SynOx Therapeutics Announces Positive Topline Results from the Phase 3 TANGENT Study, Supporting Emactuzumab as a Differentiated, Next-generation Treatment for Patients with Tenosynovial Giant Cell Tumor (TGCT)

• TANGENT met its primary and secondary endpoints with a high level of statistical significance vs. placebo at 6 months, including ORR by RECIST V1.1 and Tumor Volume Score (TVS), and clinically meaningful improvements in PROMIS-PF and other patient -relevant functional measures
• Rapid onset and significant functional improvement observed
• Short-course regimen demonstrated sustained and durable clinical benefits, highlighting the potential to avoid chronic treatment burden
• Emactuzumab demonstrated a manageable safety profile, highly consistent with prior clinical experience
• These data reinforce emactuzumab’s differentiated profile as a next-generation, short-course therapy with the potential to address important limitations of chronic oral treatment approaches in TGCT
• Biologics License Application (BLA) submission planned for H2 2026; EU Marketing Authorization Application (MAA) to follow

DUBLIN, OXFORD, United Kingdom, and PHILADELPHIA, April 13, 2026 (GLOBE NEWSWIRE) --

SynOx Therapeutics Limited (“SynOx”) today announced positive topline results from the pivotal Phase 3 TANGENT study of emactuzumab in adult patients with TGCT.

Emactuzumab is a targeted CSF-1R inhibitor that is being developed as a short-course treatment for patients with TGCT, which is designed to deliver rapid and durable disease control without the need for continuous treatment. In the TANGENT study, patients were randomized to receive either emactuzumab or placebo. Patients assigned to the treatment arm received emactuzumab at a dose of 1,000 mg administered every two weeks, for a total of five doses over an 8-week period.

Results across the primary and key secondary endpoints demonstrated clinically meaningful and statistically significant benefit consistent with emactuzumab’s differentiated profile. These included measures of tumor volume reduction and patient-reported and functional outcomes, including PROMIS-PF, physical function, pain, range of motion, and stiffness. Importantly, these benefits were achieved rapidly in the short-course treatment cycle, were durable and were observed across clinically relevant patient segments.

Emactuzumab demonstrated a manageable safety profile in TANGENT, consistent with prior clinical experience. In a patient population with a chronic, debilitating but non-lethal disease, tolerability remains an important consideration, particularly when compared with long-term treatment approaches.

“The TANGENT results represent an important step in advancing a potential next-generation treatment for patients with TGCT,” said Dr. Ray Barlow, CEO of SynOx Therapeutics. “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. We look forward to engaging with the FDA as we advance toward a planned BLA submission in the second half of 2026.”

Dr. Jean-Yves Blay, Principal Investigator, commented further:

“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.”

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.

SynOx intends to present full data from the TANGENT trial at an upcoming medical meeting and in a peer-reviewed publication.

Based on these data, SynOx plans to submit a BLA to the U.S. Food and Drug Administration for emactuzumab in TGCT in the second half of 2026 and a MAA in the EU thereafter.

About the TANGENT Study:
The TANGENT clinical trial (NCT05417789) is a global, multicenter, randomized, double-blind, placebo-controlled, Phase 3 trial evaluating the efficacy and safety of emactuzumab in patients with TGCT. Patients in the treatment arm received 1000mg emactuzumab every two weeks for a total of five doses over 8 weeks. The primary endpoint is Objective Response Rate (ORR) at 6 months as measured by RECIST v1.1. Secondary endpoints are designed to detect the effect of emactuzumab on physical function, range of motion, stiffness, pain and duration of response as measured by both physician and patient reported assessments including Tumor Volume Score (TVS), PROMIS-PF TGCT T-score, range of motion (ROM), and assessments of pain, stiffness and quality of life.

