Despite an overall down day on the market today, the health-care sector emerged looking pretty good, with a handful of big winners. In this video, Motley Fool health-care analyst David Williamson looks at three top performers.

Regado Biosciences (NASDAQ: RGDO) is the day's biggest winner, up 33% after announcing a fast-track designation for its lead drug candidate REG1, a new type of anticoagulant therapy that would be used during percutaneous coronary intervention procedures. The drug is just beginning late stage development with enrollment ongoing in its phase 3 trial. The stock has gone on a big run over the last month as the FDA accepted an investigational new drug, or IND, application for its next drug REG2. David sees this as definitely an exciting biotech to keep an eye on this year.

Northwest Biotherapeutics (NWBO 1.78%) is today's next winner, up 29% today after some good news coming out of Europe for the company's brain cancer vaccine DCVax-L. German hospitals are allowed to give the drug to patients with any type of glioma brain cancer, whether they are newly diagnosed or recurrent, under the compassionate use standard. Shares are soaring because the company can charge full price for these treatments outside of its ongoing phase 3 clinical studies. David, however, advises caution here, saying that he doesn't see this adding any meaningful sales. With the big tear the stock has been on, any bad news coming out of these phase 3 trials could be crushing for investors.

And finally, Alexion (ALXN) is today's third winner, up 7% on great guidance for sales of its drug Soliris. The company was able to add an additional $150 million in 2014 sales up to $2.15 billion, thanks to an agreement with the French. As this is one of the most expensive drugs in the world at $400k, negotiation with each European country for reimbursement is critical to expansion. David still sees a significant upside in global sales for the drug as well as the potential here for additional indications, and says that Alexion is the one he sees as the safest investment of today's three winners for biotech growth.