# Adding Pembrolizumab to Chemotherapy Helps Patients with Advanced Biliary Tract Cancer Live Longer: Results of the KEYNOTE-966 Trial Adding the immunotherapy drug pembrolizumab (Keytruda) to standard chemotherapy helped patients with advanced biliary tract cancer live longer, according to a large international phase 3 clinical trial called KEYNOTE-966. Among 1,069 patients, median overall survival was 12.7 months with pembrolizumab plus gemcitabine and cisplatin, compared with 10.9 months with chemotherapy alone — a 17% lower risk of death at any given point in time (hazard ratio 0.83; p=0.0034, well past the pre-set statistical threshold of p=0.0200). Side effects were broadly similar between the two groups, and the combination produced no new safety concerns. The researchers conclude that pembrolizumab plus gemcitabine and cisplatin could become a new first-line treatment option for patients whose biliary tract cancer cannot be surgically removed or has spread. # Adding Pembrolizumab to Chemotherapy Helps Patients with Advanced Biliary Tract Cancer Live Longer: Results of the KEYNOTE-966 Trial ## Table of Contents - Key Points - Why This Research Matters - What Is Biliary Tract Cancer? - What Was Already Known Before This Study - How the Study Was Designed - Who Could Join the Study - The Treatment Plan - How Patients Were Monitored - What the Study Measured - How the Statistics Worked - Key Findings: Survival Results - Key Findings: Safety and Side Effects - What This Means for Patients - Limitations of the Study - Practical Recommendations - Frequently Asked Questions - Source Information ## Key Points - In a trial of 1,069 patients with advanced biliary tract cancer, adding pembrolizumab to gemcitabine and cisplatin improved median overall survival from 10.9 to 12.7 months. - The risk of death at any given time was 17% lower with pembrolizumab plus chemotherapy (hazard ratio 0.83; p=0.0034), a statistically significant result. - Side effects were broadly similar between groups, with no new safety concerns; Grade 3–4 events occurred in 79% versus 75% of patients. - Eligible patients had unresectable locally advanced or metastatic disease, ECOG status 0–1, and adequate organ function; those with ampullary cancer or active autoimmune disease were excluded. - The median survival gain was 1.8 months; patients should weigh this against additional infusions, potential immune-related side effects, and cost. ## Why This Research Matters Biliary tract cancers are a group of cancers with a poor outlook, and the number of people diagnosed with them is rising worldwide. For more than a decade, the standard first treatment for advanced disease has been a two-drug chemotherapy combination: gemcitabine and cisplatin. Doctors have long searched for a way to improve on that combination, but most attempts have failed. This study asked a straightforward question: does adding an immunotherapy drug called pembrolizumab (an anti–PD-1 monoclonal antibody — a laboratory-made immune protein that helps the body's immune system attack cancer cells) to gemcitabine and cisplatin help patients live longer than chemotherapy alone? Most biliary tract cancers create a microenvironment around themselves that suppresses the immune system. Because of that, using immunotherapy drugs by themselves produces very few tumour responses. Researchers hoped that combining immunotherapy with chemotherapy — which can also stimulate the immune system — would work better than either approach alone. ## What Is Biliary Tract Cancer? Biliary tract cancers are a family of cancers that start in the cells lining the bile ducts or the gallbladder. Specifically, they arise from: - **Intrahepatic bile ducts** — the bile ducts inside the liver - **Extrahepatic bile ducts** — the bile ducts outside the liver - **The gallbladder** — the small organ that stores bile These cancers are uncommon. They account for less than 1% of all new cancer cases worldwide. Despite being rare, their incidence is increasing. Known risk factors include: - Biliary tract injury from chronic cysts or gallstones - Liver fluke infection (a parasitic infection) - Chronic viral hepatitis (long-term liver infection with hepatitis B or C) - Cirrhosis (scarring of the liver) Biliary tract cancers are also very different from one another at the molecular level. That is, the genetic changes driving the cancer vary depending on where the tumour started and what caused it. This complexity makes the disease hard to treat with a single approach. ## What Was Already Known Before This Study The current standard of care — gemcitabine plus cisplatin — was established more than ten years ago by a phase 3 trial called ABC-02. In that study, median overall survival was 11.7 months for patients receiving gemcitabine plus cisplatin, compared with 8.1 months for gemcitabine alone. That was a hazard ratio of 0.64 (p<0.001), meaning a 36% lower risk of death at any given point in time with the two-drug combination. It was a clear win. Since then, researchers