Objectives: To study the efficacy and safety of monthly intravenous pulse cyclophosphamide (IVCYC) therapy for progressive interstitial pneumonia in polymyositis/dermatomyositis (PM/DM).
Methods: Seventeen patients with PM/DM/amyopathic DM (mean age 51.4 +/- 10.4, mean follow-up 32 months) who received IVCYC for progressive interstitial pneumonia between August 1993 and October 2002 were studied. Nine patients had failed to respond to previous treatment with high-dose steroid and/or immunosuppressant. Cyclophosphamide (300-800 mg/m2) was given at least six times every 4 weeks. Oral prednisolone (0.5-1 mg/kg/day) was administered for the first 2 weeks and was gradually tapered. Response to treatment was evaluated based on the degree of exertional dyspnea, pulmonary function test and high-resolution computed tomography (HRCT).
Results: Eleven of 17 patients showed improvement in their dyspnea; six out of seven patients who had required oxygen treatment before IVCYC no longer did so after IVCYC. Eight of 17 patients had >or=10% improvement of vital capacity (VC)% and 9/17 had >or=10 point reduction in their HRCT score. Twelve patients had exhibited at least one result. Two patients with anti-Jo-1 antibodies showed a flare-up of interstitial pneumonia or myositis. After the IVCYC therapy, mean VC% improved by 15% (from 68 to 83%, P = 0.0034). The extent of abnormal lesions in HRCT was reduced from 24 to 13% (P = 0.0055). There was neither death nor severe toxicities observed.
Conclusions: In this open-label study, IVCYC improved symptoms, pulmonary function tests and HRCT findings in patients with PM/DM. Longitudinal controlled studies are required to further confirm the efficacy of IVCYC.