Pfizer Inc. (PFE) had been just the only player in a very specific breast cancer treatment game, but now Novartis (NVS) has entered the race with a brand new drug that could be a blockbuster and threaten Pfizer’s dominance.

Written by StockNews.com

As Endpoints News reports, the new drug has been fast tracked to market:

Novartis picked up a key regulatory win today [Monday, March 13, 2017], gaining the FDA’s quick OK for LEE011, its CDK 4/6 drug now approved as a frontline therapy for postmenopausal women with hormone-receptor positive, human epidermal growth factor receptor-2 negative advanced or metastatic breast cancer in combination with any aromatase inhibitor.

The drug, also known as ribociclib, will be marketed with the brand name Kisqali. Analysts estimate peak annual sales of around $2.5 billion a year, which would be a new blockbuster for Novartis.

It also means Pfizer’s Ibrance (palbociclib) suddenly has some stiff competition. Pfizer had been the first to offer drugs in this field, while Eli Lilly & Co. (NYSE:LLY) has a treatment of its own in abemaciclib.

The drug’s success does indeed make it a formidable foe for Pfizer’s blockbuster drug:

The headline figure from ESMO, based on a study that was wrapped early due to its success, was that ribociclib combined with letrozole reduced the risk of death or progression by 44% among first-line patients compared to letrozole alone.

So, while today’s news is certainly great for cancer patients and Novartis, it’s perhaps not so good for Pfizer, which now faces stiff competition in an area where it once had none.

Pfizer Inc. shares were unchanged in premarket trading Tuesday. Year-to-date, PFE has gained 6.09%, versus a 6.39% rise in the benchmark S&P 500 index during the same period.

PFE currently has a StockNews.com POWR Rating of A (Strong Buy), and is ranked #2 of 133 stocks in the Medical – Pharmaceuticals category.