The FDA has cleared Gilead’s new treatment for three types of rare blood cancers, potentially creating another blockbuster drug for manufacturer of the hepatitis C treatment Sovaldi.

Approved under the agency’s breakthrough therapy designation pathway, Zydelig (idelalisib) is indicated for use in combination with Genentech’s Rituxan (rituximab) to treat patients whose chronic lymphotic leukemia (CLL) has returned.

The drug also received accelerated approval to treat patients with relapsed follicular B-cell non-Hodgkin lymphoma and relapsed small lymphocytic lymphoma, the FDA said. For those indications, Zydelig is intended to be used in patients who have received at least two prior systemic therapies, the agency added.

The CLL indication was approved based on results from a 220-patient clinical trial, which was stopped early because participants treated with the combination lived 10.7 months without their disease progressing compared with 5.5 months for the placebo and Rituxan group, the agency said.

The two other indications were approved based on a 123-patient trial that showed a 54 percent response rate for patients with released follicular B-cell non-Hodgkin lymphoma and 58 percent for relapsed small lymphocytic lymphoma.

Zydelig has the potential to be very profitable for Gilead, according to an EvaluatePharma analysis. The research firm projects Zydelig will generate $151 million in sales in 2015 and up to $1.2 billion in annual sales by 2020.

Zydelig is the seventh drug to win approval under the FDA’s breakthrough therapy designation pathway, which was created in 2012 for drugs that treat serious and life-threatening conditions and offer a substantial improvement over existing therapies. Drugs in the pathway receive faster reviews. — Robert King

Originally appeared in Drug Industry Daily, the pharmaceutical industry’s number one source for regulatory news and information. Click here for more information.