Cyclophosphamide (CYC) improves muscle strength and function as well as pulmonary function in patients with idiopathic inflammatory myopathies (IIMs) and/or IIM-related interstitial lung disease (IIM-ILD), a new systematic review found.
The review demonstrated that 80.8% of patients treated with CYC experienced improved muscle strength, and 73.1% had better muscle function, Yongpeng Ge, Department of Rheumatology, in Beijing, and his colleagues reported.
As well, 87.5% of the treated patients had decreased muscle enzyme levels, according to the review, which appeared in Clinical Rheumatology.
IIMs are systemic inflammatory disorders that involve the muscle, skin, and other organs or systems such as the joints, heart, and lungs. IIM mainly includes polymyositis (PM), dermatomyositis (DM), inclusion body myositis (IBM), and clinically amyopathic dermatomyositis (CADM). ILD is a main factor leading to poor prognosis in IIM patients.
Corticosteroids are widely used to treat IIM but many patients don't respond well to this treatment alone. Immunosuppressive agents (ISAs) such as CYC are often added, but to date there has been no systematic report on the efficacy of CYC treatment for IIM or IIM-ILD.
To address this issue, researchers searched , and (CNKI) for relevant studies that used CYC to treat patients with IIM and/or IIM-ILD from May 1975 to May 2014. The review included 12 studies: two prospective open studies, two open pilot clinical trials, and eight retrospective studies. Only one study included controls. The number of subjects in these studies ranged from seven to 26.
CYC was administered intravenously in 11 studies and orally in one study (the only one with controls). IV doses of 0.3-1.5 g/m2 or 10 to 15 mg/kg were administered at weekly to monthly intervals for 6 to 12 months. CYC therapy was usually supplemented with corticosteroids. As the patient's condition improved, CYC was administered in lower doses or less frequently (for example, monthly instead of weekly).
Four studies reported clinical data on changes in muscle strength and function using sum score, , and modified convey assessment, and in muscle enzymes using serum creatine kinase (CK) levels. Analyzing the data together, the review found that 80.8% and 73.1% of patients had improvement in muscle strength and function, respectively, and 71.2% had improvements in both. As well, 87.5% had decreased CK levels.
"The results show that IV CYC is an effective treatment for improving the muscle strength and function of IIM patients," wrote the authors.
Five studies evaluated IIM-ILD. Investigators used pulmonary function tests of forced vital capacity (FVC) and diffusing capacity for carbon monoxide (DLCO) as well as high resolution computed tomography (HRCT) to evaluate the response of IIM-ILD patients to treatment.
The analysis found that 57.6% and 64.3% of patients showed significant improvement (increases of ≥10%) in VC and DLCO, respectively, and that 67.3% of patients had significant improvement (decrease of ≥10% in score) in HRCT.
"This systematic review showed that most of the patients with IIM-ILD who were treated with CYC could experience improved FVC, DLCO, and HRCT scores after 6 or 12 months," said the authors.
Three studies reported survival rates of patients with acute/subacute IIM-ILD after CYC treatment. Of the 43 acute/subacute ILM-ILD patients who received CYC treatment, 58.1% survived.
Most adverse events possibly related to CYC were mild-to-moderate nausea and vomiting, which were treated with antiemetics. Opportunistic infections were another adverse reaction to CYC. No patient reported malignancy, gonadal failure, infertility, or hemorrhagic cystitis.
"Overall, adverse effects were not common, and the treatments were well tolerated by most of the patients," wrote the authors.
Limitations of the review were that most of the included studies were retrospective and nonrandomized, and sample sizes were small.
Large randomized, controlled trials involving CVC and IIM patients need to be conducted to draw more detailed conclusions regarding the efficacy of CYC in the treatment of IIM, the authors concluded.
Disclosures
No conflicts of interest were reported
Primary Source
Clinical Rheumatology
Ge Y, et al "Cyclophosphamide treatment for idiopathic inflammatory myopathies and related interstitial lung disease: a systematic review" Clin Rheumatol 2014; DOI 10.1007/s10067-014-2803-z.