Pfizer breast cancer medication Ibrance just wrapped up its first full quarter with an in-class rival, thanks to the March approval of Novartis’ Kisqali. But despite the competition, the juggernaut shows no sign of slowing down.

While it’s "a little bit early to comment" on Kisqali’s launch, "so far we have seen a minimal uptake of this product," Pfizer’s Innovative Health President Albert Bourla told investors on the company’s second-quarter conference call. The newcomer’s most recent market share figure sits at 4% across all lines of therapy, with a 5% piece of the lucrative first-line pie.

And at the same time, the CDK 4/6 class’ share is growing overall, Bourla said, expanding to about 57% from 50%. That's an indication "the Kisqali introduction could potentially grow the total market."

"As you know, only 50% of the patients that could receive benefits from CDK treatments are now under a CDK program," he reminded investors.

And a growing CDK market would obviously mean good things for Ibrance, which trounced U.S. sales expectations for the second quarter. It hauled in $727 million, compared with $640 million projections from analysts—and considering the more than 60,000 patients who have been treated in the U.S., "we remain confident in our leadership in the class," Bourla said.

That, of course, doesn’t mean Novartis is going to go away. As the Swiss drugmaker's oncology chief Bruno Strigini said on his company’s own earnings call, the company is plotting a full commercial campaign once the FDA green-lights marketing materials, an event that’s predicted for later this summer. He expects the med’s payer coverage situation to improve, too: Novartis anticipates reaching 80% by the fall, up from the 50% it currently has.

Pfizer isn’t relying on the U.S. market alone for Ibrance growth, though. Its sales abroad also beat out analysts’ $109 million predictions, reaching $126 million, and in the last few months it has added 13,000 E.U. patients to its global tally, Bourla pointed out.  

The "Ibrance Europe launch looks strong," Evercore ISI Analyst Umer Raffat wrote recently to clients.