Chelsea Therapeutics International Ltd. announced that a preliminary analysis of its dose-ranging exploratory Phase 2 trial of CH-4051, a non-metabolized antifolate, in patients with rheumatoid arthritis (RA) who experience an inadequate response to methotrexate (MTX) treatment indicates that CH-4051 did not demonstrate superior efficacy to methotrexate in the dose range evaluated.

"Results of this study provide evidence of the clinical activity of CH-4051, in a dose dependent manner, across multiple RA assessment criteria," commented Dr. Simon Pedder, president and CEO of Chelsea Therapeutics. "However, the outcome of the trial was confounded by the unexpectedly robust response reported by patients treated with methotrexate. While we believe that higher doses of CH-4051 could provide enhanced therapeutic benefit in RA and that CH-4051 could be developed for other anti-inflammatory and autoimmune indications, we believe our current resources would be better allocated toward the planned completion of our Northera (droxidopa) development program in neurogenic orthostatic hypotension. Consequently, we have no immediate plans to continue development of CH-4051."

Using a modified intent-to-treat (ITT) population of 244 patients with a post-baseline efficacy assessment, the primary efficacy analyses utilized the hybrid American College of Rheumatology score (hACR) followed by the traditional ACR 20 (20% improvement in ACR criteria) to compare responses among patients treated with 0.3 mg (n=48), 1.0 mg (n=48) or 3.0 mg (n=49) of CH-4051 daily, 3.0 mg of CH-4051 daily in combination with a folate supplement (n=49) or 20.0 mg MTX weekly (n=50) with a folate supplement for 12 weeks following a two-week MTX-washout.

At the end of the 12-week period, patients treated with MTX showed greater improvement in both mean hACR (38.4) and ACR20 response rate
(56.0%) compared to patients treated with 0.3 mg CH-4051 (hACR: 15.0, ACR20: 41.7%), 1.0 mg CH-4051 (hACR: 17.9, ACR20: 45.8%), 3.0 mg CH-4051 (hACR: 25.2, ACR20: 34.7%) or 3.0 mg CH-4051 with folate supplement (hACR: 25.5, ACR20: 45.8%).

CH-4051 was found to be safe and well tolerated in the study, with no dose-limiting toxicities or clear differences in the overall adverse event rate between the MTX (52.9%) and 0.3 mg, 1.0 mg and 3.0 mg CH-4051 (38.0%, 42.9% and 30.0%) and 3.0 mg CH-4051 plus folate (49.0%) treatment groups.

Date: May 31, 2012
Source: Chelsea Therapeutics International Ltd.