have tested many other ideas without improving on it. Three-drug chemotherapy regimens did not help. Combining targeted therapies with chemotherapy did not help either. After the cancer progressed on first-line treatment, combinations based on a drug called 5-fluorouracil showed only modest benefit. A small number of patients do benefit from targeted therapies or immunotherapy — but only if their tumours carry specific molecular features such as FGFR2 fusions, IDH1 mutations, or mismatch repair deficiency (a defect in the cell's ability to repair DNA). These findings came mostly from studies in patients who had already received prior treatment. Because each of these molecular subsets is rare, most patients were still left with chemotherapy as their only option. One earlier phase 3 trial, TOPAZ-1, provided the key precedent. TOPAZ-1 tested a different immunotherapy drug, durvalumab, which targets PD-L1 (a partner protein to PD-1). Adding durvalumab to gemcitabine and cisplatin improved overall survival compared with chemotherapy alone: median 12.8 months versus 11.5 months (hazard ratio 0.80, 95% confidence interval 0.66–0.97; two-sided p=0.021). KEYNOTE-966 was designed to test whether the same principle holds for a PD-1 inhibitor, pembrolizumab. ## How the Study Was Designed KEYNOTE-966 was a randomised, double-blind, placebo-controlled phase 3 trial — the most rigorous type of study design used in medicine. It was conducted at **175 medical centres** across Asia-Pacific, Europe, North America, and South America. Here is what those design terms mean in plain language: 1. **Randomised:** Patients were assigned to one treatment group or the other by chance, not by doctor choice. This prevents unconscious bias in who gets which treatment. 1. **Double-blind:** Neither the patients nor their doctors knew who was receiving the real immunotherapy drug and who was receiving the placebo (a saline solution with no active drug). This prevents expectations from influencing how symptoms and results are reported. 1. **Placebo-controlled:** One group received an inactive saline infusion instead of pembrolizumab, so researchers could isolate the true effect of the drug. 1. **Phase 3:** The final stage of clinical testing before a treatment is considered for regulatory approval, involving large numbers of patients. Patients were assigned in a 1:1 ratio to pembrolizumab or placebo using a central interactive voice-response system and a randomisation list generated by the study sponsor. Assignment was **stratified** — balanced — by three factors: geographic region (Asia versus outside Asia), disease stage (locally advanced versus metastatic), and where the cancer started (extrahepatic bile duct versus gallbladder versus intrahepatic bile duct). Patients were randomised in blocks of four within each stratum. Clinically important protocol deviations — meaning departures from the study plan — occurred in 13 patients in the pembrolizumab group and 17 patients in the placebo group. These related to eligibility criteria, how study drugs were given or stopped, and trial procedures. ## Who Could Join the Study To be eligible, patients had to meet all of the following requirements: - Age 18 years or older - Histologically confirmed (confirmed by examination of tumour tissue under a microscope) unresectable locally advanced or metastatic disease — meaning the cancer could not be removed by surgery or had spread to other parts of the body - Diagnosis of extrahepatic cholangiocarcinoma (including mixed hepatocellular carcinoma and cholangiocarcinoma), gallbladder cancer, or intrahepatic cholangiocarcinoma - Disease measurable according to RECIST version 1.1 (Response Evaluation Criteria in Solid Tumors, a standard set of rules for measuring tumours on scans), as determined by the treating investigator - Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1 — a scale measuring how well a patient can carry out daily activities, where 0 is fully active and 1 is restricted in strenuous activity but able to walk and do light work - Willingness to provide tumour tissue for biomarker assessment - Adequate organ function - Life expectancy greater than 3 months The only prior systemic therapy (treatment that travels through the bloodstream) allowed was neoadjuvant or adjuvant therapy — treatment given before or after surgery with the aim of curing the disease — that had been completed at least 6 months before the diagnosis of unresectable or metastatic disease. The eligibility rules around viral hepatitis were notably inclusive. Patients with past or ongoing hepatitis C virus (HCV) infection were eligible. Patients with controlled hepatitis B were also eligible, including those who tested positive for hepatitis B serum antigen (HBsAg) or had detectable hepatitis B virus (HBV) DNA — as long as they started antiviral therapy at least 4 weeks before beginning study treatment and their viral load was below 100 IU/mL. Patients were excluded if they had ampullary cancer (cancer of the