Shares of biotech BioMarin (BMRN 0.17%) spiked more than 20% today in pre-market trading after the company released exciting data from its Mucopolysaccharidosis Type IVA (or MPS IVA) clinical trial. Although this company boasts a market cap close to $6 billion, it might fly under the radar for some investors. What does this company focus on, and what should investors be watching for the long term?

Orphan drugs
BioMarin is a biopharmaceutical company that focuses on serious rare diseases, which means that the company's portfolio and pipeline have more orphans than a Charles Dickens collection. Treatments for rare diseases are often called "orphan drugs," and, in addition to potentially helping patients, this is a growing business for BioMarin. Its year-over-year net loss in the third quarter shrank from $17.7 million to $5.4 million. Revenue also grew 13% to reach $128.1 million.

Let's take a closer look at what BioMarin needs to do to maintain its positive momentum.

Product growth
BioMarin has four treatments available on the market, and the combined improved earnings, year-over-year, is what drove up overall revenues for the quarter.

Naglazyme is the biggest seller, reporting $62.5 million in revenue in the third quarter, an increase of 12%. Naglazyme treats mucopolysaccharidosis VI (MPS VI), a potentially fatal genetic deficiency of a lysosomal enzyme. MPS VI is estimated to occur  in between 1 in 250,000 and 1 in 600,000 births.

Kuvan -- a treatment for the genetic metabolic disorder phenylketonuria, or PKU -- rose 19% to $36.4 million. PKU results in dangerously high levels of the amino acid phenylalanine and can lead to devastating neurological impairments. It's estimated that there are 14,500 people in the U.S. with PKU.

BioMarin manufactures the orphan drug Aldurazyme but leaves the domestic and international commercialization to Genzyme, a Sanofi (SNY -0.18%) subsidiary. Aldurazyme treats MPS I, a potentially fatal enzyme disorder. The drug had net profits for BioMarin totaling $23.8 million, up 3.5% on the year.

Trailing behind in fourth place is Firdapse with $3.6 million, an increase of 2.9%. Firdapse treats  Lambert-Eaton myasthenic syndrome, or LEMS, a rare autoimmune disease that frequently presents with a second condition, such as cancer. Firdapse is available in the EU but is still going through the approval process in the United States.

Although the patient populations for these drugs are small, BioMarin has the benefit of having the only treatments currently available. Revenues would be damaged by a competitor bringing out a drug that at least matches, if not exceeds, the efficacy of BioMarin's products.

Potential competition
It's mostly quiet on the competition front. Zacharon Pharmaceuticals is a development partner  with Pfizer (PFE 0.40%) for the creation of MPS I, II, and III treatments, potentially creating a competitor for Adurazyme. But that project hasn't yet produced a clinical candidate.

An increasing number of big pharma companies are moving into orphan territory, but the ultra-orphan status of many of the conditions that BioMarin covers may keep the big boys away for the most part.

Flowing pipeline
BioMarin's  pipeline isn't enormous, but it has a couple of strong contenders moving toward late stages.

One of the most anticipated is the GALNS drug for MPS IVA. Phase 3 trial results were reported today, and the successful results from this study sent the stock soaring.

Following close behind on the advancement trail is the PKU treatment PEG-PAL. There will be an end of phase 2 meeting  with the FDA in the first quarter of next year, and phase 3 should start in the second quarter.

Final Thoughts
After today's share price surge, BioMarin is trading at about 60% above its 52-week low and is up nearly 40% year to date. The company has a solid set of products on the market that are showing at least modest revenue increases. The GALNS trial result was a major catalyst today, but investors still need to keep an eye on BioMarin's sales and progress in commercializing the drugs in its pipeline.