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Pembrolizumab (MK-3475) Plus Gemcitabine/Cisplatin Versus Placebo Plus Gemcitabine/Cisplatin for First-Line Advanced and/or Unresectable Biliary Tract Carcinoma (BTC) (MK-3475-966/KEYNOTE-966)

A Phase 3 Randomized, Double Blind Study of Pembrolizumab Plus Gemcitabine/Cisplatin Versus Placebo Plus Gemcitabine/Cisplatin as First-Line Therapy in Participants With Advanced and/or Unresectable Biliary Tract Carcinoma

Status
Completed
Phases
Phase 3
Study type
Interventional
Source
ClinicalTrials.gov
Registry ID
NCT04003636
Acronym
KEYNOTE-966
Enrollment
1069
Registered
2019-07-01
Start date
2019-09-24
Completion date
2025-04-01
Last updated
2026-03-24

For informational purposes only — not medical advice. Sourced from public registries and may not reflect the latest updates. Terms

Conditions

Biliary Tract Carcinoma

Keywords

Programmed cell death 1 (PD-1), Pembrolizumab, Cholangiocarcinoma, Gallbladder cancer, Checkpoint inhibitor, Immunotherapy, Biliary, Keytruda, Bile Duct Cancer

Brief summary

This is a study of pembrolizumab plus gemcitabine/cisplatin versus placebo plus gemcitabine/cisplatin as first-line therapy in participants with advanced and/or unresectable biliary tract carcinoma. The primary hypothesis is pembrolizumab plus gemcitabine/cisplatin is superior to placebo plus gemcitabine/cisplatin with respect to overall survival (OS).

Interventions

BIOLOGICALPembrolizumab

Pembrolizumab by intravenous (IV) infusion

DRUGGemcitabine

Gemcitabine by IV infusion

DRUGCisplatin

Cisplatin by IV infusion

DRUGPlacebo

Placebo to pembrolizumab

Sponsors

Merck Sharp & Dohme LLC
Lead SponsorINDUSTRY

Study design

Allocation
RANDOMIZED
Intervention model
PARALLEL
Primary purpose
TREATMENT
Masking
TRIPLE (Subject, Investigator, Outcomes Assessor)

Eligibility

Sex/Gender
ALL
Age
18 Years to No maximum
Healthy volunteers
No

Inclusion criteria

* Has histologically confirmed diagnosis of advanced (metastatic) and/or unresectable (locally advanced) biliary tract cancer (intra-or extrahepatic cholangiocarcinoma or gallbladder cancer) * Has measurable disease based on Response Evaluation Criteria in Solid Tumors (RECIST 1.1), as determined by the site investigator * Participants with a history of hepatitis B or hepatitis C can be enrolled if they meet study criteria * Is able to provide archival tumor tissue sample or newly obtained core or excisional biopsy of a tumor lesion * Has a life expectancy of greater than 3 months * Has adequate organ function

Exclusion criteria

* Has had previous systemic therapy for advanced (metastatic) or unresectable (locally advanced) biliary tract cancer (intra-or extra hepatic cholangiocarcinoma or gallbladder cancer) * Has ampullary cancer * Has small cell cancer, neuroendocrine tumors, lymphoma, sarcoma, mixed tumor histology and/or mucinous cystic neoplasms * Has received prior therapy with an anti-programmed cell death 1 (anti-PD-1), anti- programmed cell death ligand 1 or 2 (anti-PD-L1, anti-PD-L2) agent or with an agent directed to another stimulatory or coinhibitory T-cell receptor (e.g., cytotoxic T-lymphocyte-associated protein 4 \[CTLA-4\], OX-40, CD137) * Has a known history of, or any evidence of, central nervous system (CNS) metastases and/or carcinomatous meningitis, as assessed by local site investigator * Has had an allogenic tissue/solid organ transplant

Design outcomes

Primary

MeasureTime frameDescription
Overall Survival (OS)Up to approximately 38 monthsOverall survival was defined as the time from randomization to death due to any cause.

