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Petosemtamab

Phase 3

Head and Neck Squamous Cell Carcinoma | Small molecule | Oncology |Merus N.V.|Last Updated: Jul 16, 2026

Success Probability

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Trial Design

RandomizedACTIVE_CONTROLLEDDMC
Total Trials2
Total Enrollment1,300

FDA Designations

BREAKTHROUGH_THERAPYFAST_TRACK

Clinical trial landscape

Petosemtamab · 2 trials · 1 indication

Phase 3 2
NCT06525220A Phase 3 Study to Evaluate Petosemtamab Plus Pembrolizumab vs Pembrolizumab in First-line Treatment of Head and Neck Cancer (LiGeR - HN1)Head and Neck Squamous Cell Carcinoma
RECRUITING700 Analytics
NCT06496178A Phase 3 Study to Evaluate Petosemtamab Compared With Investigator's Choice Monotherapy in Previously Treated Head and Neck Squamous Cell Carcinoma Patients (LiGeR-HN2)Head and Neck Squamous Cell Carcinoma
RECRUITING600 Analytics
PHASE3RECRUITING
A Phase 3 Study to Evaluate Petosemtamab Plus Pembrolizumab vs Pembrolizumab in First-line Treatment of Head and Neck Cancer (LiGeR - HN1)
Head and Neck Squamous Cell CarcinomaUnlock trial analytics
PHASE3RECRUITING
A Phase 3 Study to Evaluate Petosemtamab Compared With Investigator's Choice Monotherapy in Previously Treated Head and Neck Squamous Cell Carcinoma Patients (LiGeR-HN2)
Head and Neck Squamous Cell CarcinomaUnlock trial analytics

Study Endpoints

Primary Endpoints

Overall Survival (OS)
Up to approximately 3 years
Objective Response Rate (ORR) per Response Evaluation Criteria in Solid Tumors (RECIST) v1.1 as assessed by blinded independent central review (BICR)
Up to approximately 2 years

Secondary Endpoints

Progression Free Survival (PFS) per RECIST v1.1 as assessed by BICR
Up to approximately 2 years
Duration of Response (DOR) per RECIST v1.1 as assessed by BICR
Up to approximately 2 years
Clinical benefit rate per RECIST v1.1 as assessed by BICR
Up to approximately 2 years
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Study Design & Arms

AllocationRANDOMIZED
MaskingNONE
ModelPARALLEL
PurposeTREATMENT

Treatment Arms

ArmTypeDescription
Petosemtamab + PembrolizumabEXPERIMENTALCombination Therapy
PembrolizumabACTIVE_COMPARATORMonotherapy
MCLA-158EXPERIMENTAL -
Investigator's ChoiceACTIVE_COMPARATOR -

Interventions

NameTypeDescription
PetosemtamabDRUGMCLA-158
PembrolizumabDRUGHumanized Antibody
Investigator's ChoiceDRUGCetuximab
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Eligibility Criteria

Age Range18 Years to N/A
SexALL
Healthy VolunteersNo
Study Sites205

Inclusion Criteria: 1. Signed ICF before initiation of any study procedures 2. Age ≥ 18 years at signing of ICF 3. Histologically confirmed HNSCC with evidence of metastatic or locally recurrent disease not amenable to local therapy with curative intent. 4. The eligible HNSCC primary tumor location...

Countries:United StatesArgentinaAustraliaBelgiumBrazilCanadaChileCroatiaCzechiaFranceGermanyGreeceHungaryIsraelItalyJapanLithuaniaMalaysiaMexicoNetherlandsPolandPortugalSouth KoreaSpainTaiwanThailandTurkey (Türkiye)United KingdomSwitzerland
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Recent Changes (Last 90 Days)

LOWJul 17, 2026NCT06496178lastUpdatePostDate: changed
LOWJul 17, 2026NCT06496178lastUpdatePostDate: changed
LOWJul 17, 2026NCT06496178lastUpdatePostDate: changed
LOWJun 3, 2026NCT06496178lastUpdatePostDate: changed
LOWJun 3, 2026NCT06496178lastUpdatePostDate: changed
LOWJun 2, 2026NCT06525220lastUpdatePostDate: changed
LOWJun 2, 2026NCT06525220lastUpdatePostDate: changed
LOWJun 2, 2026NCT06525220lastUpdatePostDate: changed
LOWMay 26, 2026NCT06496178Enrollment: 500 → 600
LOWMay 26, 2026NCT06525220primaryCompletionDate: changed
LOWMay 24, 2026NCT06496178studyFirstPostDate: changed
LOWMay 24, 2026NCT06525220studyFirstPostDate: changed

Frequently asked questions about Petosemtamab

What is Petosemtamab used for?

Petosemtamab is an investigational bispecific antibody being developed for the treatment of Head and Neck Squamous Cell Carcinoma (HNSCC). It is currently in Phase 3 clinical trials for this indication, including as a monotherapy in previously treated patients and in combination with pembrolizumab as a first-line treatment.

What does Petosemtamab target?

Petosemtamab is a bispecific antibody, a type of -mab (antibody) therapeutic. It is designed to target two antigens involved in tumor growth and immune evasion, though the specific molecular targets are not disclosed in the available information. Its mechanism of action is under investigation in clinical trials.

Who makes Petosemtamab?

Petosemtamab is being developed by Merus N.V., a clinical-stage biopharmaceutical company. Merus is publicly traded on the Nasdaq under the ticker symbol MRUS. The company is conducting Phase 3 trials to evaluate the drug in head and neck cancer.

What phase is Petosemtamab in?

Petosemtamab is in Phase 3 clinical development. It has received Breakthrough Therapy and Fast Track designations from the FDA for the treatment of Head and Neck Squamous Cell Carcinoma. It is not yet approved and remains investigational.

What clinical trials is Petosemtamab in?

Petosemtamab is being studied in two Phase 3 trials. NCT06496178 (LiGeR-HN2) compares petosemtamab monotherapy to investigator's choice in previously treated HNSCC, with 600 participants. NCT06525220 (LiGeR-HN1) evaluates petosemtamab plus pembrolizumab versus pembrolizumab alone in first-line HNSCC, with 700 participants. Both are recruiting.

Is Petosemtamab the same as any other drug?

Petosemtamab is a unique investigational bispecific antibody developed by Merus N.V. It is not known to be the same as any other approved or investigational drug. It is being studied under its own name in clinical trials for head and neck cancer.