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Favezelimab/Pembrolizumab

Phase 3

Colorectal Cancer | Monoclonal antibody | Oncology |Merck & Company, Inc.|Last Updated: Sep 1, 2026

Target and mechanism

Molecular targetLAG-3/PD-1
ModalityMonoclonal antibody

Also known as Favezelimab

Success Probability

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Market & Valuation

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Trial Design

RandomizedACTIVE_CONTROLLEDDMC
Total Trials2
Total Enrollment535

FDA Designations

No designations recorded

Clinical trial landscape

Favezelimab/Pembrolizumab · 6 trials · 8 indications

Phase 3 2Phase 2 2Phase 1 2
NCT05600309A Study of Coformulated Favezelimab/Pembrolizumab (MK-4280A) Versus Standard of Care in Subjects With Previously Treated Metastatic PD-L1 Positive Colorectal Cancer (MK-4280A-007)-China Extension StudyColorectal Cancer
COMPLETED94 Analytics
NCT05064059A Study of Coformulated Favezelimab/Pembrolizumab (MK-4280A) Versus Standard of Care in Subjects With Previously Treated Metastatic PD-L1 Positive Colorectal Cancer (MK-4280A-007)Colorectal Cancer
COMPLETED441 Analytics
PHASE3COMPLETED
A Study of Coformulated Favezelimab/Pembrolizumab (MK-4280A) Versus Standard of Care in Subjects With Previously Treated Metastatic PD-L1 Positive Colorectal Cancer (MK-4280A-007)-China Extension Study
Colorectal CancerUnlock trial analytics
PHASE3COMPLETED
A Study of Coformulated Favezelimab/Pembrolizumab (MK-4280A) Versus Standard of Care in Subjects With Previously Treated Metastatic PD-L1 Positive Colorectal Cancer (MK-4280A-007)
Colorectal CancerUnlock trial analytics

Study Endpoints

Primary Endpoints

Overall Survival (OS)
Up to approximately 26 months

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

Clinical Benefit Rate - Cohort A
Up to approximately 22 months

Clinical benefit rate is defined as the percentage of participants who have clinical benefit. Clinical benefit is defined as major pathologic response (mPR) or pCR in participants who undergo surgery, or clinical complete response (cCR) \[defined as residual tumor not visible on clinical exam nor on imaging and a negative biopsy, if biopsy is available, in participants who decline surgery.

Objective Response Rate (ORR) per Response Evaluation Criteria in Solid Tumors Version 1.1 (RECIST 1.1) as assessed by Investigator - Cohort B
Up to approximately 21 months

The ORR is defined as the percentage of participants who have an OR per investigator assessment. The OR is defined as a Complete Response (CR: disappearance of all target lesions) or Partial Response (PR: at least a 30% decrease in the sum of diameters of target lesions) per Response Evaluation Criteria In Solid Tumors Version 1.1 (RECIST 1.1). The percentage of participants who experience CR or PR as assessed by Blinded Independent Central Review (BICR) will be presented.

Progression Free Survival (PFS) Per Lugano Response Criteria as Assessed by Investigator
Up to approximately 34 months

PFS was defined as the time from randomization to the first documented disease progression per Lugano criteria 2014 as assessed by investigator or death due to any cause, whichever occurred first. Progressive disease was defined as uptake moderately or markedly higher than the liver with an increase in overall uptake compared with nadir, and/or the appearance of new lesions consistent with lymphoma.

Part 1: Objective Response Rate (ORR)
Up to ~4 years

ORR is defined as the percentage of participants who achieve a confirmed complete response (CR) or partial response (PR) per Response Evaluation Criteria in Solid Tumors (RECIST) 1.1 as assessed by blinded independent central review (BICR). ORR will be reported for participants in Part 1.

Part 1: Percentage of Participants experiencing an Adverse Event (AE)
Up to ~4 years

An AE is defined as any untoward medical occurrence in a participant administered study drug, which does not necessarily have to have a causal relationship with the study drug. The number of participants experiencing an AE in Part 1 will be reported.

