Parkinson's Disease effects between 7 million and 10 million patients worldwide. Roughly 60,000 new cases will be diagnosed in the United States this year alone, yet  despite that big unmet need drug makers have stumbled in their attempts to bring new therapies to market.

While those stumbles have likely frustrated some, three emerging biotechnology companies: Chelsea (UNKNOWN:CHTP.DL), Avanir (UNKNOWN:AVNR.DL), and Prothena (NASDAQ:PRTA)continue to work on new treatments for symptoms and health problems associated with the disease.

Closing in on an FDA decision
Chelsea's Northera, a drug designed to treat neurogenic orthostatic hypotension, or NOH, may be close to commercialization.  The drug aims to help prevent falls tied to low blood pressure upon standing, a condition associated with diseases where the autonomic nervous system doesn't work properly, including Parkinson's and diabetic neuropathy.

However, Northera's path toward approval has been rocky.  Shares in Chelsea tumbled when regulators balked at approving Northera in 2012, claiming data didn't show enough benefit for long term use. But facing a condition without any other treatment options, regulators' have since agreed to consider data from an ongoing trial as part of Chelseas' resubmission. That's got investors increasingly confident Northera will get the go-ahead when the FDA makes its decision on February 14th.

The FDA's key advisory panel seems to agree that the risk of injury to NOH patients outstrips the FDA's desire for more long term data. The panel voted in favor of approving Northera by a landslide 16 to 1 margin this month; a far more convincing endorsement than the 7 to 4 vote in favor of the drug in 2012.

Making the way through the clinic
Avanir is a bit further away from reaching the market than Chelsea. However, its ongoing phase 2 trial for AVP-923, a treatment for levodopa-induced dyskinesia, or LID, in Parkinson's patients may offer more upside.

Levodopa is the most commonly prescribed treatment for Parkinson's, and its chronic use often results in dyskinesia, a movement disorder that reduces muscle control.  Of those patients treated with levodopa for more than five to 10 years, as many as 50% will develop LID.  Investors will gain additional insight into how effective Avanir's drug candidate is when the company shares trial results later this year. 

Prothena is the furthest away of these three from having a commercial product, but the company has a strong pedigree given it was spun out of Elan late in 2012.  Elan is best known for its collaboration with Biogen on the multi-billion multiple sclerosis drug Tysabri. Since being spun-off, shares in Prothena have marched more than 250% higher thanks in part to enthusiasm surrounding its pre-clinical Parkinson's drug, PRX-002.

Roche found PRX-002 intriguing enough to ink a deal in December that could be worth as much as $600 million in milestone payments to Prothena over time.  The two companies plan to initiate a phase 1 study of PRX-002 in the coming months.  

Fool-worthy final thoughts
A potential approval of Chelsea's Northera may come with asterisks, including requiring the company to conduct additional studies to determine Northera's long-term benefit. Those additional trials will weigh on the company's profitability. However investors may find demand is solid enough to support the extra costs. At Avanir, investors should watch the company's press releases to determine whether phase 2 trial results for AVP-923 are strong enough to support moving the compound into phase 3. As for Prothera, investors will need to wait a bit longer before there's any human trial data to examine.  In the meantime, keep a look out to see when PRX-002 starts enrolling patients in Phase 1.