Photo source: Beximco Pharma, Flickr Creative Commons.

This article was originally published on September 29th, 2015 and was updated on January 15th, 2016 to reflect recent developments. 

One of the most exciting developments in recent years in the fight against cancer is the growing field of immunotherapy, which aims to harness the power of a patient's own immune system to seek out and destroy cancer cells. Huge amounts of money are being thrown at this exciting area that offers hope to patients around the world who suffer from this disease.

Given the huge opportunity that exists for this new class of medicine, we asked our team of Motley Fool healthcare contributors to share with us the big pharma company they think has the best chance of grabbing a big piece of this emerging market.

Brian Feroldi: One of the more exciting immunotherapies being developed right now is called Chimeric Antigen Receptors, which work with the body's own T cells -- hence its name, CAR-T, which train the body's immune system to recognize and kill cancer cells.

There are plenty of companies of all sizes that are investing heavily in the space, like Juno Therapeutics (JUNO) and Kite Pharma, so picking a company that will end up a winner ahead of time is extremely difficult. Knowing that, I think it makes more sense to invest in the winners likely partner of choice, Celgene (CELG), as a way to ride the wave.

Celgene has already made a $1 billion bet on Juno Therapeutics, who it clearly believes is the leader in the space, but it has also inked a number of other deals as a way to diverse its risk. The company has made investments in other immuno-oncology players like Sutro Biopharma and it has also inked a long-term deal with AstraZeneca's MedImmune division.

While it's likely that several of these partnerships won't turn into anything, it does show that the company is willing to invest early to get a foothold in the space. With its strong history of being a big player in the cancer treatments coupled with its deep pockets, Celgene stands a good chance of partnering with the company that will ultimately become the winner.

Picking the winners in a new field of medicine ahead of time is extremely difficult, but one shortcut is to have a strong management team with experience in the space do the picking for you. If I had to bet on one company eventually becoming the leader in the space, my bet would be on Celgene.

Todd Campbell: A lot of intriguing companies are developing immuno-oncology therapies, but only a few rate the "been-there-done-that" status that's associated with notching an FDA approval. Bristol-Myers Squibb (BMY -0.72%) is one of them, and its success in developing the immunotherapy Opdivo has me thinking that it has the chops necessary to develop at least one of the five other immuno-oncology programs it has in its pipeline.

Unlike traditional chemotherapy's shock-and-awe approach, Opdivo prevents cancer cells from flipping a switch that can deactivate a patient's T-cells. Following success in phase 3 trials, Opdivo has won FDA approval for use in metastatic melanoma and non-small-cell lung cancer patients, resulting in sales of more than $467 million worldwide through the first three quarter of 2015. Because there are roughly 50 other Opdivo trials under way, Opdivo has a good shot at becoming a blockbuster drug, but Bristol-Myers' other immuno-oncology drugs could be top sellers, too.

Two therapies -- elotuzumab and prostvac -- are in phase 3 studies, and in August, Bristol-Myers reported that multiple myeloma patients receiving elotuzumab alongside standard of care had a 30% reduction in disease progression or death. That finding prompted the company to file for elotuzumab's approval in September, clearing the way for a decision by the FDA next February.

Meanwhile, prostvac is currently in phase 3 studies as a therapy for prostate cancer, with results expected early in 2017. Overall, if those two drugs pass muster with regulators, Bristol-Myers could be hauling in billions of dollars in sales from three immuno-oncology drugs by 2018 -- and that's why I believe it's the one to watch.

George BudwellPfizer (PFE 0.66%) is extremely far behind its competitors in the field of immuno-oncology. But that might be by design. 

The pharma giant appears to be content to let other drugmakers take the lead when it comes to bringing new classes of therapies to market, and then use its vast resources to try and scoop them by developing so-called "best-in-class" medicines -- that is, once the commercial value of these entirely new treatments has been established. 

As an example, Pfizer has allowed its fellow drugmakers battle it out over which one gets to bring the first PCSK9 inhibitor to market for high cholesterol. In the meantime, Pfizer has instead concentrated on developing a competing therapy that would be far easier to use, presumably giving it a significant competitive advantage going forward.

The same scenario may be playing out in immuno-oncology. Not long ago, Pfizer had almost no footprint whatsoever in immuno-oncology, preferring to quietly remain on the sidelines, as other companies brought the science to where it is now.

Having the benefit of seeing where some of the biggest pitfalls lay, Pfizer recently jumped into the game with both feet, signing a deal with Merck KGaA to initially develop the company's anti-PD-L1 drug, avelumab, for a variety of cancers. Since then, Pfizer has announced that it plans on developing several additional immunotherapies that span a wide range of treatment regimens such as pills and injected drugs, as well as vaccines. 

Although it remains too early to tell where Pfizer might try to gain the biggest competitive advantage in immuno-oncology, I wouldn't hold their late start against them. After all, they have more than enough resources -- and the experience to match -- to eventually gobble up an oversized portion of this market.