Part 1: Percentage of Participants who Discontinue study interventions due to an AE
Up to ~4 years

An AE is defined as any untoward medical occurrence in a participant administered study drug, which does not necessarily have to have a causal relationship with the study drug. The number of participants who discontinue study interventions due to an AE in Part 1 will be reported.

Part 1: Percentage of Participants with Dose-limiting toxicities (DLT)
Up to 21 days

A DLT is defined as an event with toxicity including the type, severity, time of onset, time of resolution, and the probable association with study treatment that are not due to pre-existing conditions as defined by the National Cancer Institute (NCI) Common Terminology Criteria for Adverse Events, Version 5.0 (CTCAE 5.0). The number of participants who experience a DLT in Part 1 will be reported.

Part 2: Progression Free Survival (PFS)
Up to ~4 years

PFS is defined as the time from randomization to the first documented disease progression per RECIST 1.1 by BICR or death due to any cause, whichever occurs first. PFS will be reported for participants in Part 2.

Number of Participants Who Experienced a Dose-Limiting Toxicity (DLT)
Up to 21 days (Cycle 1)

DLTs were assessed during the first cycle (21 days) \& were defined as: Grade (Gr) 4 nonhematologic toxicity; Gr 4 hematologic toxicity lasting ≥7 days, except Gr 4 thrombocytopenia of any duration or Gr 3 thrombocytopenia associated with bleeding; Gr 3 nonhematologic toxicity lasting ≥3 days despite optimal supportive care (with exceptions); Gr 3 or 4 nonhematologic lab abnormality (if medical intervention was required, lead to hospitalization, or persisted for \>1 week); Gr 3 or 4 febrile neutropenia; any drug-related AE that caused the participant to discontinue treatment during Cycle 1; Grade 5 toxicity; Any treatment-related toxicity that causes ≥2-week delay in initiation of Cycle 2.

Number of Participants Who Experienced an Adverse Event (AE)
Up to approximately 31.3 months

An AE was defined as any untoward medical occurrence in a participant administered study treatment and which did not necessarily have to have a causal relationship with this treatment. The number of participants who experienced an AE is presented.

Number of Participants Who Discontinued Study Treatment Due to an AE
Up to approximately 28.3 months

An AE was defined as any untoward medical occurrence in a participant administered study treatment and which did not necessarily have to have a causal relationship with this treatment. The number of participants who discontinued study treatment due to an AE is presented.

Secondary Endpoints

Progression-Free Survival (PFS) According 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 months
Objective Response Rate (ORR) Per RECIST 1.1 as Assessed by BICR
Up to approximately 26 months
Duration of Response (DOR) Per RECIST 1.1 as Assessed by BICR
Up to approximately 26 months
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Study Design & Arms