Secondary

MeasureTime frameDescription
Progression-free Survival (PFS) Per Response Evaluation Criteria in Solid Tumors Version 1.1 (RECIST 1.1) as Assessed by Response Evaluation Criteria in Solid Tumors Version 1.1 (BICR)Up to approximately 26 monthsPFS was defined as the time from randomization to the first documented disease progression (PD) or death due to any cause, whichever occurred first. Per RECIST 1.1, PD was defined as ≥20% increase in the sum of diameters of target lesions. In addition to the relative increase of 20%, the sum must also have demonstrated an absolute increase of ≥5 mm. The appearance of one or more new lesions was also considered PD. PFS as assessed by BICR per RECIST 1.1 was presented.
Objective Response Rate (ORR) Per Response Evaluation Criteria in Solid Tumors Version 1.1 (RECIST 1.1) as Assessed by Blinded Independent Central Review (BICR)Up to approximately 26 monthsORR was defined as the percentage of participants who have a confirmed Complete Response (CR: disappearance of all target lesions) or Partial Response (PR: a ≥30% decrease in the sum of diameters \[SOD\] of target lesions) as assessed by BICR per RECIST 1.1, which was adjusted for this study to allow a maximum of 10 target lesions in total and 5 per organ.
Duration of Response (DOR) Per RECIST 1.1 as Assessed by BICRUp to approximately 38 monthsFor participants who demonstrated a confirmed CR (disappearance of all target lesions) or PR (at least a 30% decrease in the sum of diameters of target lesions) per RECIST 1.1, DOR was defined as the time from first documented evidence of a CR or PR until PD or death. DOR for participants who had not progressed or died at the time of analysis was to be censored at the date of their last tumor assessment. Per RECIST 1.1, PD was defined as at least a 20% increase in the sum of diameters of target lesions as well as an absolute increase of at least a 5 mm in the sum of diameters. The appearance of one or more new lesions was also considered PD. DOR assessments were based on BICR with confirmation. The DOR as assessed using RECIST 1.1 for all participants who experienced a confirmed CR or PR was presented.
Number of Participants Who Experience One or More Adverse Events (AE)Up to approximately 65 monthsAn adverse event (AE) was defined as any unfavorable and unintended sign including an abnormal laboratory finding, symptom or disease associated with the use of a medical treatment or procedure, regardless of whether it was considered related to the medical treatment or procedure, that occurred during the course of the study. Number of participants who experienced one or more AEs were reported.
Number of Participants Who Discontinued Study Intervention Due to an AEUp to approximately 63 monthsAn AE was defined as any unfavorable and unintended sign including an abnormal laboratory finding, symptom or disease associated with the use of a medical treatment or procedure, regardless of whether it was considered related to the medical treatment or procedure, that occurs during the course of the study. Number of participants who discontinued study intervention due to an AE were reported.

Countries

Argentina, Australia, Belgium, Brazil, Canada, Chile, China, France, Germany, Hong Kong, Ireland, Israel, Italy, Japan, Malaysia, Netherlands, New Zealand, South Korea, Spain, Taiwan, Thailand, Turkey (Türkiye), United Kingdom, United States

Contacts

STUDY_DIRECTORMedical Director

Merck Sharp & Dohme LLC

Participant flow

Pre-assignment details

Per protocol, response or progression during the second course treatment was not counted towards efficacy outcome measures, and adverse events during the second course treatment were not counted towards safety outcome measures.

Participants by arm

ArmCount
Arm A (Pembrolizumab+Gemcitabine+Cisplatin)
Pembrolizumab, 200 mg, every 3 weeks (Q3W), Day 1 of each 3-week cycle for up to 35 cycles PLUS Gemcitabine, 1000 mg/m\^2, Q3W, Day 1 and Day 8 of each cycle until progressive disease or unacceptable toxicity plus Cisplatin, 25 mg/m\^2, Q3W, Day 1 and Day 8 of each cycle for up to 8 cycles. Participants in Arm A who stopped study intervention after achieving stable-disease (SD) or better may have been eligible to receive additional pembrolizumab for up to 17 cycles if they experienced radiographic disease progression while off study intervention, according to the protocol-defined criteria. Gemcitabine may have been continued until progressive disease (PD) or unacceptable toxicity during second course at investigator's discretion.
533
Arm B (Placebo+Gemcitabine+Cisplatin)
Placebo to Pembrolizumab, 200 mg, every 3 weeks (Q3W), Day 1 of each 3-week cycle for up to 35 cycles PLUS Gemcitabine, 1000 mg/m\^2, Q3W, Day 1 and Day 8 of each cycle until progressive disease or unacceptable toxicity PLUS Cisplatin, 25 mg/m\^2, Q3W, Day 1 and Day 8 of each cycle for up to 8 cycles.
536
Total1,069

