You can't turn back the clock and buy Celgene 12 years ago when it first won approval for its multibillion-dollar blockbuster multiple myeloma drug Revlimid, but you can buy stocks that have similar prospects. One such company is Portola Pharmaceuticals (NASDAQ:PTLA), an emerging commercial-stage biotech that's recently won Food and Drug Administration (FDA) approval for two potential blockbuster drugs.

Making the leap

It takes a lot of time, energy, and money to develop new medicines, and the failure rate in clinical trials is incredibly high. Over 90% of the drugs that companies test in clinical trials end up in the dustbin, so making the leap from clinical-stage biotech to commercial-stage biotech is no easy feat.

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Yet Portola Pharmaceuticals has managed to overcome the stiff odds of failure twice in the past year, and each of its drugs could soon end up generating hundreds of millions of dollars or more in annual sales per year.

The first of its two drugs to win the FDA's nod was Bevyxxa, an anticoagulant for use in acute medically ill patients. In the past, clotting was prevented in this patient group by Lovenox, a drug that generated over $2.7 billion per year in sales, prior to generic versions winning approval in 2010.

Bevyxxa is a factor Xa inhibitor that binds to factor Xa to prevent the formation of blood clots. Its advantages over Lovenox include oral dosing rather than daily injection and a longer half-life. While Lovenox is given over a six-to-14 day period, Bevyxxa is taken once daily for up to 42 days. Because many patients treated with Lovenox end up having a clotting event requiring rehospitalization within a month of hospital discharge, Bevyxxa may provide greater protection from clots for patients as they recover their mobility following hospitalization.

In head-to-head trials against Lovenox, Bevyxxa outperformed it in reducing clotting-related events requiring hospitalization and death due to clotting.

Portola Pharmaceuticals estimates there are over 24 million patients who could benefit from Bevyxxa in the G7 countries, and that over 1 million patients suffer a blood clot within 35 days of hospital discharge. As a result, there's a significant unmet opportunity for Bevyxxa to replace Lovenox as standard care.

The second of its drugs to win approval is AndexXa, a factor Xa inhibitor antidote that received the FDA green light on May 4.

AndexXa acts as a factor Xa decoy that factor Xa inhibitors bind to instead of factor Xa itself. In effect, it tricks factor Xa inhibitors into inhibiting it instead, thereby restoring a person's ability to form clots. It's a novel approach, and in trials, it was able to reverse greater than 90% of the anticoagulant activity of the bestselling factor Xa drugs, Johnson & Johnson's Xarelto and Bristol-Myers Squibb and Pfizer's Eliquis.

AndexXa's availability is an important advance for doctors and patients. In 2016, there were about 117,000 factor Xa inhibitor patients admitted to U.S. hospitals per month because of bleeding events. Of those, 2,000 people per month died.

Over the past couple of years, those figures likely increased because Xarelto and Eliquis are getting more commonly used than Warfarin, the anticoagulant that dominated the anticoagulant market for 50 years. To put the size of the increase in factor Xa drug use in perspective, consider that Xarelto's and Eliquis' combined first-quarter 2018 sales topped $2 billion, up 25% from the first quarter of 2016.

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Capitalizing on commercialization

To help fund its commercial-stage investments, Portola Pharmaceuticals inked a deal in March 2017 that exchanged double-digit royalties on AndexXa's global sales for $50 million upfront and $100 million upon AndexXa's FDA approval. Portola's already used some of that money to build up a sales and marketing team for Bevyxxa, and soon that team will be hitting the ground running, marketing AndexXa, too.

As of December, the company had hired 56 sales reps, and by the end of June, it plans to have 72 sales reps. By the end of 2018, it hopes to have 120 people calling on more than 1,500 hospitals throughout the country. Overall, Portola Pharmaceuticals pegs Bevyxxa's addressable market at between $3 billion to $4 billion and estimates that AndexXa's market could exceed $2 billion.

If the company's anywhere close to those estimates, then revenue from these two drugs should go a long way toward funding the development of other drugs in its clinical-stage pipeline. For instance, Portola Pharmaceuticals already is conducting phase 2a studies of cerdulatinib in patients with relapsed or treatment-resistant hematological cancers, and data from that study should be available soon.

In this respect, Portola Pharmaceuticals could be building its business by following a similar blueprint to Celgene. Celgene began with one game-changing drug, Revlimid, and then it leveraged its success to finance the development of a slate of other blockbuster drugs. 

It remains to be seen if owning Portola Pharmaceuticals shares will be as profitable for investors as owning Celgene has been for the last 12 years. Given the market opportunity ahead of Portola Pharmaceuticals, however, buying shares now could be a lot like buying Celgene back when it launched Revlimid.

Todd Campbell owns shares of Celgene, Pfizer, and Portola Pharmaceuticals. His clients may have positions in the companies mentioned. The Motley Fool owns shares of and recommends Celgene and Johnson & Johnson. The Motley Fool has the following options: short May 2018 $140 calls on Johnson & Johnson. The Motley Fool has a disclosure policy.