AllocationRANDOMIZED
MaskingNONE
ModelPARALLEL
PurposeTREATMENT

Treatment Arms

ArmTypeDescription
Favezelimab/PembrolizumabEXPERIMENTALParticipants will receive coformulated favezelimab/pembrolizumab (800 mg/200 mg) intravenously (IV) on Day 1, then every 3 weeks (Q3W), for up to 35 infusions.
Standard of Care (Regorafenib or TAS-102)ACTIVE_COMPARATORAt the Investigator's choice, participants will receive 160 mg regorafenib orally daily on Days 1-12 of each 28-day cycle or 35 mg/m\^2 TAS-102 orally twice daily on Days 1-5 and Days 8-12 of each 28-day cycle.
PembrolizumabEXPERIMENTALParticipants will receive 200 mg pembrolizumab via an IV infusion Q3W for 3 cycles in the neoadjuvant period and 14 cycles of adjuvant therapy. Each cycle is 21 days. Participants who do not complete all 3 neoadjuvant cycles should have additional cycles in the adjuvant period so that the total number of study intervention administrations is 17 treatment cycles.
Favezelimab/Pembrolizumab + Lenvatinib (Cohort B)EXPERIMENTALParticipants will receive coformulated favezelimab/pembrolizumab (800 mg/200 mg) via IV infusion Q3W for up to 35 cycles (each cycle is 21 days) PLUS lenvatinib every day (QD) 20 mg orally until disease progression, unacceptable toxicity, or discontinuation criteria are met.
Pembrolizumab + Lenvatinib (Cohort B)EXPERIMENTALParticipants will receive 200 mg pembrolizumab via IV infusion Q3W for up to 35 cycles (each cycle is 21 days) PLUS lenvatinib QD 20 mg orally until disease progression, unacceptable toxicity, or discontinuation criteria are met.
Chemotherapy (Bendamustine or Gemcitabine)ACTIVE_COMPARATORParticipants will receive physician's choice of EITHER bendamustine by IV infusion at a dose between 90 and 120 mg/m\^2 on Day 1 and Day 2 of either a 3- or 4-week cycle for up to 6 cycles OR gemcitabine by IV infusion at a dose between 800 and 1200 mg/m\^2 on Day 1 and Day 8 of a 3-week cycle for up to 6 cycles.
Arm A: Coformulated favezelimab/pembrolizumab plus EVEXPERIMENTALParticipants will receive coformulated favezelimab/pembrolizumab (800 mg/200 mg) as an intravenous (IV) infusion on Day 1 of every 3-week cycle for up to \~2 years (35 cycles) and EV at 1.25 mg/kg, administered as an IV infusion on Days 1 and 8 of every 3-week cycle until disease progression, intolerable toxicity, or investigator decision.
Arm B: Coformulated vibostolimab/pembrolizumab plus EVEXPERIMENTALParticipants will receive coformulated vibostolimab/pembrolizumab (200 mg/200 mg) as an IV infusion on Day 1 of every 3-week cycle, for up to \~2 years (35 cycles) and EV at 1.25 mg/kg, administered as an IV infusion on Days 1 and 8 of every 3-week cycle until disease progression, intolerable toxicity, or investigator decision.
Arm C: Pembrolizumab plus EVACTIVE_COMPARATORParticipants will receive 200 mg pembrolizumab as an IV infusion on Day 1 of every 3-week cycle for up to \~2 years (35 cycles) and EV at 1.25 mg/kg, administered as an IV infusion on Days 1 and 8 of every 3-week cycle, until disease progression, intolerable toxicity, or investigator decision.
Part A: Favezelimab 7 mg MonotherapyEXPERIMENTALParticipants received favezelimab 7 mg intravenous (IV) infusion on Day 1 of each 21-day cycle.
Part A: Favezelimab 21 mg MonotherapyEXPERIMENTALParticipants received favezelimab 21 mg IV infusion on Day 1 of each 21-day cycle.
Part A: Favezelimab 70 mg MonotherapyEXPERIMENTALParticipants received favezelimab 70 mg IV infusion on Day 1 of each 21-day cycle.
Part A: Favezelimab 210 mg MonotherapyEXPERIMENTALParticipants received favezelimab 210 mg IV infusion on Day 1 of each 21-day cycle.
