GlaxoSmithKline (GSK) and Genmab A/S announced preliminary top-line results from a phase-III study of ofatumumab administered intravenously for the treatment of rheumatoid arthritis (RA) in patients who had an inadequate response to methotrexate. The study met the primary endpoint, ACR20 at 24 weeks, which indicates a 20 per cent or greater improvement in the number of swollen and tender joints, as well as improvements in other disease-activity measures.

In the study, 260 patients were treated and included in the analysis. At week 24, the ACR20 response rate was significantly greater for RA patients on ofatumumab (n=129) than on placebo (n=131) with a 50 per cent response rate in the patients receiving ofatumumab, compared to 27 per cent for patients on placebo (p-value less than 0.001). All key secondary endpoints were significant (p-value less than or equal to 0.001).

There were no unexpected safety findings. The most common adverse events in the ofatumumab treated patients (greater than 5 per cent) were rash, urticaria, nasopharyngitis, pruritus, throat irritation and hypersensitivity. Other than nasopharyngitis, these events generally occurred within 24 hours of the first infusion. One death, judged by the investigator as unrelated to ofatumumab, was reported in the study during the 24-week study period.

"We have always believed in ofatumumab's potential to make a difference in patients' lives. We are pleased with the results of this study, supporting the further investigation of this antibody's promise in the treatment of RA," said Lisa N Drakeman, chief executive officer of Genmab.

"RA can be a highly debilitating disease. It is encouraging to see the reduction in disease symptoms achieved with intravenous ofatumumab, and we look forward to presenting the full study results," said Carlo Russo, senior vice president, Biopharm Development, GSK.

Ofatumumab is a novel, investigational, fully human monoclonal antibody that targets a membrane-proximal (close to the cell surface) small loop epitope (a portion of a molecule to which an antibody binds) on the CD20 molecule of B-cells.