EMA puts Gilead's Zydelig under the lens after deaths crop up in trials

Gilead's ($GILD) Zydelig has been working to carve out a place for itself as it battles other blood cancer heavyweights. But now, European regulators are undertaking a safety review of the med that could stop it in its tracks.

On Friday, the European Medicines Agency announced it would be taking a hard look at the product thanks to an increase in the rate of serious adverse events--including deaths, mostly due to infections--in three clinical trials.

Those studies involved chronic lymphocytic leukemia and non-Hodgkin lymphoma patients--whom the med is approved to treat--but the CLL study involved currently unapproved combos of meds, while the lymphoma study included patients with disease characteristics not covered by the drug's label.

Gilead has been working hard to find its niche with Zydelig in the face of hefty competition. Right now, it's up against heavyweights such as Imbruvica from Johnson & Johnson ($JNJ) and AbbVie ($ABBV)--a med AbbVie CEO Richard Gonzalez expects to bring in $7 billion in peak sales for his company alone--and Gazyva from Roche ($RHHBY), the follow-up to smash-hit blockbuster Rituxan.

And things looked promising late last year, when the California company rolled out positive interim results from a Phase III trial of patients with relapsed and refractory chronic lymphocytic leukemia (CLL). Delivering Zydelig alongside standard-of-care tandem Treanda from Teva ($TEVA) and Rituxan produced a 67% reduction in the risk of disease progression or death compared with the Treanda/Rituxan duo on its own, researchers found.

The new safety analysis could pose a hurdle, though--especially since the med already bears a black-box warning highlighting serious risks, such as potentially fatal liver problems. Because of those issues and the drug's sluggish start--it brought in just $132 million last year--investors are skeptical.

"Most investors and analysts have written off Zydelig," Leerink Partners analysts Michael Schmidt and Seamus Fernandez wrote to clients in December.

- read the EMA's release

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