(Reuters): Alzheimer’s patients in Britain’s state-run health service are unlikely to get access to Eisai and Biogen’s new Leqembi drug, after it was approved on Thursday by the country’s regulator but deemed too expensive for wide use. The Medicines and Healthcare products Regulatory Agency (MHRA) said the drug, also known as lecanemab, is the first treatment for Alzheimer’s licensed for use in the country that shows some evidence of slowing the progression of the disease. But in draft guidance published simultaneously, the National Institute for Health and Care Excellence (NICE), said the medicine’s high cost and need for intensive monitoring for side effects “means it cannot be considered good value for the taxpayer”.

NICE also cited a lack of evidence on the long-term effects of taking the treatment, noting that the clinical trial only reported outcomes when people had been taking lecanemab for 18 months. The UK cost effectiveness body’s findings mark the latest blow faced by the drugmakers amid slow take-up of the drug in the U.S.

due to the cost and concerns over side effects and efficacy. It also highlights the complexities of a new class of drugs that benefit early-stage Alzheimer’s patients but carry the risk of rare and serious side effects. NICE’s guidance on the drug is open for public consultation until Sept.

20, and a final recommendation will follow its evaluation of the responses. NICE also said that around 70,000 adults in England would .