It's a disease that doesn't often find itself in the spotlight, but multiple sclerosis is quickly becoming an ailment that drugmakers are focusing their efforts on to make a quality-of-life difference for patients.

MS is a disease in which the body's own autoimmune system attacks its central nervous system, consisting of the brain, spinal cord, and optic nerves, disabling it over time. Some of the symptoms of MS can be relatively minor, such as tingling of the limbs, but others can be considerably more severe, including loss of vision and/or paralysis.

In recent years, the incidence rate of MS has been on the rise. However, one of the few tidbits of good news here is that this may be because of earlier and proper diagnosis rather than an actual increase in MS as a disease.

In total, an estimated 400,000 people in the U.S. suffer from MS, with approximately 10,000 new cases diagnosed each year. Women are more susceptible than men to getting MS, with the diseases in both genders most often diagnosed between the ages of 20 and 50. Researchers have also discovered a correlation between age and aggressiveness of the disease. The older a person is at the time of their diagnosis, the more aggressive the disease tends to be.

With this in mind, biopharmaceutical companies have been working their behinds off to create medications designed to slow down or stop the degradation of the central nervous system brought on by MS. While we'd love a cure, there are still too many unknowns about this disease to even dream of one at the moment.

Where we've been
Two drugs that have had a long-tenured and rich history in treating MS over the years are Tysabri and Copaxone.

Tysabri is a drug that was developed by Elan and licensed by Biogen Idec (NASDAQ:BIIB) to treat patients with relapsing MS. It was approved by the Food and Drug Administration in 2004 and generated $1.6 billion in sales last year. Recently, Biogen ponied up $3.25 billion, plus future royalties, to purchase the full global rights to Tysabri from Elan. In addition, Biogen is testing Tysabri as a treatment for secondary-progressive MS, a form of the disease that comes after relapse-remitting MS and progresses at a much faster pace. Although Tysabri's days as a patented drug for relapsing MS are numbered, Tysabri's overseas opportunity, and perhaps even domestic opportunity in a new indication, is still bright. 

The same can be said for Teva Pharmaceutical (NYSE:TEVA), whose once-daily relapse-remitting MS injection, Copaxone, has been nothing short of a blockbuster. Even more impressive, for Copaxone you have to go all the way back to December 1996 to find its FDA approval date! Copaxone is a $4 billion-plus drug for Teva and accounted for close to 20% of its revenue last year -- but it's also only two years away from losing patent protection.

Source: Pixabay.

Where we are now
We've come an incredibly long way over the past three years in MS treatments. Specifically, we're beginning to see a shift away from injection-based administration to pill form.

Novartis (NYSE:NVS) led things off in 2010 with the approval of Gilenya, a capsule-based relapsing MS treatment that is cleared for use in first-line and second-line MS cases and works by blocking some red blood cells in lymph nodes and curtailing their travel to the brain and spinal cord. Overall, Gilenya delivered $1.2 billion in net sales worldwide in 2012, a 142% increase in U.S. dollars. The one downside to Gilenya, though, is that it can lower a patient's heart rate, which has the potential to cause cardiovascular problems, and in rare cases it's been linked to macular edema and liver problems.

Last September, Sanofi (NASDAQ:SNY) brought Aubagio, a capsule-based relapsing MS drug, to market. In trials, Aubagio was quite effective, reducing the relapse rate of MS patients by roughly 30% relative to the placebo. However, being slapped with a black-box warning by the FDA for severe liver problems that can lead to death have seriously curbed its sales potential. In the second quarter, Aubagio brought in just $44 million in sales. 

The big winner and truly revolutionary new treatment in the MS space is Biogen Idec's Tecfidera. Keep in mind that Biogen Idec already has Tysabri and Avonex as MS treatments, so it's not a slouch by any means in the MS space. Tecfidera, like Gilenya and Aubagio, is an oral treatment given twice daily that, in trials, reduced relapse rates by 49% compared with the placebo and reduced new or expanding lesions by 71% to 99% across both trials. More importantly, Tecfidera's safety profile is considerably rosier than Aubagio and Gilenya, with far fewer potentially serious complications. Despite only recently launching Tecfidera, sales of the drug totaled $192 million in second-quarter and look well on their way to multibillion-dollar potential.

The future of MS treatment
The really great news is that researchers and biopharmaceuticals aren't done here.

Biogen Idec, which as you can see is arguably the most dominant company in MS research, currently has five additional MS compounds in clinical-stage studies. Perhaps the most exciting of the bunch, in my opinion as least, is daclizumab, which is being co-developed with AbbVie and is being tested as a relapse-remitting MS therapy that's injected just once every four weeks. Daclizumab itself is a humanized monoclonal antibody that works along the IL-2 receptor pathway by binding to CD25, a receptor subunit. In mid-stage trials, daclizumab demonstrated a 54% and 50% reduction in annualized relapse rates compared with the placebo in the 150mg and 300mg dosages. Currently in phase 3 trials, if all goes well it could be on the market in roughly two years.

Alkermes (NASDAQ:ALKS) is another surprise entrant into the MS drug development fray. Last month Alkermes' CEO, Richard Pops, announced his intention to take Alkermes down the path less traveled these days: treating chronic global diseases, but adding a twist of personalization to some of the treatments. One target squarely on Pops' list is developing the next-generation Tecfidera. Pops' idea is to develop a drug that'll turn into monomethyl fumarate, or MMF, once in the body, and needs to be taken only once daily as opposed to the twice-daily Tecfidera. The ultimate goal here is to create a non-inferior MMF drug to Tecifidera that has far fewer long-term adverse side effects. Early-stage studies of its MMF drug are expected by mid-2014.

The evidence is clear that treatment options are improving and that biopharmaceuticals are devoting the time and money to improve patient quality of life. While it certainly looks as if this is Biogen Idec's show to run away with, Novartis, Alkermes, Teva, and Sanofi may still have tricks, and new indications, up their sleeve to give Biogen a run for its money and to drastically improve MS treatment potential.

This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.