Two oncology-focused biotech stocks began 2016 with a dip but have diverged a great deal ever since. A successful label expansion made Exelixis, Inc. (NASDAQ:EXEL) a top industry performer this year, and a surprising clinical trial failure made it a year Celldex Therapeutics (NASDAQ:CLDX) shareholders would rather forget.

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Should investors try to ride the Exelixis rocket even higher, or look for value in Celldex's burgeoning pipeline? Let's see how these two stack up to each other to find the better pick right now.

Arguments for Celldex Therapeutics

Shares of this biotech went south last winter along with the rest of its industry, and it fell again in early spring when its lead candidate failed to outperform the standard of care in a difficult-to-treat form of brain cancer. Without a commercial-stage product to sell, the stock remains depressed in spite of a pipeline containing several potential first-in-class therapies winding their way through clinical-stage development.

In the lead is glemba for treatment of triple-negative breast cancer patients with tumors that express the candidate's target protein, gpNMB. The drug is in a study designed to support an application for this underserved patient population that could lead to over $1 billion in annual sales if successful.

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The odds of success for glemba in the triple-negative indication look pretty good following results from a small group of similar patients that showed a highly significant progression-free survival benefit over standard chemotherapy. Outside of breast cancer, it has a shot at a couple rare malignancies through two independently sponsored studies, plus the company recently reported positive results in a mid-stage melanoma trial.

Beyond glemba, Celldex is testing its immune-response stimulator, varlilumab ("varli"), in combination with Opdivo from Bristol-Myers Squibb  and Tecentriq from Roche, two therapies that make it difficult for tumor cells to shut down an immune response. Another wholly owned candidate, CDX-1401 is in a combination study with Incyte's epacadostat for treatment of ovarian cancer patients, and in November the company picked up two more clinical-stage candidates from a privately held biotech. All told, it has enough compounds in clinical trials to make a blue-chip biotech turn green with envy.

Arguments for Exelixis, Inc.

Exelixis doesn't have nearly as many irons in the fire as Celldex, but it is generating revenue, and it looks as if sustainable profits are on the way as well. Exelixis' lead drug, Cabometyx, first earned approval in 2012 as a treatment of a rare thyroid cancer, but it didn't generate much in the way of sales. A late-stage clinical trial failure with prostate-cancer patients had many expecting very little from the drug, but a recent expansion to second-line kidney cancer with compelling data has fueled hopes of blockbuster sales and sent the stock soaring.

Bristol-Myers Squibb's Opdivo earned an FDA approval for the same group of patients nearly half a year ahead of Cabometyx, but it looks as if Exelixis isn't about to be outmaneuvered by the big pharma. Third-quarter Cabometyx sales of $62.2 million exceeded analysts' expectations by about $17 million. Perhaps oncologists are responding to data that made it the first advanced kidney-cancer therapy to outperform the standard of care on three common efficacy measurements.

More recent data suggests that Cabometyx also has a shot at moving up to the front of the line for newly diagnosed patients with advanced kidney cancer. In a mid-stage study, it beat the standard treatment for this group, and repeating the success in a larger study would go a long way toward helping the therapy reach peak annual sales of more than $1 billion.

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Exelixis recently earned approval for a second drug, Cotellic, in combination with Roche's chemotherapy Zelboraf for treatment of advanced melanoma. So far sales have been lackluster, but they could get a big boost if phase 3 studies that the Swiss pharma is running with Cotellic and Tecentriq prove successful.

It's all in the numbers

While Exelixis has a couple of drugs in commercial stages, its market capitalization of about $4.76 billion is a tall perch to fall from if any hint of a flattening sales trajectory permeates the market in the quarters ahead. In stark contrast, Celldex Therapeutics still has nothing to sell, but its enterprise value of just $188.9 million at recent prices suggests it's already near a bottom.

I'd say glemba's odds of success in the ongoing pivotal breast-cancer study alone justify Celldex's current price. Its dizzying array of candidates and ongoing trials are icing on the cake, or a safety net in case of another surprise upset. If Exelixis were a bit less expensive, I'd call it the winner, but at recent prices, it looks as if Celldex Therapeutics stock is in a slightly better position to provide market-thumping gains over the long term.