Primarily expressed in leukocytes as a tyrosine kinase, PIK3δ is essential in BCR signaling for the promotion of B cell survival and proliferation.3 Idelalisib, a specific inhibitor of PIK3δ, was approved by the US FDA for the treatment of relapsed CLL.1,2 Initial registration trials, when combined with rituximab, an anti-CD20 monoclonal antibody, showed promising results including increased progression-free survival (PFS) with equal rates of adverse events in comparison to rituximab alone. The gene discussed is BCR; the disease is B-cell chronic lymphocytic leukemia.