Zydelig gets FDA approval for treatment of patients with three types of blood cancers

The U.S. Food and Drug Administration today approved Zydelig (idelalisib) to treat patients with three types of blood cancers.

Zydelig is being granted traditional approval to treat patients whose chronic lymphocytic leukemia (CLL) has returned (relapsed). Used in combination with Rituxan (rituximab), Zydelig is to be used in patients for whom Rituxan alone would be considered appropriate therapy due to other existing medical conditions (co-morbidities). Zydelig is the fifth new drug with breakthrough therapy designation to be approved by the FDA and the third drug with this designation approved to treat CLL.

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

"In less than a year, we have seen considerable progress in the availability of treatments for chronic lymphocytic leukemia," said Richard Pazdur, M.D., director of the Office of Hematology and Oncology Products in the FDA's Center for Drug Evaluation and Research. "Zydelig's approval to treat CLL reflects the promise of the breakthrough therapy designation program and represents the FDA's commitment to working cooperatively with companies to expedite a drug's development, review and approval."

The FDA approved Gazyva (obinutuzumab) in November 2013, Imbruvica (ibrutinib) in February 2014 and a new use for Arzerra (ofatumumab) in April 2014 to treat CLL. Both Gazyva and Arzerra also received breakthrough therapy designation for this indication. Like the other two drugs, Zydelig was also granted orphan product designation because it is intended to treat a rare disease.

Zydelig's safety and effectiveness to treat relapsed CLL were established in a clinical trial of 220 participants who were randomly assigned to receive Zydelig and Rituxan or placebo and Rituxan. The trial was stopped for efficacy following the first pre-specified interim analysis point, which showed participants treated with Zydelig and Rituxan lived 10.7 months without their disease progressing (progression-free survival) compared to about 5.5 months for participants treated with placebo and Rituxan. Results from a second interim analysis continued to show a statistically significant improvement for Zydelig and Rituxan over placebo and Rituxan.

Zydelig's safety and effectiveness to treat relapsed FL and relapsed SLL were established in a clinical trial with 123 participants with slow-growing (indolent) non-Hodgkin lymphomas. All participants were treated with Zydelig and were evaluated for complete or partial disappearance of their cancer after treatment (objective response rate, or ORR). Results showed 54 percent of participants with relapsed FL and 58 percent of participants with SLL experienced ORR.

The FDA is approving Zydelig to treat FL and SLL under the agency's accelerated approval program, which allows approval of a drug to treat a serious or life-threatening disease based on clinical data showing the drug has an effect on a surrogate endpoint reasonably likely to predict clinical benefit to patients. This program provides earlier patient access to promising new drugs while the company conducts confirmatory clinical trials.

Zydelig carries a Boxed Warning alerting patients and health care professionals of fatal and serious toxicities including liver toxicity, diarrhea and colon inflammation (colitis), lung inflammation (pneumonitis) and intestinal perforation that can occur in Zydelig-treated patients. Zydelig is also being approved with a Risk Evaluation and Mitigation Strategy (REMS) comprised of a communication plan to ensure healthcare providers who are likely to prescribe Zydelig are fully informed about these risks.

Common side effects include diarrhea, fever (pyrexia), fatigue, nausea, cough, pneumonia, abdominal pain, chills and rash. Common laboratory abnormalities include decreased levels of white blood cells (neutropenia), high levels of triglycerides in the blood (hypertriglyceridemia), high blood sugar (hyperglycemia) and elevated levels of liver enzymes.

Zydelig is marketed by Foster City, California-based Gilead Sciences. Rituxan and Gazyva are marketed by Genentech, a member of the Roche Group, based in South San Francisco, California. Imbruvica is co-marketed by Sunnyvale, California-based Pharmacyclics and Raritan, New Jersey-based Janssen Biotech, Inc. Arzerra is marketed by Research Triangle Park, North Carolina-based GlaxoSmithKline.