80%); (ii) in NET G3 if curative surgery is considered (82%); and (iii) in NEC prior to surgery with curative intent (98%). FDG use in NET G3, even in the presence of matched lesions, as a baseline for response assessment was favoured by 74%. Four statements obtained more than 60% consensus: (i) FDG use in NET G3 if locoregional therapy is considered (65%); (ii) in neuroendocrine carcinoma before initiating active therapy as a baseline for response assessment (61%); (iii) biopsy to re-assess tumour grade prior to a change in therapeutic management (68%) upon detection of FDG-positivity on the background of a prior G1-2 NET; (iv) 67% were in favour to reconsider PRRT to treat residual SST-positive lesions after achieving complete remission on FDG of the SST-negative disease component. Multidisciplinary opinion broadly supports the use of FDG PET/CT for characterisation of disease biology and to guide treatment selection across a range of indications, despite the lack of full consensus in many situations. This may reflect existing clinical access due to lack of reimbursement or experience with this investigation, which should be addressed by further research.

Exploring the Promise of Second-Line Chemotherapy in Biliary Tract Tumours: A Glimpse into Novel Treatment Approaches.

Biliary tract tumours, including bile duct, gallbladder, and ampulla of Vater malignancies, pose a rare but formidable oncologic challenge. Typically diagnosed at advanced stages, these tumours offer limited treatment options and dismal prognoses, with a five-year survival rate below 20%. First-line chemotherapy with gemcitabine-cisplatin has demonstrated only modest efficacy, leaving a pressing need for improved therapeutic strategies. This comprehensive review provides a detailed examination of the current landscape of second-line chemotherapy for biliary tract tumours. The pivotal ABC-06 trial established FOLFOX (5-fluorouracil, leucovorin, and oxaliplatin) as the standard second-line therapy, demonstrating improved overall survival compared to active symptom control alone. Conversely, the NIFTY trial introduced nal-IRI (nanoliposomal irinotecan) plus 5-FU/LV (5-fluorouracil and leucovorin) as an alternative option, demonstrating substantial gains in progression-free and overall survival. However, the posterior NALIRICC trial presented conflicting results, raising questions about the added benefit of nal-IRI. Challenges in delivering second-line chemotherapy include rapid patient performance deterioration post-first-line treatment and limited access to second-line therapy. Only a fraction of eligible patients receive second-line therapy, emphasising the need for more effective first-line therapies to maintain patient fitness. The role of monotherapy in the second-line setting remains uncertain, particularly in unfit patients, and the absence of biomarkers for tailored treatment underscores the need for ongoing research. While challenges persist, ongoing investigations offer hope for optimising second-line therapy for biliary tract tumours, promising improved outcomes for patients facing this disease. This review provides an overview of current facts and challenges when delivering second-line chemotherapy for advanced biliary tract tumours.

Resistance mechanism to fibroblast growth factor receptor (FGFR) inhibitors in cholangiocarcinoma.

Precision medicine is a major achievement that has impacted on management of patients diagnosed with advanced cholangiocarcinoma (CCA) over the last decade. Molecular profiling of CCA has identified targetable alterations, such as fibroblast growth factor receptor-2 (FGFR-2) fusions, and has thus led to the development of a wide spectrum of compounds. Despite favourable response rates, especially with the latest generation FGFRi, there are still a proportion of patients who will not achieve a radiological response to treatment, or who will have disease progression as the best response. In addition, for patients who do respond to treatment, secondary resistance frequently develops and mechanisms of such resistance are not fully understood. This review will summarise the current state of development of FGFR inhibitors in CCA, their mechanism of action, activity, and the hypothesised mechanisms of resistance.

Prognosis Discussion and Referral to Community Palliative Care Services in Patients with Advanced Pancreatic Cancer Treated in a Tertiary Cancer Centre.

Advanced pancreatic cancer is associated with a poor prognosis, often less than 1 year. Honest prognosis discussions guide early community palliative care services input, facilitating timely advance care planning and improving quality of life. The aims were to assess if patients were offered prognosis discussions and community palliative care services referral. A retrospective analysis of consecutive case-notes of new advanced pancreatic cancer patients was conducted. Chi-squared test assessed the association with prognosis discussion and community palliative care services referral. In total, 365 cases (60%) had a documented prognosis discussion at any time-point in the treatment pathway; 54.4% during the first appointment. The frequency of prognosis discussion was greater with nurse clinician review at first appointment (p < 0.001). In total, 171 patients (28.1%) were known to community palliative care services at the first appointment. Of those not known, 171 (39.1%) and 143 (32.7%) were referred at this initial time-point or later, respectively. There was a significant association between the referral to community palliative care services at first appointment and the reviewing professional (this was greatest for nurse clinicians (frequency 65.2%)) (p < 0.001), and also if reviewed by clinical nurse specialist at first visit or not (47.8% vs. 35.6%) (p < 0.01). Prognosis discussions were documented in approximately two-thirds of cases, highlighting missed opportunities. Prognosis discussion was associated with clinician review and was most frequent for nurse clinician, as was referral to community palliative care services. Clinical nurse specialist review increased referral to community palliative care services if seen at the initial visit. Multi-disciplinary review, specifically nursing, therefore, during the first consultation is imperative and additive. It should be considered best practice to offer and negotiate the content and timing of prognosis discussions with cancer patients, and revisit this offer throughout their treatment pathway. Greater attention to prognosis discussion documentation is recommended.

