Mycophenolate mofetil treatment with or without a calcineurin inhibitor in resistant inflammatory myopathy

To evaluate the efficacy and tolerability of mycophenolate mofetil (MMF) with or without calcineurin inhibitors (CNIs) in patients with inflammatory myopathy taking prednisolone, but refractory to conventional immunosuppressive therapy. The records of patients with inflammatory myopathy who had previously failed treatment with at least one immunosuppressant were retrospectively evaluated. We selected patients treated with MMF and divided them into two groups depending on whether or not there was concomitant use of CNIs. We investigated the efficacy by changes in creatine kinase (CK) levels, forced vital capacity (%FVC), prednisolone dose, and high-resolution computed tomography (HRCT) findings. Interstitial lung disease (ILD) progression was defined by more than 10% decline of %FVC from baseline. We identified 19 patients on MMF treatment. There were seven (36.8%) patients on MMF and CNIs, including five on cyclosporine and two on tacrolimus. At baseline, no significant difference was seen in the prevalence of ILD between patients taking or not taking CNIs (85.7% vs. 75.0%, P = 0.68). Improvement in CK was seen in patients treated with CNIs (P = 0.04) but not in those without (P = 0.39). No significant improvement in %FVC and HRCT findings were found in patients with ILD in either group, and there were no differences in death or ILD progression. The combination of CNIs and MMF might be more effective for decreasing CK levels than MMF alone. Neither treatment arm had a beneficial effect on ILD over a variable observation period.