LONDON — Britain’s drug regulator has approved Leqembi, an Alzheimer’s treatment, marking it as the first medication to demonstrate some ability to slow the progression of the disease. However, the U.K. government is unlikely to fund the drug after the National Institute for Health and Care Excellence (NICE) issued draft guidance stating that the benefits do not justify the costs to taxpayers. The treatment requires bi-weekly hospital visits for administration and monitoring, raising concerns about its overall value