---
title: "Ionis, AstraZeneca Stumble in ATTR-CM Trial as Rivals Stand to Gain"
type: "News"
locale: "en"
url: "https://longbridge.com/en/news/292339700.md"
description: "Ionis Pharmaceuticals and AstraZeneca announced that their Phase 3 CARDIO-TTRansform trial for eplontersen in ATTR-CM failed to meet its primary efficacy endpoint. The study showed no significant benefit when adding eplontersen to standard care, including stabilizers. Analysts view this as positive for competitors like Alnylam's Amvuttra and Pfizer's tafamidis, reinforcing a monotherapy approach. Ionis stock dropped nearly 9% following the announcement."
datetime: "2026-07-10T15:30:43.000Z"
locales:
  - [zh-CN](https://longbridge.com/zh-CN/news/292339700.md)
  - [en](https://longbridge.com/en/news/292339700.md)
  - [zh-HK](https://longbridge.com/zh-HK/news/292339700.md)
---

# Ionis, AstraZeneca Stumble in ATTR-CM Trial as Rivals Stand to Gain

**Ionis Pharmaceuticals Inc.** (NASDAQ:IONS) and partner **AstraZeneca** **Plc** (NYSE:AZN) said on Thursday that their Phase 3 CARDIO-TTRansform study of eplontersen for transthyretin-mediated amyloid cardiomyopathy (ATTR-CM) failed to meet its primary efficacy endpoint.

**• Ionis Pharmaceuticals stock is taking a hit today. What’s pressuring IONS stock?**

In patients receiving contemporary standard of care, including a majority treated with a transthyretin stabilizer, adding eplontersen did not significantly reduce the combined risk of cardiovascular mortality and recurrent cardiovascular clinical events through Week 140 versus placebo.

At baseline, 57% of participants in both treatment groups were receiving stabilizer therapy, while another 24% in each arm started a stabilizer during the study.

**Read Also: Ionis Climbs As FDA Clears New Therapy To Lower Triglycerides, Pancreatitis Risk**

## **Analysts Say Existing ATTR-CM Therapies Benefit From Trial Failure**

William Blair wrote on Thursday, “The miss is surprising to us given the well-documented combination use benefit of stabilizers and silencers reported in the HELIOS-B trial of Amvuttra.”

The failure of CARDIO-TTRansform removes a competitor from the ATTR-CM market and is seen as positive for existing therapies, including **Alnylam Pharmaceuticals Inc.’s** (NASDAQ:ALNY) Amvuttra (vutrisiran) (silencer, same mechanism as eplontersen), **BridgeBio Pharma Inc.’s** (NASDAQ:BBIO) Attruby (second-gen stabilizer), and **Pfizer Inc.’s** (NYSE:PFE) tafamidis (first-gen stabilizer).

## **Trial Results Reinforce Monotherapy Approach**

The results also reinforce the view that combining a silencer such as eplontersen with a stabilizer does not improve outcomes, supporting the use of monotherapy and benefiting second-generation treatments like Amvuttra, Attruby and **Intellia Therapeutics Inc.’s** (NASDAQ:NTLA) nexiguran ziclumeran (nex-z).

Analyst **Myles R. Minter** said physician discussions had already indicated that second-generation therapies such as Attruby and Amvuttra are differentiated from first-generation tafamidis.

The CARDIO-TTRansform results further suggest that using a single therapy from these newer options is sufficient for treating ATTR-CM patients.

**IONS Stock Price Activity**: Ionis Pharmaceuticals shares were down 8.96% at $58.51 at the time of publication on Friday, according to Benzinga Pro data.

_Photo: Shutterstock_

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