UDPATE2: Novartis' Ibrance challenger cuts breast cancer progression risk by 44%

Novartis HQ cropped

COPENHAGEN, Denmark--Back in May, Novartis called an early halt to a Phase III study of breast cancer med LEE011--a future rival to Pfizer’s Ibrance--because the drug had already shown it could beat a standard treatment at stalling the disease. Saturday, the Swiss drugmaker revealed just now much.

The combination of LEE011--also known as ribociclib--and Femara (letrozole) cut the risk of disease progression or death by 44% over solo Femara in women with cancers classified as hormone receptor positive and human epidermal growth factor receptor-2 negative (HR+/HER2-), Novartis said at the ESMO 2016 Congress.

The duo regimen also bumped up tumor shrinkage, with more than half of women with measurable disease seeing their tumor size cut by at least 30%. 

Now, Novartis is looking forward to “working closely with health authorities” to shepherd the drug onto the market “as quickly as possible"--and then take on Pfizer's med in a head-to-head fight for market share. The Novartis med already has a breakthrough therapy designation from the regulator, and the company says it's on track for a filing by year's end.

Given that breakthrough tag, the agency might just make its decision quickly, analysts said. But even so, Ibrance will have had a long head start--two years, in fact, if ribociclib wins its nod early next year.

That first-to-market advantage is the only big difference between the two products, Bernstein analyst Tim Anderson said in a Saturday note. "The phase 3 results for these two products look nearly identical,  as if these were twins separated at birth," he said.

"Both drugs have shown a significant benefit on progression free survival (PFS) of similar magnitude, with a hazard ratio being an impressive 56-58%," Anderson said. "The side effect profiles, and metrics like dose reductions due to side effects, are also largely comparable."

Novartis acknowledges that, for now, ribociclib hasn't shown itself to be superior to Ibrance or to a candidate from Eli Lilly & Co, its drug could distinguish itself down the line as more data accumulate.

The early detection of LEE011's benefit "doesn't say that the drug is better than the other two drugs, it suggests that it has a magnitude of benefit that is at the very least comparable," lead LEE011 investigator Gabriel Hortobagyi told FiercePharma in an interview at ESMO. "Perhaps additional follow-up will suggest it might differentiate itself."

Meanwhile, Pfizer has made the most of its first-mover status. Since Ibrance won a speedy approval last February, it’s been cruising: The drug raked in $723 million in 2015 sales, and it handily topped that figure in the first half of 2016 alone, with $942 million for the period.

The New York pharma giant hasn’t been sitting around waiting for competition to arrive, either. Ibrance already has a second indication, for women whose disease has progressed after hormone therapy, where it's used alongside AstraZeneca’s Faslodex. And Pfizer is well on its way to broadening the med’s reach further. The company has said it has a “very heavy” clinical program in other breast cancer uses, and it’s studying Ibrance in a range of other cancers--including head and neck, and advanced pancreatic--too.

"As you can see, we are investing heavily to stay ahead of the competition," Albert Bourla, Pfizer's president of vaccines, oncology and consumer health, told investors on the company’s Q4 earnings call earlier this year.

Evercore ISI Group analyst John Scotti figures that Pfizer's Ibrance work will continue to pay off even in the face of competition. "While Novartis' data were impressive, they were largely in line with Pfizer's, and we believe Ibrance has a good chance to retain leadership in the CDK class," Scotti said in a Saturday note.

Eli Lilly has said that its candidate, abemaciclib, could be a best-in-class product, however. If that drug can come up with a stronger clinical profile than that of its rivals, a third-to-market status wouldn't stop it from making waves, Anderson has said. In his Saturday note, he quoted 2021 sales estimates of $5.6 billion for Ibrance, $1 billion for ribociclib and $1.5 billion for abemaciclib.

The Lilly drug will likely be quite a bit behind the other two. Abemaciclib missed a shot at speeding along the regulatory process in August: At the time, Lilly said it would roll ahead with a Phase III trial testing the drug alongside Faslodex, rather than stopping early as it might have hoped. The Indianapolis drugmaker cited a data monitoring committee assessment that the “interim efficacy criteria” for an early cutoff “were not met.”

Related Articles:
Lilly’s abemaciclib-Faslodex breast cancer combo trial not stopping early
The mano-a-mano between Pfizer's Ibrance and Novartis' LEE011 nears with early PhIII wrap-up
Pfizer's hot-selling Ibrance gets even hotter with new $710M sales estimate for 2015
Pfizer's Ibrance pricing shows multiyear market analysis the source of some high costs
Prevnar, Ibrance beat again to help Pfizer pass Q1 forecasts

Editor's note: This story was updated with comments from analysts and an interview with Novartis.