ampulla of Vater, where the bile duct and pancreatic duct empty into the small intestine) or active autoimmune disease requiring systemic treatment within the previous two years. Participants self-reported their sex as female or male at birth. ## The Treatment Plan All patients received the same chemotherapy backbone, with half also receiving pembrolizumab. The specific doses and schedules were: - **Pembrolizumab or placebo:** 200 mg given intravenously (through a vein) once every 3 weeks, for a maximum of 35 cycles - **Gemcitabine:** 1000 mg/m² given intravenously on days 1 and 8 of each 3-week cycle, with no maximum duration - **Cisplatin:** 25 mg/m² given intravenously on days 1 and 8 of each 3-week cycle, for a maximum of 8 cycles Treatment continued until the cancer progressed, side effects became unacceptable, the investigator decided to stop, the patient withdrew consent, or another reason arose — whichever came first. Importantly, if a patient had to stop gemcitabine or cisplatin (or both) because of side effects, they could continue pembrolizumab or placebo, and vice versa. This "one drug at a time" flexibility gave patients the best chance of staying on whatever part of the treatment they tolerated. Crossover was not permitted. That means patients who received placebo were not later given pembrolizumab as part of the study. ## How Patients Were Monitored Patients received thorough and regular assessments. Tumour imaging used contrast-enhanced computed tomography (CT) as the preferred method, or magnetic resonance imaging (MRI), covering the chest, abdomen, and pelvis. Scans were performed: 1. Within 4 weeks before randomisation 1. 6 weeks after the first dose of study treatment 1. Every 6 weeks through week 54 1. Every 12 weeks thereafter Brain imaging (contrast-enhanced MRI preferred, or CT) and whole-body radionuclide bone scans were performed when clinically indicated. Imaging continued until the cancer progressed, as judged by masked independent central review (radiologists who did not know which treatment the patient had received), until new anticancer therapy began, until death, or until the patient withdrew consent. Survival was assessed every 12 weeks until death, withdrawal of consent, or the end of the study. Several laboratory tests were done at screening. Blood was tested for antibodies (IgG) against hepatitis C, and if those were present, HCV viral load was measured. Blood was also tested for hepatitis B core antibodies (total and IgM), HBV viral load, and HBsAg. Tumour tissue was tested for PD-L1 combined positive score (CPS) using a specific laboratory test called PD-L1 IHC 22C3 pharmDx, and for microsatellite instability (MSI) status — a measure of how error-prone a tumour's DNA repair is. Physical examinations and laboratory, blood count, and chemistry analyses were performed during screening, regularly during treatment, and at the end of treatment. Side effects and laboratory abnormalities were recorded throughout treatment and for up to 30 days after stopping (up to 90 days for serious events if no new anticancer therapy had started). They were classified using the Medical Dictionary for Regulatory Activities, version 25.1, and graded using the National Cancer Institute Common Terminology Criteria for Adverse Events, version 5. The study team also specifically tracked potentially immune-mediated side effects and infusion reactions, using a pre-prepared list of terms, regardless of whether the investigator believed the study drug caused them. ## What the Study Measured The primary endpoint — the main question the study was designed to answer — was **overall survival**, defined as the time from randomisation to death from any cause. The secondary endpoints were: - **Progression-free survival:** time from randomisation to the first documented worsening of the cancer or death from any cause, whichever came first - **Objective response rate:** the proportion of patients whose best response was a complete response (no detectable cancer) or partial response (meaningful shrinkage) - **Duration of response:** time from the first evidence of complete or partial response until the cancer progressed or the patient died - **Safety** Progression-free survival, objective response rate, and duration of response were all assessed according to RECIST version 1.1 by masked independent central review. One prespecified exploratory endpoint was the change from baseline to week 18 in the global health status/quality of life scale of the European Organisation for Research and Treatment of Cancer 30-Item Core Quality of Life Questionnaire (EORTC QLQ-C30). Other exploratory endpoints were planned for future publications. ## How the Statistics Worked The study was carefully designed to avoid false-positive results. The overall type 1 error rate — the chance of declaring a benefit that is not real — was strictly controlled at a one-sided alpha of 0.025. This is a standard statistical threshold meaning there is no more than a 2.5% chance of a false