Idelalisib is a targeted therapy which is approved in combination with rituximab for the treatment of patients with relapsed chronic lymphocytic leukaemia (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.

Researchers conducted a Phase III, randomised, placebo-controlled study that evaluated the efficacy of idelalisib when added to bendamustine and rituximab (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.

A pre-specified 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 anaemia.

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.

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Source: ASH