Celgene arthritis drug effective in mid-stage study

* Drug meets primary goal at 2 doses in Phase II trial

* Plans to move drug into Phase III studies

NEW YORK, June 15 (Reuters) - An experimental anti-inflammatory drug being developed by Celgene Corp(CELG.O) met the primary goal of a mid-stage study of patients with psoriatic arthritis, according to preliminary results announced by the biotechnology company on Monday.

The oral drug, apremilast, which was tested at 20 milligrams twice per day and 40 mg once per day, was significantly better than a placebo at both dosing regimens in the 12-week, 204-patient trial, Celgene said.

The company said it would proceed with late-stage testing of the drug for both psoriatic arthritis and the related skin condition psoriasis. The drug is also being studied in several other inflammatory diseases, the company said.

The primary goal was improvement in ACR20 outcome -- the percentage of patients achieving a 20 percent or better improvement in arthritis symptoms -- versus placebo.

In the 20 mg twice daily apremilast group, 43.5 percent of patients achieved ACR20 scores, while 35.8 percent of patients in the 40 mg once daily group reached ACR20. That compared with just 11.8 percent in the placebo arm, Celgene said.

The study also measured ACR50 and ACR70 -- 50 percent and 70 percent improvement responses.

In the 20 mg group, 17.4 percent of patients achieved ACR50 and 5.8 percent reached 70 percent improvement. Among those who took the 40 mg dose, 13.4 percent hit ACR50 and 7.5 percent reached ACR70. That compared with 2.9 percent ACR50 and just 1.5 percent ACR70 in patients who received a placebo, according to the preliminary data.

Psoriatic arthritis is a debilitating type of inflammatory arthritis that affects more than a million people in the United States and Europe. The condition causes pain, stiffness and swelling in and around the joints, as well as joint destruction.

The most common adverse events reported in the study were nausea, diarrhea, headache, cold-like symptoms and fatigue. There was not a significant difference in infections between apremilast and placebo, Celgene said. (Reporting by Bill Berkrot; Editing Bernard Orr)