You may not see it in sales numbers yet, but Pfizer and Astellas’ Xtandi is crushing Johnson & Johnson’s Erleada in the nonmetastatic, castration-resistant prostate cancer market—according to Pfizer's executives, at least.
Xtandi, which launched in the blockbuster indication last July on the back of data from the Prosper trial, has picked up a market share quadruple Erleada’s in six months, Angela Hwang, president of Pfizer’s biopharmaceuticals group, told investors on Tuesday’s fourth-quarter conference call. Looked at another way, Xtandi has staked out a piece of the market equivalent to the combined share of Erleada on one hand and chemo on the other.
Why aren’t sales telling that story? “New patients are coming into therapy—new patients are coming every day. So you may not see the full impact of this pool of patients which is still accumulating,” she said, adding that, “it will take time to realize.”
Xtandi pulled in $189 million in U.S. sales for Pfizer in the fourth quarter, up 12% from the $168 million it posted in the same period of 2017. In the nonmetastatic field, Erleada—the follow-up drug to Xtandi’s longtime nemesis Zytiga—got the head start, winning an approval last February, thanks to a trial that “essentially delivered” an “identical” outcome to Prosper, Barclays analyst Geoff Meacham wrote at the time, acknowledging that “cross-trial comparisons are fraught with issues.”
Xtandi also had its original indication—in metastatic castration-resistant prostate cancer-chipping into its quarterly top line, though, and Hwang said Pfizer’s growth strategy in the metastatic arena has been “focused on driving uptake among urologists.”
“Today, more than 30% of our new scripts are written by urologists, and we're continuing to see market share growth in this segment,” she said.
There’s just one problem with counting on that market, though: Zytiga generics, which came into focus after key J&J defeats in court in 2018.
That’s where the nonmetastatic green light becomes even more clutch for Xtandi.
“Xtandi … has indications that are different from Zytiga's," Hwang said, noting that “we expect the Zytiga generics to have a minimal impact on our business." She also pointed to Xtandi’s different dosing frequency, as well as the fact that it doesn’t bear Zytiga’s requirement for coadministration with the steroid prednisone, a fact that's been one of Xtandi's talking points from the get-go.
“I think that all of these will stand well in terms of making switching less likely and for the impact on Xtandi to be minimal as we expect,” she said.
And Pfizer and Astellas are hoping to widen that lineup of additional indications, too. The opportunity “we’re really excited about,” she said, lies in the hormone-sensitive prostate cancer market, where patients tend to stay on therapy the longest. After releasing data last December in metastatic hormone-sensitive patients—a group that swells by about 38,000 new patients per year, Hwang said—Pfizer is prepping for discussions with regulators about a potential new nod. And it’s studying Xtandi in nonmetastatic hormone-sensitive patients, too.