FDA has accelerated the review process for Pfizer’s experimental cancer therapy palbociclib, PD-991,by giving the pipeline drug breakthrough status, meaning the treatment will enter one of several regulatory channels that help drugs move through the review process at a faster pace.

The drug’s notable status looks even better given its Phase II progression-free survival status among breast cancer patients when paired with older drug letrozole (versus letrazole alone), noted Leerink Swann analyst Seamus Fernandez in a research note. Phase III results have yet to roll in, but Fernandez suggests KOLs are predisposed towards the drug based on feedback at the December San Antonio Breast Cancer Symposium. In addition to being impressed with the drugs no-progression status, Fernandez wrote at the time that the drug could play somewhat nicely if it made it to market, since KOLs didn’t see it as a direct threat to Novartis’ Afinitor. He wrote that watchers said the two drugs may fight it out based on tolerability, but that it could eventually impede on Afinitor’s turf.

Bernstein analyst Tim Anderson observed in March that Pfizer—which he noted boasts a relatively slim R&D budget—is looking to put the drug on several sales paths and is testing the oral CDK 4/6 kinase inhibitor in cancers including NSCLC, ovarian cancer, glioblastoma and multiple myeloma, among others. Indication expansion is not just Pfizer’s game—in July, the FDA approved Novartis’ Afinitor for women with advanced hormone receptor positive 2 breast cancer with exemestane. Anderson also noted that indication wins would mean few financial losses, since Pfizer licensed the experimental therapy from Onyx at an early stage. That probably means single-digit-level royalties.

Fernandez wrote Wednesday he forecasts a $5 billion palbociclib future, garnering around $3 billion in” first-line metastatic cancer alone.”