UPDATE 1-Idera says drug safe, well tolerated in skin disease study

(Adds details; updates shares)

March 28 (Reuters) - Idera Pharmaceuticals Inc said its lead experimental drug for the most common form of psoriasis was found to be safe and well tolerated by patients after 12 weeks of treatment in a mid-stage trial.

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

Idera also said the drug, codenamed IMO-8400, reduced the severity of skin lesions in patients with plaque psoriasis compared with a placebo.

The drug reduced the severity of lesions by 50 percent in nine of the 20 patients and by 75 percent in four patients, the company said.

Idera said data from the study would support the drug's development as a treatment for rare autoimmune diseases and a common form of blood cancer with certain genetic mutations.

There were no treatment-related discontinuations or severe adverse events reported in the 32 patients enrolled in the study, the Cambridge, Massachusetts-based company said.

The trial tested three doses of the drug in patients with moderate-to-severe plaque psoriasis. The drug works by inhibiting a type of protein that plays a role in worsening autoimmune diseases and B-cell lymphoma.

Idera said the drug was also being tested in a study on patients with Waldenstrom's macroglobulinemia, a rare form of B-cell lymphoma.

The company's shares closed at $3.88 on the Nasdaq on Thursday.

(Reporting by Vrinda Manocha in Bangalore; Editing by Kirti Pandey)