A comparison of the efficacy of cyclophosphamide as first-line therapy versus other immunosuppressive therapies (azathioprine, glucocorticoids, mycophenolate mofetil, calcineurin inhibitors, rituximab) was performed in 47 patients with interstitial lung disease associated with myositis (excluding anti-MDA5 dermatomyositis):
- 22 were on cyclophosphamide, 25 on other immunosuppressive therapy;
- 64% of the participants on cyclophosphamide (compared to 32% for the others) had an improvement in their vital capacity of more than 10% on this treatment, the primary endpoint of the study;
- no participant on cyclophosphamide had a deterioration in vital capacity compared to six (24%) on another immunosuppressive drug;
- there was no significant difference in carbon monoxide diffusing capacity (DLCO) or number of deaths between the two groups.
Taking into account a probable potentiating effect of mycophenolate mofetil allowing to decrease the doses of corticosteroids, the authors conclude to the interest of using cyclophosphamide in association with mycophenolate mofetil as a first line treatment of interstitial lung disease in myositis.
It should be noted that a phase III trial underway in France aims to compare the efficacy of cyclophosphamide followed by azathioprine to that of tacrolimus in diffuse infiltrative lung disease related to antisynthetase syndrome (Catr-Pat trial, in French).
