Genmab A/S has initiated a Phase II study with HuMax-CD20 to treat patients with active rheumatoid arthritis (RA) who have failed one treatment with one or more disease modifying anti-rheumatic drugs (DMARDs). Genmab has completed treatment of 33 patients in a Phase I/II dose escalation trial and expanded the study into a Phase II trial, which will include 200 additional patients.

In the Phase II trial, a total of 200 patients will be randomized into four treatment groups. In each group, 50 patients will receive two infusions of either 300, 700, or 1000 mg doses of HuMax-CD20 or placebo. The doses will be given two weeks apart. Patients receiving a stable dose of methotrexate between 7.5 and 25 mg per week at the time of screening will continue with it. Patients will be followed for 24 weeks to evaluate safety and efficacy and then every 12 weeks until B-cell counts return to baseline levels, according to a company release.

HuMax-CD20 is a human antibody which is effective at binding to the CD20 molecule on B-cells. In June 2005, Genmab presented positive data from a Phase I/II trial with patients with relapsed or refractory follicular lymphoma showing response rates up to 63% in patients treated with HuMax-CD20.