Merus N.V. has announced that updated interim clinical data from its Phase 2 trial of petosemtamab in combination with pembrolizumab will be presented at the upcoming 2025 American Society of Clinical Oncology (ASCO) Annual Meeting in Chicago from May 30 to June 3.
The poster presentation will feature comprehensive data from the entire 45-patient cohort receiving petosemtamab with pembrolizumab as first-line treatment for PD-L1-positive recurrent/metastatic head and neck squamous cell carcinoma (HNSCC). This follows earlier promising results presented at last year's ASCO meeting.
"We continue to believe that petosemtamab has the potential to be a first and best-in-class, practice-changing medicine for the treatment of r/m HNSCC," said Bill Lundberg, M.D., President and Chief Executive Officer of Merus. "We are very much looking forward to sharing the robust updated interim phase 2 data on the entire 45 patient data set."
Promising Clinical Activity
According to Merus executives, petosemtamab continues to demonstrate substantial clinical activity that appears superior to historical controls. The company highlights the consistency of efficacy across multiple endpoints, including overall response rate (ORR), progression-free survival (PFS), and overall survival (OS), both in the overall study population and within important subgroups stratified by HPV disease status and PD-L1 expression levels.
Based on these encouraging results and ongoing Phase 3 trials, Merus believes petosemtamab could potentially become a new standard of care for recurrent/metastatic HNSCC, a cancer with historically poor prognosis despite current treatment options.
Presentation Details
The poster presentation, titled "Petosemtamab (MCLA-158) with pembrolizumab as first-line (1L) treatment of PD-L1+ recurrent/metastatic (r/m) head and neck squamous cell carcinoma (HNSCC): Phase 2 trial," is scheduled for June 2, 2025, from 9:00 AM to 12:00 PM CT. The abstract (#6024) will be available on the ASCO website on May 22, 2025, at 5:00 PM ET.
Merus will also host a conference call and webcast for investors on Thursday, May 22, 2025, at 5:30 PM ET to discuss the complete ASCO data set.
About Petosemtamab
Petosemtamab (MCLA-158) is a Biclonics® low-fucose human full-length IgG1 antibody targeting the epidermal growth factor receptor (EGFR) and the leucine-rich repeat containing G-protein-coupled receptor 5 (LGR5). The drug candidate is designed to work through three independent mechanisms:
- Inhibition of EGFR-dependent signaling
- LGR5 binding leading to EGFR internalization and degradation in cancer cells
- Enhanced antibody-dependent cell-mediated cytotoxicity (ADCC) and antibody-dependent cellular phagocytosis (ADCP)
Head and Neck Cancer: A Growing Global Burden
Head and neck squamous cell carcinoma develops in the squamous cells lining the mucosal surfaces of the mouth, throat, and larynx. The disease is commonly associated with tobacco use, alcohol consumption, and/or HPV infections.
HNSCC represents a significant global health burden as the sixth most common cancer worldwide. In 2020, there were more than 930,000 new cases and over 465,000 deaths globally. The incidence continues to rise and is projected to increase by 30% to more than 1 million new cases annually by 2030.
Despite available treatments, HNSCC remains a serious and life-threatening disease with poor prognosis.
Phase 3 Trial Underway
Merus is currently conducting LiGeR-HN1, a Phase 3 trial evaluating the safety and efficacy of petosemtamab in combination with pembrolizumab compared to pembrolizumab alone in first-line PD-L1-positive recurrent/metastatic HNSCC patients. The trial is enrolling adult patients eligible to receive pembrolizumab as first-line monotherapy with tumors expressing PD-L1 (Combined Positive Score ≥1).
The primary endpoints are overall response rate as assessed by blinded independent central review based on RECIST v1.1 criteria and overall survival. Secondary endpoints include duration of response and progression-free survival. Merus plans to enroll approximately 500 patients in this pivotal trial.
About Merus N.V.
Merus is an oncology company developing innovative full-length human bispecific and trispecific antibody therapeutics, referred to as Multiclonics®. These proprietary antibodies are manufactured using industry-standard processes and have demonstrated several features of conventional human monoclonal antibodies in preclinical and clinical studies, including long half-life and low immunogenicity.
The company's technology platforms include Biclonics®, Triclonics®, and ADClonics®, which are being developed for various oncology indications.
