Dr. Abedin on PI3K Inhibitors in CLL

Sameem Abedin, MD, assistant professor, Medical College of Wisconsin, discusses the use of PI3K inhibitors in the treatment of patients with chronic lymphocytic leukemia (CLL).

There are two approved PI3K inhibitors in CLL: duvelisib (Copiktra) and idelalisib (Zydelig). In 2018, the FDA approved duvelisib for the treatment of patients with relapsed/refractory CLL based on results from the phase III DUO study. In the trial, patients with relapsed/refractory CLL who had received ≥2 prior lines of therapy experienced a 60% reduction in the risk of disease progression or death versus ofatumumab (Arzerra).

In 2014, idelalisib was approved for use in combination with rituximab (Rituxan) in the relapsed/refractory setting based on data from the phase III Study 116 trial (NCT01539512). The trial was stopped early due to the dramatic improvement in progression-free survival (PFS) with the combination. At 24 weeks, the PFS rate of PFS was 93% in the combination arm and 46% in the rituximab-alone arm. The agents have slightly different mechanisms of action, and duvelisib has more immune properties, says Abedin.

In terms of administration, duvelisib is given as monotherapy, whereas idelalisib is given in combination with rituximab. For patients, the ease of taking a pill may be preferable to the combination, according to Abedin.