The TGA has declined to register lecanemab (LEQEMBI) for treatment of mild cognitive impairment due to Alzheimer’s disease and mild Alzheimer’s dementia, saying the “demonstrated efficacy did not outweigh the safety risks.”

The drug has been approved in the UK, USA, Japan, China, South Korea, Hong Kong, United Arab Emirates and Israel—but the TGA joined the European Medicines Agency (EMA) in rejecting it.

“Clinical study data demonstrated that patients treated with LEQEMBI experienced a reduction in disease progression compared to those given a placebo, however this difference was not deemed significant enough to provide a meaningful clinical benefit or to outweigh the associated safety risks,” the TGA explained in a statement.

“In particular, the TGA delegate considered the frequent occurrence of amyloid-related imaging abnormalities (ARIA) in patients treated with LEQEMBI.”

Similarly, when the EMA refused marketing authorisation for lecanemab in July, it said the small effect on delayed cognitive decline “does not counterbalance the risk of serious adverse events associated with the medicine.”

The EMA also noted that the risk of ARIA is increased in people with a gene abnormality which also raises the risk of Alzheimer’s disease, meaning the people most likely to take the drug might be more likely to develop the side effect.

Dementia Australia has criticised the TGA’s decision, which is being appealed by lecanemab’s manufacturer, Eisai.

“Should this decision be upheld it will be a blow to Australians who may be able to benefit from lecanemab,” Dementia Australia CEO Professor Tanya Buchanan said.

“Dementia Australia is disappointed that Australians living with Alzheimer’s disease in its early stages may be unable to access the same choice of treatments as people living in other countries.”

Lecanemab is a monoclonal antibody that attaches to amyloid beta, which forms plaques in the brains of people with Alzheimer’s disease. It works by reducing the amyloid plaques in the brain.

Dementia Australia medical advisor, GP and Clinical Associate Professor Marita Long says there are still treatments and interventions to support people living with dementia and optimise their quality of life.

“We must continue to work hard to support a more timely diagnosis of dementia and remember that we can prevent or delay the onset of nearly 50% of cases globally by addressing the 14 known modifiable risk factors,” she says.