positive. The researchers used a formal method (the graphical method of Maurer and Bretz) to decide the order in which endpoints were tested. All statistical "alpha" — the allowance for error — was initially assigned to overall survival. Only if the overall survival comparison was significant would the allowance be reallocated to test progression-free survival and objective response rate. This sequential approach protects against over-interpreting secondary results. The specific one-sided p-value boundaries for declaring pembrolizumab plus chemotherapy superior to placebo plus chemotherapy were: - Overall survival: **0.0200** - Progression-free survival: **0.0125** - Objective response rate: **0.0125** With 1,069 patients enrolled, the study was designed with a target of 818 deaths and two interim analyses. Assuming the risk of death was equal between groups for the first two months and 25% lower with pembrolizumab afterward, the study had approximately **93% power** to detect a significant overall survival benefit. For progression-free survival, with 786 events at the final analysis and assuming a 30% lower risk with pembrolizumab after two months, the study had approximately **92% power** at a one-sided alpha of 0.0125. For objective response rate, assuming a 25% response rate in the placebo group, the study had **91% power** to detect a true difference of 10 percentage points at a one-sided alpha of 0.0125. The prespecified final analysis of progression-free survival and objective response rate was planned for the first interim analysis. Post hoc analyses (additional analyses done after the fact) of those endpoints were also performed at the final analysis. Overall survival, progression-free survival, and duration of response were all estimated using the Kaplan-Meier method, a standard statistical technique for measuring how long patients survive or remain progression-free over time. ## Key Findings: Survival Results The main result was positive. Adding pembrolizumab to chemotherapy significantly extended survival. Between **October 4, 2019, and June 8, 2021**, a total of **1,069 patients** were enrolled and randomised: - **Pembrolizumab group:** 533 patients received pembrolizumab plus gemcitabine and cisplatin - **Placebo group:** 536 patients received placebo plus gemcitabine and cisplatin Median study follow-up at the final analysis was **25.6 months** (interquartile range 21.7 to 30.4 months). An interquartile range describes the middle 50% of patients — so half of all patients were followed for between roughly 22 and 30 months. Median overall survival — the length of time at which half the patients in a group were still alive — was: - **12.7 months** in the pembrolizumab group (95% confidence interval 11.5 to 13.6 months) - **10.9 months** in the placebo group (95% confidence interval 9.9 to 11.6 months) The hazard ratio was **0.83** (95% confidence interval 0.72 to 0.95). In plain language, that means patients receiving pembrolizumab had a **17% lower risk of death at any given point in time** compared with those receiving chemotherapy alone. The absolute difference in median survival was **1.8 months** — but note that a median is only one way of describing the benefit, and the hazard ratio reflects the difference across the entire duration of the study, not just at the midpoint. The statistical result was a one-sided p-value of **0.0034**. The pre-set significance threshold was 0.0200. The result comfortably cleared that bar. The p-value means that if pembrolizumab truly had no effect, there would be only about a 0.34% chance — roughly 1 in 294 — of seeing a survival difference this large purely by chance. ## Key Findings: Safety and Side Effects Safety was evaluated in the as-treated population — the patients who actually received at least one dose of study treatment. That amounted to 529 patients in the pembrolizumab group and 534 in the placebo group (4 and 2 patients respectively were randomised but not treated). The highest-grade side effect experienced by each patient was recorded: - **Grade 3–4 adverse events** (serious but not immediately life-threatening): 420 of 529 patients (79%) in the pembrolizumab group versus 400 of 534 patients (75%) in the placebo group — roughly 4 in 5 versus 3 in 4 - **Grade 5 adverse events** (fatal): 31 of 529 patients (6%) in the pembrolizumab group versus 49 of 534 patients (9%) in the placebo group Notably, serious side effects were similar between the groups, and fatal adverse events were actually somewhat less common in the pembrolizumab group. The study authors stated that the combination produced **no new safety signals** — meaning no unexpected side effects appeared that had not already been seen with these drugs. ## What This Means for Patients KEYNOTE-966 is the first placebo-controlled study of a PD-1 inhibitor and only the second study of a PD-1/PD-L1 pathway inhibitor to show a statistically significant overall survival improvement with a manageable safety profile in advanced biliary tract