With hundreds of biotech stocks on the market, who can keep up with them all? Probably no one. What happens as a result is that usually only the biggest biotechs (or the small biotechs getting bought by the biggest biotechs) get a lot of coverage. But sometimes those aren't the stocks to watch most closely. 

You might not have heard too much about Akebia Therapeutics (NASDAQ:AKBA), BioMarin Pharmaceutical (NASDAQ:BMRN), and Idera Pharmaceuticals (NASDAQ:IDRA). These are three biotech stocks that you could be overlooking -- but deserve your attention. Here's why.

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Akebia Therapeutics: Altitude matters

If you've ever gone mountain climbing, you probably noticed some effects on your body as you ascended. Akebia's niche is developing drugs that mimic those effects by inhibiting hypoxia inducible factor-prolyl hydroxylase (HIF-PH). HIF-PH inhibitors can increase red blood cell (RBC) production and improve stabilization of the bone marrow's iron supply. 

Akebia's lead candidate, vadadustat, is in two late-stage clinical studies targeting treatment of anemia in chronic kidney disease (CKD). One study is focused on dialysis-dependent CKD patients, while the other targets non-dialysis-dependent CKD patients. Results from a phase 2 study for vadaustat were encouraging.

Although potential regulatory approval for vadadustat is still a few years away, Akebia already has lined up two big partners. Otsuka will market the drug in the U.S. if approved. Another Japanese drugmaker, Mitsubishi Tanabe, will market vadadustat in Japan and other Asian countries except China. 

Akebia's market cap currently stands around $400 million. The tremendous potential for vadadustat could drive this biotech stock much higher. 

BioMarin Pharmaceutical: A rare find

Many investors are at least somewhat aware of BioMarin. The biotech claims five products on the market treating rare diseases. However, I think some still overlook BioMarin's considerable prospects for growth.

The biotech is already experiencing solid growth from its current product lineup. Vimizim, Naglazyme, and Kuvan led the way to drive BioMarin's revenue to around $1.1 billion. Morquio A syndrome drug Vimizim particularly has bright prospects. BioMarin thinks sales for the drug could reach $700 million annually.

BioMarin expects to obtain even more growth from two of its late-stage pipeline candidates. Regulatory approval for Brineura in treating CLN2 disease, a form of Batten disease, could be on the way in 2017 for both the U.S. and Europe. Pegvaliase, a potential treatment for genetic condition phenylketonuria (PKU), could win regulatory approval in 2018.

Although BioMarin already claims a market cap of more than $15 billion, the biotech should be able to become even larger with its growing rare-disease franchise. The company isn't profitable yet, but BioMarin thinks it will reach break-even on a non-GAAP basis this year.

Idera Pharmaceuticals: Diamond in the rough

Idera doesn't have any products on the market like BioMarin does. And the company doesn't even have a late-stage candidate like Akebia does. However, Idera's pipeline makes this small biotech one to keep your eyes on.

IMO-8400 is Idera's most advanced candidate. The experimental drug is currently being evaluated in a phase 2 study for treating dermatomyositis, a rare inflammatory disease affecting skin and muscle. Although there are treatments for this disease, they aren't tremendously effective and can produce serious side effects. Idera expects to report results from the phase 2 study of IMO-8400 in 2018.

Another promising candidate for Idera is IMO-2125. Like IMO-8400, the experimental drug is a toll-like receptor (TLR) agonist. The biotech is targeting PD-1 refractory melanoma as the first potential indication in an early stage study of IMO-2125. Idera is also exploring use of the drug in treating other forms of cancer. 

Idera is still tiny, with a market cap of less than $300 million. However, Wall Street analysts think the stock could be a big winner. I suspect they could be right. Idera just might be the biotech equivalent of a diamond in the rough. 

Best of the bunch

Because it's the smallest of the three biotechs, Idera probably has the greatest upside potential. However, with a pipeline that isn't as far along, it also has the most risk.

I think the best pick of the bunch is BioMarin. Everything seems to be going right for the biotech. It wouldn't be surprising to see BioMarin on the radar screen of a bigger company. Even if not, the company's current products and new drugs that are likely on the way should propel the stock higher. Don't overlook any of these biotech stocks, but especially watch BioMarin.