Telitacicept Demonstrates Deep and Durable Minimal Symptom  Expression Through 48 Weeks in Generalized Myasthenia Gravis

The open-label extension switched placebo recipients to telitacicept, leaving no placebo comparison after Week 24.

Rhea-AI Summary

Vor Bio (VOR) reported a post hoc analysis of telitacicept responses through 48 weeks in a China-based Phase 3 myasthenia gravis trial.

In the 114-adult study conducted by collaborator RemeGen, participants received weekly telitacicept or placebo for 24 weeks, followed by a 24-week open-label extension in which placebo recipients switched to telitacicept. More than 94% of participants achieved at least a five-point improvement on the MG-ADL symptom scale at Week 48. Approximately 42% of telitacicept-treated participants reached minimal symptom expression—an MG-ADL score of 0 or 1—at some point over 48 weeks, compared with 23.7% over the first 24 weeks.

Of minimal-symptom events, 86.7% persisted to the next monthly assessment. After reaching that state, participants initially assigned telitacicept spent 83% of their remaining follow-up there, versus 85% for those who switched from placebo. No new safety signals were observed through 48 weeks.

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Positive

• Moderate pointMinimal symptom expression was reached by approximately 42% of telitacicept-treated participants over 48 weeks, versus 23.7% over the first 24 weeks.
• Minor pointAt least five-point MG-ADL improvement was achieved by more than 94% of participants at Week 48.
• Minor pointMinimal-symptom durability: 86.7% of events persisted to the next monthly assessment.
• Minor pointRemaining follow-up in minimal symptom expression was 83% for initial telitacicept recipients and 85% for those switched from placebo.
• Minor pointMG-ADL improvement of up to 13 points was observed at Week 48.
• Minor pointSafety: No new safety signals were observed through 48 weeks.

Negative

• Minor pointPost hoc analysis means these reported response findings were assessed after the study was designed.
• Minor pointOpen-label extension switched placebo recipients to telitacicept, leaving no placebo group during Weeks 24–48.
• Minor pointHigher baseline symptom scores: 20.5% with MG-ADL scores of at least 11 reached minimal symptom expression, versus 51.2% at scores of 6–8 and 51.7% at 9–10.

News Explained

In the post hoc analysis, MSE was achieved by 51.2% of participants with baseline MG-ADL scores of 6–8 and 51.7% with scores of 9–10, compared with 20.5% among those starting at 11 or higher.

Market Context

On Sep 8, Vor reported completing enrollment in global UPSTREAM MG and expected topline data in 1H 2...

Analysis

On Sep 8, Vor reported completing enrollment in global UPSTREAM MG and expected topline data in 1H 2027; that platform record contextualizes the collaborator’s China analysis while remaining distinct from its dataset.

Key Figures

MG-ADL improvement: More than 94% MSE attainment: 42% MSE sustained: 86.7% +4 more

MG-ADL improvement

More than 94%

Participants with a ≥5-point improvement at Week 48

MSE attainment

42%

Telitacicept-treated participants achieving MSE at any time over 48 weeks

MSE sustained

86.7%

MSE events sustained at the next monthly assessment

Time in MSE after achievement

83% and 85%

Remaining follow-up for participants initially randomized to telitacicept and those crossing over from placebo, respectively

MSE by baseline severity

51.2%, 51.7%, and 20.5%

Baseline MG-ADL scores of 6-8, 9-10, and ≥11, respectively

Maximum MG-ADL improvement

Up to 13 points

Observed at Week 48

Study participants

114 adults

Phase 3 study randomized to telitacicept or placebo

Historical Context

1 past event · Latest: Sep 08

1 event

1. Sep 08

   Phase 3 enrollment

   24h Move

   -0.1%

   Global UPSTREAM MG enrollment was complete; topline data were expected in the first half of 2027.

24h Move is the share-price change in the day after each event; other market factors may also have contributed.

Key Terms

post hoc analysis, mg-adl, open-label extension, generalized myasthenia gravis

4 terms

post hoc analysis technical

"announced a new post hoc analysis from the Phase 3 trial"

Post hoc analysis is an exploratory look at data carried out after a study or trial is finished to search for patterns or effects that were not specified beforehand. Because it’s done after seeing the results, findings can arise by chance and are less reliable than preplanned tests; investors should treat post hoc claims as hypothesis-generating signals that may need confirmatory studies or regulatory review before they meaningfully affect a company’s value.

mg-adl medical

"Myasthenia Gravis Activities of Daily Living (MG-ADL) score of 0 or 1"

