The treatment of Alzheimer’s disease has been a long-standing challenge and area of interest. The knowledge in pathogenesis and an increased disease burden have prompted innovative therapeutics over the last two decades.
There are six drugs approved by Food and Drug Administration (FDA) for the treatment, but there is no cure for Alzheimer’s disease despite all scientific efforts and many protracted and expensive clinical trials.
Lecanemab as a newly developed drug for Alzheimer’s disease has the potential to slow down the disease progression. On Nov. 29, 2022, the development company announced the results from a large global phase 3 confirmatory clinical study (Clarity AD) on lecanemab.
6 FDA-Approved Alzheimer’s Drugs
Aducanumab (Aduhelm®) was approved by the FDA in June 2021, and is the first approved Alzheimer’s disease drug to address the underlying cause of the disease rather than the symptoms.The five other drugs are donepezil, rivastigmine, galantamine, memantine, and a combination of memantine with donepezil. These drugs can temporarily treat symptom, but cannot affect the underlying brain changes of Alzheimer’s disease or alter the course of the disease. Nonetheless, these five drugs have relatively mild side effects, such as headache and nausea.
Aduhelm is a human IgG1 anti-amyloid monoclonal antibody. It works to reduce amyloid beta, the main component of amyloid plaques. The treatment does not result in cognitive improvement in Alzheimer’s disease, and therefore is not an efficient treatment for the disease itself.
The sales of Aduhelm have been slow, largely because Medicare will only cover the drug for patients participating in a clinical trial.
In addition, aducanumab is
associated with a 40 percent increased risk of a serious condition called amyloid-related imaging abnormalities (ARIA), an indicator of brain swelling. Individuals receiving aducanumab should be monitored closely so ARIA is quickly identified and safely managed.
The Next Potential Alzheimer’s Disease Drug
Similar to aducanumab, lecanemab is a humanized IgG1 monoclonal antibody that binds with high affinity to amyloid beta soluble protofibrils; it is being tested in the clinic trial for persons with early Alzheimer’s disease.
Aducamumab and lecanemab are developed by the Japanese company Eisai along with the U.S. company Biogen. Lecanemab targets a soluble version of amyloid-beta, while Aduhelm binds to those plaques more strongly.
Moreover,
lecanemab takes the first therapeutic intention to slow mental decline in a robust clinical trial.
A newly
published multicenter, double-blind, phase 3 trial in The New England Journal of Medicine demonstrated that lecanemab can reduce the rate of cognitive decline by 27 percent after a 18-month clinical investigation on approximately 1,800 people in the early stages of Alzheimer’s disease.
The selected subjects with early-stage Alzheimer’s were administered with biweekly intravenous infusions of lecanemab, while the controls received a placebo for 18 months. The participants’ cognition performance was assessed primarily with a metric called the Clinical Dementia Rating–Sum of Boxes (CDR-SB).
The results showed that 59.1 percent participants had brain amyloid reduction; 44 percent of them have cognition improvement on the CDR-SB evaluation scores, and the average daily living (ADL) level increased double.
Side Effect of Lecanemab
Side effects of lecanemab were observed in the clinic trial.It was reported that about one in five (20 percent) people who got
lecanemab in the study experienced an adverse event, such as swelling or bleeding in the brain.
People also reported symptoms including headaches, visual disturbances, and confusion.
The treatment was also linked to two deaths. One was a first-time lecanemab
user who had suffered from stroke previously and was taking a blood thinner.
The other death was a woman who participated in the lecanemab trial; she experienced an attack of stroke symptoms, followed by a series of seizures, and was placed on a ventilator in the emergency room. A few days later, she died. The doctor
found massive bleeding in her brain.
In addition, the acceleration of brain shrinkage, also known as atrophy or reduction in brain volume, has been presented in the clinical trials of lecanemab and aducanumab (Aduhelm). It indicated the progression of Alzheimer’s disease and severity of the pathological changes of the brain rather than
slowing of the symptoms.
In summary, it was suggested that longer trials were warranted to determine the efficacy and safety of lecanemab in early Alzheimer’s disease. The risks and benefits should be evaluated carefully.
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