TOKYO, Dec 13 (Reuters) - Eisai said on Wednesday its Alzheimer's drug Leqembi will launch in Japan on Dec. 20 following its inclusion on the National Health Insurance price list.

Intravenous treatment of the drug, co-developed with U.S. partner Biogen, will cost about 2.98 million yen ($20,438) per patient per year, based on a Japanese health ministry panel ruling the same day.

Peak annual sales are expected to be 98.6 billion yen ($676.22 million), chief executive Haruo Naito told a briefing.

The drug is priced at about $26,500 in the United States, where it gained full approval in July. Leqembi was given the nod by Japanese regulators in September.

Eisai is aiming to have 4,000-5,000 patients on the drug in Japan in fiscal 2024. In the United States, the company expects 10,000 patients by the end of March.

Leqembi is an antibody designed to remove sticky deposits of a protein called amyloid beta from the brains of Alzheimer's patients.

The drug is the first treatment shown to slow progression of the disease for people in the earlier stages of Alzheimer's. ($1 = 145.8100 yen) (Reporting by Rocky Swift Editing by Tomasz Janowski)