Donald Trump won the U.S. presidency on promises to lower drug prices. Yet biotech stocks have outperformed the S&P 500 since his move into the White House, and some biotech stocks have more than doubled since his inauguration on Jan. 20. Among the best performing of these biotech stocks are Esperion Therapeutics (ESPR 4.28%), TG Therapeutics (TGTX -1.50%), and Aurinia Pharmaceuticals (AUPH 3.74%), so let's learn more about them.

No. 1: Esperion Therapeutics -- up 223%

Roger Newton led the team responsible for developing Lipitor, the best-selling cholesterol drug of all time. Newton has assembled a team at Esperion Therapeutics that's working on what could turn out to be another top-selling medicine.

A business person views a rising stock price chart.

IMAGE SOURCE: GETTY IMAGES.

Esperion is working on bempedoic acid, an oral drug that can be taken alongside statins like Lipitor to lower bad cholesterol levels in patients who don't respond adequately to statins. In mid-stage clinical trials, combining bempedoic acid with statins lowered bad cholesterol levels by about an additional 20%.

The company has reported two important pieces of information that are exciting investors this year.

First, Esperion Therapeutics reported that it has fully enrolled patients in a phase 3 trial, and that data from that trial should be available next year. Second, the company said that the FDA has confirmed this trial can support an approval of bempedoic acid, removing any lingering doubt that the FDA would wait to see results from a separate cardiovascular outcomes trial before considering it for approval.

Because heart disease is the second most common cause of death, and studies show lowering bad cholesterol can reduce major cardiovascular events, this medicine could be a big hit. Tens of millions of patients are prescribed statins annually, and millions of them aren't reaching their cholesterol targets.

Only time will tell if bempedoic acid's trials confirm its efficacy and safety, but the potential for use in so many patients was more than enough good news to send this company's shares flying. 

No. 2: Aurinia Pharmaceuticals -- up 177%

There are about 500,000 patients in the U.S. with systemic lupus erythematosus, and up to 60% of them suffer from lupus nephritis (LN), an inflammation of the kidneys that can cause end-stage renal failure.

Currently, patients with LN are treated off-label with CellCept, a medicine that delivers mixed response rates in patients.

In March, Aurinia Pharmaceuticals reported that using voclosporin and CellCept together resulted in complete remission rates of between 40% to 49% in LN patients, depending on dosage. The complete remission rate in patients receiving CellCept plus a placebo was only 24%. 

Aurinia Pharmaceuticals announced in April that it will conduct a single phase 3 study to confirm these results, and if this global, 52-week, double-blind, placebo-controlled study is successful, it will support regulatory filings for approval in the U.S., Europe, and Japan. 

CellCept's lackluster efficacy suggests that approvals could turn voclosporin into a big commercial success, and that's got some industry watchers thinking this drug could eventually rack up sales of $1 billion annually. While that's certainly possible, investors might want to temper a little of their enthusiasm. After all, there's no guarantee that Aurinia Pharmaceuticals' phase 3 trial will pan out. 

No. 3: TG Therapeutics -- up 163%

TG Therapeutics shares have been on a tear since management announced in March that its experimental drug TG-1101, or ublituximab, could reshape how doctors treat leukemia.

A phase 3 trial evaluating TG-1101 in combination with AbbVie's billion-dollar blockbuster blood cancer drug Imbruvica showed that 80% of patients with chronic lymphocytic leukemia and high-risk gene mutations responded to treatment. For comparison, only 47% of patients had an overall response to Imbruvica alone.

Management plans to share more complete data in an oral presentation at the American Society of Clinical Oncology conference in early June. Shortly thereafter, it plans on discussing its chances for an accelerated filing for TG-1101's approval with the FDA.

TG Therapeutics is also studying TG-1101 in multiple sclerosis, and it plans to begin a phase 3 trial of it in that indication this year. Additionally, the company is developing TGR-1202, and an abstract regarding its use with TG-1101 and Imbruvica is planned for ASCO too.

With so much going on at this company, it's easy to see why investors have looked beyond the potential negative impact of changes in Washington and driven the company's share price higher.