Telitacicept Shows Deepening, Durable Response in Myasthenia Gravis

A post hoc analysis of 48-week phase 3 data found that a meaningful share of patients with generalized myasthenia gravis (gMG) treated with telitacicept reached minimal symptom expression, and that most who did sustained that level of disease control over time. Vor Bio, which is developing telitacicept outside China with partner RemeGen, presented the findings at the recently concluded 2026 American Association of Neuromuscular and Electrodiagnostic Medicine (AANEM) Annual Meeting in Orlando, Florida.¹

“Clinically, reaching MSE once or over a short period is not the same as sustaining that level of disease control over time,” Richard J. Nowak, MD, MS, director of the Yale Myasthenia Gravis Clinic and associate professor of neurology at Yale School of Medicine, said in a statement.

Post hoc analysis of 48-week data

The analysis drew on 48-week outcomes from a phase 3 trial that randomized 114 adults with AChR or MuSK antibody-positive gMG to weekly subcutaneous telitacicept 240 mg or placebo for 24 weeks, followed by a 24-week open-label extension in which placebo recipients crossed over to telitacicept. Vor Bio defined minimal symptom expression (MSE) as an MG-ADL score of 0 or 1, and examined whether participants reached that threshold, whether they sustained it at their next monthly assessment, and what share of their remaining follow-up time was spent in MSE.

Minimal symptom expression findings

About 42% of telitacicept-treated participants reached MSE at some point across the full 48 weeks, up from 23.7% within the first 24 weeks. MSE was reached by 51.2% of participants with a baseline MG-ADL score of 6 to 8, 51.7% of those with a baseline score of 9 or 10, and 20.5% of those with a baseline score of 11 or higher.

Among participants who reached MSE, 86.7% of those events were sustained at the following monthly assessment. Participants initially randomized to telitacicept spent about 83% of their remaining follow-up time in MSE after first reaching it, as did about 85% of placebo recipients who crossed over to telitacicept during the open-label extension.

Depth and breadth of MG-ADL improvement

More than 94% of participants achieved at least a 5-point improvement in MG-ADL by week 48, with improvements of up to 13 points observed. Responses generally deepened between weeks 24 and 48, with more participants meeting stricter improvement thresholds as treatment continued.

“What stands out in these data are the breadth, depth, and durability of response,” said Jean-Paul Kress, MD, chairman and chief executive officer of Vor Bio.

How telitacicept works

Most MG therapies on the market or in development act downstream, decreasing circulating IgG through FcRn blockade or blocking complement activation at the neuromuscular junction; a newer anti-CD19 approach works further upstream. Telitacicept is a fusion protein combining the extracellular domain of the TACI receptor with the Fc portion of human immunoglobulin G, which Jeremy Sokolove, MD, chief medical officer of Vor Bio, described in an interview with NeurologyLive as becoming "basically a sump for BAFF and APRIL" once solubilized, neutralizing both in circulation and in tissue.

Telitacicept is “pretty unique in that it does two things,” Sokolove said. It reduces autoantibody-producing plasma cells and plasmablasts by withdrawing the APRIL signal they depend on for survival, while also inhibiting BAFF's effect on earlier B-cell progenitors, which Sokolove said prevents those depleted autoreactive cell populations from repopulating.

“Any improvement you get, you get to keep,” Sokolove said. “You don't have to go back again to lose it and to regain it.” He added that B cells likely also contribute to MG independent of antibody production, noting that anti-CD19 therapies are effective in MG without substantially lowering total immunoglobulin levels.

Earlier phase 3 trial and China approval

Telitacicept's MG development began in China, where RemeGen's original phase 3 trial randomized 114 adults with AChR or MuSK antibody-positive gMG, MGFA class II, III, or IVa, to weekly telitacicept 240 mg or placebo for 24 weeks. Using an analysis that imputed missing data as non-response, telitacicept reduced MG-ADL by 5.74 points from baseline compared with 0.91 points with placebo (P <.001), and reduced QMG scores by 8.66 points compared with 2.27 points with placebo (P <.001); 98.1% of telitacicept-treated participants achieved at least a 3-point MG-ADL improvement, compared with 12.0% of placebo recipients.²

Treatment-emergent adverse events (TEAEs) occurred in 86.0% of telitacicept-treated participants and 82.5% of placebo recipients in that trial; infection-related AEs were less frequent with telitacicept (45.6%) than placebo (59.6%), and serious AEs occurred in 7.0% versus 10.5%, respectively. Based on these results, China's National Medical Products Administration approved telitacicept in May 2025 for adults with AChR antibody-positive gMG used with conventional therapy, the drug's first approval in the indication.^2,3

What's next

Vor Bio and RemeGen are now running a global phase 3 trial, UPSTREAM MG (NCT06456580), designed to test whether the China results translate to a broader population. The trial is randomizing adults with AChR or MuSK antibody-positive gMG, MGFA class II through IV, with an MG-ADL score of at least 6 and a QMG score of at least 8, to weekly subcutaneous telitacicept or placebo for 24 weeks, followed by a 48-week open-label extension.⁴

Enrollment in UPSTREAM MG finished in 2026, and Sokolove said in the interview that Vor Bio expects a data lock roughly six months after the last patient enrolled, with topline results anticipated in the first half of 2027. “There's very little doubt that this drug should work in myasthenia gravis,” he said. “The questions become how efficient we can be about the BLA process, getting this drug approved by regulators in the U.S. and globally, and then how we plan to launch it into the market.”

Sokolove also pointed to the open-label extension design as central to answering durability questions directly. “It's not, do I do well on a couple of days of the week,” he said, “but how well do I do in the course of a chronic disease, because that's really what's important to patients.”

Click here for more AANEM 2026 coverage.

REFERENCES
1. Telitacicept demonstrates deep and durable minimal symptom expression in generalized myasthenia gravis in new analysis presented at AANEM. News release. Vor Bio. Published September 29, 2026. Accessed October 9, 2026. https://ir.vorbio.com/news-releases/news-release-details/telitacicept-demonstrates-deep-and-durable-minimal-symptom
2. Yin J, Wang W, Li L, Sun Y, Zuraw Q, Fang J. Efficacy and safety of telitacicept in patients with generalized myasthenia gravis: results of a phase 3 study. Presented at: 2025 American Academy of Neurology Annual Meeting; April 5-9, 2025; San Diego, CA.
3. RemeGen: telitacicept for the treatment of generalized myasthenia gravis approved in China. News release. Published May 27, 2025. Accessed October 9, 2026. https://www.stocktitan.net/news/REGMY/reme-gen-telitacicept-for-the-treatment-of-generalized-myasthenia-fzvr6xyvzq8v.html
4. ClinicalTrials.gov. A study of telitacicept for the treatment of generalized myasthenia gravis (UPSTREAM MG). NCT06456580. Accessed October 9, 2026. https://clinicaltrials.gov/study/NCT06456580