What happened

Shares of Clovis Oncology (NASDAQ:CLVS) opened up trading today 46% higher than they were at Friday's close. The drugmaker's stock is surging as a result of the successful Phase 3 readout for its BRCA-mutant ovarian cancer drug Rubraca in a confirmatory study known as ARIEL3. Specifically, Clovis reported that Rubraca met is primary endpoint of improving progression free survival in all three efficacy analyses: tumor BRCA-mutant, HRD-positive and overall intent-to-treat populations.

Rubraca belongs to a class of drugs known as "PARP inhibitors" that function by interfering with cells' ability to repair their DNA. Normal cells have other pathways by which to make those repairs, but certain types of cancers don't, so blocking that mechanism triggers genomic instability and cancer cell death.

AstraZeneca's (NYSE:AZN) Lynparza and Tesaro's (NASDAQ:TSRO) Zejula are also PARP inhibitors indicated for advanced ovarian cancer; the two constitute Rubraca's chief competition.   

Rocket

Image Source: Getty Images.

So what

This positive top-line readout opens the door for a potentially lucrative label expansion for Rubraca as a second-line and later maintenance treatment for women with platinum-sensitive ovarian cancer who have responded to their most recent platinum therapy. As a result, Rubraca should be able to keep pace with AstraZeneca's and Tesaro's rival drugs in the battle to grab market share in this rapidly emerging treatment area. 

Now what

With ARIEL3's positive readout in hand, Clovis plans on filing a supplemental New Drug Application (sNDA) within the next four months. If the FDA review cycle is typical, the fate of Rubraca's sNDA should be known by the third quarter of 2018 at the latest.

In the interim, investors can probably bank on the Clovis buyout rumors kicking into overdrive. After all, there are multiple large-cap drugmakers that presently lack a PARP inhibitor in their arsenal, and Rubraca has proven itself to be a potent anti-cancer agent.

George Budwell has no position in any stocks mentioned. The Motley Fool has no position in any of the stocks mentioned. The Motley Fool has a disclosure policy.