Denmark’s Genmab and partner GlaxoSmithKline say that they are ready to put the fully human monoclonal antibody HuMax-CD20 into late-stage trials as a treatment for rheumatoid arthritis.

The decision comes after the firm presented data from a Phase II study of HuMax-CD20 (ofatumumab) at the European League Against Rheumatism congress in Barcelona, Spain. In the 24-week, 244-patient trial, 46% people taking ofatumumab experienced a 20% response in symptoms, 24% had a 50% improvement and a 70% improvement was achieved by 6%, compared to 15%, 5% and 0% respectively in the placebo treatment group. Overall, 72% taking HuMax-CD20 at any of the various dosages (300mg, 700mg and 1,000 mg) experienced at least a moderate response compared to 40% of patients receiving placebo at week 24.

“The level of response of patients in the study illustrates the potential of ofatumumab in the treatment of RA and we hope to see similar results in the Phase III study being planned for later this year,” said Genmab’s chief executive Lisa Drakeman. The company also noted that it has initiated a Phase II study of HuMax-CD20 in combination with cyclophosphamide, doxorubicin, vincristine and prednisone in 56 patients with previously untreated follicular non-Hodgkin’s lymphoma, and the compound is also in late stage development for CD20 positive B-cell chronic lymphocytic leukaemia.

Analysts believe that the NHL indication is where most potential lies for HuMax-CD20 because in rheumatoid arthritis it will be up against Roche’s MabThera (rituximab), sold as Rituxan by Genentech in the USA, and the data revealed so far on ofatumumab does not suggest any advantages in terms of efficacy against the Swiss firm’s product.

GSK signed up as a partner for HuMax-CD20 in December in a deal that could be worth over £1 billion to Genmab. Ms Drakeman has previously suggested that the drug could generate well over $2 billion in annual sales, though some feel even that is a little conservative, if it receives approval in all three indications. Other potential therapeutic areas for HuMax-CD20 include Crohn's disease and Wegener's Granulomatosis.