Eisai and Biogen released positive results from a phase III clinical trial of the Alzheimer’s drug lecanemab, which analysts believe is sufficient for an FDA approval that would avoid the most severe restrictions that curbed spending on the Alzheimer’s drug Aduhelm, which the two companies also developed. Aduhelm received an accelerated approval based on surrogate endpoints, and Medicare placed harsh restrictions on the drug’s coverage; Medicare only pays for the drug when taken by patients in post-market clinical trials. Those...