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The U.S. Food and Drug Administration has approved the use of Zydelig (idelalisib) for the treatment of patients with relapsed chronic lymphocytic leukemia (CLL). The drug, made by Gilead Sciences, is to be used in combination with rituximab in patients for whom rituximab alone would be considered appropriate therapy due to other existing comorbidities.

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"In less than a year, we have seen considerable progress in the availability of treatments for chronic lymphocytic leukemia," Richard Pazdur, MD, Director of the Office of Hematology and Oncology Products in the FDA's Center for Drug Evaluation and Research, said in a news release.


Since November last year, the FDA has approved Gazyva (obinutuzumab)(OT 12/10/13 issue), Imbruvica (ibrutinib)(OT 3/10/14 issue), and a new indication for Arzerra (ofatumumab)(OT 5/10/14 issue) to treat CLL. Gazyva, Arzerra, and Zydelig were all granted orphan product designation because they are intended to treat a rare disease.


Zydelig also received accelerated approval to treat patients with relapsed follicular B-cell non-Hodgkin lymphoma (FL) and relapsed small lymphocytic lymphoma (SLL). The drug is intended to be used in patients who have received at least two prior systemic therapies.


The accelerated approval program allows for approval of a drug based on surrogate or intermediate endpoints reasonably likely to predict clinical benefit for patients with serious conditions with unmet medical needs. Drugs receiving accelerated approval are subject to confirmatory trials verifying clinical benefit.


The safety and effectiveness for Zydelig for the treatment of patients with CLL were evaluated in a clinical trial of 220 patients randomly assigned to receive Zydelig and rituximab or placebo and rituximab. The trial was stopped for efficacy following the first pre-specified interim analysis point, which showed participants treated with Zydelig and rituximab had a longer progression-free survival (10.7 months) compared with patients treated with the placebo and rituximab (approximately 5.5 months).


Results from a second interim analysis continued to show a statistically significant improvement for Zydelig and rituximab over placebo and rituximab.


Zydelig's safety and effectiveness to treat relapsed FL and relapsed SLL were established in a clinical trial with 123 patients with indolent non-Hodgkin lymphomas. All patients were treated with Zydelig, and the results showed that 54 percent of patients with relapsed FL and 58 percent of patients with SLL experienced complete or partial disappearance of their cancer after treatment.


Zydelig carries a Boxed Warning alerting patients and health care professionals of fatal and serious toxicities including liver toxicity, diarrhea and colitis, pneumonitis, and intestinal perforation. The drug was also approved with a Risk Evaluation and Mitigation Strategy comprised of a communication plan to ensure that health care providers who are likely to prescribe Zydelig are fully informed about these risks.


Common side effects reported for Zydelig include diarrhea, pyrexia, fatigue, nausea, cough, pneumonia, abdominal pain, chills, and rash. Common laboratory abnormalities include neutropenia, hypertriglyceridemia, hyperglycemia, and elevated levels of liver enzymes.