Biogen's tau-targeting drug slowed cognitive decline in a mid-stage Alzheimer's trial
Biogen reported that diranersen, an experimental antisense drug developed with Ionis that targets the tau protein, slowed cognitive decline in a mid-stage Alzheimer’s trial at rates roughly on par with approved medicines. Multiple doses showed improvements across cognitive tests versus placebo and lowered levels of tau, the protein that forms toxic tangles associated with the disease.
The result matters because most recently approved Alzheimer’s drugs work by clearing amyloid, another hallmark protein; a therapy acting on tau would attack the disease through a different mechanism. The positive Phase 2 data supports advancing to a Phase 3 pivotal trial.
Researchers were measured about the findings. Because the drug’s benefit looked comparable to, rather than clearly better than, existing options, some questioned how large an effect a tau therapy needs to show to be meaningful for patients and caregivers — a judgment that will depend on the larger trial still to come.