Human understanding of biology is progressing like never before. Those advancements could ultimately help millions of humans live longer, better lives. For investors, the companies that are helping to move the ball forward could create vast wealth for their shareholders. 

With that in mind, we asked a team of Motley Fool investors to highlight a biotech stock that they think is a strong buy right now. Here's why they picked Exelixis (NASDAQ:EXEL), Celgene (NASDAQ:CELG), and Ionis Pharmaceuticals (NASDAQ:IONS)

Dollar bills rolled up in pill bottles being manufactured.

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This growth and value biotech is the perfect bad-news buy

Sean Williams (Exelixis): Feel free to call me a "homer" or biased since it currently resides in my portfolio, but I simply won't stop beating the drum on cancer-drug developer Exelixis as long as it sits well below $30 a share.

Earlier this month, Exelixis was clobbered after announcing that a partnered phase 3 trial known as IMblaze, which combined its Food and Drug Administration-approved drug Cotellic with Roche's cancer immunotherapy Tecentriq, failed to improve overall survival in patients with difficult-to-treat, advanced or metastatic colorectal cancer. Considering how impressive Exelixis's run higher has been, failures have been few and far between. 

However, it's worth pointing out that Cotellic has been a relative non-factor for Exelixis. Sure, positive pivotal-stage results would have been great, and it would have given the company another shared source of revenue. But at the end of the day, the advancement of Cabometyx is what matters, and a setback in Cotellic can be easily overlooked.

In the company's first-quarter operating results, Cabometyx generated $134.3 million in sales, which was practically double the $68.9 million registered in the year-ago quarter. Not only is the company seeing solid organic growth in second-line and later renal cell carcinoma (RCC) patients, but it's benefited from the December 2017 label expansion into first-line RCC patients. 

Let's also remember that Cabometyx dazzled in the late-stage Celestial study for advanced hepatocellular carcinoma. The trial was actually stopped early after the drug demonstrated an overall survival of 10.2 months, compared to just 8 months for patients given the placebo. All key secondary endpoints were met as well, with progression-free survival and objective response rates significantly higher in the Cabometyx arm. A label expansion seems pretty likely at this point. 

What we're left with is a company that's quickly barreling toward $1 billion in annual sales, and that could generate more than $2 in annual EPS by 2022. Wall Street also expects a compound annual sales growth rate of 30% through 2021. Long story short, we're talking about a growth and value play in the biotech sector all nicely wrapped up into one stock. Needless to say, this shareholder has no intentions of selling, and he'd suggest you give Exelixis another look right now.

A prime comeback candidate

Keith Speights (Celgene): How would you like a biotech stock that trades at less than eight times expected earnings but should be able to increase earnings by nearly 20% annually over the next few years? For most investors, that stock would sound like a great deal. The good news is that there's a stock that fits the bill: Celgene.

It's definitely been a rough stretch for Celgene over the last year. The big biotech experienced a major late-stage clinical setback for a once-promising Crohn's disease drug. It fumbled the FDA submission of one of its top pipeline prospects, multiple sclerosis drug ozanimod. And Health and Human Services Secretary Alex Azar recently singled out Celgene's blood cancer drug Revlimid as an example of why Medicare's drug costs are rising.

Still, there's an awful lot to like about Celgene. The company has two other blockbusters besides Revlimid that are enjoying strong sales growth -- Pomalyst and Otezla. Cancer drug Abraxane should be close to the $1 billion annual sales mark this year. 

But what I really like about Celgene is its pipeline. The company completed two acquisitions earlier this year, landing myelofibrosis drug fedratinib and non-Hodgkin lymphoma drug JCAR017. Both of the drugs hold the potential to become blockbusters for Celgene. The biotech expects to submit ozanimod for approval again in early 2019. And it has plenty of other promising experimental drugs in its pipeline, including bb2121 and luspatercept.

A stock with Celgene's growth prospects can only be beaten down for so long. I see this biotech as a prime comeback candidate. 

Betting on a platform

Brian Feroldi (Ionis Pharmaceuticals): Scores of biotech companies have bet their future on the success of a single drug. That can work out extremely well for shareholders if the company churns out a winner. However, given the long odds of success, more often than not those one drug biotechs wind up destroying shareholder value. That's why I prefer to put my support behind biotech companies that are building drug discovery platforms instead of just praying that a single drug works out. If you agree with that strategy then you should get to know Ionis Pharmaceuticals.

Ionis has been churning out new compounds for years thanks to its innovative antisense technology. In a nutshell, this drug discovery platform works by targeting RNA that is causing problems in the body and then turns them off. This results in less prevalence of the troublesome RNA and can lead to an improved health outcome for patients.

What's wonderful about antisense is that it can be used to quickly churn out new drugs that treat a wide range of diseases. Ionis' pipeline is literally packed with dozens of compounds that could be used to treat cancer, neurological disorders, renal diseases, and more.

I also like that Ionis has proven that its antisense technology is the real deal. The company has already crossed the finish line with two drugs, Spinraza, which is marketed by Biogen, and Kynamro, which is marketed by Kastle Therapeutics. Two other drugs that are used to treat cardiovascular disease are currently pending FDA approval, too.

Overall, an investment in Ionis isn't just a bet on the success or failure of any specific drug. It's a bet on the company's antisense platform. Given the company's history of using its platform to create value for shareholders, that's a bet that I think is worth making.

Brian Feroldi owns shares of Celgene and Ionis Pharmaceuticals. Keith Speights owns shares of Celgene. Sean Williams owns shares of Exelixis. The Motley Fool owns shares of and recommends Biogen, Celgene, Exelixis, and Ionis Pharmaceuticals. The Motley Fool has a disclosure policy.