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MCLA-158

Phase 1

Advanced/Metastatic Solid Tumors | Small molecule | Oncology |Merus N.V.|Last Updated: Jul 29, 2026

Target and mechanism

Molecular targetEGFR
Target classReceptor
ModalitySmall molecule

Success Probability

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Market & Valuation

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Trial Design

CONTROLLEDDMC
Total Trials1
Total Enrollment560

FDA Designations

No designations recorded

Clinical trial landscape

MCLA-158 · 1 trial · 8 indications

Phase 1 1
NCT03526835A Study of Bispecific Antibody MCLA-158 in Patients With Advanced Solid TumorsAdvanced/Metastatic Solid Tumors
RECRUITING560 Analytics
PHASE1RECRUITING
A Study of Bispecific Antibody MCLA-158 in Patients With Advanced Solid Tumors
Advanced/Metastatic Solid TumorsUnlock trial analytics

Study Endpoints

Primary Endpoints

Escalation: Number of patients with Dose Limiting Toxicities (DLTs) during Cycle 1
4 weeks

Evaluation of the number and severity of participants with treatment related toxicities observed during the dose escalation.

Expansion (Single agent - randomized expansion in 2/3L Head and Neck cancer, and combination cohorts): Safety and tolerability: AEs and SAEs
6-12 months

Incidence, severity, and relationship of AEs and SAEs

Expansion (Single agent - randomized expansion in 2/3L Head and Neck cancer): Treatment discontinuations and dose modifications due to AEs
6-12 months

Treatment discontinuations due to AEs and dose modifications due to AEs

Expansion (single agent - randomized expansion in 2/3L Head and Neck cancer): Best overall response (BOR)
36 months

Evaluation of clinical benefit assessed by RECIST v1.1 determining Best overall response (BOR)

Expansion (Single agent - non-randomized, and combination cohorts): Objective response rate (ORR)
36 months

Evaluation of clinical benefit assessed by RECIST v1.1 determining objective response rate (ORR)

Expansion (single agent - randomized expansion in 2/3L Head and Neck cancer): exposure-safety relationship of petosemtamab administered at 1100 mg and 1500 mg: TEAEs
8 weeks

Incidence of TEAEs at Week 8

Expansion: (mCRC subcutaneous cohort): Bioavailability of subcutaneous vs intravenous administration
6 weeks

Bioavailability of subcutaneous vs intravenous administration

Expansion: (mCRC subcutaneous cohort): Area under the concentration versus time curve from time zero to time t [AUC0-t]
6 weeks

Area under the concentration versus time curve from time zero to time t \[AUC0-t\]

Expansion: (mCRC subcutaneous cohort): Maximum plasma concentration [Cmax]
8 weeks

Maximum plasma concentration as measured from all individual plasma concentrations

Expansion: (mCRC subcutaneous cohort): Minimum plasma drug concentration [Ctrough]
6 weeks

Minimum plasma concentration as measured from all individual plasma concentrations

Secondary Endpoints

Escalation & Expansion: (mCRC subcutaneous cohort): Best Overall Response (BOR)
36 months
Expansion: Duration of response (DOR)
36 months
Expansion: Progression Free Survival (PFS)
36 months
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Study Design & Arms

AllocationNON_RANDOMIZED
MaskingNONE
ModelPARALLEL
PurposeTREATMENT

Treatment Arms

ArmTypeDescription
MCLA-158 (Single-Agent)EXPERIMENTALIn Part 1, the dose escalation phase, patients with metastatic CRC will receive escalating doses of MCLA-158 (every 2 weeks) until MTD or RP2D is reached. Each Cycle is 28 days. Single agent treatment. In Part 2, the expansion phase, participants with metastatic CRC and certain other solid tumors will receive intravenous infusion (i.v.) of MCLA-158 at the recommended Phase II dose (RP2D) every 2 weeks, at Day 1 and Day 15. The duration of each treatment cycle is 28 days. In addition, in the expansion phase, one randomized cohort will evaluate 2 doses (1100 mg and 1500 mg) of MCLA-158 in head and neck squamous cell carcinoma patients. Also in the expansion phase, a subcutaneous formulation of MCLA-158 will be evaluated.
MCLA-158 + PembrolizumabEXPERIMENTALMCLA-158 in combination with pembrolizumab will be explored first in head and neck squamous cell carcinoma patients eligible to receive pembrolizumab as first-line monotherapy.
MCLA-158 + FOLFIRI combination chemotherapyEXPERIMENTALMCLA-158 in combination with FOLFIRI will be explored in mCRC patients with up to 1 line of prior regimen.
MCLA-158 + FOLFOX combination chemotherapyEXPERIMENTALMCLA-158 in combination with FOLFOX will be explored in mCRC patients with up to 1 line of prior regimen.

