This year has brought about reversals of fortunes for two biotech stocks. Shares of Exelixis, Inc. (NASDAQ:EXEL) soared in 2016 and 2017, but the stock is down close to 30% so far in 2018. It's the opposite scenario for Intra-Cellular Therapies, Inc. (NASDAQ:ITCI). The biotech stock floundered in the two years prior to 2018 but has skyrocketed nearly 50% year to date.

But which of these two stocks is the better pick for investors over the long run? Here's how Exelixis and Intra-Cellular Therapies stack up against each other.

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The case for Exelixis

Let's first examine why Exelixis' performance has been dismal this year. The biggest factor is that the company reported disappointing Q4 results in late February, with investors concerned about slowing growth for cancer drug Cabometyx. Exelixis also announced in early May that the combination of its Cotellic and Roche's Tecentriq failed to meet the primary endpoint in a late-stage clinical study targeting treatment of colorectal cancer.

So is there any good news for Exelixis? Sure. Cabometyx remains a huge winner. The drug won Food and Drug Administration approval in December 2017 as a first-line treatment for advanced renal cell carcinoma (RCC), the most common type of kidney cancer. This approval helped Exelixis return to tremendous revenue growth in the first quarter.

Cabometyx is definitely the top reason to buy Exelixis stock. The drug could reach peak annual sales in the ballpark of $2 billion. An FDA decision on potential approval for Cabometyx as a treatment for patients with previously treated hepatocellular carcinoma (HCC), the most common form of liver cancer, is expected by Jan. 14, 2019. Exelixis is also evaluating Cabometyx in combination with other drugs in treating various types of cancer.

Don't count Cotellic out yet, either. Although the combo with Tecentriq wasn't successful in treating colorectal cancer, Exelixis and Roche are also evaluating a combination of Cotellic, Tecentriq, and Zelboraf in a pivotal phase 3 study targeting treatment of melanoma.

Thanks to the continued success for Cabometyx, Exelixis is in great financial shape. The company reported cash and cash equivalents totaling $525.6 million at the end of March. Look for Exelixis to use its growing cash stockpile to build up its pipeline. 

The case for Intra-Cellular Therapies

What's behind Intra-Cellular Therapies' fantastic stock gains so far this year? Investors eagerly await the prospects for the biotech to have its first approved drug on the market.

In June, Intra-Cellular initiated a rolling submission of its New Drug Application (NDA) for lumateperone in treating schizophrenia. The company expects to complete this NDA submission soon. Lumateperone could potentially become a blockbuster for Intra-Cellular if it's approved for the schizophrenia indication.

Actually, peak revenue for the drug could rise well above $1 billion if Intra-Cellular is successful in its other clinical studies. The biotech is evaluating lumateperone in two phase 3 clinical studies for treating bipolar depression and behavioral disturbances associated with dementia, including Alzheimer's disease.

There are some concerns, though. In April, Alkermes received a refusal to file letter from the FDA for depression drug ALKS 5461. This news caused Intra-Cellular stock to drop because investors worried that Intra-Cellular could face a tougher challenge than expected in winning approval for lumateperone. 

But Intra-Cellular should be in pretty good shape with its NDA submission. Lumateperone met its primary endpoint in two late-stage clinical studies. The drug's safety profile also looked similar to placebo in these studies.

The biotch could have another positive catalyst on the way as well. Intra-Cellular expects to announce results from an interim analysis of a phase 3 study of lumateperone in treating behavioral disturbances associated with dementia in the second half of 2018.

Better buy

Exelixis' market cap currently stands at around $6.3 billion, while Intra-Cellular Therapies' market cap is close to $1.2 billion. Intra-Cellular stock should have more room to run than Exelixis if lumateperone wins FDA approval.

However, Intra-Cellular also comes with a lot more risk. There's a distinct chance that lumateperone won't win approval. Clinical studies targeting other indications might not be successful. Exelixis' Cabometyx is largely de-risked thanks to its previous approvals for kidney cancer and its solid late-stage results in treating liver cancer.

I'm a relatively conservative investor, so my pick as the better stock is Exelixis. The drubbing the stock has taken so far in 2018 makes it an even more attractive choice, in my view. I won't be surprised if Intra-Cellular is a big winner, too, but I'll go with the safer bet on Exelixis.

Keith Speights has no position in any of the stocks mentioned. The Motley Fool owns shares of and recommends Alkermes and Exelixis. The Motley Fool has a disclosure policy.