Can new PhIII data help Gilead's Zydelig stage a comeback in CLL?

Gilead's ($GILD) Zydelig is set to pull in less than $200 million in annual sales, a tally that pales in comparison with the blockbuster numbers rival Imbruvica from Johnson & Johnson ($JNJ) and AbbVie ($ABBV) is tracking toward. But according to Leerink Research analysts, new data suggest there may be more room for growth than some industry watchers think.

On Tuesday, the California company rolled out positive interim results from a Phase III trial of patients with relapsed and refractory chronic lymphocytic leukemia (CLL). Administering Zydelig alongside standard-of-care combo Treanda from Teva ($TEVA) and Rituxan from Roche ($RHHBY) produced a 67% reduction in the risk of disease progression or death compared with the Treanda/Rituxan cocktail on its own, researchers found.

As Leerink's Michael Schmidt and Seamus Fernandez wrote in a Wednesday note to clients, those data suggest "the drug has considerable benefit, and perhaps could be used more frequently in the future." That would certainly be fine by Gilead, which saw the med bring in just $23 million last year after winning approval in July. "Most investors and analysts have written off Zydelig," Schmidt and Fernandez wrote.

Nemesis Imbruvica, by contrast, is gearing up for a $1.2 billion year, the analysts noted, and its makers think that's only the beginning. AbbVie, for one, predicts its own share of Imbruvica revenues to eventually reach $7 billion, with 25% of that growth coming from continued penetration in its already-approved indications--previously treated CLL among them.

According to the analysts, it's difficult to compare the new Zydelig results with any of Imbruvica's performances; "the similar studies have not been disclosed," they pointed out. But in the near term, for many patients, the Zydelig-Treanda-Rituxan lineup "could be attractive, particularly since it produces high response rates and durable responses," they wrote.

They're not getting carried away, however. While they think "revenue may have more growth potential than currently expected," with the adverse event liabilities surrounding the Gilead drug--it bears a black box warning highlighting serious risks, such as potentially fatal liver problems--they don't expect "a big step-up in sales" from this trial or a potential label expansion.

- read Gilead's release

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