Ofatumumab retreatment and maintenance in patients with fludarabine-refractory CLL.

6584 Background: In Study 406, the anti-CD20 monoclonal antibody ofatumumab (ofa), given as monotherapy over 6 months, showed 47% overall response rate (ORR) in patients (pts) with chronic lymphocytic leukemia (CLL) refractory to fludarabine and alemtuzumab (FA-ref), or to fludarabine with bulky (>5cm) lymphadenopathy (BF-ref). The effects of ofa retreatment (retx) and maintenance (mt) are unknown. Methods: Pts who responded to ofa and then progressed or had stable disease (SD) in Study 406, were offered retx in Study 416 (NCT00802737; GSK/Genmab) with ofa 1 x 300 mg + 7 x 2000 mg weekly followed by mt with ofa 2000 mg monthly for up to 2 years (if SD or better). Primary endpoint was OR…