Source: Bristol-Myers Squibb.

One of the most important new drugs to win regulatory approval this year is Opdivo, a novel medicine developed by Bristol-Myers Squibb (NYSE:BMY) that keeps cancer from evading detection by a patient's immune system. Opdivo has already secured the FDA's go-ahead for use in advanced melanoma, lung cancer, and kidney cancer, and if trials pan out, it could similarly help pancreatic cancer patients live longer someday, too.

Overcoming cancer's defense
What often makes cancer cells tough to treat is their ability to fool the immune system into thinking that they're harmless. They do that by sending a signal to a receptor on a patient's immune system's T-cells, which are known as PD-1, that effectively render the T-cell inactive. Opdivo overcomes this defense by blocking the PD-1 receptor from being able to receive the cancer cell's message to turn itself off, thereby allowing T-cells to continue identifying and destroying cancer cells.

Source: Bristol-Myers Squibb.

Teaming up in pancreatic cancer
Opdivo is a pretty potent drug on its own, but when it comes to fighting the toughest cancer, teaming up Opdivo with other therapies may be the best approach. The company is working closely with Celgene (NASDAQ:CELG) and Aduro BioTech (NASDAQ:ADRO), for example, to determine if combining Opdivo with their therapies can significantly improve survival in pancreatic cancer patients.

Last year, Bristol-Myers Squibb and Celgene announced that they'll study a one-two punch combination approach in pancreatic cancer that combines Opdivo with Celgene's Abraxane, a chemotherapy drug.

Abraxane is already approved for use in metastatic pancreatic cancer patients. In clinical trials, patients receiving Abraxane and the commonly used cancer drug gemcitabine lived 1.8 months longer than patients taking gemcitabine alone.

Bristol-Myers Squibb and Celgene hope that adding Opdivo to that regimen could add additional months to survival, and the two companies are currently recruiting patients for a phase 1 safety study that will run until mid-2017. Although the primary goal of this study is to make sure that the combination is safe, the trial will also evaluate progression-free survival and overall survival.

Bristol-Myers Squibb is also studying Opdivo alongside Aduro BioTech's CRS-207 and GVAX Pancreas in pancreatic cancer. CRS-207 is a clinical-stage immunotherapy that relies on modified listeria bacteria to elicit an immune-system response to cancer, and GVAX Pancreas is a cancer vaccine.

In phase 2a studies, patients taking CRS-207 and GVAX Pancreas had a median overall survival of 6.1 months versus 3.9 months for GVAX Pancreas alone. Those results led to Aduro BioTech launching a 303 patient phase 2b study of the two-drug combination, and the initiation of a second study with Bristol-Myers Squibb that adds Opdivo to the mix.

Bristol-Myers Squibb and Aduro BioTech began enrolling patients in this trial earlier this year. Interim results should be available by the end of next year.

Looking ahead
Opdivo has secured six FDA approvals in the past 12 months, and a lot more approvals could be coming given that there are more than 50 trials underway studying it. Whether one of those approvals will eventually be for pancreatic cancer is anyone's guess, but ongoing trials in the indication suggest that Bristol-Myers Squibb thinks it's possible. Based on Celgene's success with Abraxane, it may be worth keeping close tabs on that trial.

Todd Campbell owns shares of Celgene. Todd owns E.B. Capital Markets, LLC. E.B. Capital's clients may have positions in the companies mentioned. The Motley Fool owns shares of and recommends Celgene. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.