OnCo
drugsProductPhase 3

Petosemtamab

A two-armed antibody that blocks EGFR while gripping LGR5, a marker of cancer stem cells, so it hits the cells that regrow tumours.

Merus Biclonics antibody; Breakthrough Therapy designation. Phase 2 with pembrolizumab in first-line PD-L1-positive HNSCC: ORR ~63%; monotherapy ORR ~37% in second line. Phase 3 LiGeR-HN1 and LiGeR-HN2 enrolling; also in colorectal cancer. Merus was acquired by Genmab (2025).

Schematic of the modality · Bispecific antibody (EGFR × LGR5) · not a molecule; see the Bispecific antibodies page
Mechanism, step by step
auto-advancing · hover to pause

1.The LGR5 arm binds cancer stem-like cells

Modality
Bispecific antibody (EGFR × LGR5)
Mechanism
Simultaneous EGFR blockade and LGR5-mediated internalisation and degradation of EGFR; ADCC-enhanced Fc.
Brand / code
MCLA-158
Dosing & schedule
Route
Intravenous
Schedule
1500 mg every 2 weeks (phase 3 dose)
Monitoring
Infusion reactions (premedication), rash, hypomagnesaemia

Source: clinicaltrials.gov/study/NCT06525220. Doses are for orientation; the current label governs.

Where it is approved
USunder reviewEUUKJPCNAUcompare regions →

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Regulatory

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  1. 2024DesignationUS

    Breakthrough Therapy designation for HNSCC

Trials

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ClinicalTrials.gov · phase 2/3
refreshed 2026-09-09
6 studies4 recruiting2 Phase 24 Phase 3
Search “Petosemtamab” on ClinicalTrials.gov →
Counts are from a name search and may include unrelated studies; up to 100 studies are summarised.

Recruiting now (live from ClinicalTrials.gov)

Recruiting trials near you · live from ClinicalTrials.gov
Petosemtamab
intervention: Petosemtamab
Open on ClinicalTrials.gov →

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Landmark trials in OnCo

LiGeR-HN1

Latest papers

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Literature trend4 papers in the last 12 monthsHow this is computed
Latest papers · live from Europe PMC
Open in Europe PMC

Query for this drug: (TITLE:"Petosemtamab" OR ABSTRACT:"Petosemtamab" OR TITLE:"MCLA-158" OR ABSTRACT:"MCLA-158") AND (cancer OR tumor OR tumour OR oncology OR carcinoma OR lymphoma OR leukemia OR leukaemia OR myeloma OR sarcoma OR melanoma OR glioma). Results are unfiltered search hits about Petosemtamab, not a curated reading list.

Connected

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Pages like this

not linked directly; found by shared links

cancers

2
Colorectal cancerHead and neck squamous cell carcinoma

technologies

1
Bispecific antibodies

targets

1
EGFR

drugs

1
ApprovedMonoclonal antibody (anti-PD-1)
Pembrolizumab · Keytruda / Keytruda Qlex (SC)

companies

2
GenmabMerus

terms

1
LGR5

trials

1
LiGeR-HN1

pairings

1
EGFR-directed bispecific + PD-1 blockade