A phase 3 clinical trial compared ibrutinib, a Bruton's tyrosine kinase inhibitor, with ofatumumab, an anti-CD20 antibody, in patients with previously treated chronic lymphoid leukemia (CLL) or small lymphocytic lymphoma (SLL). The study enrolled 391 patients who had relapsed or refractory disease and were at high risk for poor outcomes. The primary endpoint was progression-free survival (PFS), with overall survival (OS) and overall response rate (ORR) as secondary endpoints. At a median follow-up of 9.4 months, ibrutinib significantly improved PFS, with a median PFS not reached in the ibrutinib group (88% PFS at 6 months) compared to 8.1 months in the ofatumumab group (hazard ratio 0.22, P<0.001). Ibrutinib also significantly improved OS (hazard ratio 0.43, P=0.005), with 90% OS at 12 months versus 81% in the ofatumumab group. The ORR was significantly higher in the ibrutinib group (42.6% vs. 4.1%, P<0.001). Ibrutinib showed benefits regardless of prior resistance to purine analogues or chromosome 17p13.1 deletion. Common adverse events included diarrhea, fatigue, and nausea in the ibrutinib group, and fatigue, infusion reactions, and cough in the ofatumumab group. Ibrutinib was generally well-tolerated, with no frequent dose reductions or discontinuations. The study demonstrated that ibrutinib significantly improved PFS, OS, and ORR compared to ofatumumab in patients with previously treated CLL or SLL. The results support ibrutinib as a superior treatment option for this patient population. The study was funded by Pharmacyclics and Janssen.A phase 3 clinical trial compared ibrutinib, a Bruton's tyrosine kinase inhibitor, with ofatumumab, an anti-CD20 antibody, in patients with previously treated chronic lymphoid leukemia (CLL) or small lymphocytic lymphoma (SLL). The study enrolled 391 patients who had relapsed or refractory disease and were at high risk for poor outcomes. The primary endpoint was progression-free survival (PFS), with overall survival (OS) and overall response rate (ORR) as secondary endpoints. At a median follow-up of 9.4 months, ibrutinib significantly improved PFS, with a median PFS not reached in the ibrutinib group (88% PFS at 6 months) compared to 8.1 months in the ofatumumab group (hazard ratio 0.22, P<0.001). Ibrutinib also significantly improved OS (hazard ratio 0.43, P=0.005), with 90% OS at 12 months versus 81% in the ofatumumab group. The ORR was significantly higher in the ibrutinib group (42.6% vs. 4.1%, P<0.001). Ibrutinib showed benefits regardless of prior resistance to purine analogues or chromosome 17p13.1 deletion. Common adverse events included diarrhea, fatigue, and nausea in the ibrutinib group, and fatigue, infusion reactions, and cough in the ofatumumab group. Ibrutinib was generally well-tolerated, with no frequent dose reductions or discontinuations. The study demonstrated that ibrutinib significantly improved PFS, OS, and ORR compared to ofatumumab in patients with previously treated CLL or SLL. The results support ibrutinib as a superior treatment option for this patient population. The study was funded by Pharmacyclics and Janssen.