Image source: Sarepta Therapeutics.

Duchenne muscular dystrophy, or DMD, is an awful childhood disease that leads to the weakening of muscles throughout the body, and it affects about 1 in every 3,500 newborn boys. Boys with the disease can begin to show symptoms as early as age 2, and as they age, the symptoms tend to get worse. Many boys become dependent on a wheelchair before age 12, and the disease can lead to death at a young age, primarily due to respiratory or heart failure.

DMD is a disease that currently has no cure or FDA-approved treatments, but two companies, Sarepta Therapeutics (NASDAQ:SRPT) and BioMarin Pharmaceuticals (NASDAQ:BMRN), are looking to change that. Each of them have successfully submitted a potential treatment for the disease to the FDA for approval, and the race is on to see which company will cross the finish line first and offer hope to patients with this rare disease.

We asked our team of Motley Fool contributors to weigh in on which company they believe has the best chance of getting its drug to market first.

George Budwell: BioMarin and Sarepta's respective DMD drugs are both barreling toward their long-awaited regulatory reviews with the FDA. Investors and patients alike are thus waiting to see whether the FDA will approve both drugs, just one, or perhaps neither.

While I hate to play the part of the skeptic when it comes to new drugs that are desperately needed for rare diseases like DMD, I find it hard to believe that the FDA will green light either drug following these upcoming reviews.

BioMarin's drug, drisapersen, actually failed to meet its primary endpoint in late-stage testing. Drisapersen's regulatory review thus hinges on the hypothesis that it might be more effective if given to younger patients, but there is limited empirical support for this notion right now.

Sarepta's problem comes from the small sample size of the mid-stage study that's serving as the basis for the regulatory filing of its experimental DMD offering, eteplirsen. The FDA has repeatedly raised concerns that the 12 patients receiving eteplirsen in the study in question may not be sufficient to rule out a possible placebo or other experimental effect.

Although Sarepta is attempting to counter this criticism by showing that patients taking eteplirsen experienced a significantly slower rate of disease progression than normal, the current data set can't speak to these concerns. Put simply, Sarepta is asking the FDA to take a leap of faith that further clinical data will confirm these promising mid-stage results, and that is something the agency has almost never been willing to do.  

A compelling case could certainly be made that the potential benefits of these drugs may far outweigh their risks for a disease that is always fatal. But my guess is that the FDA is going to ask BioMarin and Sarepta for more data before approving their drugs. At this point, I think there are just too many questions regarding their efficacy to warrant an approval. 

Todd Campbell: Clinical-stage biotech stocks developing much-needed new therapies for DMD have been among biotech's most frustrating investments; however, now that BioMarin and Sarepta's FDA decision dates are fast-approaching, investors will soon find out if sticking with these stocks through their nausea-inspiring volatility was worth it.

Unfortunately, picking a winner in this horse race isn't going to be easy. Both BioMarin and Sarepta's drugs have a similar mechanism of action, and data from trials raised as many questions as it did answers for both companies.

BioMarin's phase 3 failure following phase 2 success calls into question the efficacy of its drug, and despite Sarepta's mid-stage trial results being encouraging, Sarepta's findings are based on just 12 patients, and its three-year follow-up data suggests that efficacy for its drug may fade over time.

Assuming regulators look beyond those question marks and both drugs win approval, I think BioMarin stands the best chance at commercial success because the drug maker has already proven that it knows how to commercialize rare disease treatments.

However, since both companies were granted a rare pediatric disease designation for their drugs that nets them a transferable priority review voucher if their drugs get approved, both companies could get a big windfall next year.

Similar vouchers have sold on the open market for hundreds of millions of dollars recently, and if those prices hold up, selling them would have a bigger impact on the much smaller Sarepta, which boasts a market cap of just $1.37 billion. Regardless, I'm content to watch this race from the sidelines.

Brian Feroldi: BioMarin bought its way into this race in 2014 with its purchase of Prosensa, the original developer of their potential DMD treatment drisapersen. Considering that BioMarin forked over $680 million for the transaction, plus potential milestone payments, the management team must have had strong conviction that drisapersen would find its way to market and be successful. Given the company's long history of success in treating orphan diseases, I'm inclined to give its management team the benefit of the doubt.

In addition, the company was faster in getting its drug before the FDA for review, and regulators have set a target date for a decision of December 27, 2015. Sarepta has also already submitted, but its review date of February 26, 2016, is nearly two months later than BioMarin's. 

Given that the DMD community is rooting for both of these medicines to succeed, I'm sure doctors will be giving them a try as soon as they become available, which could give BioMarin a slight edge in the race given its potential two-month head start. If forced to choose a winner, I would pick BioMarin, but like Todd, I'm not confident enough in that outcome to put money in either of these names based solely on their DMD opportunities.