ASCO fallout: Roche does 'damage control' after Perjeta combo disappoints investors

Let’s just say investors were hoping for more than a one-percentage-point difference when it came to how much difference Roche’s Perjeta could make when added to Herceptin in a recent study of breast cancer patients. 

After announcing a benefit to the two-drug approach back in March, the Swiss drugmaker Monday unveiled detailed results from a three-year follow-up in its Aphinity trial—and its investors weren’t pleased. The results “appear to have gone down like a lead balloon,” Mirabaud Securities analyst Nick Turner wrote in a note seen by Bloomberg, with Roche shares making their sharpest drop since last June.

The reason? The “weak” data “very likely will confine use to higher-risk" patients, Bernstein analyst Tim Anderson wrote in a Monday note to clients—and not the broader population Roche was hoping for.

Related: How much does Perjeta add to Herceptin postsurgery? Depends how you slice it

At a three-year follow-up, 94.1% of those in Aphinity’s Perjeta arm—which added the med to Herceptin in postsurgery, early-stage breast cancer patients—hadn’t developed an invasive form of the HER2-positive disease. But 93.2% of women taking Herceptin on its own hadn’t, either.

Roche, for its part, was quick to point out that that difference translated into a 19% lower chance of developing invasive breast cancer. At an ASCO investor event—which Anderson dubbed “damage control”—Memorial Sloan Kettering Cancer Center’s Jose Baselga, a “well-respected breast cancer key opinion leader,” called that difference “very meaningful, on par with many other cancer therapies,” Anderson wrote.

Wall Street, though, had expected a 20% risk reduction, and the fact that the mark met expectations “gives little relief,” Anderson said.

While the data may have disappointed investors, though, there’s still time for them to improve, Baselga pointed out. “He also claimed that the data are ‘far from mature’ and will likely get even better; patients will be followed for 10 years, and he is confident–based on the experience with HER2+ trials–that the benefit will get better,” Anderson wrote.

That would certainly help out Roche, which is currently watching its big money-makers come under biosimilar attack. Herceptin, in particular, has a couple of challengers in the works; Mylan and Biocon are developing the leading candidate, while Celltrion over the weekend reported that its version had stacked up to Roche’s product in a late-stage trial.