Less than one day after Novartis CEO Vas Narasimhan talked up a potential key approval for lagging breast cancer drug Kisqali, the company has that approval in hand.

The FDA go-ahead gives Kisqali "the broadest first-line indications of any" member of the CDK 4/6 class, which also includes Pfizer blockbuster Ibrance and Eli Lilly newcomer Verzenio. And Kisqali, which is struggling in the sales department—it pulled in just $59 million in the second quarter—can certainly use the sales edge.

On Wednesday, the Swiss drugmaker said the FDA had greenlighted the drug in tandem with an aromatase inhibitor as an initial endocrine-based treatment for pre, peri- or postmenopausal women with hormone receptor-positive, HER2-negative breast cancer.

It also gave the drug a go-ahead, in combo with fulvestrant, to treat postmenopausal HR-positive, HER2-negative breast cancer sufferers either as a first endocrine-based treatment or after disease progression or other endocrine therapy.

"I think a real key moment for us will be the approval of Monaleesa 3 and Monaleesa 7 data, which will enable us to have a full label for physicians to then fully consider Kisqali’s benefits and overall profile. And that will enable us to really fully understand the trajectory of the medicine into the future," Narasimhan told analysts early Wednesday on the company’s second-quarter conference call.

Critical to Kisqali’s success in the new indication, though, will be how doctors respond.

Up until Novartis rolled out the data that helped snag the approval, "the dogma" had been that "these patients should receive hormonal therapy first, and then if they progress on that, then you give the combination," study investigator Dennis Slamon, M.D., Ph.D., said in an interview at the American Society of Clinical Oncology annual meeting last month.

But he added that he’s seen plenty of doctors, who can be conservative, hold back on using new combinations until after further lines of chemo, even in the wake of data supporting front-line use.

"I’d like to tell you I think it’s going to be used a lot more given these data, but just given what I’ve seen in the past, it’s going to be interesting" to see how prescribing patterns play out, Slamon said.

Meanwhile, though, Novartis is still working to give Kisqali a boost, and it doesn’t intend to let the data do all the talking. "In the U.S., we’re refining our messages and continuing to work on how best to position Kisqali," Narasimhan said.