We randomly assigned patients ( 1:1 ) to receive oral chlorambucil ( 10 mg/m ( 2 ) ) on days 1-7 of a 28 day treatment course or to receive chlorambucil by this schedule plus intravenous ofatumumab ( cycle 1 : 300 mg on day 1 and 1000 mg on day 8 ; subsequent cycles : 1000 mg on day 1 ) for three to 12 cycles .