Array BioPharma has reported that the Phase 2 trial of ARRY-797 in 157 osteoarthritis patients suffering from moderate to severe knee pain despite the use of non-steroidal anti-inflammatory drugs (NSAIDs) met its primary endpoint.

The treatment with ARRY-797, a novel, oral, selective p38 inhibitor, resulted in a statistically significant reduction in pain over a 28-day period compared to placebo, as measured using the Western Ontario and McMaster Universities Arthritis Index (WOMAC) pain subscale (a 0-10 numerical pain rating scale).

The Altoona Arthritis and Osteoporosis Center founder and a study investigator Alan Kivitz said the study results with ARRY-797 showed promising benefit in the management of pain in osteoarthritis patients who are refractory to NSAIDS.

"This study was designed with a high hurdle in mind, which this drug was able to overcome," Kivitz added.

Patients receiving ARRY-797 in the study experienced a mean reduction in the WOMAC pain subscale score at day 28 vs. baseline that was 0.8 greater than those receiving placebo (2.4 vs. 1.6; one-sided p = 0.0247).

WOMAC physical function, WOMAC stiffness, responder analysis and the Patient’s Global Impression of Change, additional endpoints, also showed improvement relative to placebo.

ARRY-797 was considered to be well-tolerated at the selected dose of 400mg twice-daily, with the most common adverse events observed in patients being dizziness, diarrhoea and nausea.

ARRY-797 treatment was associated with sporadic, transient increases in creatine kinase and aspartate aminotransferase.

The mild prolongations of the QTc interval and sustained decreases in systolic and diastolic blood pressure were also observed in the trial.

Array BioPharma chief executive officer Ron Squarer said, "These results, together with our earlier studies in acute pain, provide evidence that ARRY-797 delivers therapeutic utility in both acute and chronic pain settings."