SynOx Therapeutics Announces Positive Phase 3 Results for Emactuzumab in Tenosynovial Giant Cell Tumor

Short-course treatment demonstrates rapid tumor reduction, functional improvement, and durable benefits

Apr. 13, 2026 at 8:25am

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A translucent X-ray image showing the internal structure of a human joint, with signs of inflammation and distortion caused by a tenosynovial giant cell tumor. The ghostly, glowing lines trace the tumor's growth, conceptually illustrating the clinical challenges of this rare joint disease.An X-ray view exposes the internal damage caused by tenosynovial giant cell tumor, a debilitating joint disease that a new targeted therapy aims to treat.Philadelphia Today

SynOx Therapeutics announced positive topline results from the pivotal Phase 3 TANGENT study of emactuzumab, a targeted CSF-1R inhibitor, in adult patients with tenosynovial giant cell tumor (TGCT). The study met its primary and secondary endpoints, including objective response rate and improvements in patient-reported physical function, pain, range of motion, and other measures. Emactuzumab demonstrated a manageable safety profile and the potential to address limitations of current chronic treatment approaches for this debilitating disease.

Why it matters

TGCT is a rare, non-cancerous but locally aggressive tumor that can significantly impact joint function and quality of life. Current treatment options, including surgery and long-term oral therapies, have limitations in terms of efficacy, safety, and patient burden. Emactuzumab's short-course regimen and ability to rapidly and durably improve clinical outcomes could represent an important advancement for TGCT patients.

The details

In the TANGENT study, patients were randomized to receive either emactuzumab or placebo. The treatment arm received 1,000 mg of emactuzumab every two weeks for a total of five doses over an 8-week period. Results demonstrated clinically meaningful and statistically significant benefits across primary and secondary endpoints, including tumor volume reduction and improvements in patient-reported physical function, pain, range of motion, and other measures. These benefits were achieved rapidly and were durable. Emactuzumab also had a manageable safety profile consistent with prior clinical experience.

  • The TANGENT study enrolled patients in 2025.
  • Topline results were announced on April 13, 2026.
  • SynOx plans to submit a Biologics License Application (BLA) to the FDA in the second half of 2026.
  • SynOx plans to submit a Marketing Authorization Application (MAA) in the EU after the BLA submission.

The players

SynOx Therapeutics Limited

A late-stage biopharmaceutical company developing emactuzumab, a monoclonal antibody against CSF-1R, for the treatment of TGCT and other macrophage-driven disorders.

Dr. Ray Barlow

The CEO of SynOx Therapeutics.

Dr. Jean-Yves Blay

The Principal Investigator for the TANGENT study.

Emactuzumab

A targeted CSF-1R inhibitor being developed by SynOx as a short-course treatment for TGCT.

TANGENT Study

The global, Phase 3 clinical trial evaluating the efficacy and safety of emactuzumab in TGCT patients.

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What they’re saying

“The TANGENT results represent an important step in advancing a potential next-generation treatment for patients with TGCT. Emactuzumab's combination of rapid onset, response rate, meaningful functional improvement, and a defined short-course regimen positions it as a potential alternative to chronic therapy. We believe this approach directly addresses key limitations of existing treatments and represents an important advancement for patients suffering from this debilitating disease.”

— Dr. Ray Barlow, CEO of SynOx Therapeutics

“Emactuzumab is the only short course treatment option in late-stage development for patients suffering with TGCT. These Phase 3 data provide compelling evidence of tumor response, a manageable safety profile, and most importantly for patients, of significant durable functional and quality of life benefits that allow patients struggling with TGCT to move forward with their lives, without continuous therapy.”

— Dr. Jean-Yves Blay, Principal Investigator

What’s next

SynOx continues to follow patients enrolled in the TANGENT study to further characterize the durability of response, and the potential role of retreatment and crossover open label emactuzumab. The company plans to submit a BLA to the FDA for emactuzumab in TGCT in the second half of 2026 and a MAA in the EU thereafter.

The takeaway

The positive results from the TANGENT study demonstrate emactuzumab's potential to address key limitations of current TGCT treatments by providing rapid, durable, and functional improvements for patients with this debilitating disease through a short-course targeted therapy approach. If approved, emactuzumab could represent an important new treatment option for the TGCT community.