Study Shows Experimental Drug Idelalisib Effective Against Chronic Lymphocytic Leukemia

A study of idelalisib finds that this experimental targeted therapy drug may effectively treat chronic lymphocytic leukemia (CLL) patients without the need for chemotherapy. CLL starts from white blood cells called lymphocytes in the bone marrow. Treatment often includes chemotherapy, which can produce serious side effects and is not recommended for patients in very poor health.

"The treatment today for CLL can be worse than the disease, leading to a great deal of side effects and death,” said lead investigator Richard R. Furman, MD, in a statement. “This study, and others we have conducted on idelalisib, demonstrates that we may no longer need to use chemotherapy in CLL."

Idelalisib is not yet available outside of clinical trials. The US Food and Drug Administration (FDA) has granted the drug breakthrough therapy status, which means it is eligible for faster FDA review. Targeted therapies like idelalisib attack the parts of cancer cells that allow them to develop and grow. They often have less severe side effects than standard chemotherapy drugs.

Cancer ‘melted away’

Furman and other researchers from Weill Cornell Medical College and cancer centers around the world tested idelalisib and the existing immunotherapy drug rituximab in 220 people with CLL that had returned or had worsened after previous treatment, and who were not eligible for chemotherapy. Half the people received rituximab and idelalisib pills, and the other half received rituximab and a placebo (dummy pills).

Those who received the combination of idelalisib and rituximab had better response rates to the treatment – 81 percent had their leukemia get better and tumors shrink. Only 13 percent of the placebo group responded to the therapy. Side effects were similar in the 2 groups and included fever, fatigue, nausea, chills, and diarrhea.

A year after the study began, 92 percent of the idelalisib group were still alive compared to 80 percent of the placebo group. The response was so significant that the study was stopped early, in October 2013, so that all the trial participants could receive idelalisib.

"We saw incredible responses in patients who used idelalisib. Their cancer quickly melted away," said Furman.

However, he and his co-authors note that longer-term studies are needed to assess how safe idelalisib is with longer use. They also call for more studies to determine the best way to use this drug.

The study was published in the January 23, 2014 issue of the New England Journal of Medicine. Another study published in the same issue finds that idelalisib shrank tumors in patients with slow-growing non-Hodgkin lymphoma.

The American Cancer Society medical and editorial content team
Our team is made up of doctors and master's-prepared nurses with deep knowledge of cancer care as well as journalists, editors, and translators with extensive experience in medical writing.

Idelalisib and Rituximab in Relapsed Chronic Lymphocytic Leukemia. Published in the January 22, 2014 issue of New England Journal of Medicine. First author Richard R. Furman, MD, Weill Cornell Medical College, New York. 

PI3Kδ Inhibition by Idelalisib in Patients with Relapsed Indolent Lymphoma. Published in the January 22, 2014 issue of New England Journal of Medicine. First author Ajay K. Gopal, MD, University of Washington School of Medicine, Seattle. 

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