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ASH 2015: Combination Therapy With Idelalisib Improves Progression-Free Survival vs Bendamustine/Rituximab Alone in Relapsed/Refractory CLL

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Key Points

  • A prespecified interim analysis revealed that median progression-free survival was 23 months in the idelalisib arm compared to 11 months in the placebo arm.
  • In addition, there was a statistically significant improvement in overall survival for patients treated on the idelalisib-plus-BR arm compared to the BR-plus-placebo arm.

In a phase III study to be presented by Zelenetz et al at the 57th American Society of Hematology Annual Meeting, idelalisib (Zydelig) plus bendamustine (Treanda) and rituximab (Rituxan), or BR, proved superior to BR alone in patients with relapsed/refractory chronic lymphocytic leukemia (CLL) [Abstract LBA-5].

Idelalisib is a targeted therapy that is approved in combination with rituximab for the treatment of patients with relapsed CLL. This highly selective compound targets the delta isoform of the PI3 kinase enzyme, which is critical for the activation and survival of CLL cells and other low-grade B-cell lymphomas.

Study Details

Researchers conducted a phase III, randomized, placebo-controlled study that evaluated the efficacy of idelalisib when added to BR, the standard treatment regimen for patients with relapsed or treatment-resistant CLL.

A total of 416 patients were enrolled. Of those, 207 received 150 mg of idelalisib twice daily plus BR, and 209 received placebo plus BR. Patients received six cycles of therapy until their disease progressed or they experienced unacceptable toxicity.

Key Findings

A prespecified interim analysis revealed that median progression-free survival, the primary endpoint, was 23 months in the idelalisib arm compared to 11 months in the placebo arm. Based on this result, the Independent Data Monitoring Committee recommended the study be unblinded based on “overwhelming efficacy.”

In addition, there was a statistically significant improvement in overall survival, a secondary endpoint, for patients treated on the idelalisib-plus-BR arm compared to the BR-plus-placebo arm.

The safety profile of idelalisib plus BR was consistent with prior reported studies. The most common severe adverse events were related to low white blood cell count and anemia.

This study suggests that idelalisib in combination with BR provides better outcomes for patients than BR alone, reducing the risk of both disease progression and death with a tolerable safety provide. This combination is an important new option for patients with relapsed or treatment-resistant CLL, the investigators concluded. 

The content in this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO®) and does not necessarily reflect the ideas and opinions of ASCO®.


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