Part A: Favezelimab 700 mg MonotherapyEXPERIMENTALParticipants received favezelimab 700 mg IV infusion on Day 1 of each 21-day cycle.
Part A: Favezelimab 7 mg + Pembrolizumab 200 mgEXPERIMENTALParticipants received favezelimab 7 mg IV infusion on Day 1 of each 21-day cycle PLUS pembrolizumab 200 mg IV infusion administered sequentially on Day 1 of each 21-day cycle.
Part A: Favezelimab 21 mg + Pembrolizumab 200 mgEXPERIMENTALParticipants received favezelimab 21 mg IV infusion on Day 1 of each 21-day cycle PLUS pembrolizumab 200 mg IV infusion administered sequentially on Day 1 of each 21-day cycle.
Part A: Favezelimab 70 mg + Pembrolizumab 200 mgEXPERIMENTALParticipants received favezelimab 70 mg IV infusion on Day 1 of each 21-day cycle PLUS pembrolizumab 200 mg IV infusion administered sequentially on Day 1 of each 21-day cycle.
Part A: Favezelimab 210 mg + Pembrolizumab 200 mgEXPERIMENTALParticipants received favezelimab 210 mg IV infusion on Day 1 of each 21-day cycle PLUS pembrolizumab 200 mg IV infusion administered sequentially on Day 1 of each 21-day cycle.
Part A: Favezelimab 700 mg + Pembrolizumab 200 mgEXPERIMENTALParticipants received favezelimab 700 mg IV infusion on Day 1 of each 21-day cycle PLUS pembrolizumab 200 mg IV infusion administered sequentially on Day 1 of each 21-day cycle.
Part B: Favezelimab 800 mg Monotherapy (Arm 1)EXPERIMENTALParticipants received favezelimab 800 mg monotherapy IV infusion on Day 1 of each 21-day cycle.
Part B: Favezelimab 200 mg + Pembrolizumab 200 mg (Arm 2A)EXPERIMENTALParticipants received favezelimab 200 mg IV infusion on Day 1 of each 21-day cycle PLUS pembrolizumab 200 mg IV infusion administered sequentially on Day 1 of each 21-day cycle.
Part B: Favezelimab 700 mg + Pembrolizumab 200 mg (Arm 2B)EXPERIMENTALParticipants received favezelimab 700 mg IV infusion on Day 1 of each 21-day cycle PLUS pembrolizumab 200 mg IV infusion administered sequentially on Day 1 of each 21-day cycle.
Part B: Favezelimab 800 mg + Pembrolizumab 200 mg (Arm 2C)EXPERIMENTALParticipants received favezelimab 800 mg IV infusion on Day 1 of each 21-day cycle PLUS pembrolizumab 200 mg IV infusion administered sequentially on Day 1 of each 21-day cycle.
Part B: Favezelimab 800 mg + Pembrolizumab 200 mg + mFOLFOX7 (Arm 3)EXPERIMENTALParticipants received favezelimab 800 mg IV infusion on Day 1 of each 21-day cycle PLUS pembrolizumab 200 mg IV infusion administered sequentially on Day 1 of each 21-day cycle PLUS mFOLFOX7 (oxaliplatin 85 mg/m\^2 IV, leucovorin \[calcium folinate\] 400 mg/m\^2 IV, and fluorouracil \[5-FU\] 2400 mg/m\^2 IV over 46 to 48 hours, every 2 weeks \[Q2W\]).
Part B: Favezelimab 800 mg + Pembrolizumab 200 mg + FOLFIRI (Arm 4)EXPERIMENTALParticipants received favezelimab 800 mg IV infusion on Day 1 of each 21-day cycle PLUS pembrolizumab 200 mg IV infusion administered sequentially on Day 1 of each 21-day cycle PLUS FOLFIRI (irinotecan 180 mg/m\^2 IV, leucovorin \[calcium folinate\] 400 mg/m\^2 IV and 5-FU 2400 mg/m\^2 IV over 46 to 48 hours, Q2W).
Part B: MK-4280A (Arm 5)EXPERIMENTALParticipants received MK-4280A, a coformulation of favezelimab 800 mg + pembrolizumab 200 mg IV infusion on Day 1 of each 21-day cycle.
Part B: Favezelimab 800 mg + Pembrolizumab 200 mg + Lenvatinib 20 mg (Arm 6)EXPERIMENTALParticipants received favezelimab 800 mg IV infusion on Day 1 of each 21-day cycle PLUS pembrolizumab 200 mg IV infusion administered sequentially on Day 1 of each 21-day cycle PLUS oral lenvatinib 20 mg once daily.