Baseline characteristics

CharacteristicTotalArm A (Pembrolizumab+Gemcitabine+Cisplatin)Arm B (Placebo+Gemcitabine+Cisplatin)
Age, Continuous62.5 Years
STANDARD_DEVIATION 10.7
63.3 Years
STANDARD_DEVIATION 10.3
61.8 Years
STANDARD_DEVIATION 11
Disease Status
Locally Advanced
126 Participants60 Participants66 Participants
Disease Status
Metastatic
943 Participants473 Participants470 Participants
Ethnicity (NIH/OMB)
Hispanic or Latino
111 Participants59 Participants52 Participants
Ethnicity (NIH/OMB)
Not Hispanic or Latino
882 Participants433 Participants449 Participants
Ethnicity (NIH/OMB)
Unknown or Not Reported
76 Participants41 Participants35 Participants
Geographic Region
Asian
486 Participants242 Participants244 Participants
Geographic Region
Non-Asian
583 Participants291 Participants292 Participants
Race (NIH/OMB)
American Indian or Alaska Native
3 Participants2 Participants1 Participants
Race (NIH/OMB)
Asian
495 Participants245 Participants250 Participants
Race (NIH/OMB)
Black or African American
14 Participants11 Participants3 Participants
Race (NIH/OMB)
More than one race
7 Participants5 Participants2 Participants
Race (NIH/OMB)
Native Hawaiian or Other Pacific Islander
1 Participants1 Participants0 Participants
Race (NIH/OMB)
Unknown or Not Reported
25 Participants13 Participants12 Participants
Race (NIH/OMB)
White
524 Participants256 Participants268 Participants
Sex: Female, Male
Female
517 Participants253 Participants264 Participants
Sex: Female, Male
Male
552 Participants280 Participants272 Participants
Site of Origin
Extrahepatic
203 Participants98 Participants105 Participants
Site of Origin
Gallbladder
233 Participants115 Participants118 Participants
Site of Origin
Intrahepatic
633 Participants320 Participants313 Participants

Adverse events

Event typeEG000
affected / at risk
EG001
affected / at risk
EG002
affected / at risk
deaths
Total, all-cause mortality
483 / 533505 / 5364 / 10
other
Total, other adverse events
513 / 529522 / 53410 / 10
serious
Total, serious adverse events
280 / 529264 / 5340 / 10

Outcome results

Primary

Overall Survival (OS)

Overall survival was defined as the time from randomization to death due to any cause.

Time frame: Up to approximately 38 months

Population: All randomized participants

ArmMeasureValue (MEDIAN)
Arm A (Pembrolizumab+Gemcitabine+Cisplatin)Overall Survival (OS)12.7 Months
Arm B (Placebo+Gemcitabine+Cisplatin)Overall Survival (OS)10.9 Months
p-value: 0.003495% CI: [0.72, 0.95]Regression, Cox
Secondary

Duration of Response (DOR) Per RECIST 1.1 as Assessed by BICR

For participants who demonstrate a confirmed CR or PR, DOR was the time from the first documented evidence of CR or PR until disease progression or death due to any cause, whichever occurred first.

Time frame: Up to approximately 38 months

Population: All randomized participants with CR or PR

ArmMeasureValue (MEDIAN)
Arm A (Pembrolizumab+Gemcitabine+Cisplatin)Duration of Response (DOR) Per RECIST 1.1 as Assessed by BICR9.7 Months
Arm B (Placebo+Gemcitabine+Cisplatin)Duration of Response (DOR) Per RECIST 1.1 as Assessed by BICR6.9 Months
Secondary

Number of Participants Who Discontinued Study Intervention Due to an Adverse Event (AE)

An AE was defined as any unfavorable and unintended sign including an abnormal laboratory finding, symptom or disease associated with the use of a medical treatment or procedure, regardless of whether it was considered related to the medical treatment or procedure, that occurs during the course of the study.

