On July 23, 2014, the FDA approved idelalisib (Zydelig; Gilead Sciences) for the treatment of patients with relapsed CLL to be used in combination with rituximab. Idelalisib is recommended for use in this patient population in those for whom rituximab alone would be considered inappropriate therapy because of potential comorbidities.
Also on July 23, the FDA granted idelalisib an accelerated approval for the treatment of patients with relapsed follicular B-cell non-Hodgkin lymphoma (FL), as well as relapsed small lymphocytic lymphoma (SLL). Idelalisib is intended to be used in patients who have received at least 2 previous systemic therapies.
Idelalisib’s safety and effectiveness for relapsed CLL were established in a clinical trial of 220 patients with this condition who were randomized to receive idelalisib plus rituximab or placebo plus rituximab. The trial was stopped after the first prespecified interim analysis point, which showed that the active combination resulted in 10.7 months PFS compared with approximately 5.5 months with rituximab plus placebo.
The safety and effectiveness of idelalisib in the treatment of FL and relapsed SLL were established in a clinical trial with 123 patients with indolent non-Hodgkin lymphomas. Results showed a 54% objective response rate (ORR) in patients with relapsed FL and 58% ORR for patients with SLL.
Idelalisib carries a Boxed Warning regarding the risk of fatal and serious toxicities. The drug was also approved with a REMS (Risk Evaluation and Mitigation Strategy) program.