Idera Pharmaceuticals Inc. said its experimental drug for an inflammatory skin disease was found safe and well tolerated by patients after 12 weeks of treatment in a mid-stage trial.

The company's shares rose about 40 percent to $5.40 in premarket trading on Friday.

Idera said there were no treatment-related discontinuations or severe adverse events reported in the 32 patients with moderate-to-severe plaque psoriasis enrolled in the study.