Cyclophosphamide Improves Functional Outcomes in Inflammatory Myopathy-Related ILD

Intravenous cyclophosphamide (CYC) was found to be associated with better functional outcomes compared with other immunosuppressive agents in the treatment of idiopathic inflammatory myopathy (IIM)-associated interstitial lung disease (ILD), according to study findings published in Seminars in Arthritis and Rheumatism.

In an observational comparative study, researchers analyzed data from patients with IIM-ILD in Argentina, Spain, and Uruguay. Clinical and demographic information were collected from electronic health records.

“Time to treatment” was calculated as the number of months from the onset of ILD symptoms to the initiation of immunosuppressive treatment.

Patients were divided into 2 groups – intravenous CYC and non-CYC – based on treatment regimen. All patients underwent lung function tests at baseline and between 6 to 12 months after induction of therapy.

The primary study outcome was improvement in forced vital capacity (FVC) compared with baseline levels, defined as an increase of greater than 10%.

Binary logistic regression analysis was used to identify factors independently associated with FVC improvement.

Data from 47 patients (22 [47%] in the CYC group and 25 [53%] in the non-CYC group) were included in the analysis. In the non-CYC group, 32% received azathioprine; 28% received glucocorticoids only; 20% received mycophenolate; 16% received calcineurin inhibitors or methotrexate; and 4% received rituximab. In the total cohort, mean age at ILD diagnosis was 50.4 ± 13.7 years, and 81% were women. Baseline demographic and clinical characteristics were not significantly different between the 2 groups.

Overall, 64% of patients in the CYC group achieved FVC improvement compared with 32% in the non-CYC group (P =.03). In addition, 24% of patients in the non-CYC group vs none of the patients in the CYC group had worsening of FVC (P =.021). In the logistic regression model, CYC emerged as the only independent predictor of FVC improvement (odds ratio, 3.97; 95% CI, 1.07-14.75).

Treatment characteristics in the CYC group differed from the non-CYC group. Patients in the CYC vs non-CYC group received more methylprednisolone pulses (59% vs 28%; P =.03), initial glucocorticoid doses of less than 30 mg/day (19% vs 77%; P =.001) and lower 6-month average doses of prednisone (11 vs 31.1 mg/d; P =.001).

Because patients in the CYC group received more methylprednisolone pulses and lower average prednisone doses, the researchers hypothesized that methylprednisolone may potentiate the effects of CYC and lower the need for prednisone.

Study limitations included the small cohort size and non-randomized design.

“Therefore, CYC in combination with [methylprednisone] could be considered as the first line induction therapy in IIM-ILD,” the study authors noted.