Ionis-AstraZeneca Eplontersen Trial Misses Primary Endpoint in ATTR-CM Study — Ionis Pharmaceuticals, Inc.

Event summary

Ionis and AstraZeneca's Phase 3 CARDIO-TTRansform trial for eplontersen in ATTR-CM patients failed to meet the primary efficacy endpoint.
The study enrolled 1,432 participants across 130 sites in 20 countries, with 57% on stabilizer therapy at baseline.
Prespecified subgroup analysis showed a nominally significant hazard ratio of 0.71 for eplontersen monotherapy vs. placebo.
Eplontersen demonstrated large and sustained reductions in transthyretin (TTR) and was well tolerated with a favorable safety profile.

The big picture

The trial's failure underscores the challenges of developing new treatments in a rapidly evolving therapeutic landscape where stabilizer therapies are increasingly standard. Ionis and AstraZeneca's collaboration highlights the growing focus on RNA-targeted therapies, but this setback may prompt reassessment of eplontersen's role in ATTR-CM treatment. The results contribute to broader industry trends in cardiovascular disease management, emphasizing the need for earlier diagnosis and targeted interventions.

What we're watching

Pipeline Strategy: Whether Ionis can offset this setback with its other wholly owned pipeline assets, including TRYNGOLZA.
Regulatory Insights: How the full data set analysis and presentation at ESC Congress in August 2026 may impact future treatment paradigms for ATTR-CM.
Commercial Dynamics: The pace at which Ionis achieves cash flow breakeven by 2028 amid evolving competitive landscapes in cardiovascular therapies.