What is emactuzumab’s mechanism of action?
TGCT develops when a small subset of tumor cells produces too much of a protein called colony-stimulating factor 1 (CSF-1). 1 This attracts immune cells called macrophages, which accumulate in the affected tissue and contribute to tumor growth and inflammation.
Emactuzumab is an investigational monoclonal antibody targeting CSF-1R. It has a distinct mechanism of action against CSF-1R, designed to block receptor activation, deplete tumor-promoting macrophages and reduce inflammation in the TGCT tumor microenvironment. 2
Emactuzumab is being developed as a systemic treatment that targets the underlying biology of the disease. 2 Emactuzumab is an investigational product and not yet approved for use.
The development of emactuzumab
In April 2026, SynOx announced positive topline results from the Phase 3 TANGENT study of emactuzumab in people with TGCT.
The study met its primary endpoint of objective response rate assessed by RECIST v1.1 and its key secondary endpoint of objective response rate assessed by tumor volume score (TVS), both at Month 6.
Following the positive Phase 3 TANGENT results, SynOx is planning for regulatory submissions in the United States and Europe in the future as the next stage in the development of emactuzumab.
Emactuzumab is an investigational agent and is not currently approved for the treatment of TGCT. Its safety and efficacy have not yet been established by regulatory authorities.
Ray Barlow
Chief Executive Officer
The Phase 3 TANGENT study represents an important milestone in TGCT research. For people living with this rare and often debilitating condition, continued progress in understanding potential treatment options is hugely important. The results of this study will help inform the ongoing evaluation of emactuzumab and its potential role in the treatment of TGCT.
Beyond TGCT
While SynOx’s immediate focus is advancing emactuzumab for people living with TGCT, our ambition extends further. We believe our expertise in macrophage biology may have relevance in other serious diseases where macrophages play an important role.
We continue to explore opportunities to apply our expertise in CSF-1R biology beyond TGCT.
(1) Stacchiotti S, et al. Best clinical management of tenosynovial giant cell tumor (TGCT): A consensus paper from the community of experts. Cancer Treat Rev. 2023;112:102491. doi:10.1016/j.ctrv.2022.102491
(2) Gelderblom, H. et al. (2026). TANGENT study design: a phase III, randomized study of emactuzumab for the treatment of tenosynovial giant cell tumors. Future Oncology, 22(18), 2109–2119. https://doi.org/10.1080/14796694.2026.2702768