May 14 (Reuters) - Eisai ( ESALF ) and partner Biogen

said on Tuesday that the Japanese drugmaker has begun

submitting data on a rolling basis to the US health regulator

for a marketing application of a subcutaneous form of their

Alzheimer's disease drug Leqembi.

The companies are seeking the Food and Drug Administration's

(FDA) approval of a weekly dose of Leqembi to be given as an

under-the-skin injection.

Under a rolling submission the regulator assesses the data

as and when it becomes available, and the process continues

until there is enough data for a formal marketing application.

Eisai ( ESALF ) in April delayed filing for marketing approval of the

subcutaneous form of Leqembi, as the FDA had requested for

additional three-month immunogenicity data.

If approved, the injectable version of the drug could be

given to patients at home or at medical facilities as the

process requires less time than the intravenous formulation, the

companies said.

Under the weekly maintenance regimen, patients who have

completed the bi-weekly intravenous version would receive weekly

360 milligram doses of the drug as an under-the-skin injection.

The intravenous formulation of Leqembi, which received

standard approval last year, has requirements such as additional

diagnostic tests, twice-monthly infusions and regular brain

scans which have contributed to a slower adoption of the drug

than markets were expecting.

Leqembi is an antibody designed to remove sticky deposits of

a protein called amyloid beta from the brains of Alzheimer's

patients.

Leqembi's sales are projected to grow 13-fold to 56.5

billion yen ($361.28 million) in fiscal 2024 from the year ended

in March, Eisai ( ESALF ) said in its annual results on Wednesday.

Eisai ( ESALF ) expects most of the sales growth to come from the

US market, with plans to launch the drug in China in July.

($1 = 156.3900 yen)