ESMO: Lilly pads case for third-to-market abemaciclib with more positive breast cancer data

MADRID, Spain—Eli Lilly is gearing up to challenge Pfizer’s Ibrance and Novartis’ Kisqali in HR-positive, HER2-negative breast cancer, and it rolled out more positive data for candidate abemaciclib over the weekend to help it get there.

Squaring off against placebo in a phase 3 study unveiled at the European Society for Medical Oncology (ESMO) annual meeting in Madrid, the prospect cut the risk of disease progression or death by 46%, Lilly said.

Overall response rate measured 59.2% for the abemaciclib arm—compared with 44% in the placebo arm—and “certainly that is at least as good as the other agents that have been reported,” according to Levi Garraway, the company’s head of global development and medical affairs.

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Results from the trial, dubbed Monarch 3, back up positive findings from Monarch 1 and Monarch 2—the data that prompted the FDA in July to grant the med its priority review designation. With that regulatory speed-up, abemaciclib could be providing Ibrance and Kisqali new competition sooner rather than later, though analysts have questioned whether the third-to-market med will really be able to give them a run for their money.

One reason is the side effects: 81.3% of Monarch 3’s abemaciclib cohort experienced diarrhea, compared with just 29.8% of placebo patients. In Monarch 2, the abemaciclib diarrhea rate reached 86.4%.

As Garraway was quick to point out, only 9.5% of Monarch 3’s diarrhea sufferers experienced grade 3 diarrhea, and the malady was “highly predictable and readily manageable” with OTC remedy loperamide. It “tended to reverse after a few days,” he said, noting that “by the time you get to the third cycle, only about 2% of patients were bothered at that stage.”

Analysts, though, have been a little more skeptical. “Even if low-grade—may influence physician/patient choice adversely,” Bernstein’s Tim Anderson has written. “It is not the kind of differentiation a manufacturer seeks.”

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But Garraway sees other factors setting the Lilly up-and-comer apart, too. For one, the drug has completely eliminated cancer in 16 patients across the Monarch 2 and 3 studies, he pointed out. And among patients who have “more concerning characteristics”such as metastases to the liver, or disease that has returned rapidly“abemaciclib tends to do particularly well,” he said.

“We think there are going to be recognizable, concerning characteristics” among patients “for whom abemaciclib might be an interesting addition to the treatment armamentarium for oncologists treating breast cancer,” he said.