Dr William Wierda speaks about his work developing a treatment for patients with chronic lymphocytic leukaemia (CLL) that are refractory to standard therapies. Patients were divided into those refractory to fludarabine and alemtuzumab and those refractory to fludarabine with bulky lymph nodes, and were treated with the human CD20 monoclonal antibody ofatumumab. The trial demonstrated that ofatumumab can be used as a safe effective monotherapy for these patient populations. Dr Wierda explains how the patient groups were defined, what treatment regimen they received, outlines the adverse effect that were encountered and discusses how this treatment may be incorporated in first line CLL treatment.