Pfizer Inc.’s (PFE - Analyst Report) breast cancer drug, Ibrance (palbociclib) received accelerated approval from the FDA to be used in combination with Novartis’ (NVS - Analyst Report) Femara (letrozole) for the first-line treatment of postmenopausal women with estrogen receptor-positive, human epidermal growth factor receptor 2-negative (ER+/HER2-) advanced breast cancer as an initial endocrine-based therapy for their metastatic disease.

This makes Ibrance the first CDK 4/6 inhibitor to be approved by the FDA. Approval came more than two months ahead of schedule. Pfizer’s shares were up 1.2% on the news.

We remind investors that approval came well ahead of expectations as the FDA action date for the candidate was Apr 13, 2015. The drug was reviewed and approved under the FDA’s Breakthrough Therapy designation and priority review programs.

The accelerated approval was based on positive data from the phase II PALOMA-1 study. Results from the study revealed that a combination treatment of Ibrance and Femara led to a statistically significant improvement in progression-free survival (20.2 months) versus Femara alone (10.2 months).

The FDA approval of Ibrance comes as a major boost for Pfizer considering several products in the company’s portfolio are expected to face patent expirations in the coming quarters. Taking into account the advanced breast cancer patient population, we believe Ibrance has the potential to bring in multi-billion dollar sales for Pfizer.

We expect investor focus to remain on the commercialization and sales ramp up of Ibrance.

Pfizer is a Zacks Rank #3 (Hold) stock. Some better-ranked stocks in the health care sector include Impax Laboratories Inc. (IPXL - Snapshot Report) and Allergan Inc. (AGN - Analyst Report). While Impax is a Zacks Rank #1 (Strong Buy) stock, Allergan carries a Zacks Rank #2 (Buy).