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Both Ionis Pharmaceuticals (IONS 0.42%) and Celgene (CELG) have seen better days. While both stocks soared over the past several years, 2016 hasn't been so hot. Shares of Ionis are down around 50% so far this year, and Celgene's stock has dropped by 16% year to date.

Ionis and Celgene have a lot going for them, though. Which biotech stock is the better pick for investors right now? Let's see how they compare.

The case for Ionis

Although Ionis does have a couple of products on the market, none present a compelling reason to buy the biotech's stock right now. The company terminated Sanofi's license for homozygous familial hypercholesterolemia (HoFH) drug Kynamro in January, then licensed the drug out to Kastle Therapeutics a few months later. Kynamro should have pretty good commercial potential, but that potential has yet to be realized.

Ionis developed anti-inflammatory drug alicaforsen and licensed it to Atlantic Pharmaceuticals in 2007. The drug is technically available for sale in Europe, but only under named-patient supply regulations that allow physicians to access medications that haven't yet been approved.

The biotech took a big hit in May when GlaxoSmithKline chose to hold off on moving forward with a planned late-stage study of IONIS-TTRRX in treating TTR amyloid cardiomyopathy. The FDA had placed a clinical hold on another study of the drug, which led to Glaxo's jitters. 

So what's the investing case for Ionis in light of all of this bad news? The company's pipeline should still produce plenty of winners. First of all, the story isn't over for IONIS-TTRRX. Ionis has its own phase 3 study under way for the drug as a treatment for  familial amyloid polyneuropathy (FAP) and expects to report data from the study in 2017. Glaxo and Ionis intend to submit for regulatory approval pending positive results from the study.

Ionis also has 29 other clinical studies in progress, most of them in collaboration with partners. I particularly like the prospects for nusinersen. Biogen, which licensed marketing rights to the drug, recently completed its submission of nusinersen to the FDA as a treatment for spinal muscular atrophy. The big biotech is also working to secure regulatory approval in Europe. Evercore ISI analyst Mark Schoenebaum thinks nusinersen can hit peak annual sales of $1.7 billion.

The case for Celgene

A lot seems to be going right for Celgene these days -- although the biotech's stock doesn't show it. Celgene topped Wall Street's revenue and earnings expectations so far this year. The company has announced positive results from several clinical studies. 

There was one fly in the ointment, though. Interim results announced in July from a phase 3 study of Revlimid in treating diffuse large B-cell lymphoma (DLBCL) were disappointing. While the results showed significant improvement for patients taking Revlimid in progression-free survival, no benefit was seen in overall survival. Celgene ended up abandoning plans to seek approval for the DLBCL indication.

Is this setback significant enough to seriously hurt the investing case for Celgene? Not in my view. Revlimid's sales are growing at a solid rate (18% year-over-year in the second quarter). The drug still has potential in treating other types of cancers. 

More importantly, Celgene doesn't depend solely on Revlimid. Sure, the drug accounts for over 60% of total revenue. However, the biotech is seeing sizzling growth with multiple myeoloma drug Pomalyst, as well as Otezla, which treats plaque psoriasis and psoriatic arthritis. 

Don't overlook Celgene's pipeline, either. The biotech is looking to win approval for additional indications for several of its current drugs. Several new drugs also look promising. Ozanimod is in a couple of late-stage studies, one targeting multiple sclerosis and the other focusing on ulcerative colitis. Mongersen is in a phase 3 study for treatment of Crohn's disease. I also like the potential for sotatercept, which is in a phase 2 study targeting chronic kidney disease.

Celgene believes that it can increase sales at an 18% compounded annual growth rate and earnings per share by 23% annually through 2020. Based on Celgene's past performance, strong product lineup, and solid pipeline, as well as its knack for innovative partnerships, I think the company will achieve those goals.  

Better buy

You've probably already figured out which one of these two biotechs I think is the better buy. Ionis has plenty of potential, but Celgene is the clear winner in my view.

Celgene provides investors strong growth prospects with relatively low risk compared to most biotechs. Expect Celgene to use its $6.4 billion cash stockpile (including cash, cash equivalents, and marketable securities) in ways that reward shareholders. Celgene's stock might be down so far in 2016, but I like the odds that shares return to their winning ways soon.