WASHINGTON — Yesterday, the US Food and Drug Administration published a notice to the Federal Register ahead of a speech by President Donald Trump, approving a version of leucovorin made by GlaxoSmithKline that the company had previously withdrawn from the FDA’s consideration when it stopped manufacturing the drug.

The FDA cited a review of the use of leucovorin in 40 patients with a rare metabolic disorder called cerebral folate deficiency that can lead to a range of neurological symptoms, some of which are seen in people with autism.

GSK stopped manufacturing and marketing its version of leucovorin in 1997 but still holds the New Drug Application (NDA), meaning it is responsible for requesting new indications to be added. It said yesterday it would, at the request of the US FDA, submit an application to update the label to include an indication for the treatment of cerebral folate deficiency.

Here’s what is known about leucovorin and autism.

What is leucovorin?

Leucovorin, also known as folinic acid, is a form of folate, an essential B vitamin, or B9.

Leucovorin has been approved by the US Food and Drug Administration for counteracting the toxic effects of certain cancer drugs, like methotrexate, that block the body’s use of folate.

Leucovorin is also used to enhance the effects of other chemotherapy drugs and to treat specific types of anaemia. The drug can be given orally or intravenously.

It is made by more than half a dozen companies, according to the US Food and Drug Administration website.