UC Irvine

Three agents have received Food and Drug Administration (FDA) approval for treatment of chronic lymphocytic leukemia (CLL) within the past year. Ibrutinib and idelalisib block B-cell receptor signaling through inhibition of Bruton tyrosine kinase and phosphatidylinositol 3-kinase δ molecules respectively, interfering with several pathways required for leukemia cell survival. Idelalisib has shown efficacy in the relapsed setting and is currently approved by the FDA for use in combination with rituximab. Ibrutinib has been studied in patients with relapsed CLL and as frontline therapy. In the relapsed setting, these agents produce durable remissions, and might be preferable to re-treatment with chemoimmunotherapy for many patients. Ibrutinib is also effective treatment for patients with deletion 17p and is approved by the FDA as frontline therapy in this patient group, although it does not appear to completely abrogate this adverse prognostic factor. These agents have a unique side effect profile and longer follow-up is required to further understand tolerability and rare adverse effects. Obinutuzumab is a type-2 monoclonal anti-CD20 antibody which results in direct and antibody-dependent cell-mediated cytotoxicity of leukemia cells. It is approved by the FDA for use in combination with chlorambucil, and has shown efficacy in the frontline setting in patients unfit for more intensive chemoimmunotherapy. It produces increased response rates and minimal residual disease negativity compared with chlorambucil/rituximab and is associated with an advantage in progression-free survival but not yet overall survival. These agents underscore our advancement in the understanding of the biology of CLL and will improve outcomes for many patients with CLL.