Investors cheered Portola's hard-won Bevyxxa nod. Could a takeover be next?

The FDA approved Portola Pharmaceuticals’ Bevyxxa, the first factor Xa inhibitor to prevent venous thromboembolism in hospitalized patients.

Just one year ago, the prospects for Portola Pharmaceuticals’ anticoagulant Bevyxxa looked anything but certain. The drug had faltered in a phase 3 trial, forcing the company to reanalyze the data to make its case for FDA approval. It worked: The agency gave Bevyxxa a thumbs-up on Friday as a clot-preventing treatment for patients hospitalized for acute illnesses.

Investors cheered, pushing shares of the San Francisco company up nearly 50% on Friday afternoon, to $56.06. Shares opened on Monday north of $58, as some analysts predicted peak sales of Bevyxxa (betrixaban) could surpass $1.5 billion. Portola expects to launch the drug between August and November of this year, it said in a statement.

The key to Portola’s success was its ability to recast results from the phase 3 trial, APEX, which tested Bevyxxa's ability to stave off venous thromboembolism (VTE) in hospitalized patients. In a study published in the New England Journal of Medicine, the company's investigators focused on levels of D-dimer, a blood protein measured to determine the success of treatment. They showed evidence that VTE events were reduced in patients taking Bevyxxa, including an up to 45% reduction in the most seriously ill patients.

RELATED: Following a pivotal failure, Portola lays out its case for betrixaban

“The FDA was clearly comfortable with the full data set and provided a relatively clean and broad label,” said Credit Suisse analyst Vamil Divan in a note to investors on Sunday. He estimates the drug could eventually bring in about $1.7 billion in sales globally.

Still, Portola is facing plenty of challenges. It could see competitive challenges from Johnson & Johnson’s Xarelto, which is also being tried in patients at risk of VTE. Xarelto already has a host of indications to its credit, and, as a therapy that's been on the market for several years, has built up real-world experience. Sanofi's Lovenox (enoxaparin), available in generic form, could also prove to be a formidable competitor.

RELATED: Bayer, J&J beef up Xarelto research to keep market-share gains coming

And even as Portola works to launch Bevyxxa, it’s struggling to get manufacturing up to par on another drug in its pipeline, AndexXa, which is designed to reverse the effects of factor Xa anticoagulants, specifically Pfizer and Bristol-Myers Squibb's Eliquis. Last August, the FDA handed down a complete response letter on that drug after raising questions about its manufacturing process.

The delay gave a leg up to Boehringer Ingelheim, whose anticoagulant Pradaxa competes with Eliquis and has its own companion reversal agent in Praxbind.

Portola does have some high-profile partners helping it to get past its obstacles. In December, it pulled in $50 million in loans from Pfizer and Bristol-Myers to help cover the costs of additional studies of AndexXa. The FDA is expecting Portola to provide more information about its manufacturing process, as well as additional data to justify including the anticoagulants Savaysa (edoxaban) and Lovenox in the label.

RELATED: Pfizer, BMS loan Portola $50M to help deal with CRL for antibleeding agent AndexXa

With Portola’s successful slog to FDA approval of Bevyxxa, coupled with the prospects for AndexXa, some are predicting the company could become a takeover target. Divan cites Pfizer and Bristol-Myers as likely acquirers, as well as Merck & Co. So is there any more upside to Portola’s stock? If combined sales of Portola’s two drugs eventually surpass $3 billion—the best case scenario to be sure, Divan says—he sees the company’s shares hitting $84.