Entospletinib monotherapy in patients with relapsed or refractory chronic lymphocytic leukemia previously treated with B-cell receptor inhibitors: results of a phase 2 study.

Entospletinib (GS-9973), an oral, selective inhibitor of spleen tyrosine kinase (SYK), was evaluated as monotherapy in this multicenter, phase 2 study (NCT01799889) of 49 patients with relapsed or refractory chronic lymphocytic leukemia (CLL), including those with Richter's transformation (RT), who had received prior therapy with a B-cell receptor (BCR) inhibitor. Patients were treated with entospletinib 400 mg BID as the starting dose. Sixteen patients achieved partial response and 21 had stable disease.