TUESDAY, Feb. 14 (HealthDay News) -- The U.S. Food and Drug Administration said Tuesday that it was cautiously optimistic that a feared shortage of a life-saving drug used to treat a form of childhood leukemia will be averted.

The drug, methotrexate, is used in combination with other drugs to combat acute lymphoblastic leukemia (ALL), which typically strikes children ages 2 to 5 and is the most common type of cancer in children.

Methotrexate is a linchpin in the treatment of children battling acute lymphoblastic leukemia. In high doses, the generic drug has been successful in curing patients and beneficial in preventing recurrence. Without the drug, a patient's chance for a cure is reduced while the risk of recurrence rises, oncologists report.

"We are seeing the [three] companies [that make methotrexate] respond to this shortage and they are planning on some very large releases, and we are planning on having the situation resolved," said Valerie Jensen, associate director of the FDA's drug shortage program.

"Right now, from what we are understanding from the companies, the releases will resolve these shortages. So we are watching this very closely," Jensen added. "We are expecting some good releases at the end of this month and continuing into March and beyond."

Oncologists are worried that supplies of methotrexate could be gone in as little as two weeks.

One of the three makers of methotrexate, Hospira Inc., based in Lake Forest, Ill., said Tuesday that it had increased production to "make up for the supply gap."

Thomas Moore, president of U.S. Hospira, said in a news release: "Hospira is doing everything it can to help bring more product to market. This includes working with the U.S. Food and Drug Administration to qualify a second supplier of the drug's active ingredient to enable increased production. Hospira believes that it can increase its supply to the market if it can secure additional methotrexate active ingredient supply."

The other two manufacturers are Mylan Inc., of Canonsburg, Penn., and Sandoz US Inc., of Princeton, N.J. Both said they are working to head off a shortage of the drug.

Mylan, in a Tuesday news release, said it has "ramped up its production in order to try to meet the resulting increased demand. We are working both on the manufacturing and regulatory fronts to expedite the FDA regulatory approvals necessary to further increase capacity to the extent possible to support the additional demand."

Dr. Elizabeth Raetz, an associate professor of pediatric hematology/oncology at NYU Langone Medical Center in New York City, said methotrexate is a "critical component of ALL therapy."

The concern is that there is a 90 percent chance for cure of acute lymphoblastic leukemia, but that's based on the total drug regimen including methotrexate, Raetz said. "There is a deep concern that if that key component is eliminated there would be a reduced chance for cure," she said.

There hasn't been a shortage of the drug at her hospital, Raetz noted, but many other hospitals across the country have reached a critical point, and some centers don't have any at all, she said.

Acute lymphoblastic leukemia is the most common type of cancer in children. It's a disease that affects white blood cells, which help to fight infections in the body. Blood cells are produced in bone marrow. But in leukemia patients, the bone marrow produces abnormal white blood cells, which crowd out healthy blood cells. In acute lymphoblastic leukemia, the excess white blood cells are called lymphocytes or lymphoblasts, according to the U.S. National Library of Medicine.

The potential shortage of methotrexate is just the latest in a series of drug shortages that have existed for several years.

In 2011, prescription drug shortages in the United States hit an all-time high. Last fall, some 200 drug shortages had been reported, compared to 178 in all of 2010, the FDA reported.

Many of the scarce drugs are injectables, such as cytarabine and cisplatin, used to treat serious conditions such as cancer. Some are only given in hospitals and are "absolutely critical," Jensen said during a news conference in late September.

More than half (54 percent) of shortages in 2010 were due to quality issues, such as sterility or drug impurities. Some were caused by delays or manufacturing capacity problems, while 11 percent were caused by discontinuation of a drug and 5 percent resulted from raw material shortages, Jensen said.

Jensen also said the shortages tend to occur in drugs that aren't "economically attractive." This could mean that only one company produces the drug, making it harder to find alternatives if the supply dries up.

A lot of the problems are tied to generic drugs, health experts explained, because few manufacturers make them and profit margins aren't as high as for drugs still under patent protection.

On Oct. 31, 2011, President Barack Obama signed an executive order designed to help ease the drug shortages. The order directed the FDA to "take action" to prevent and reduce the worsening prescription drug shortages.

Specifically, the order directed the FDA to take steps to require drug manufacturers to report any impending shortages or discontinuances six months ahead of the shortage. The agency should also speed up its review of new manufacturing sites, new suppliers and new manufacturing protocols, and also add more staff to its drug-shortage office, the order stated.

More information

For more on drug shortages, visit the U.S. Food and Drug Administration.