Photo/Illutration An expert panel under the health ministry discusses the Alzheimer’s drug lecanemab in Tokyo on Aug. 21. (Kazuhiro Fujitani)

A medication that could help treat early stages of Alzheimer's disease is on track to be approved for manufacturing and sales in Japan after being endorsed by a health ministry expert panel on Aug. 21.

Eisai Co. and U.S. partner Biogen Inc. developed lecanemab, the first medication designed to remove a protein believed to cause Alzheimer's, a type of dementia.

It will be commercially available by the end of the year, at the earliest, pending approval from the health minister.

The medication is targeted at patients with mild Alzheimer’s disease and those with mild cognitive impairment, a slight decline in mental abilities, such as memory loss, that is less severe than mild dementia. 

It is not expected to be effective for patients at an advanced stage of Alzheimer's because it is difficult to regenerate damaged nerve cells.

About 6 million people have dementia in Japan, and hundreds of thousands of patients can potentially benefit from a lecanemab-type medication, experts said.

U.S. authorities gave full approval to lecanemab, sold as Leqembi, in July.

When a person develops Alzheimer’s disease, nerve cells in the brain break down, and cognitive functions gradually decline.

Scientists believe the disease is caused when a protein called amyloid beta accumulates in the brain.

Conventional dementia medications are designed to relieve symptoms by activating certain operations in the nervous system.

Lecanemab, on the other hand, is designed to slow the development of Alzheimer’s by removing amyloid beta.

The medication is administered once every other week through an intravenous drip.

A test is conducted before prescription to confirm a buildup of amyloid beta.

Positron emission tomography (PET) is mainly used for such tests, but only about 60 facilities with PET scanners in Japan are certified by the Japanese Society of Nuclear Medicine.

In an international clinical trial in which about 1,800 patients participated for 18 months, a decline in memory, judgment and other functions was 27 percent lower compared with those who had received a placebo.

However, side effects from the medication were reported, such as cerebral edemas found in 12.6 percent of patients and cerebral microbleeds found in 17.3 percent of patients.

In the United States, genotype testing was recommended before administration to determine whether a patient would likely experience such side effects.

At the meeting on Aug. 21, the health ministry’s expert panel did not call for such testing.

But it said doctors should check for bleeding in the brain after administration and alert patients taking anticoagulants to the potential risks of taking lecanemab.

The expensive medication could weigh heavily on public health insurance programs.

In the United States, treatment with lecanemab, which is covered by medical insurance for the elderly, costs $26,500 (3.84 million yen) a year.

In Japan, outpatients 70 or older with a standard annual income are expected to pay up to 144,000 yen ($986) a year after taking into account public health insurance coverage and benefits for expensive medical treatment.

(This article was written by Kazuhiro Fujitani and Kazuya Goto.)

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