CAMBRIDGE, Massachusetts - Genzyme Corp. won approval for a childhood leukemia drug under an accelerated government approval process for potentially lifesaving treatments.

The drug Clolar on Wednesday won Food and Drug Administration approval to treat patients aged 1 to 21 who have exhausted other treatment options for acute lymphoblastic leukemia. Clolar was developed by Southern Research Institute of Birmingham, Ala.

The medication is the first new leukemia treatment cleared specifically for pediatric use in more than a decade, Cambridge-based Genzyme said.

The FDA granted Clolar orphan drug status, which provides seven years of market exclusivity for treating pediatric cases of the most common form of childhood leukemia.

The drug was approved under the FDA's accelerated approval process for products that may offer improvements over existing therapies for serious or life-threatening diseases. Such approvals require studies after a drug's approval to verify clinical benefits.

In mid-stage trials, Genzyme said 20 percent of patients treated with Clolar showed complete remission, while 10 percent of all patients achieved a partial response.

Genzyme said it expects to make Clolar commercially available "as quickly as possible in January."

Genzyme said an estimated 3,400 new cases of child leukemia will be diagnosed in the United States next year.

The company said it also will study Clolar for use in treating adult leukemia and solid tumor cancers.

Genzyme acquired rights to the drug through its $1 billion stock acquisition of San Antonio-based Ilex Oncology Inc. The deal, which closed Dec. 21, allowed Genzyme to bolster its lineup of drugs for rare genetic disorders with cancer treatments.

Shares of Genzyme closed up 1 percent, or 63 cents, at $58.16 in heavy trading Wednesday on the Nasdaq Stock Exchange.

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Genzyme Corp.: www.genzyme.com