Influence of cirrhosis on outcomes of patients with advanced intrahepatic cholangiocarcinoma receiving chemotherapy.

BACKGROUND: Cirrhosis is a risk factor for intrahepatic cholangiocarcinoma (iCC). However, its exact prevalence is uncertain and its impact on the management of advanced disease is not established. METHODS: Retrospective analysis of patients treated with systemic chemotherapy for advanced iCC in the 1st-line setting at 2 tertiary cancer referral centres. Cirrhosis was diagnosed based on at least one element prior to any treatment: pathological diagnosis, baseline platelets <150 × 109/L, portal hypertension and/or dysmorphic liver on imaging. RESULTS: In the cohort of patients (n = 287), 82 (28.6%) had cirrhosis (45 based on pathological diagnosis). Patients with cirrhosis experienced more grade 3/4 haematologic toxicity (44% vs 22%, respectively, P = 0.001), and more grade 3/4 non-haematologic toxicity (34% vs 14%, respectively, P = 0.001) than those without. The overall survival (OS) was significantly shorter in patients with cirrhosis: median 9.1 vs 13.1 months for those without (HR = 1.56 [95% CI: 1.19-2.05]); P = 0.002), confirmed on multivariable analysis (HR = 1.48 [95% CI: 1.04-2.60]; P = 0.028). CONCLUSION: Cirrhosis was relatively common in patients with advanced iCC and was associated with increased chemotherapy-induced toxicity and shorter OS. Formal assessment and consideration of cirrhosis in therapeutic management is recommended.

Locoregional Treatment in Intrahepatic Cholangiocarcinoma: Which Treatment for Which Patient?

For unresectable intrahepatic cholangiocarcinoma (iCC), different locoregional treatments (LRT) could be proposed to patients, including radiofrequency ablation (RFA) and microwave ablation (MWA), external beam radiotherapy (EBRT) or transarterial treatments, depending on patient and tumor characteristics and local expertise. These different techniques of LRT have not been compared in a randomized clinical trial; most of the relevant studies are retrospective and not comparative. The aim of this narrative review is to help clinicians in their everyday practice discuss the pros and cons of each LRT, depending on the individual characteristics of their patients.

Current Evidence for Immune Checkpoint Inhibition in Advanced Hepatocellular Carcinoma.

The treatment of advanced unresectable HCC (aHCC) remains a clinical challenge, with limited therapeutic options and poor prognosis. The results of IMbrave150 and HIMALAYA have changed the treatment paradigm for HCC and established immune checkpoint inhibition (ICI), either combined with anti-angiogenic therapy or dual ICI, as preferred first-line therapy for eligible patients with aHCC. Numerous other combination regimens involving ICI are under investigation with the aim of improving the tumour response and survival of patients with all stages of HCC. This review will explore the current evidence for ICI in patients with advanced HCC and discuss future directions, including the unmet clinical need for predictive biomarkers to facilitate patient selection, the effects of cirrhosis aetiology on response to ICI, and the safety of its use in patients with impaired liver function.

Lacking Immunotherapy Biomarkers for Biliary Tract Cancer: A Comprehensive Systematic Literature Review and Meta-Analysis.

BACKGROUND: Immunotherapy has recently been incorporated into the spectrum of biliary tract cancer (BTC) treatment. The identification of predictive response biomarkers is essential in order to identify those patients who may benefit most from this novel treatment option. Here, we propose a systematic literature review and a meta-analysis of PD-1, PD-L1, and other immune-related biomarker expression levels in patients with BTC. METHODS: Prisma guidelines were followed for this systematic review and meta-analysis. Eligible studies were searched on PubMed. Studies published between 2017 and 2022, reporting data on PD-1/PD-L1 expression and other immune-related biomarkers in patients with BTC, were considered eligible. RESULTS: A total of 61 eligible studies were identified. Despite the great heterogeneity between 39 studies reporting data on PD-L1 expression, we found a mean PD-L1 expression percentage (by choosing the lowest cut-off per study) of 25.6% (95% CI 21.0 to 30.3) in BTCs. The mean expression percentages of PD-L1 were 27.3%, 21.3%, and 27.4% in intrahepatic cholangiocarcinomas (iCCAs-15 studies), perihilar-distal CCAs (p/dCCAs-7 studies), and gallbladder cancer (GBC-5 studies), respectively. Furthermore, 4.6% (95% CI 2.38 to 6.97) and 2.5% (95% CI 1.75 to 3.34) of BTCs could be classified as TMB-H and MSI/MMRd tumors, respectively. CONCLUSION: From our analysis, PD-L1 expression was found to occur approximately in 26% of BTC patients, with minimal differences based on anatomical location. TMB-H and MSI molecular phenotypes occurred less frequently. We still lack a reliable biomarker, especially in patients with mismatch-proficient tumors, and we must need to make an effort to conceive new prospective biomarker discovery studies.