Merus and Halozyme announced a global collaboration to develop a subcutaneous formulation of petosemtamab, a bispecific antibody that targets EGFR and LGR5 in solid tumors. The partnership leverages Halozyme’s ENHANZE technology, which uses recombinant human hyaluronidase to enable subcutaneous delivery of drugs that are normally given intravenously.
Under the agreement, Merus will provide an upfront payment to Halozyme and may make milestone payments tied to commercial and sales milestones if the product is approved. Halozyme will receive low‑to‑mid single‑digit royalties on net sales of the subcutaneous formulation during the royalty term. While the exact upfront amount has not been disclosed, the structure reflects a typical licensing arrangement that balances early cash flow for Merus with long‑term revenue potential for Halozyme.
The collaboration is strategically significant for Merus, which reported a net loss of $95.5 million in Q3 2025 and a nine‑month loss of $350.21 million. The partnership is part of Merus’s broader strategy to accelerate petosemtamab’s development ahead of a pending $8 billion acquisition by Genmab. By enabling a more convenient subcutaneous route, the partnership could broaden petosemtamab’s market reach beyond infusion centers and improve patient adherence, potentially increasing commercial upside.
Petosemtamab is currently in Phase 3 trials for recurrent/metastatic head and neck squamous cell carcinoma and is also being evaluated in metastatic colorectal cancer. The bispecific antibody blocks EGFR ligand binding, induces EGFR receptor internalization and degradation in LGR5+ cells, and activates the innate immune system via Fc‑mediated mechanisms. These multiple mechanisms aim to target cancer stem cells and overcome resistance.
Halozyme’s ENHANZE platform has been licensed to major pharmaceutical companies including Roche, Takeda, Pfizer, and Eli Lilly. The new partnership with Merus adds another high‑profile application of the technology and further validates its commercial viability. Dr. Helen Torley, CEO of Halozyme, emphasized that the collaboration will accelerate innovation for patients with r/m HNSCC and other indications.
Management comments underscore confidence in the partnership. Peter Silverman, COO and General Counsel of Merus, said the collaboration would “enhance the commercial prospects of petosemtamab and position the company to capture a broader patient population.” The partnership aligns with Merus’s goal of delivering a subcutaneous formulation that could improve patient experience and expand market access.
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