Novartis‘ (NYSE: NVS) application for FDA approval of ribociclib for first-line use alongside letrozole, in patients who have advanced breast cancer with an amenable genetic makeup, has been accepted by regulators under priority review. The priority-review timeline accelerates a decision to six months from 10 months, meaning that an official go/no-go decision from the FDA could be on tap next spring. If approved, ribociclib could challenge Pfizer‘s (NYSE: PFE) Ibrance for market share in the indication, so let’s take a closer look.