MMF treatment may act faster than azathioprine for gMG: Study
Immunosuppressive medications similarly effective at controlling symptoms
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- Mycophenolate mofetil (MMF) and azathioprine (AZA) are similarly effective for generalized myasthenia gravis (gMG).
- MMF achieves symptom control faster than AZA in gMG patients.
- Both treatments are more effective with corticosteroids; early treatment improves outcomes.
The immunosuppressive medications azathioprine and mycophenolate mofetil are similarly effective at controlling symptoms of generalized myasthenia gravis (gMG), but mycophenolate mofetil tends to act more quickly, according to a study in the U.S.
Data also indicated that both medications were generally more effective when combined with corticosteroids, a type of anti-inflammatory and immunosuppressive treatment commonly used in MG.
These findings “should assist clinicians in making informed decisions about the use of [azathioprine] and [mycophenolate mofetil] in the treatment of people with [MG],” researchers wrote.
The study, “The Duke MG Patient Registry III. Comparative Effectiveness of Azathioprine and Mycophenolate Mofetil in Generalized Myasthenia Gravis, a Retrospective Single Center Review,” was published in Muscle & Nerve.
Immunosuppressants AZA, MMF commonly used to help manage MG
Myasthenia gravis (MG) is an autoimmune disorder marked by self-reactive antibodies that interfere with the communication between nerve and muscle cells, resulting in symptoms such as muscle weakness and fatigue. Generalized MG is a form of the disease that affects several parts of the body.
Immunosuppressants, or medications that suppress the immune system, are commonly used to help manage MG. In the U.S., the two most common oral immunosuppressive medications used for MG are azathioprine (AZA), sold as Imuran, with generics available, and mycophenolate mofetil (MMF), sold as CellCept, with generics available.
Although both these medicines are considered mainstay treatments for MG, few studies have directly compared whether one tends to yield better outcomes than the other.
With this in mind, a team of scientists at Duke University in the U.S. retrospectively analyzed data from 320 gMG patients who were seen at their MG clinic. A total of 177 participants were treated with AZA and 143 with MMF for at least three months as their first non-corticosteroid immunosuppressive treatment.
Patients in each group were generally matched for demographic and clinical features. All were positive for the most common MG-driving antibody, targeting the acetylcholine receptor (AChR) protein. In both groups, most participants were white, male, and were also receiving the corticosteroid prednisone.
The researchers specifically compared the proportion of patients achieving Myasthenia Gravis Foundation of America Post-Intervention Status Minimal Manifestations, essentially meaning little to no symptoms of MG, at least 30 days after beginning AZA or MM.
Results showed that about two-thirds of patients achieved this outcome, with no significant differences between the AZA and MMF groups. This was seen regardless of whether patients were also given prednisone.
Findings emphasize importance of starting treatment early
However, among patients who achieved minimal manifestations, the median time to reach this outcome was significantly shorter among those given MMF compared with those given AZA (10.5 months vs. 17.5 months).
“Although we found no difference in the proportion of patients taking AZA vs. MMF who reached [minimal manifestations], those taking MMF reached [minimal manifestations] sooner than those taking AZA,” the researchers wrote.
Notably, significant differences were seen both in patients also taking prednisone (15.5 months with MMF vs. 25.8 months with AZA) and in those not on the corticosteroid (21.1 vs. 40.4 months).
The data “are consistent with estimates that the maximum benefit in MG may take up to 24 months for AZA and more than 13 months for MMF,” the team wrote. “These timelines highlight the need for patience and close monitoring when using these [immunosuppressant] agents in the treatment of patients with gMG.”
Further statistical analyses on the whole patient population showed that participants were significantly more likely to achieve minimal manifestations, and significantly faster, if they were also given prednisone.
“Concomitant prednisone increased the likelihood of reaching [minimal manifestations] and reduced the time to [minimal manifestations] in patients taking either AZA or MMF,” the scientists wrote.
Additional statistical analyses showed that a shorter disease duration at treatment initiation was significantly associated with a shorter time to achieve minimal manifestations. These findings emphasize the importance of starting treatment as early as possible to achieve maximum benefit, the researchers noted.
“Results from this study emphasize the value of concomitant prednisone and the early use of [immunosuppressant] treatment in patients with gMG,” the team concluded.
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