cancer. This means that for patients newly diagnosed with unresectable locally advanced or metastatic biliary tract cancer, combining pembrolizumab with gemcitabine and cisplatin is now a reasonable first-line treatment option to discuss with an oncologist. The trial added value beyond the earlier TOPAZ-1 study in several specific ways: - A **larger patient population** (1,069 patients) - Enrolment of a **greater proportion of patients outside Asia**, making the results more broadly applicable to a global population - Continuation of **gemcitabine until disease progression**, rather than stopping it earlier - More complete collection of important clinical biomarkers, including **hepatitis B and C viral status** Together with the earlier evidence, these results support adding immune checkpoint inhibitors that target the PD-1/PD-L1 pathway to standard chemotherapy in biliary tract cancer. The authors conclude that the statistically significant and clinically meaningful survival benefit, achieved without new safety concerns, supports pembrolizumab plus gemcitabine and cisplatin as a potential new first-line option. ## Limitations of the Study Several points deserve careful consideration before applying these results. The absolute survival gain was modest — 1.8 months at the median. Patients and doctors should weigh this against the burden of additional infusions, the potential for immune-related side effects, and cost. Grade 3–4 side effects were common in both groups (79% versus 75%), so this treatment regimen is not easy to tolerate. Nearly 4 in 5 patients experienced serious side effects of some kind. Patients in this trial had to be relatively well at the start — ECOG performance status 0 or 1 and adequate organ function. Results may not apply to patients who are more unwell, who would generally not have been eligible. Patients with ampullary cancer and those with active autoimmune disease requiring systemic treatment in the previous two years were excluded, so no conclusions can be drawn for those groups. Although the manuscript describes the study's statistical plan for progression-free survival and objective response rate, the detailed results for those secondary endpoints, as well as the quality-of-life analysis at week 18, were not included in the text available for this summary and remain to be reported in full. Finally, this trial compares pembrolizumab plus chemotherapy with chemotherapy alone. It does not tell us whether pembrolizumab is better than, worse than, or equivalent to durvalumab (the drug tested in TOPAZ-1), because the two trials enrolled different populations and were not compared head to head. ## Practical Recommendations 1. **Ask about immunotherapy as part of first-line treatment.** If you or a loved one has been newly diagnosed with unresectable locally advanced or metastatic biliary tract cancer, ask your oncologist whether adding pembrolizumab to gemcitabine and cisplatin is appropriate for you. 1. **Discuss your hepatitis status.** This trial included patients with hepatitis B and C under specific conditions. If you have either infection, that does not automatically rule out this treatment — but antiviral therapy and viral load monitoring would need to be part of the plan. 1. **Prepare for monitoring.** Expect CT or MRI scans roughly every 6 weeks for the first year, then every 12 weeks. Blood tests and physical exams will be frequent. 1. **Report side effects early.** Immune-based treatments can cause inflammation in the lungs, liver, gut, thyroid, and other organs. Because these can appear at any time — even after treatment ends — tell your care team about new cough, diarrhoea, rash, fatigue, or any unusual symptom. 1. **Understand the realistic benefit.** The median survival gain was about 1.8 months, with a 17% lower risk of death at any given time. For some patients the benefit is larger; for others, smaller. Ask your doctor to put these numbers in the context of your individual situation. 1. **Consider tumour testing.** Ask whether your tumour has been tested for PD-L1, microsatellite instability, and molecular features such as FGFR2 fusions or IDH1 mutations, since these may open additional treatment options. ## Frequently Asked Questions ### What is biliary tract cancer? Biliary tract cancers start in the cells lining the bile ducts or gallbladder. They include intrahepatic bile ducts (inside the liver), extrahepatic bile ducts (outside the liver), and the gallbladder. These cancers are uncommon, accounting for less than 1% of all new cancer cases worldwide, but their incidence is increasing. Risk factors include chronic cysts or gallstones, liver fluke infection, chronic hepatitis B or C, and cirrhosis. ### Who was eligible to join the KEYNOTE-966 trial? Patients had to be 18 or older with confirmed unresectable locally advanced or metastatic biliary tract cancer (extrahepatic, gallbladder, or intrahepatic). They needed measurable disease by RECIST 1.1, an ECOG performance status of 0 or 1, adequate organ function, and a life expectancy over 3 months. Prior neoadjuvant or adjuvant therapy was allowed if completed at least 6 months before diagnosis. Hepatitis B or C patients could join under specific conditions. ### What did the trial find about survival? Among 1,069 patients, median overall survival was 12.7 months with pembrolizumab plus gemcitabine and cisplatin, compared with 10.9 months with chemotherapy alone. This represented a 17% lower risk of death at any given point in time (hazard ratio 0.83). The result was statistically significant, with a one-sided p-value of 0.0034, well past the pre-set threshold of 0.0200. ### What were the side effects of adding pembrolizumab? Side effects were broadly similar between groups. Grade 3–4 adverse events occurred in 79% of the pembrolizumab group versus 75% of the placebo group. Fatal (Grade 5) adverse events occurred in 6% versus 9%, respectively. The combination produced no new safety concerns. However, serious side effects were common, affecting roughly 4 in 5 patients in the pembrolizumab group. ### What does a hazard ratio of 0.83 mean for patients? A hazard ratio of 0.83 means that, at any given point during the study, patients receiving pembrolizumab had a 17% lower risk of death compared with those receiving chemotherapy alone. It reflects the difference across the entire duration of the study, not just at the midpoint. The median survival difference was 1.8 months, but the hazard ratio captures the benefit over time. ### How often were scans and monitoring done during the trial? Tumour imaging with contrast-enhanced CT or MRI covered the chest, abdomen, and pelvis. Scans were done within 4 weeks before randomisation, 6 weeks after the first dose, every 6 weeks through week 54, and every 12 weeks thereafter. Survival was assessed every 12 weeks. Blood tests and physical exams were frequent during treatment and follow-up. ### What should patients discuss with their oncologist about this treatment? Ask whether adding pembrolizumab to gemcitabine and cisplatin is appropriate for your unresectable locally advanced or metastatic biliary tract cancer. Discuss your hepatitis status, as antiviral therapy and viral load monitoring may be needed. Prepare for regular scans and blood tests. Report new symptoms like cough, diarrhoea, rash, or fatigue early. Ask about tumour testing for PD-L1, microsatellite instability, and molecular features. ### When should a patient with newly diagnosed advanced biliary tract cancer seek a second opinion before starting pembrolizumab plus chemotherapy? A second opinion is worth considering when pembrolizumab plus gemcitabine and cisplatin is offered as first-line treatment for unresectable locally advanced or metastatic biliary tract cancer. Median overall survival was 12.7 months with pembrolizumab versus 10.9 months with chemotherapy alone, a 1.8-month median gain, and 79% of patients had grade 3-4 side effects. An independent review can help confirm the diagnosis, check tumour testing for PD-L1, microsatellite instability, FGFR2 fusions or IDH1 mutations, and weigh whether this regimen suits your situation. Diagnostic Detectives Network provides independent expert second opinions. ## Source Information **Original article title:** Pembrolizumab with gemcitabine and cisplatin versus gemcitabine and cisplatin alone in biliary tract cancer (KEYNOTE-966) **Lead authors:** Prof Robin Kate Kelley, MD (UCSF Helen Diller Family Comprehensive Cancer Center); Makoto Ueno, MD (Kanagawa Cancer Center, Yokohama, Japan); and Prof Arndt Vogel, MD (Hannover Medical School, Germany) — contributed equally — on behalf of the KEYNOTE-966 Investigators. The full author list includes Prof Changhoon Yoo, Prof Richard S Finn, Prof Junji Furuse, Prof Zhenggang Ren, Thomas Yau, Heinz-Josef Klümpen, Prof Stephen L Chan, Masato Ozaka, Prof Chris Verslype, Mohamed Bouattour, Prof Joon Oh Park, Olga Barajas, Uwe Pelzer, Prof Juan W Valle, Li Yu, Usha Malhotra, Abby B Siegel, and Prof Julien Edeline. **Publication:** *The Lancet*, 2023, volume 401, issue 10391, pages 1853–1865. DOI: 10.1016/S0140-6736(23)00727-4. Article type: Fast-track randomised controlled trial. **Trial registration:** ClinicalTrials.gov number NCT04003636. **Funding:** Merck Sharp & Dohme LLC, a subsidiary of Merck & Co., Inc., Rahway, NJ, USA. **Note:** This patient-friendly article is based on peer-reviewed research. It is intended for educational purposes and does not replace consultation with a qualified healthcare professional. Treatment decisions should always be made together with your medical team. --- Publisher: Diagnostic Detectives Network (https://diagnosticdetectives.com) — independent multi-expert medical second opinions, worldwide, private-pay. Author byline: Anton Titov, MD, PhD. Contact: https://diagnosticdetectives.com/pages/contact Canonical page: https://diagnosticdetectives.com/products/adding-pembrolizumab-to-chemotherapy-helps-patients-with-advanced-biliary-tract-cancer-live-longer-results-of-the-keynote-966-trial