Acalabrutinib Plus Obinutuzumab in Treatment-Naive and Relapsed/Refractory Chronic Lymphocytic Leukemia

Acalabrutinib is a selective irreversible Bruton tyrosine kinase inhibitor that does not affect interleukin-2 associated tyrosine kinase or antibody-dependent cellular cytotoxicity, making it an attractive candidate for combination therapy with anti-CD20 antibodies. We investigated acalabrutinib plus obinutuzumab in a phase 1b/2 study (NCT02296918) of patients with treatment-naive or relapsed/refractory chronic lymphocytic leukemia (CLL). Nineteen treatment-naive and 26 relapsed/refractory patients were treated with acalabrutinib (100 mg twice daily) until progression and obinutuzumab (cycle 1: 100 mg day 1, 900 mg day 2, 1000 mg days 8 and 15; cycles 2-6: 1000 mg day 1). Grade 3/4 adverse events occurred in 71% of patients. Overall response rates were 95% (treatment-naive) and 92% (relapsed/refractory). Thirty-two percent of treatment-naive and 8% of relapsed/refractory patients achieved complete remission. At 36 months, 94% (treatment-naive) and 88% (relapsed/refractory) were progression free. Acalabrutinib plus obinutuzumab was well tolerated, producing high and durable responses in treatment-naive and relapsed/refractory CLL.