Open-label study on treatment with 20 % subcutaneous IgG administration in polymyositis and dermatomyositis.

The objective of this study is to describe the benefit of 20 % subcutaneous infusions of immunoglobulin (SCIg) in patients with dermatomyositis (DM) or polymyositis (PM) after a switch from previous 16 % SCIg treatment. Eight patients with DM or PM, who met the Bohan and Peter's criteria, previously treated with 16 % SCIg, were switched to weekly 20 % SCIg infusions (Hizentra®; CSL Behring) at doses equivalent to their previous subcutaneous treatment. A standardised protocol was used to evaluate patients, disease activity and treatment response. The disease remained stable in three and improved in four other patients, as documented by increased Medical Research Council scores and normal serum CK levels. No relapse of disease occurred. Local reactions were mild and self-limiting. No serious adverse events were reported. The mean duration of infusion per week was significantly lower compared to the mean duration of the 16 % SCIg preparation. A specifically designed questionnaire documented the patients' satisfaction with treatment. The weekly administration of 20 % SCIg is effective in maintaining a quiescent disease in patients with DM or PM with no increased safety concerns. SCIg therapy is particularly attractive for patients because it does not require venous access and hospitalisation and requires less assistance from healthcare provider services.Key messages• The administration of 20 % SCIg was beneficial and safe in maintaining a quiescent disease and in inducing a complete remission in moderately active disease in patients with DM or PM.• The treatment with 20 % SCIg lead to the possibility to discontinue and to reduce the use of glucocorticoids and/or the immunosuppressants.• Patients reported their satisfaction in terms of contact with health professionals, quality of treatment-related information and administration convenience, with an improved quality of life.