Combination treatment with idelalisib plus rituximab may have a beneficial effect compared with rituximab alone in patients with relapsed or refractory chronic lymphocytic leukemia (CLL) regardless of the presence of a complex karyotype (CK), according to the results of a recent post-hoc analysis.

The study was really an exploratory analysis of 2 studies: a primary study comparing rituximab with or without idelalisib and an extension study of idelalisib monotherapy.

The original study randomly assigned 220 patients to idelalisib-rituximab or placebo-rituximab. This study was closed early because of the superior efficacy of the idelalisib-rituximab regimen, according to researchers. The extension study included 161 patients from the primary study.

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Researchers looked at clinical outcomes of patients treated with idelalisib from both studies with or without CKs. Successful karyotypes were obtained in 127 patients of the original 220 patients: 57% in the idelalisib arm and 52% in the placebo arm.

About 40% of patients in both arms were CK-positive. A higher percentage of patients with CK also had del17p and/or TP53 mutation compared with patients who were CK-negative.

With a median follow-up of 29.2 months, 81% of CK-positive patients and 89% of CK-negative patients responded to idelalisib/rituximab. Additionally, progression-free survival was also similar between CK-positive and CK-negative patients, with a median of about 20 months.

Death occurred in half of CK-positive patients who were assigned to receive idelalisib-rituximab compared with 66.7% of patients treated with placebo-rituximab. Median overall survival was 28.3 months in the CK-positive group treated with idelalisib-rituximab compared with 9.2 months in CK-positive patients treated with placebo-rituximab.

No difference in overall survival was noted between CK-positive and CK-negative patients treated with idelalisib-rituximab.

“Our analysis suggests that CK-positive patients treated with idelalisib/rituximab did not exhibit a significantly shortened survival compared with those who were CK-negative,” the researchers wrote. “In addition, the primary beneficial effect of adding idelalisib to rituximab treatment in relapsed/refractory CLL patients with CK was reflected in OS prolongation compared to those who received only rituximab.”

Disclosure: Some of the authors reported financial ties to pharmaceutical companies. For a full list of disclosures, please refer to the primary study.

Reference

Kreuzer K-A, Furman RR, Stilgenbauer S, et al. The impact of complex karyotype of the overall survival of patients with relapsed chronic lymphocytic leukemia treated with idelalisib plus rituximab [published online August 19, 2019]. Leukemia. doi: 10.1038/s41375-019-0533-6

This article originally appeared on Cancer Therapy Advisor