From the Guidelines
Mycophenolate mofetil is a conditionally recommended first-line treatment option for interstitial lung disease (ILD) associated with mixed connective tissue disease (MCTD), as stated in the 2023 American College of Rheumatology (ACR)/American College of Chest Physicians (CHEST) guideline for the treatment of ILD in people with systemic autoimmune rheumatic diseases 1.
Key Points
- The typical dosing regimen for mycophenolate mofetil starts at 500 mg twice daily, gradually increasing to a target dose of 1,000-1,500 mg twice daily as tolerated.
- Treatment duration typically lasts at least 6-12 months before considering dose reduction based on clinical response.
- Regular monitoring is essential, including complete blood counts every 2-4 weeks initially then every 1-3 months, liver function tests, and pulmonary function tests every 3-6 months to assess treatment efficacy.
- Mycophenolate works by inhibiting lymphocyte proliferation and reducing inflammation in lung tissue, making it particularly useful for MCTD-ILD which involves immune-mediated inflammation and fibrosis.
- Common side effects include gastrointestinal disturbances, increased infection risk, and potential bone marrow suppression.
- Patients should take the medication with food to minimize GI side effects, maintain adequate hydration, avoid live vaccines during treatment, and practice careful infection prevention.
- Alternative treatments for MCTD-ILD include cyclophosphamide, rituximab, or tacrolimus if mycophenolate is not tolerated or ineffective.
Considerations
- The decision to use mycophenolate mofetil should be based on individual patient factors and preferences, as well as the specific clinical situation.
- The guideline emphasizes co-management of people with SARD-ILD by rheumatologists and pulmonologists.
- Glucocorticoids should be used cautiously in patients with MCTD with an SSc phenotype who may be at increased risk of renal crisis.
- Nintedanib and pirfenidone are not recommended as first-line treatment options for MCTD-ILD due to limited evidence and concerns about cost and adverse effects.
From the Research
Mixed Connective Tissue Disease and Interstitial Lung Disease
- Mixed connective tissue disease (MCTD) is a condition that combines features of different connective tissue diseases, including lupus, scleroderma, and rheumatoid arthritis 2.
- Interstitial lung disease (ILD) is a common complication of MCTD, affecting approximately 53.6% of patients 3.
- ILD in MCTD can lead to significant morbidity and mortality, with severe fibrosis developing in 25% of patients within 4 years of diagnosis 3.
Treatment of ILD in MCTD
- Corticosteroids and cyclophosphamide are commonly used to treat ILD in MCTD, with some patients showing significant improvement in lung function and reduction in disease activity 2, 3.
- Mycophenolate mofetil (MMF) is also used to treat ILD in MCTD, with studies showing similar efficacy to cyclophosphamide in stabilizing lung function and reducing prednisone dose 4, 5.
- Azathioprine is another immunosuppressive agent used to treat ILD in MCTD, with some studies showing improved lung function and reduced prednisone dose, although it may be associated with more adverse events than MMF 4, 5.
Comparison of Treatment Options
- A study comparing cyclophosphamide and MMF in patients with connective tissue disease-associated ILD found no significant difference in lung function or disease activity between the two groups, although cyclophosphamide was associated with more adverse events 6.
- Another study comparing azathioprine and MMF in patients with myositis-related ILD found similar efficacy in improving lung function and reducing prednisone dose, although azathioprine was associated with more adverse events 4.
- The choice of treatment for ILD in MCTD should be individualized based on patient characteristics, disease severity, and potential side effects of treatment 6, 4, 5.