TANGENT Phase 3 Study Meets Primary and Secondary Endpoints, SynOx Reports

A short-course antibody therapy may offer a new approach for managing tenosynovial giant cell tumor (TGCT), as late-stage data suggest patients can achieve meaningful and sustained benefit without the need for continuous treatment.

SynOx Therapeutics’ pivotal Phase 3 TANGENT study¹ evaluating emactuzumab, a CSF-1R–targeting monoclonal antibody, in patients with TGCT,

showed positive topline results. The randomized, placebo-controlled trial met

both its primary and secondary endpoints with high statistical significance at six months, including objective response rate by RECIST v1.1 and tumor volume score.

Beyond tumor shrinkage, the study also demonstrated clinically meaningful improvements in physical function and patient-reported outcomes, including PROMIS-PF and measures of pain, stiffness, and range of motion.

Rapid Onset, Functional Gains, and Durability

One of the defining features of emactuzumab in TANGENT was the speed of response. Patients experienced rapid improvements during the treatment period, paired with significant functional gains—an important consideration in TGCT, in which joint impairment can severely impact quality of life.

Notably, these benefits were not fleeting. The therapy’s short-course regimen—five doses over eight weeks—produced durable responses that persisted beyond the treatment window, reinforcing its potential to reduce long-term treatment burden.

A Different Approach to TGCT Treatment

TGCT is a rare, often debilitating condition that affects joints and surrounding tissues. While not typically life-threatening, it can lead to chronic pain, reduced mobility, and repeated surgeries.

Current systemic treatment approaches often rely on chronic oral therapies, such as pexidartinib, which offer significant symptom relief but require long-term management and introduce safety risks (specifically hepatotoxicity) and adherence challenges. While providing substantial reductions in pain and stiffness, these targeted oral therapies require rigorous monitoring due to potentially severe AEs like liver injury and hair color changes.²

Emactuzumab is being developed specifically to address these limitations by offering a finite, high-impact treatment course. By targeting the CSF-1 receptor, the therapy works to reduce tumor-associated macrophages—key drivers of disease pathology—while aiming to preserve tolerability.

Safety Profile Remains Consistent

Safety findings from TANGENT were reported as manageable and consistent with prior clinical experience, an important factor in a disease in which treatment tolerability is closely tied to quality of life.

Given TGCT’s chronic nature, therapies that can balance efficacy with a predictable safety profile are particularly valuable, especially if they can avoid continuous exposure.

Regulatory Pathway and What Comes Next

With positive Phase 3 data in hand, SynOx is now preparing for a Biologics License Application submission to the FDA in the second half of 2026, with a European Marketing Authorization Application to follow.

Full data from the TANGENT study are expected to be presented at an upcoming medical meeting and submitted for peer-reviewed publication.

Could Short-Course Therapy Redefine TGCT Care?

The TANGENT results position emactuzumab as a potential next-generation therapy in TGCT, with a profile that emphasizes rapid efficacy, durable outcomes, and reduced treatment burden.

The broader implication is a shift in how the disease might be managed: moving away from continuous suppression toward intermittent, finite treatment strategies. If confirmed in full datasets and regulatory review, emactuzumab could help reshape expectations not just for efficacy, but for how long patients need to stay on therapy to achieve meaningful benefit.

References:

1. Palmerini et al. (March 2025). 151TiP TANGENT: A phase III, global, randomized, double-blind, placebo-controlled trial to assess the efficacy and safety of emactuzumab in patients with tenosynovial giant cell tumor. EMSO Open. https://www.esmoopen.com/article/S2059-7029(25)00333-3/fulltext
2. Chen et al. (28 August 2025). A disproportionality analysis of adverse events caused by pexidartinib from the FDA adverse event reporting system. PubMed Central. https://pmc.ncbi.nlm.nih.gov/articles/PMC12394515/