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Gilead’s Zydelig gets FDA nod for three blood cancers

By Jennifer Boggs, Managing Editor

As the Street awaits second quarter Sovaldi (sofosbuvir) sales figures this afternoon, the FDA surprised Gilead Sciences Inc. with an earlier-than-expected nod for breakthrough therapy-designated Zydelig (idelalisib), planting the first stake in the ground for what investors hope will be a hematology  franchise to rival the firm’s offerings in HIV and hepatitis C.

The good news is the agency’s approval grants use of Zydelig, an oral PI3K delta inhibitor, in three hematological cancers: traditional approval in patients with relapsed chronic lymphocytic leukemia (CLL) in combination with Rituxan (rituximab, Biogen Idec Inc. and Roche AG); and accelerated approval in relapsed follicular B-cell non-Hodgkin lymphoma (FL) and in relapsed small lymphocytic lymphoma (SLL), for use in those patients who have received at least two prior therapies.

The bad news is that the approval comes with a boxed warning of fatal and serious toxicities, including liver toxicity, diarrhea, colitis, pneumonitis and intestinal perforation. That could give doctors pause in prescribing the drug, particularly in CLL, an indication that has seen three other entrants to the market in less than a year.

Imbruvica (ibrutinib), developed by Pharmacyclics Inc., gained approval in February. Both Gazyva (obinutuzumab, Roche AG), which gained approval in November, and Arzerra (ofatumumab, Genmab A/S), which was cleared for expanded use in CLL in April, also were designated breakthrough therapies. (See BioWorld Today, Nov. 4, 2013, and June 5, 2014.)

While Zydelig had been known to be associated with colitis, the boxed warning was unexpected, according to RBC Capital Markets analyst Michael Yee, “so this might mute some of the initial launch” of Gilead’s drug. He pointed out, however, that there were “already very low expectations for this drug,” with a possible 10 percent to 20 percent share of the market long term.

That could be good news for Sunnyvale, Calif.-based Pharmacyclics, and investors seemed to agree, sending shares (NASDAQ:PCYC) up $8.88, or 9 percent, shortly after the announcement of Zydelig’s approval.

Shares of Gilead (NASDAQ:GILD) were trading at midday up 20 cents.

Foster City, Calif.-based Gilead picked up Zydelig in its 2011 acquisition of Calistoga Pharmaceuticals Inc., for $375 million cash and $225 million in potential milestones, as part of a move to diversify its pipeline. (See BioWorld Today, Feb. 23, 2011.)