Merus and Halozyme Partner to Develop Subcutaneous Formulation of Petosemtamab for Cancer Treatment
Key Insights
Merus N.V. and Halozyme Therapeutics have entered a global collaboration to develop a subcutaneous formulation of petosemtamab using Halozyme's ENHANZE (search)® drug delivery technology.
Petosemtamab, an EGFR (search) x LGR5 (search) bispecific antibody, has shown encouraging results in clinical studies across numerous solid tumor cancers (search) and has potential to become first-in-class treatment for head and neck cancer (search).
The collaboration aims to improve treatment efficiency and enhance patient experience through subcutaneous delivery, with Halozyme receiving upfront payments, milestone payments, and low-mid single digit royalties on net sales.
Merus N.V. and Halozyme Therapeutics announced on November 17, 2025, that they have entered into a global non-exclusive collaboration and license agreement to develop a subcutaneous formulation of petosemtamab, an EGFR (search) x LGR5 (search) bispecific antibody. The partnership leverages Halozyme's ENHANZE (search)® drug delivery technology to potentially transform the administration of this promising cancer treatment.
Clinical Promise of Petosemtamab
Petosemtamab continues to demonstrate encouraging results in clinical studies across numerous solid tumor cancers (search). According to Peter Silverman, Chief Operating Officer and General Counsel of Merus, the bispecific antibody "has the potential to become a first and best in class treatment in head and neck cancer (search) and beyond."
The drug represents part of Merus's innovative approach to cancer treatment through its Multiclonics® platform, which includes full-length human bispecific and trispecific antibody therapeutics. These Multiclonics® are manufactured using industry standard processes and have been observed in preclinical and clinical studies to have several features of conventional human monoclonal antibodies, including long half-life and low immunogenicity.
ENHANZE® Technology Platform
Halozyme's ENHANZE (search)® drug delivery technology utilizes the proprietary enzyme rHuPH20 to facilitate subcutaneous delivery of injected drugs and fluids. The technology aims to improve patient experience through rapid subcutaneous delivery and reduced treatment burden.
Dr. Helen Torley, President and Chief Executive Officer of Halozyme, expressed enthusiasm about the collaboration: "This collaboration represents a new opportunity for our ENHANZE (search)® technology to improve treatment efficiency and enhance the patient treatment experience. Together, we aim to accelerate innovation for patients and healthcare providers."
The ENHANZE (search)® platform has demonstrated significant commercial validation, having touched one million patient lives in post-marketing use across ten commercialized products in at least one major region and spanning more than 100 global markets. Halozyme has licensed its technology to leading pharmaceutical companies including Roche, Takeda (search), Pfizer, Janssen, AbbVie (search), Eli Lilly, Bristol-Myers Squibb (search), argenx, ViiV Healthcare, Chugai Pharmaceutical, and Acumen Pharmaceuticals.
Financial Terms and Structure
Under the collaboration agreement, Merus will make an upfront payment to Halozyme, along with potential future milestone payments related to commercial and sales attainment, if approved. Halozyme will be entitled to receive up to low-mid single digit royalties on net sales of petosemtamab formulated with the ENHANZE (search)® technology during the royalty term.
Strategic Implications
The partnership represents a strategic move for both companies to advance treatment options for patients with recurrent/metastatic head and neck squamous cell carcinoma (search) (r/m HNSCC) and other potential indications. The subcutaneous formulation could offer significant advantages over traditional intravenous administration, including improved convenience for patients and healthcare providers, reduced treatment time, and enhanced patient comfort.
Halozyme's broader portfolio includes two commercial proprietary products, Hylenex® and XYOSTED®, along with partnered commercial products and ongoing development programs with Teva Pharmaceuticals and McDermott Laboratories Limited, an affiliate of Viatris Inc. The company also develops drug-device combination products using advanced auto-injector technologies designed to provide improved convenience, reliability, tolerability, and enhanced patient comfort and adherence.