The phase 4 study evaluating H.P. Acthar Gel in patients with rheumatoid arthritis exceeded its enrollment goal, Mallinckrodt Pharmaceuticals announced. The ongoing study enrolled more than 230 adult patients over the age of 18 with active rheumatoid arthritis at 100 sites across the United States.

H.P. Acthar Gel (repository corticotropin injection) is a short-term treatment approved by the U.S. Food and Drug Administration (FDA) for patients with rheumatoid arthritis including juvenile arthritis.

Acthar gel is an injectable adrenocorticotropic hormone that acts as an anti-inflammatory drug. It is approved as a treatment for 19 different conditions, including lupus and sarcoidosis.

“This is an exciting milestone achievement in this important clinical trial,” Steven Romano, MD, executive vice president and chief scientific officer at Mallinckrodt, said in a press release. “As prescribers consider the potential benefit H.P. Acthar Gel may provide for appropriate RA [rheumatoid arthritis] patients with persistent disease activity, we are hopeful the findings from this study will help guide those decisions.”

Arthritis treatments aim to reduce inflammation, which in turn can relieve pain and stiffness, thus improving a patient’s quality of life.

In this two-part, multicenter Phase 4 study (NCT02919761), patients with active rheumatoid arthritis who did not respond to corticosteroids and disease-modifying anti-rheumatic drugs will receive Acthar Gel for 12 weeks.

Disease activity in these patients will be evaluated at the end of the 12 weeks using the Disease Activity Score 28-joint-count Erythrocyte Sedimentation Rate (DAS28-ESR). Patients with a DAS28-ESR that is less than 3.2, considered low disease activity, will enter the second part of the study.

In the second part, the qualifying patients will be randomly divided to receive either Acthar Gel or placebo for another 12 weeks. Researchers will monitor the ability of the patients to maintain low disease activity throughout the total of 24 weeks.

Partial data from the study was recently presented at the Annual European Congress of Rheumatology. In total, 48 patients have completed the first part of the study. Researchers reported that 58 percent of these patients achieved low disease activity supporting the effectiveness of the treatment.

“Our clinical programs for H.P. Acthar Gel are conducted specifically to further establish its clinical utility in tough-to-treat patient populations. … It is our intent to use the data from these programs to better inform prescribers, facilitating access for appropriate patients in both commercial plans and government programs,” said Mark Trudeau, president and chief executive officer at Mallinckrodt.