AstraZeneca’s and Ionis’ gene-silencing therapy eplontersen (Wainua) failed in a Phase 3 trial in transthyretin-mediated amyloid cardiomyopathy (ATTR-CM). The 1,432-patient Cardio-TTRransform study missed the composite endpoint of reducing cardiovascular mortality and recurrent cardiovascular events. Despite reported large and sustained reductions in transthyretin levels consistent with the drug’s mechanism, the trial outcome breaks the presumed link between biomarker lowering and clinical benefit for this approach. The setback is already reshaping competitive expectations across the growing ATTR-CM pipeline. The immediate market implication is continued volatility for gene-silencing and knockdown strategies in ATTR-CM, pushing stakeholders toward alternative modalities and subgroup hypotheses.