TG Therapeutics Reports Positive Phase 1 MG Data, Initiates Phase 2 Trial, and Publishes Five-Year BRIUMVI Data

TG Therapeutics, Inc. announced positive topline Phase 1 data for subcutaneous BRIUMVI (ublituximab-xiiy) in patients with myasthenia gravis (MG) and the initiation of a potential registration-directed Phase 2 trial, while also reporting the publication of five-year efficacy data for BRIUMVI in relapsing multiple sclerosis in JAMA Neurology.

In the Phase 1 MG cohort, 11 patients with AChR-antibody-positive MG received subcutaneous BRIUMVI. At Week 24, 82% of patients achieved the Minimal Clinically Important Difference (MCID) in MG-ADL, defined as a decrease of ≥2, with a median time to MCID of 30 days, and a mean 4.6 point improvement in MG-ADL was observed. Subcutaneous BRIUMVI was generally well tolerated, with a safety profile appearing consistent with the established safety profile of IV BRIUMVI in multiple sclerosis patients.

The Phase 2 trial will enroll approximately 120 patients. All patients will first receive a single induction cycle of efgartigimod, consisting of four weekly infusions. Patients who achieve a clinical response, defined as at least a 2-point improvement in MG-ADL score, will then be randomized 1:1 to receive either BRIUMVI or placebo during a 24-week randomized controlled period. The primary endpoint is time to clinical worsening, defined as a ≥2-point increase in MG-ADL score from baseline or a myasthenic crisis requiring hospitalization. Following the randomized period, all patients will be eligible to enter a 72-week open-label extension. The study will initially utilize the approved intravenous BRIUMVI dosing regimen, with subcutaneous administration incorporated later.

Long-term data from the open-label extension of the Phase 3 ULTIMATE I and II studies, published in JAMA Neurology, showed that during year 5 of treatment with BRIUMVI the annualized relapse rate was 0.020, equivalent to one relapse every 50 years of patient treatment. The overall safety profile remained consistent over five years of continuous treatment, with no new safety signals emerging. The analysis included more than 3,600 participant-years of ublituximab exposure, with more than 85% of eligible participants enrolling in the extension and more than 70% remaining on treatment at Year 5.

TG Therapeutics also announced its schedule of data presentations at the American Academy of Neurology (AAN) 2026 annual meeting, being held April 18–22, 2026, in Chicago. The presentations will highlight real-world clinical experience from ENABLE, the first Phase 4 observational study for patients with relapsing multiple sclerosis initiating ublituximab, and safety and tolerability updates from the ENHANCE study of a modified ublituximab dosing regimen.

BRIUMVI is a novel monoclonal antibody that targets a unique epitope on CD20-expressing B-cells. It is designed to lack certain sugar molecules normally expressed on the antibody, a process called glycoengineering, which allows for efficient B-cell depletion at low doses. BRIUMVI is indicated in the U.S. for the treatment of adults with relapsing forms of multiple sclerosis, including clinically isolated syndrome, relapsing-remitting disease, and active secondary progressive disease. Myasthenia gravis is a chronic autoimmune neuromuscular disease characterized by muscle weakness and fatigue caused by autoantibodies targeting the neuromuscular junction.