Interventions

NameTypeDescription
MCLA-158DRUGfull-length IgG1 bispecific antibody targeting EGFR and LGR5
MCLA-158 + PembrolizumabCOMBINATION_PRODUCTMCLA-158 in combination with pembrolizumab will be explored first in HNSCC patients eligible to receive pembrolizumab as first-line monotherapy.
MCLA-158 + FOLFIRICOMBINATION_PRODUCTMCLA-158 in combination with FOLFIRI will be explored in mCRC patients with up to 1 line of prior regimen.
MCLA-158 + FOLFOXCOMBINATION_PRODUCTMCLA-158 in combination with FOLFOX will be explored in mCRC patients with up to 1 line of prior regimen.
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Eligibility Criteria

Age Range18 Years to N/A
SexALL
Healthy VolunteersNo
Study Sites54

Inclusion Criteria: * Histologically or cytologically confirmed solid tumors with evidence of metastatic or locally advanced disease not amenable to standard therapy with curative intent. * A baseline fresh tumor sample (FFPE) from a metastatic or primary site (if safe/feasible). * Amenable for bio...

Countries:United StatesBelgiumFranceItalyNetherlandsSpainUnited Kingdom
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Competitive Landscape -Other Solid Tumors 9 trials (matched to "Advanced/Metastatic Solid Tumors")

Recent Changes (Last 90 Days)

MEDIUMJul 29, 2026NCT03526835Enrollment: 523 → 560
MEDIUMJul 29, 2026NCT03526835Enrollment: 523 → 560
LOWMay 26, 2026NCT03526835primaryCompletionDate: changed
LOWMay 24, 2026NCT03526835studyFirstPostDate: changed

Frequently asked questions about MCLA-158

What is MCLA-158 used for?

MCLA-158 is an investigational bispecific antibody being developed for the treatment of advanced or metastatic solid tumors, including colorectal cancer, gastric cancer, gastroesophageal-junction cancer, non-small cell lung cancer, head and neck squamous cell carcinoma, and esophageal cancer. It is currently being studied in a Phase 1 clinical trial.

What does MCLA-158 target?

MCLA-158 targets EGFR, a receptor involved in cell growth and survival. By binding to EGFR, the bispecific antibody aims to interfere with signaling pathways that can drive tumor growth. This mechanism is being evaluated in patients with advanced solid tumors.

Who is developing MCLA-158?

MCLA-158 is being developed by Merus N.V., a biopharmaceutical company traded on the NASDAQ under the ticker symbol MRUS. The company is conducting a Phase 1 clinical trial to evaluate the safety and efficacy of MCLA-158 in patients with advanced solid tumors.

What phase is MCLA-158 in?

MCLA-158 is in Phase 1 clinical development. It is an investigational drug and has not been approved by regulatory authorities. The ongoing Phase 1 trial is recruiting patients with advanced or metastatic solid tumors to assess the drug's safety, tolerability, and preliminary efficacy.

What clinical trials is MCLA-158 in?

MCLA-158 is being evaluated in a single Phase 1 clinical trial with the identifier NCT03526835. This study is recruiting patients with advanced solid tumors, including colorectal, gastric, and esophageal cancers, across multiple countries including the United States, Belgium, France, Italy, Netherlands, Spain, and the United Kingdom.

Is MCLA-158 the same as any other drug?

MCLA-158 is a bispecific antibody developed by Merus N.V. It is not known to have alternative names. The drug is being investigated under the clinical trial identifier NCT03526835 for the treatment of advanced solid tumors.