Results of Phase 2 rheumatoid arthritis clinical trial announced

Array BioPharma Inc. (Nasdaq: ARRY) announced its preliminary analysis of results from a study examining ARRY-162, a small molecule MEK inhibitor, in a 12-week Phase 2 clinical trial with 201 patients. The patients had active rheumatoid arthritis (RA) that was not completely responsive to methotrexate. This study included a placebo group and three different dose groups of ARRY-162, all on a stable background of methotrexate. None of the treatment groups demonstrated a statistically significant ACR20 response rate compared to the placebo group at 12 weeks>

Overall, the placebo response rates in this study were higher than expected for this patient population and showed regional differences, with patients in South America (99 patients) having substantially higher placebo response rates than those in Eastern Europe (101 patients). In Eastern Europe when patients in the three active treatment arms were combined, there was a trend towards efficacy, as measured by DAS28-4(CRP)>

“This is the first clinical trial evaluating the modulation of the MEK pathway for the treatment of chronic inflammatory disease,” said Kevin Koch, Ph.D., President and Chief Scientific Officer. “While we are disappointed in the overall efficacy outcome, we were pleased with the confirmation of the favorable safety profile and are continuing to evaluate the regional results. Previously we announced our strategy to rapidly advance ARRY-162 for the treatment of cancer patients. We initiated a Phase 1 oncology trial last month and patient dosing is underway.”

Array will host a conference call on Friday, September 4, 2009, at 9:00 a.m. ET to discuss these results (see conference call details below). Array has also posted additional slides discussing these results on the Investor Relations section of Array’s website at www.arraybiopharma.com.

Efficacy Results

The table below shows the ACR20 response rates at 12 weeks evaluated overall and by region in the efficacy evaluable population using last observation carried forward method.

ACR20 Response Rates at 12 weeks – Overall and by Region

*Global P value compares all four treatment arms.

Safety Results

Consistent with earlier studies of up to 28 days with ARRY-162, the most common drug-related adverse events (AEs) observed in the study were skin-related (e.g., rash, dermatitis) and diarrhea. The incidence of these findings were most common in the 20 mg BID and 40 mg QD dose groups, and were generally mild-to-moderate in intensity. There were no drug-related serious adverse events. The table below shows the most frequently reported drug-related adverse events in the safety population.

Most Commonly Reported Drug-Related Adverse Events

Drug-related as assessed by investigators, blinded to treatment.
* includes any event of rash, rash pustular, rash erytematous, rash papular, folliculitis, acne, dermatitis acneiform, eczema, prurigo, rosacea, urticaria and erythema.
** includes any event of alanine aminotransferase increased, aspartate aminotransferase increased, gamma-glutamyltransferase increased, hepatic enzyme increased, liver function test abnormal and transaminases increased. All events were Grade 1 in severity.