MGFA Session 2026: Year of treatment brings gMG symptom relief

More than 90% of people with generalized myasthenia gravis (gMG) treated with telitacicept for about a year achieved deep reductions in symptom severity, with more than 40% showing minimal symptoms that had little to no impact on daily life.

That’s according to new data from a China-based Phase 3 clinical trial (NCT05737160), top-line results of which supported telitacicept’s approval in the country as an add-on treatment for adults with gMG and the most common type of disease-driving antibody. The therapy is sold in China by developer Remegen, which sponsored the trial.

The findings were shared in an oral presentation at the Myasthenia Gravis Foundation of America (MGFA) scientific session during the American Association of Neuromuscular & Electrodiagnostic Medicine annual meeting, and by Vor Bio, the therapy’s developer outside greater China, in a press release.

Trial investigator Richard Nowak, MD, a neurology professor at Yale School of Medicine, gave the presentation, titled “Telitacicept for Generalized Myasthenia Gravis: Depth of Response Across 48 Weeks in a Phase 3 Study Conducted in China.”

Vor Bio is spearheading a global Phase 3 trial, UPSTREAM MG (NCT06456580), to further evaluate the therapy’s effectiveness in adults with gMG. The study has completed patient enrollment, according to Nowak, with top-line results expected in the first half of 2027.

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Broad, deep, durable response

“What stands out in these data are the breadth, depth, and durability of response,” said Jean-Paul Kress, MD, Vor Bio’s chairman and CEO. “If UPSTREAM MG can reproduce this profile globally, we believe telitacicept could give physicians greater confidence in treatment choice and patients greater predictability in how they live their lives.”

People with gMG experience MG symptoms such as muscle weakness and fatigue as the immune system erroneously attacks proteins needed for nerve-muscle communication. The self-reactive antibodies that mediate these attacks are produced by immune B-cells and most commonly target the acetylcholine receptor (AChR) protein.

Telitacicept is designed to reduce B-cell activity by targeting two proteins that are important for B-cell development and function: APRIL and BAFF. In doing so, the therapy aims to reduce the production of disease-driving antibodies and lower gMG severity.

The China-based Phase 3 study enrolled 114 adults with gMG, most of whom were positive for anti-AChR antibodies. Participants received weekly under-the-skin injections of either telitacicept or a placebo, in addition to their previously prescribed standard-of-care therapies, for 24 weeks (about six months). That was followed by another 24-week period during which all received weekly telitacicept.

Data presented at last year’s MGFA scientific session showed that telitacicept led to reductions (improvements) in scores on the MG Activities of Daily Living (MG-ADL), a measure of the disease’s impact on daily activities, after 24 weeks. These gains were sustained over 48 weeks (nearly one year) of treatment.

In the recent analysis, investigators examined the depth and durability of these treatment responses. They found that more than 90% of participants — including those originally assigned telitacicept and those who later switched from the placebo — achieved at least a 3-point reduction in MG-ADL scores by week 48, reflecting a clinically meaningful improvement. Also, more than 94% of those on telitacicept for the full 48 weeks achieved at least a 5-point score reduction.

The probability of achieving minimal symptom expression (MSE) after 24 weeks was about 23.7% in telitacicept-treated participants compared with 3.6% in those given the placebo. MSE is defined as MG-ADL scores of 0 to 1, which indicates gMG symptoms that have little to no impact on daily life.

However, this difference dissipated after 48 weeks, with about 40% of participants in both the always-on-telitacicept group and the placebo-to-telitacicept group meeting MSE. After achieving MSE, participants in both groups spent more than 80% of the remaining study time in that state.

“Maintenance or achievement of [MSE] … is an important treatment goal for our patients,” Nowak said, noting that once study participants achieved MSE, the effect was “highly durable.”

Across the study group, about half of those who had started the study with moderate disease severity (MG-ADL scores of 6-10) achieved MSE at some point, as did 20.5% of participants with severe disease (MG-ADL scores of 11 or higher).

“These data are encouraging because the response to telitacicept appears to deepen with continued treatment and extends across a broad range of [initial] disease severity,” Nowak said.

The treatment was generally well tolerated for up to 48 weeks, with no new safety signals reported.

The global UPSTREAM MG study is designed similarly to the China-based Phase 3 trial, with the main goal of evaluating whether telitacicept is superior to a placebo at reducing MG-ADL scores after about six months.

Note: The Myasthenia Gravis News team is providing virtual coverage of the Myasthenia Gravis Foundation of America’s scientific session at the American Association of Neuromuscular & Electrodiagnostic Medicine Annual Meeting on Sept. 29. Go here to see the latest stories from the conference.