MG-ADL is a short, self-reported checklist that measures how the neuromuscular disease myasthenia gravis affects basic daily activities like talking, chewing, breathing, and walking. Investors pay attention because changes on this scale are commonly used as a clinical trial endpoint and a practical signal of patient benefit; clearer improvement can boost a treatment’s chances of regulatory approval, uptake by doctors, and commercial value—like a thermometer showing clinical impact.

open-label extension medical

"followed by a 24-week open-label extension (OLE)"

An open-label extension is a continuation of a clinical trial where all participants and researchers know which treatment is being given, often after an initial blinded phase. It allows further study of a drug's long-term safety and effectiveness. For investors, it can indicate ongoing interest and confidence in a product's potential, influencing perceptions of its future value.

generalized myasthenia gravis medical

"evaluating telitacicept in adults with generalized myasthenia gravis"

A chronic neurological condition in which the immune system disrupts the chemical signals between nerves and muscles, causing muscle weakness that typically fluctuates and worsens with activity. Think of it as a faulty light switch or loose wiring that prevents muscles from responding reliably; severity and daily variability make treatment and long-term management important. For investors, the condition matters because it defines patient need, market size, and demand for approved therapies, clinical trial outcomes, and reimbursement decisions that drive company valuation.

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More than 94% of participants achieved a ≥5-point MG-ADL improvement at Week 48

42% of telitacicept-treated participants achieved minimal symptom expression (MSE) at any time over 48 weeks, increasing from 23.7% over the first 24 weeks

After achieving MSE, 86.7% of MSE events were sustained at the next monthly assessment and participants spent 83-85% of remaining study follow-up in MSE

Approximately 51% of participants with baseline MG-ADL scores of 6-10 and 21% of participants with baseline MG-ADL scores ≥11 achieved MSE

BOSTON, Sept. 29, 2026 (GLOBE NEWSWIRE) -- Vor Bio (Nasdaq: VOR), a clinical-stage biotechnology company transforming the treatment of autoimmune diseases, today announced a new post hoc analysis from the Phase 3 trial conducted in China by its collaborator, RemeGen Co., Ltd (HKEX: 9995, SHA: 688331), evaluating telitacicept in adults with generalized myasthenia gravis (gMG). The findings were presented in an oral presentation during the Myasthenia Gravis Foundation of America (MGFA) Scientific Session at the 2026 American Association of Neuromuscular & Electrodiagnostic Medicine (AANEM) Annual Meeting in Orlando, Florida.

The analysis evaluated the depth and durability of clinical response to telitacicept over 48 weeks, including achievement of MSE, defined as a Myasthenia Gravis Activities of Daily Living (MG-ADL) score of 0 or 1. In addition to evaluating whether participants achieved MSE, the analysis assessed whether MSE was sustained at the subsequent monthly assessment and the proportion of remaining follow-up participants spent in MSE after achieving it. The Phase 3 study randomized 114 adults with gMG to telitacicept 240 mg once weekly or placebo for 24 weeks, followed by a 24-week open-label extension (OLE), with those previously on placebo crossing over to telitacicept 240mg. The initial 48-week OLE data were presented at the MGFA Scientific Session at the 2025 AANEM Annual Meeting.

“Over the past decade, myasthenia gravis has seen meaningful therapeutic innovation, but patients and physicians still live with uncertainty about whether a treatment will work broadly and whether that benefit will last,” said Jean-Paul Kress, M.D., Chairman and Chief Executive Officer of Vor Bio. “What stands out in these data are the breadth, depth, and durability of response, with more than 94% of participants achieving at least a five-point improvement in MG-ADL, more than half of those starting with MG-ADL scores of 6-10 reaching MSE, and once MSE was achieved, participants spent the vast majority of their remaining follow-up in that state. 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.”

“Clinically, reaching MSE once or over a short period is not the same as sustaining that level of disease control over time,” said Richard J. Nowak, M.D., M.S., Director of the Yale Myasthenia Gravis Clinic and Associate Professor of Neurology at Yale School of Medicine. “Myasthenia gravis symptoms can fluctuate over time, so a single assessment provides only a limited window into patient outcomes. These data are encouraging because the response to telitacicept appears to deepen with continued treatment and extends across a broad range of baseline disease severity. As treatment options improve, longitudinal assessment and transparent reporting of MSE durability should become an increasingly important standard so patients and clinicians can better understand not only whether minimal symptoms can be achieved but how consistently they can be maintained.”

Key Findings from the Post Hoc 48-week Analysis:

• Durability of MSE: Among participants who reached MSE, 86.7% of MSE events were sustained at the next monthly assessment. Following achievement of MSE, participants spent the vast majority of their remaining study follow-up in MSE, specifically 83% among those initially randomized to telitacicept and 85% among those who crossed over from placebo to telitacicept.
  