Time frame: Up to approximately 38 months

Population: All Participants as Treated (APaT) population, which consisted of all randomized participants who received at least 1 dose of study intervention.

ArmMeasureValue (COUNT_OF_PARTICIPANTS)
Arm A (Pembrolizumab+Gemcitabine+Cisplatin)Number of Participants Who Discontinued Study Intervention Due to an Adverse Event (AE)138 Participants
Arm B (Placebo+Gemcitabine+Cisplatin)Number of Participants Who Discontinued Study Intervention Due to an Adverse Event (AE)122 Participants
Secondary

Number of Participants Who Experience One or More Adverse Events (AE)

An adverse event (AE) was defined as any unfavorable and unintended sign including an abnormal laboratory finding, symptom or disease associated with the use of a medical treatment or procedure, regardless of whether it was considered related to the medical treatment or procedure, that occurred during the course of the study.

Time frame: Up to approximately 38 months

Population: All Participants as Treated (APaT) population, which consisted of all randomized participants who received at least 1 dose of study intervention

ArmMeasureValue (COUNT_OF_PARTICIPANTS)
Arm A (Pembrolizumab+Gemcitabine+Cisplatin)Number of Participants Who Experience One or More Adverse Events (AE)524 Participants
Arm B (Placebo+Gemcitabine+Cisplatin)Number of Participants Who Experience One or More Adverse Events (AE)532 Participants
Secondary

Objective Response Rate (ORR) Per Response Evaluation Criteria in Solid Tumors Version 1.1 (RECIST 1.1) as Assessed by Blinded Independent Central Review (BICR)

ORR was defined as the percentage of participants who have a confirmed Complete Response (CR: disappearance of all target lesions) or Partial Response (PR: a ≥30% decrease in the sum of diameters \[SOD\] of target lesions) as assessed by BICR per RECIST 1.1, which was adjusted for this study to allow a maximum of 10 target lesions in total and 5 per organ.

Time frame: Up to approximately 26 months

Population: All randomized participants

ArmMeasureValue (NUMBER)
Arm A (Pembrolizumab+Gemcitabine+Cisplatin)Objective Response Rate (ORR) Per Response Evaluation Criteria in Solid Tumors Version 1.1 (RECIST 1.1) as Assessed by Blinded Independent Central Review (BICR)28.7 Percentage of Participants
Arm B (Placebo+Gemcitabine+Cisplatin)Objective Response Rate (ORR) Per Response Evaluation Criteria in Solid Tumors Version 1.1 (RECIST 1.1) as Assessed by Blinded Independent Central Review (BICR)28.5 Percentage of Participants
p-value: 0.473595% CI: [-5.2, 5.6]Miettinen & Nurminen
Secondary

Progression-free Survival (PFS) Per Response Evaluation Criteria in Solid Tumors Version 1.1 (RECIST 1.1) as Assessed by Response Evaluation Criteria in Solid Tumors Version 1.1 (BICR)

PFS was defined as the time from randomization to the first documented progressive disease (PD) per RECIST 1.1 by BICR, or death due to any cause, whichever occurred first.

Time frame: Up to approximately 26 months

Population: All randomized participants

ArmMeasureValue (MEDIAN)
Arm A (Pembrolizumab+Gemcitabine+Cisplatin)Progression-free Survival (PFS) Per Response Evaluation Criteria in Solid Tumors Version 1.1 (RECIST 1.1) as Assessed by Response Evaluation Criteria in Solid Tumors Version 1.1 (BICR)6.5 Months
Arm B (Placebo+Gemcitabine+Cisplatin)Progression-free Survival (PFS) Per Response Evaluation Criteria in Solid Tumors Version 1.1 (RECIST 1.1) as Assessed by Response Evaluation Criteria in Solid Tumors Version 1.1 (BICR)5.6 Months
p-value: 0.022595% CI: [0.75, 1]Regression, Cox

Source: ClinicalTrials.gov · Data processed: May 25, 2026