Top-line data from global telitacicept trial in MG expected next year

Enrollment is ongoing in a global, late-stage clinical trial testing the safety and efficacy of telitacicept in adults with generalized myasthenia gravis (gMG), with top-line data expected in the first half of next year, Vor Bio said.

The Phase 3 UPSTREAM MG study (NCT06456580), previously known as RemeMG, expects to enroll up to 180 participants at 84 locations in the U.S., Canada, South America, Australia, Europe, and Japan. Data from the trial may support potential regulatory approvals of telitacicept in the U.S., Europe, and Japan.

The therapy, originally developed by Remegen, is approved in China as an add-on treatment for adults with gMG and the most common type of gMG-driving antibodies, as well as people with other autoimmune diseases. Vor Bio has partnered with Remegen to develop and market telitacicept outside of China, Hong Kong, Macau, and Taiwan.

The company expects the early trial data “to be a significant catalyst for both the company and [the myasthenia gravis] landscape,” Jean-Paul Kress, MD, Vor Bio’s CEO and chairman, said in a company press release. “The promising Phase 3 results seen from telitacicept in China across multiple indications … provide an invaluable foundation as we work to bring a meaningful new treatment option to patients living with these serious autoimmune diseases,” Kress said.

gMG symptoms include widespread muscle weakness and fatigue. The disease is caused by self-reactive antibodies that attack proteins, most commonly acetylcholine receptors (AChRs), involved in communication between nerve and muscle cells. Immune B-cells produce these self-reactive antibodies, which often target another protein in gMG, called muscle-specific kinase (MuSK).

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Targeting proteins

Telitacicept works by reducing B-cells’ activity by targeting two proteins involved in their development and maturation, known as B-cell stimulator and A proliferation-inducing ligand. This is expected to reduce the levels of self-reactive antibodies and ease gMG symptoms.

Telitacicept has been approved in China for gMG associated with anti-AChR antibodies and two other autoimmune diseases mediated by B-cells and self-reactive antibodies: systemic lupus erythematosus and rheumatoid arthritis.

The therapy’s approval for gMG was based mainly on data from a Remegen-sponsored Phase 3 trial (NCT05737160) in China, which tested telitacicept against a placebo in 114 adults with gMG and anti-AChR or anti-MuSK antibodies.

Patients in the trial treated with telitacicept for six months showed a rapid reduction in MG Activities of Daily Living (MG-ADL) scores, which assess how symptoms affect everyday activities, compared with the placebo.

The therapy was also linked to a greater reduction in symptom severity, as assessed with the Quantitative MG (QMG) score, and levels of self-reactive antibodies. These improvements were sustained for up to one year of treatment.

Similar to the trial in China, UPSTREAM MG participants are randomly assigned to receive either telitacicept or a placebo, given as weekly under-the-skin injections, for 24 weeks (about six months).

The trial’s main goal is to assess whether telitacicept can ease symptoms and improve patients’ ability to engage in daily activities, as measured by the MG-ADL score, compared with a placebo. It will also evaluate whether the therapy can reduce disease severity, as measured by the QMG score, and improve patients’ quality of life.

Vor Bio is also testing telitacicept in a global trial involving people with Sjögren’s disease, an autoimmune disorder that primarily affects the glands that produce tears and saliva.