Doctors across the country fear they may be forced to ration a critical childhood cancer drug because of nationwide shortages, The New York Times reports.

Vincristine is used to treat several types of childhood cancer including leukemias, lymphomas and brain tumors. It’s in short supply because Teva Pharmaceutical, one of only two U.S. manufacturers of the drug, discontinued its production this summer. 

Meanwhile, Pfizer, the other manufacturer, is boosting its production to try to make up for the shortage. But doctors say supplies are already dangerously low.

Childhood cancer drug protocols are different from those for adults. They are carefully designed not only to treat the primary cancer but to manage side effects while reducing the chance of recurrence. Doctors keep kids on tight schedules of chemotherapy agents that may significantly increase their chances of going into remission. Many of these drugs have no viable alternative. These protocols may last more than two years; disrupting them may increase the risk of cancer recurrence. 

Vincristine works by blocking cancer cells from assembling their “skeleton,” which they use to divide and then conquer healthy cells in the body. Currently on the World Health Organization’s list of essential medicines, the drug is derived from the Madagascar periwinkle plant but is now synthetically produced in labs. 

“This is a health care crisis. The government needs to take a position,” said Yoram Unguru, MD, a pediatric oncologist at the Herman and Walter Samuelson Children’s Hospital, in a recent interview with Cancer Therapy Advisor about the impending shortage. “Profitable drugs, including those that may extend lives by only a few months, are not in short supply, but lifesaving drugs for which there is no alternative and which are reimbursed at dollars per dose are—what’s the logic?”

To learn more about childhood cancer and its treatments, click here.