AstraZeneca and Ionis delivered a major disappointment in transthyretin-mediated amyloid cardiomyopathy (ATTR-CM), with their antisense therapy Wainua (eplontersen) failing to beat placebo in a pivotal phase 3 trial. The program targeted reductions in cardiovascular death and recurrent events, but did not achieve the composite endpoint, despite transthyretin reductions consistent with the gene-silencing mechanism. The setback adds pressure to the competitive landscape for ATTR-CM, where multiple RNA-based and other disease-modifying approaches are competing for next-generation therapy positioning. For Ionis, the result also marks another chapter in a high-stakes portfolio that has seen multiple development reversals. The trial outcome is likely to shift near-term attention toward alternative modalities in ATTR-CM and recalibrate expectations around where gene-silencing can deliver durable clinical benefit beyond biomarker effects.