If you're looking for great stocks to buy, there are a couple of high-flying biotechs that still have fuel in the tank to continue climbing. 

Shares of these two drugmakers are way up this year, but their valuations still seem far too low to account for the potential blockbusters they're developing. Have a look at the key reasons these biotech stocks could continue climbing for years to come.

Company (Symbol) Gain in 2021 Market Cap
BioCryst Pharmaceuticals (BCRX 6.27%) 91% $2.5 billion
Fulcrum Therapeutics (FULC 2.48%) 119% $1.0 million

Data source: Yahoo! Finance.

BioCryst Pharmaceuticals

BioCryst Pharmaceuticals discovers, develops, and markets novel small-molecule drugs to treat rare diseases. BioCryst already has a growing revenue source in Orladeyo. This is a once-daily capsule that the FDA approved this year to prevent hereditary angioedema (HAE) attacks.

A seated man and woman in professional dress look at a laptop screen.

Image source: Getty Images.

BioCryst stock has been soaring in response to Orladeyo's successful launch. Sales surged from $10.9 million during the first three months of 2021 up to $28.5 million in the second quarter, and it still has a long way to run.

BioCryst's popular new HAE drug is just starting to gain traction in the EU following its approval by the European Commission this April. Negotiating with individual member states makes European drug launches slower and less predictable than U.S. launches. By the end of 2023, though, global Orladeyo sales could reach an annualized $500 million.

Orladeyo on its own justifies BioCryst's relatively modest market cap at recent prices, but a stronger growth driver could be on its way. The company's oral factor D inhibitor, BCX9930, is in a pivotal trial with paroxysmal nocturnal hemoglobinuria (PNH) patients who had an inadequate response to treatments like Soliris. In a human proof-of-concept trial, treatment with BCX9930 helped five out of six patients who previously had an inadequate response to standard care end their reliance on problematic blood transfusions. Moreover, all nine PNH patients treated with BCX9930 were free from blood transfusions.

Fulcrum Therapeutics

Fulcrum Therapeutics is a biotech that's turned a lot of heads recently with early data for a sickle-cell disease (SCD) candidate, tentatively named FTX-6058. This is a once-daily tablet that Fulcrum designed to restart fetal hemoglobin (HbF) production in a way that other companies developing new SCD drugs hadn't considered yet.

Fulcrum Therapeutics stock rocketed recently, after the company reported positive results from a trial with healthy volunteers who showed signs of HbF production after taking FTX-6058 tablets for a couple of weeks. Fulcrum's candidate takes a whole new approach to restarting HbF production that was elucidated by the company's unique drug discovery platform.

More than a few companies are developing complex gene therapies to help SCD patients reduce their reliance on blood transfusions, but they're rife with extra challenges. For example, Bluebird Bio (BLUE 2.27%) recently decided to quit marketing a hemoglobin-related gene therapy called Zynteglo throughout the EU despite earning approval there last year.

It turns out that Bluebird Bio couldn't get end payers to agree to high up-front prices for a treatment that gets administered just once. This won't be an issue for Fulcrum Therapeutics because it's focused on small-molecule drugs that can be packaged into pills.

Three people in medical attire looking at a tablet.

Image source: Getty Images.

Looking ahead

BioCryst stock could explode higher if BCX9930 can repeat previous success with PNH patients. Not long ago, AstraZeneca (AZN 0.60%) spent $39 billion to acquire Alexion Pharmaceuticals mainly for its Soliris franchise. BioCryst's market cap is still low enough that plenty of big pharmas could easily pay a premium to get their hands of Orladeyo, BCX9930, and the rest of the company's clinical-stage pipeline.

Almost every new biotech company claims to have new technology capable of discovering lots of valuable new drugs, but they almost never prove themselves. Fate Therapeutics' initial success with FTX-6058 suggests it could be a rare exception to the rule, but there's still a long way to go. It might be best to see if FTX-6058 can help SCD patients produce HbF in a study expected to start in the fourth quarter.