TANGENT enrollment criteria include patients with biopsy-confirmed localized or diffuse TGCT where surgical resection would be associated with predicted worsening functional limitations through surgical joint damage, and/or subjects with anticipated high risk of early recurrence, or any other morbidity associated with the surgery, and/or subjects for whom surgical treatment is not expected to improve clinical outcomes. Following the 6-month double-blind period, patients can enter an 18-month follow-up phase during which patients who demonstrate signs of disease progression may receive open label emactuzumab.

About Tenosynovial Giant Cell Tumor (TGCT)
TGCT is a rare, non-malignant, but locally aggressive and destructive tumor affecting the synovium, tendon sheaths, and bursa membranes primarily located in knee, hip, and ankle joints but can also occur in other locations such as the cervical spine. It is a chronically debilitating disease, which causes loss of function of the affected joints, as well as pain, stiffness, and limited range of motion, which can significantly impact quality of life.

TGCT is estimated to affect approximately 200,000 patients in the U.S. and 179,000 patients in the EU4 +UK, with an estimated incidence of approximately 50 per million ⁽¹⁾. As patients are typically diagnosed between the ages of 35 and 50, TGCT is a long-term disease.

Existing treatment options for TGCT include surgery and oral systemic therapies, but both options are of limited benefit. Surgery is often the first-line approach, although it comes with a risk of surgical complications, severe morbidity, and can require a lengthy recovery. Surgical recurrence rates are also high, including 17% for those with localized disease ⁽²⁾ and 72% for those with diffuse disease ⁽³⁾. Additionally, many patients have tumors that are not amenable to surgery. Treatment with approved oral TKI therapies require long-term chronic administration (daily or biweekly).

About Emactuzumab:
Emactuzumab is a next-generation monoclonal antibody. As a high-affinity CSF1-R inhibitor, emactuzumab is designed to block receptor activation, deplete tumor-promoting macrophages and reduce inflammation in the tumor microenvironment.

Emactuzumab is designed to address the limitations of current treatment options as a short-course, targeted therapy intended to deliver rapid tumor reduction, meaningful functional improvement, durable benefit, and manageable tolerability following limited treatment exposure.

Emactuzumab has received Fast Track Designation (FTD) from the U.S. Food and Drug Administration (FDA) and Orphan Medicinal Product designation from the European Medicines Agency for the treatment of TGCT.

About SynOx Therapeutics
SynOx Therapeutics Limited is a Dublin, Oxford and Philadelphia-based, late-stage biopharmaceutical company developing emactuzumab, a differentiated, next-generation monoclonal antibody against CSF-1R, for the treatment of Tenosynovial Giant Cell Tumor (TGCT) and other CSF-1-related and macrophage-driven disorders. SynOx is led by an experienced team of industry professionals with a successful track record of developing and bringing products to commercialization. The company is backed by a strong syndicate of premier life science investors including Forbion, Gilde Healthcare, HealthCap, Bioqube Ventures, and Medicxi.

For further information please contact:
SynOx Therapeutics
Ray Barlow, CEO
Tel: +44 (0) 208 058 5619
Email: enquiries@synoxtherapeutics.com

Investor Relations Contact
Precision AQ
Danielle Dudgeon
Email: Danielle.Dudgeon@precisionaq.com

References
⁽¹⁾ Stacchiotti S, et. al. Best clinical management of Tenosynovial Giant Cell Tumour (TGCT): A consensus paper from the community of experts. Cancer Treat Rev. 2023;112:102491. doi:10.1016/j.ctrv.2022.102491.

⁽²⁾ Mastboom M, Palmerini E, Verspoor F et al. Surgical outcomes of patients with diffuse-type tenosynovial giant-cell tumours: an international, retrospective, cohort study The Lancet Oncology, 2019; 20, 877-886.

⁽³⁾ Verspoor FG, Zee AA, Hannink G, van der Geest IC, Veth RP, Schreuder HW. Long-term follow-up results of primary and recurrent pigmented villonodular synovitis. Rheumatology (Oxford). 2014 Nov;53(11):2063-70. doi: 10.1093/rheumatology/keu230.

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