Treatment eases gMG symptoms, cuts need for corticosteroid use

Long-term rituximab treatment safely and effectively eased symptoms and reduced the need for anti-inflammatory corticosteroids in adults with hard-to-treat generalized myasthenia gravis (gMG), according to a small, real-world study in Italy.

The benefits were seen in patients with the two most common gMG-driving self-reactive antibodies, but were greater among those with antibodies targeting the muscle-specific kinase (MuSK) protein.

Among adults with anti-MuSK antibodies, the standard rituximab regimen generally produced stronger clinical responses, but lower rituximab doses also led to significant improvements.

The study, “Rituximab in AChR and MusK Myasthenia Gravis: long-term follow-up with different therapeutic protocols,” was published in the Journal of the Neurological Sciences.

An autoimmune disease, gMG is caused by self-reactive antibodies that target proteins involved in communication between nerves and muscles. In about 85% of cases, these antibodies target the acetylcholine receptor (AChR) protein, while about 5%-8% of patients have anti-MuSK antibodies.

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Off-label treatment

Rituximab (sold as Rituxan and others, with biosimilars available) kills B-cells, the immune cells responsible for producing antibodies, including those driving gMG. Although not specifically approved as a treatment for gMG, it is used off label to ease disease severity in certain patients. The treatment is administered directly into the bloodstream.

Current international guidelines recommend rituximab as an early treatment option for gMG patients with anti-MuSK antibodies whose disease remains inadequately controlled with first-line treatment.

For people with AChR-related gMG, rituximab may also be considered when subsequent treatment with corticosteroids or other immunosuppressants fails to adequately control the disease, or when those therapies cannot be tolerated.

However, “as more effective targeted treatments … have become available, further evidence regarding the efficacy and safety of rituximab should be gathered,” the researchers wrote.

With several new gMG treatments approved or nearing approval, the team of researchers raised a question: Could clinicians be moving away from a treatment that is still safe, effective, and cost-effective?

To add long-term, real-world evidence of rituximab’s safety and efficacy, the researchers reviewed the medical records of 44 adults with gMG treated with rituximab at a single Italian center from 2009 to 2025. Half had anti-AChR antibodies, and half had anti-MuSK antibodies.

Participants in the two groups were similar in age (mean age of 42.9) and in disease severity at the start of rituximab treatment. However, those with MuSK-related gMG were significantly more often women (95% vs. 55%), had lived with the disease for a significantly shorter time (mean 6.6 years vs. 11 years), and were receiving significantly lower doses of the corticosteroid prednisone (24.4 mg/day vs. 35.2 mg/day).

Before starting rituximab, all participants in the AChR group and half of those in the MuSK group were taking other immunosuppressants.

All AChR-related gMG patients and 41% of MuSK-related gMG patients received the standard rituximab regimen of two 1,000-mg infusions given two weeks apart. The remaining MuSK-related gMG participants received a lower-dose regimen consisting of a single 500-mg infusion.

Median follow-up was 86.1 months (about 7.2 years) for the AChR group and 33.2 months (about 2.8 years) for the MuSK group.

Treatment success according to the Myasthenia Gravis Foundation of America post-intervention status was significantly more common in the MuSK group after one year (44.4% vs. 4.55%) and two years (52.9% vs. 13.6%). By five years, rates of treatment success remained higher in the MuSK group (66.7% vs. 33.3%), but this difference failed to reach statistical significance.

Scores on the MG Activities of Daily Living scale, which measures the disease’s impact on daily life activities, dropped significantly in both groups, reflecting less severe disease. Again, such improvements were generally greater in the MuSK group.

Rituximab also reduced reliance on corticosteroids and other immunosuppressants. In the MuSK group, 90.9% of patients lowered their daily prednisone dose to 10 mg or lower after a median of six months, and 68.2% stopped taking it altogether after a median of 12 months. At the last follow-up, 81.8% also discontinued immunosuppressive medications.

In comparison, 76.2% of AChR-related gMG patients reduced their prednisone after a median of one year, 42.9% stopped taking it after a median of seven years, and half had discontinued immunosuppressive drugs by the last follow-up.

Statistical analyses accounting for potential influencing factors identified the presence of anti-MuSK antibodies as the strongest predictor of a favorable response to rituximab. Participants with anti-MuSK gMG were significantly more likely to achieve treatment success (by about nine times) and to remain free of corticosteroids (by about 15 times).

Data from the MuSK group showed that the standard rituximab regimen generally produced better clinical outcomes, while the two regimens were similarly effective at reducing corticosteroid use. status as the strongest predictor of a favorable response to rituximab.

“Rituximab will probably remain a relevant, [clinical profile-specific] treatment, rather than a universal option for all [gMG] patients,” the researchers wrote.

They suggested its clearest role may remain in the treatment of MuSK-related gMG, while its use in AChR-related gMG may become more selective, potentially focusing on patients who do not respond to newer targeted therapies or where long-term B-cell depletion is considered appropriate.