• MSE across disease severity: More than half of participants with baseline MG-ADL scores of 6-8 (51.2%) and 9-10 (51.7%) achieved MSE during the 48-week study. Importantly, 20.5% of participants with baseline MG-ADL scores ≥11 also achieved MSE.
  

• Depth of response increased with continued treatment: MG-ADL responses continued to deepen from Week 24 through Week 48, with increasingly stringent response thresholds achieved over time and MG-ADL improvements of up to 13 points observed at Week 48.
  

• Overall MSE attainment: The probability of achieving MSE at any time over the 48-week study was approximately 42% among participants treated with telitacicept.
  

• Safety: Telitacicept was generally well tolerated through 48 weeks with no new safety signals observed, consistent with the previously reported safety profile from the study.
  
  

About Generalized Myasthenia Gravis
gMG is a rare, chronic autoimmune neuromuscular disorder that disrupts communication between nerves and muscles, leading to muscle weakness that can impact mobility, vision, swallowing, and breathing. The disease is mediated by autoantibodies, most commonly targeting the acetylcholine receptor (AChR) or muscle-specific kinase (MuSK), which interfere with neuromuscular transmission. While several therapies are available, many patients continue to experience persistent symptoms or intolerable side effects. As a result, there remains a significant unmet need for new therapies that offer durable efficacy, a favorable safety profile, and convenient administration to improve the quality of life for people living with gMG.

About Telitacicept
Telitacicept is a novel recombinant fusion protein designed to treat autoimmune diseases through dual inhibition of BLyS (BAFF) and APRIL - two cytokines essential to B cell and plasma cell survival. This dual-target mechanism reduces autoreactive B cells and autoantibody production, key drivers of autoimmune pathology.

Telitacicept is approved in China for systemic lupus erythematosus (SLE), rheumatoid arthritis (RA), generalized myasthenia gravis (gMG), IgA nephropathy (IgAN), and Sjögren’s disease (SjD).

Vor Bio is advancing telitacicept in global Phase 3 trials in gMG and SjD to support potential regulatory approvals in the United States, Europe, and Japan.

About Vor Bio
Vor Bio is a clinical-stage biotechnology company transforming the treatment of autoimmune diseases. The Company is focused on rapidly advancing telitacicept, a novel dual-target fusion protein, through Phase 3 clinical development and potential commercialization to address serious autoantibody-driven conditions worldwide. For more information visit www.vorbio.com. Vor Bio routinely posts information that may be important to investors in the “Investors” section of its website. The Company encourages investors to consult that section of its website regularly.

Forward-Looking Statements
This press release contains forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995. The words “anticipate," "believe," "continue,” “could,” “design,” “expect,” “intend,” “may,” “ongoing,” “plan,” “potential,” “should,” “update,” “will,” “would,” and similar expressions are intended to identify forward-looking statements, although not all forward-looking statements contain these identifying words. Forward-looking statements in this press release include telitacicept’s potential benefits, including its potential to give physicians greater confidence in treatment choice and patients greater predictability in how they live their lives, Vor Bio’s development and commercialization plans, including potential regulatory approvals in the United States, Europe, and Japan; and other statements that are not historical fact.

Vor Bio may not actually achieve the plans, intentions, or expectations disclosed in these forward-looking statements, and you should not place undue reliance on these forward-looking statements. Actual results or events could differ materially from the plans, intentions and expectations disclosed in these forward-looking statements as a result of various factors, including that the data for our product candidates may not be sufficient for obtaining regulatory approval to commercialize products; we may not be able to execute our business plans, including meeting our planned clinical and regulatory milestones and timelines, and possible limitations of financial and other resources. These and other risks are described in greater detail under the caption “Risk Factors” included in Vor Bio’s most recent annual or quarterly report and in other reports it has filed or may file with the Securities and Exchange Commission.

Any forward-looking statements contained in this press release speak only as of the date hereof, and Vor Bio expressly disclaims any obligation to update any forward-looking statements, whether because of new information, future events or otherwise, except as may be required by law.

Media & Investor Contacts:
Carl Mauch
cmauch@vorbio.com

FAQ

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What did Vor Bio's telitacicept analysis find at 48 weeks?

More than 94% of participants achieved at least a five-point MG-ADL improvement at Week 48. Approximately 42% of telitacicept-treated participants reached minimal symptom expression at some point over 48 weeks; 86.7% of minimal-symptom events persisted to the next monthly assessment.

How did baseline symptom severity affect minimal symptom expression in Vor Bio's telitacicept trial?

Minimal symptom expression was reached by 51.2% of participants starting with MG-ADL scores of 6–8, 51.7% of those starting at 9–10, and 20.5% of those starting at 11 or higher during the 48-week study.