April 27 update:

The FDA approved Brineura, a new medicine from Biomarin Pharmaceuticals (BMRN) - Get Report as the first treatment for CLN2 disease, a form of Batten disease.

"The FDA is committed to approving new and innovative therapies for patients with rare diseases, particularly where there are no approved treatment options," said Dr. Julie Beitz, director of the Office of Drug Evaluation III in the FDA's Center for Drug Evaluation and Research. "Approving the first drug for the treatment of this form of Batten disease is an important advance for patients suffering with this condition."

Brineura will cost $27,000 for a treatment given every two weeks. That translates into an annual cost of $700,000, making Brineura among the most expensive drugs.

Shares of Biomarin closed Thursday at $96.26.

The original story published on April 24 is below:

Biomarin Pharmaceuticals (BMRN) - Get Report picked up an important European approval endorsement on Friday for a new drug targeting a rare and fatal neurodegenerative disease in children. The FDA is expected to announce its own approval decision no later than Thursday.

The Biomarin drug is known as Brineura. If approved, Brineura will be the first and only treatment for CLN2 disease, a form of Batten disease.

Biomarin shares were up $5.63, or 6.36%, to $94.10 through mid-day trading Monday.

Kids with CLN2 look healthy at birth but by the age of 3, they start to lose the ability to speak and walk. The disease progresses fairly rapidly and most children die by the time they reach 12 years old. Biomarin believes the disease affects approximately 1,200 to 1,600 children worldwide, with 85% outside the U.S.

On Friday, the Committee for Medicinal Products for Human Use, or CHMP, the scientific committee of the European Medicines Agency, recommended Brineura's approval. The EMA is likely to formally approve the drug by June.

In the U.S., Biomarin said the FDA review is "substantially complete" and the company is engaging the FDA in labeling discussions. The FDA approval decision is expected by Thursday.

Biomarin considers CLN2 to be an ultra-orphan disease so Brineura will be priced on the "higher end" of such drugs, the company said. What's that mean? Brineura will likely cost $500,000 or more per year.

Brineura would be Biomarin's sixth approved drug and the first drug to win over regulators since the embarrassing and expensive failure of its drisapersen program. The drug is also noteworthy because Biomarin's clinical data package consisted of a single arm, open-label study of only 24 CLN2 patients. Without a placebo arm in the study, Biomarin relied on natural history data to show Brineura could slow the progression of the disease.

The use of a historical control has been a source of concern for investors heading into Thursday's FDA approval decision, particularly since an expected advisory panel to discuss the Brineura data never took place.

For 2017, Biomarin has guided to total revenue in the range of $1.25 billion to $1.3 billion and expects to achieve profitability, on an operating basis, for the full year.

Biomarin is mentioned habitually as a takeover candidate but at 12 times price-to-sales multiple, the company would not be acquired on the cheap.

Adam Feuerstein writes regularly for TheStreet. In keeping with company editorial policy, he doesn't own or short individual stocks, although he owns stock in TheStreet. He also doesn't invest in hedge funds or other private investment partnerships. Feuerstein appreciates your feedback; click here to send him an email.