The U.S. Food and Drug Administration today approved Zydelig, a drug to treat patients with three types of blood cancers.

Zydelig can be used to treat patients whose chronic lymphocytic leukemia (CLL) has relapsed. Additionally, the drug can also be used in combination with Rituxan for patients for whom Rituxan alone would be considered appropriate therapy due to other existing medical conditions.  This is the fifth cancer medication that has been approved by the FDA and third drug approved to treat CLL specifically.

The drug can also be used to treat patients with relapsed follicular B-cell non-Hodgkin lymphoma (FL) and relapsed small lymphocytic lymphoma (SLL), another type of non-Hodgkin lymphoma. The FDA has also deemed Zydelig appropriate 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, director of the Office of Hematology and Oncology Products in the FDA's Center for Drug Evaluation and Research, in a press statement. "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 drug has been approved under the FDA's accelerated approval program, which provides faster review for drugs that demonstrate the potential to be a significant improvement in safety or effectiveness in the treatment of a serious condition.

The safety and effectiveness of Zydelig to treat relapsed CLL was tested in a clinical trial including 220 participants. They were randomly given either Zydelig and Rituxan or placebo and Rituxan. Researcher found that participants treated with Zydelig and Rituxan had the possibility of living at least 10.7 months without their disease progressing (progression-free survival) compared to about 5.5 months for participants treated with placebo and Rituxan.

Its effectiveness to treat relapsed FL and relapsed SLL was tested in another trial including 123 patients. All participants were treated with Zydelig and were evaluated for complete or partial disappearance of their cancer after treatment (objective response rate, or ORR). The researchers found that 54 percent of participants with relapsed FL and 58 percent of participants with SLL experienced ORR.

The drug comes with a boxed warning that states it may have fatal and serious toxicities including liver toxicity, diarrhea and colon inflammation (colitis), lung inflammation (pneumonitis) and intestinal perforation

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.