Interventions

NameTypeDescription
favezelimab/pembrolizumabBIOLOGICALCoformulated favezelimab/pembrolizumab (800 mg/200 mg), IV infusion
regorafenibDRUGOral
TAS-102DRUGOral
pembrolizumabBIOLOGICALIV infusion
lenvatinibDRUGOral administration of capsule
bendamustineDRUGIV infusion
gemcitabineDRUGIV infusion
Coformulated favezelimab/pembrolizumabBIOLOGICALCoformulated favezelimab/pembrolizumab (800 mg/200 mg) IV infusion
Coformulated vibostolimab/pembrolizumabBIOLOGICALCoformulated vibostolimab/pembrolizumab (200 mg/200 mg) IV infusion
EVCOMBINATION_PRODUCT1.25 mg/kg IV infusion
FavezelimabBIOLOGICALIV infusion
OxaliplatinDRUGIV infusion
IrinotecanDRUGIV infusion
Leucovorin (Calcium Folinate)DRUGIV infusion
Fluorouracil [5-FU]DRUGIV infusion
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Eligibility Criteria

Age Range18 Years to N/A
SexALL
Healthy VolunteersNo
Study Sites24

Inclusion Criteria: * Has a histologically confirmed colorectal adenocarcinoma that is metastatic and unresectable. * Has measurable disease per RECIST 1.1 as assessed by the local site investigator. * Has been previously treated for the disease and radiographically progressed on or after or could ...

Countries:ChinaUnited StatesAustraliaCanadaChileCzechiaFranceGermanyIsraelItalyJapanMalaysiaNorwayRussiaSouth AfricaSouth KoreaSpainTaiwanTurkey (Türkiye)UkraineUnited KingdomNetherlandsArgentinaBelgiumBrazilMexicoPolandSwedenSwitzerland
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Recent Changes (Last 90 Days)

MEDIUMJun 26, 2026NCT05064059TRIAL_REMOVED: changed
MEDIUMJun 26, 2026NCT05064059TRIAL_REMOVED: changed
MEDIUMJun 26, 2026NCT05064059TRIAL_REMOVED: changed

Frequently asked questions about Favezelimab/Pembrolizumab

What is favezelimab/pembrolizumab used for?

Favezelimab/pembrolizumab is an investigational coformulated monoclonal antibody combination being studied for colorectal cancer, Hodgkin lymphoma, solid tumors, cutaneous squamous cell carcinoma, and endometrial cancer. It is developed by Merck & Company, Inc. (MRK) and is currently in Phase 3 clinical development for certain indications.

What does favezelimab/pembrolizumab target?

Favezelimab/pembrolizumab targets LAG-3 and PD-1, two immune checkpoint proteins. By blocking these targets, the combination is designed to enhance the immune system's ability to fight cancer cells. This mechanism is being evaluated across multiple oncology indications.

Who makes favezelimab/pembrolizumab?

Favezelimab/pembrolizumab is developed by Merck & Company, Inc., traded on the New York Stock Exchange under the ticker MRK. The company is conducting clinical trials to evaluate this coformulated antibody combination in various cancer types.

What phase is favezelimab/pembrolizumab in?

Favezelimab/pembrolizumab is in Phase 3 clinical development for previously treated metastatic PD-L1 positive colorectal cancer. It has completed Phase 2 trials in solid tumors and Hodgkin lymphoma. The drug is investigational and not yet approved by regulatory authorities.

What clinical trials is favezelimab/pembrolizumab in?

Favezelimab/pembrolizumab has been studied in several completed trials, including NCT06036836 for solid tumors, NCT05600309 for colorectal cancer in China, NCT05508867 for Hodgkin lymphoma, and NCT05064059 for colorectal cancer. These trials enrolled a total of 535 participants across multiple countries.

Is favezelimab/pembrolizumab the same as MK-4280A?

Yes, favezelimab/pembrolizumab is also known as MK-4280A. Clinical trial titles refer to the coformulated combination as MK-4280A, and it is being investigated under this name in studies for solid tumors, colorectal cancer, and Hodgkin lymphoma.