FDA Approval for Idelalisib

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Brand name(s): Zydelig®

  • Approved for relapsed chronic lymphocytic leukemia, follicular lymphoma, and small lymphocytic lymphoma

Full prescribing information is available, including clinical trial information, safety, dosing, drug–drug interactions, and contraindications. 

On July 23, 2014, the Food and Drug Administration (FDA) approved idelalisib (Zydelig® tablets, Gilead Sciences, Inc.) for the treatment of patients with relapsed chronic lymphocytic leukemia (CLL), in combination with rituximab, for whom rituximab alone would be considered appropriate therapy due to other comorbidities. 

In addition, the FDA granted accelerated approval to idelalisib for the treatment of patients with relapsed follicular B-cell non-Hodgkin lymphoma (FL) or relapsed small lymphocytic lymphoma (SLL) who have received at least two prior systemic therapies.

The approval for CLL was based on the results of an international multicenter randomized placebo-controlled trial of 220 patients comparing idelalisib 150 mg twice daily in combination with rituximab to placebo in combination with rituximab. Rituximab was administered in eight doses (first dose at 375 mg/m2, subsequent doses at 500 mg/m2) every 2 weeks for four infusions, then every 4 weeks for four infusions.

Progression-free survival (PFS), as assessed by a blinded independent review committee, was the primary efficacy endpoint. The trial was stopped early based on an interim analysis; median duration of exposure to idelalisib was 5.0 months. Median PFS was not reached (95 percent CI 10.7, NR) in the idelalisib plus rituximab arm and was 5.5 months (95 percent CI 3.8, 7.1) in the placebo plus rituximab arm [HR 0.18 (95 percent CI: 0.10, 0.32); p < 0.0001]. 

Accelerated approval for FL and SLL was based on the results of a multicenter single-arm open-label trial enrolling patients with relapsed indolent non-Hodgkin lymphomas who were started on idelalisib 150 mg twice daily. The primary efficacy endpoint was overall response rate as assessed by an independent review committee. In the 72 patients with FL, the overall response rate was 54 percent (95 percent CI: 42, 66), and the median response duration was not evaluable. In the 26 patients with SLL, the overall response rate was 58 percent (95 percent CI: 37, 77), and the median response duration was 11.9 months.

Idelalisib is being approved with a Boxed Warning alerting patients and healthcare professionals of the following fatal and serious adverse reactions: liver toxicity, severe diarrhea or colitis, inflammation of the lungs, and intestinal perforation. The most common adverse reactions (incidence 20 percent or greater) are diarrhea, fever, fatigue, nausea, cough, pneumonia, abdominal pain, chills, and rash. The most common lab abnormalities (incidence 30 percent or greater) are neutropenia, high triglycerides, high blood sugar, and elevated serum enzymes (alanine transaminase and aspartate transaminase).

The recommended dose and schedule for idelalisib is 150 mg orally twice daily for patients with FL and SLL and in combination with rituximab for patients with CLL.

  • Posted: July 29, 2014