December is certainly a busy month in the biotech industry, with a slew of upcoming regulatory reviews and clinical trial data readouts. With that in mind, here's a Foolish look at three biopharmas with imminent drug reviews at the U.S. Food and Drug Administration, or FDA.

A new treatment for a delicate condition
Auxilium Pharmaceuticals (NASDAQ: AUXL) is awaiting word on its supplemental Biologics License Application, or sBLA, for XIAFLEX, currently under review with the FDA for Peyronie's Disease. The Prescription Drug User Fee Act, or PDUFA, target review date for the drug is Dec. 6.

Peyronie's Disease is a poorly understood disorder characterized by scar tissue or abnormal curvature of the penis resulting from chronic inflammation of the connective tissue. A handful of therapies have been tested so far, with generally poor results, and many patients aren't willing to undergo corrective surgery, the treatment of last resort.

Xiaflex is currently approved in the U.S., EU, Canada, and Australia for the treatment of adult Dupuytren's contracture, and is also being studied in a number of other soft tissue disorders. It looks like a promising candidate for Peyronie's Disease, based on late-stage trial results released last week, which showed that the drug significantly reduces Peyronie's Disease symptoms and is generally well-tolerated.

That said, six patients in earlier clinical trials did experience severe adverse events that required medical intervention, which may be a point of contention during the drug's regulatory review.

In terms of market opportunity, this expanded label indication for Xiaflex could be worth as much as $120 million in peak annual sales. As such, Foolish investors might want to dig deeper into this specialty biopharma.

Better medicine for hepatitis C
Gilead Sciences (GILD -2.70%) also has a target review of Dec. 6 with the FDA for its hepatitis C drug sofosubuvir.

Last October, sofosubuvir was reviewed by the FDA's Antiviral Drugs Advisory Committee, which voted unanimously to approve the drug in combination with ribavirin for the treatment of adults with chronic hepatitis C virus genotypes 2 and 3. Additionally, the committee unanimously recommended the drug be approved for use in combination with pegylated interferon and ribavirin for treatment of chronic HCV in adults with genotypes 1 and 4 infections who have not received prior therapy. 

Last month, the European Medicines Agency's Committee for Medicinal Products for Human use, or CHMP, also recommended granting marketing authorization for sofosubuvir for the treatment of chronic hepatitis C in adults. Final approval in Europe is thus expected in early 2014.

Why are these approvals a big deal? Although Gilead is already a large-cap biopharma with multiple blockbuster drugs in its portfolio, sofosubuvir is projected to see sales exceeding $6 billion as early as 2016 if it's approved in both the U.S. and EU.

Sofosubuvir is thus expected to be a megablockbuster, and a major revenue generator for Gilead for years to come. It's simply another good reason to keep a close watch on Gilead.

An update on Anoro
GlaxoSmithKline (GSK 0.12%) and Theravance (NASDAQ: THRX) have a target PDUFA date for their chronic obstructive pulmonary disorder, or COPD, drug Anoro Ellipta set for Dec. 18. Back in mid-September, the FDA's Pulmonary-Allergy Drugs Advisory Committee voted 11-2 in favor of the drug's effectiveness as a treatment for COPD, and signed off on its safety profile as well. As a result, Anoro stands a good chance of approval come Dec. 18.

Anoro's potential approval is worth keeping on your radar, because the drug could see peak sales of $1.4 billion as soon as 2017. Even so, a slew of big pharmas including Pfizer, AstraZeneca, Novartis, and a host of smaller companies are all racing to get their own COPD drugs approved in the near future.

As such, Anoro will likely be facing stiff competition in the not-so-distant future, assuming it's approved later this month. Nonetheless, a successful Anoro could be a nice addition to both GlaxoSmithKline and Theravance's respective drug portfolios. Foolish investors would be wise to keep tabs on this pending drug approval.

One incredible growth stock to watch