Donanemab, the latest drug to treat Alzheimer's disease appears to slow cognitive decline by 35%, according to the phase 3 clinical trial results published in the Journal of American Medical Association. While experts have praised the drug's effects, there are safety and cost concerns that loom.
Alzheimers is a type of dementia which affects a person's memory, thinking ability and behaviour. The prevalence of Alzheimers in India is 7.4% among adults over the age of 60—meaning about 8.8 million Indians are currently living with dementia, Dr Hrishikesh Sarkar, Senior Consultant, Neurosurgery, Apollo Cancer Centre, Chennai told BOOM.
What did the Donanemab trial find?
The clinical trial included 1,736 participants with early symptomatic Alzheimer's disease. Half received Donanemab intravenously while the remaining were treated with a placebo. Donanemab, developed by Eli Lilly a pharmaceutical company based in the United States, is an antibody made to clear a substance called beta-amyloid, a sticky plaque from the brain. Beta amyloid tends to form plaques in the brains of those with Alzheimers. The study found that the progression of Alzheimers was slowed by about 35% in nearly 18 months.The results from the trial suggests that the earlier in the disease the treatment was given, the greater the benefit.
"They derived at this by including certain clinical parameters such as psychometric scoring and PET scans analysis. Psychometric scoring is a method to measure the mental ability of a person with Alzheimers through a questionnaire," said Dr Sarkar. Further, people taking Donanemab also had a 40% less decline in ability to carry out daily activities.
Who is eligible to take Donanemab?
Only people in the early stages of the Alzheimer's disease can take the drug. "The earliest stage is called as the mild cognitive impairment stage, Dr Pawan Ojha, Director, Neurology, Fortis Hiranandani Hospital, told BOOM. "Here, the person is aware that they are forgetting, hence they might take notes, etc. The second stage is moderate dementia and third is severe dementia. In this case, they won't remember their relatives' names, etc. When a person is diagnosed with Alzheimer's they are usually in the moderate dementia phase, so this drug has been mainly developed as a disease-modifying treatment so that patients don't progress from the mild to the moderate or severe phase, explained Dr Ojha. Patients have to take the medicine every two weeks, for a minimum of 6 months to two years, he said.
There are supportive medicines which help alleviate symptoms, for instance a person may forget lesser, but they don't modify the disease. This a new type of treatment and hence its considered as a breakthrough, Dr Ojha added.
Safety and other concerns
The study revealed that 25% of participants suffered from side effects while three three participants died. 1.6% of participants had serious symptoms relating to brain swelling and bleeding. Around 6% reported mild symptoms like headaches, nausea and confusion. "Since the drug attacks the amyloid in the brain, it can cause swelling as well as a brain haemorrhage," said Dr Ojha.
When it comes to costs, the annual cost for this drug could come up to a few crores, said Dr Ojha. Besides, it's not covered by any insurance.
It's also important to note that conflicts of interest were reported in the study. More than five doctors who are also authors of the study reported having been employees or stockholders of the pharmaceutical company Eli Lilly. Few doctors also revealed receiving personal fees from the company during the conduct of the study.
What do neurologists say?
Experts agreed that the usage of this drug is not entirely feasible in the Indian context given its high inaccessibility in terms of costs and lack of data.
"We will have to wait for regulatory approval from the government," said Dr Sarkar. "Further, it has to undergo a post market survey. There is an element of risk involved and it cannot be neglected. We need to identify those at risk of complications. The risk is higher in patients who are predisposed to Alzheimers. We can only address this with more data on the safety profile of this drug, said Dr Sarkar.
According to Dr Ojha, "We can't push the treatment on any patient. Patients must take informed judgements. The treatment does not cure the disease. Given the high costs, if someone can afford, they can take the treatment. We have been using toxic treatments for many diseases. We are used to patients taking toxic treatments for cancer."
"For now, it's only an awareness drive. As the drug becomes affordable and accessible there might be more takers. It has definitely given a boost to research. Until then, we will have to make do with existing treatment," Dr Ojha concluded.