Innovative Partnership between MSD and Mestag Therapeutics in the Field of Fibroblast Therapies

MSD, also known as Merck & Co, is entering into a collaboration with Mestag Therapeutics to develop new fibroblast therapies for the treatment of inflammatory diseases—an initiative valued at up to $1.9 billion. Although the specific details of the agreement have not been disclosed, the contract offers MSD the opportunity to acquire exclusive development and commercialization licenses for a predefined number of potential target molecules. In return, the UK-based biotech firm Mestag will receive an upfront payment, access fees, as well as options for additional fees and downstream payments. Fibroblasts are cells that form connective tissue and are responsible for the synthesis of extracellular matrix components and collagen. They play a crucial role in wound healing, inflammatory processes, and tissue repair. Mestag's product pipeline includes antibody therapies targeting the interaction between fibroblasts and immune cells to combat cancer and inflammatory diseases. A promising candidate from the company, MST-0300, is a bispecific antibody. This therapy targets the lymphotoxin-beta receptor (LTBR) in tumors by activating the fibroblast-specific marker protein FAP. The goal is the formation of tertiary lymphoid structures (TLS) in solid tumors, which are associated with improved patient outcomes and therapeutic responses. Mestag plans to file an Investigational New Drug (IND) application in the second half of 2025. Another preclinical candidate in Mestag's pipeline is M402, a stromal checkpoint-targeting antibody. This therapy aims to inhibit specific immune cell populations, including myeloid cells. According to Mestag, M402 could benefit patients with various inflammatory diseases, including rheumatoid arthritis, lupus, Sjögren's syndrome, and graft-versus-host disease. MSD is continuously investing in the expansion of its pipeline of antibody therapies. In August, the company acquired Curon Biopharmaceutical, a Chinese biopharmaceutical company specializing in the development of bispecific antibodies, for approximately $1.3 billion. As early as 2021, Mestag collaborated with Johnson & Johnson. The licensing agreement allowed J&J an exclusive licensing option to develop and commercialize up to two therapies for the treatment of inflammatory diseases.