Ibrutinib versus rituximab in relapsed or refractory chronic lymphocytic leukemia or small lymphocytic lymphoma: a randomized, open‐label phase 3 study

In the Asia‐Pacific region, treatment options are limited for patients with relapsed/refractory chronic lymphocytic leukemia (CLL)/small lymphocytic lymphoma (SLL). Rituximab is widely used in this setting when purine analog‐based therapies are not appropriate. We evaluated the efficacy and safety of ibrutinib compared with rituximab in a randomized, open‐label phase 3 study in predominantly Asian patients with relapsed/refractory CLL/SLL. Patients (N = 160) were randomly assigned 2:1 to receive 420 mg ibrutinib (n = 106) until disease progression (PD) or unacceptable toxicity or up to six cycles of rituximab (n = 54). The primary endpoint was investigator‐assessed progression‐free survival (PFS); key secondary endpoints were overall response rate (ORR), overall survival (OS), and safety. Rituximab‐treated patients could crossover to receive ibrutinib after confirmed PD. At data cutoff, median treatment duration was 16.4 months for ibrutinib and 4.6 months for rituximab. Ibrutinib significantly improved PFS (hazard ratio [HR] = 0.180, 95% confidence interval [CI]: 0.105–0.308). ORR was significantly higher (P