Tacrolimus in Patients With Interstitial Pneumonia Associated With Polymyositis or Dermatomyositis: Interim Report of Postmarketing Surveillance in Japan

Objective. The calcineurin inhibitor tacrolimus has been approved in Japan for the treatment of interstitial pneumonia (IP) in patients with polymyositis (PM) and dermatomyositis (DM). Postmarketing surveillance was initiated to examine long-term outcomes of immunosuppressive regimens containing tacrolimus in real-world settings. Methods. Observational, prospective, postmarketing surveillance is ongoing in 179 patients with PM/DM-associated IP initiating treatment with tacrolimus. We report interim findings after 2 years of follow-up. Cumulative overall survival was assessed using Kaplan-Meier analysis. Potential prognostic factors for mortality were assessed by univariate Cox proportional hazards analysis. Results. A total of 170 patients were included in this analysis. At the time of starting treatment with tacrolimus, almost all patients were receiving corticosteroids (98.8%), and cyclophosphamide was additionally used in 42 patients (24.7%). Forty-nine patients (28.8%) discontinued tacrolimus during follow-up, mainly due to loss to follow-up, patient death, and adverse events. Mean (SD) oral corticosteroid dose decreased from 32.4 (21.6) mg/day at baseline to 7.6 (4.2) mg/day at 2 years. Overall survival at 2 years was 90.3%; corresponding progression-free survival was 62.5%. Factors found to be associated with all-cause mortality included diagnosis of clinically amyopathic DM (hazard ratio [HR] 9.04, 95% CI 1.18-69.51 vs PM), ferritin level 500 to < 1500 ng/mL (HR 8.61, 95% CI 2.51-29.45 vs < 500 ng/mL), and presence of antimelanoma differentiation-associated gene 5 antibodies (HR 8.16, 95% CI 1.03–64.47 vs absence). Conclusion. Immunosuppressive regimens containing tacrolimus appear useful for the management of IP in patients with PM/DM. [ClinicalTrials.gov: NCT02159651]