UPDATE 2-US FDA declines to approve Viatris's injection for multiple sclerosis

(Adds Viatris' comment in paragraph 7)

March 11 (Reuters) - The U.S. FDA has declined to approve Viatris and Mapi Pharma's once-a-month injection for treating relapsing forms of debilitating neurological condition multiple sclerosis (MS), the companies said on Monday.

The companies were reviewing the content of the health regulator's so called complete response letter (CRL) and would soon determine the appropriate next steps, they said, without disclosing further details.

Mapi Pharma did not immediately respond to Reuters requests for additional details on the contents of the CRL, which indicates that an application would not be approved in its present form and requires more information.

The companies were seeking the FDA's nod for GA Depot, a long-acting version of glatiramer acetate, which is approved for relapsing forms of MS.

GA Depot was being studied to be administered as an intramuscular injection once every four weeks, where as Teva Pharmaceutical Industries' glatiramer acetate injection, Copaxone, is given thrice a week.

Viatris acquired the commercialization rights to GA Depot through its exclusive license agreement with Mapi Pharma in 2018.

The receipt of the FDA's letter would not impact Viatris' 2024 forecast or its new product revenue range of $450 million to $550 million, the company said.

In MS, the immune system attacks brain cells, causing motor disabilities. It affects about 400,000 people in the United States, according to the National Institutes of Health.

Relapsing MS is a type of the disease where the symptoms appear sporadically, in the form of attacks. This is followed by a period of disease inactivity and weeks, months, or even years may pass before another attack occurs. (Reporting by Sriparna Roy and Sneha S K in Bengaluru; Editing by Pooja Desai and Shinjini Ganguli)