BBIO Stock Surges 16% As AstraZeneca-Ionis Heart Drug Trial Misses Goal — BofA Calls Failure ‘A Big Surprise’

• Analysts largely viewed the miss as a significant blow to Ionis but not fatal for the company overall.
• BofA Securities called the failure “a big surprise,” attributing it to changes in the treatment landscape.
• Raymond James cut its Ionis target to $87 from $104 and removed the ATTR-CM indication from its model.

Shares of BridgeBio (BBIO) jumped 16% on Thursday after its competitor experienced a major setback in the transthyretin-mediated amyloid cardiomyopathy (ATTR-CM) treatment market.

AZN-IONS Trial Setback

AstraZeneca (AZN) and Ionis (IONS) announced on Thursday that their late-stage CARDIO-TTRansform trial for eplontersen (Wainua) failed to meet its main goal. The study tested whether adding the drug on top of current standard care reduced cardiovascular deaths and recurring heart events in patients with ATTR-CM.

The trial missed its primary endpoint in the overall patient group. However, it showed a benefit in the subgroup of patients who were not already taking a stabilizer drug.

While IONS shares traded 24% lower at the time of writing, AZN stock was down 6%.

Analyst Reactions

Analysts largely viewed the miss as a significant blow to Ionis but not fatal for the company overall.

BofA Securities called the failure “a big surprise,” attributing it to changes in the treatment landscape, including earlier diagnosis and wider use of stabilizers. The firm lowered its price target on Ionis to $90 from $111 but kept a ‘Buy’ rating, saying there is no clear regulatory path for eplontersen in cardiomyopathy. BofA’s new price target still represents a near 7% upside from the stock’s closing price on Wednesday.  

Raymond James cut its Ionis target to $87 from $104 and removed the ATTR-CM indication from its model, though it remains positive on the company’s wholly owned pipeline.

On the positive side for competitors, Raymond James raised its Alnylam (ALNY) price target to $468 from $420, stating that the failed trial strengthens Alnylam’s competitive position and could support better pricing for its ATTR silencer franchise. Shares of ALNY opened higher on Thursday but pared back gains by noon.

TD Cowen and Jefferies also lowered targets on Ionis but maintained ‘Buy’ ratings, arguing the setback is more about the challenges of combination therapy than the drug itself, and that Ionis has other upcoming catalysts.

BBIO, ALNY’s ATTR-CM Market

BridgeBio’s Attruby received FDA approval for ATTR-CM in November 2024. The drug delivered strong commercial performance, generating $362.4 million in U.S. net product revenue in 2025, its first full year on the market. Ionis’s failure is particularly positive for BridgeBio because Attruby is a TTR stabilizer, while the Ionis/AstraZeneca drug was being tested as an add-on to existing stabilizer therapy.

Meanwhile, Alnylam’s Amvuttra was approved for ATTR-CM in March 2025. The two drugs now compete directly with each other — and with Pfizer’s tafamidis — in a fast-growing ATTR-CM market.

How Did Retail Traders React?

On Stocktwits, retail sentiment around BBIO stock jumped from ‘bearish’ to ‘bullish’ over the past 24 hours, while message volume remained at ‘high’ levels.

Sentiment around IONS rose from ‘neutral’ to ‘bullish’ while sentiment around AZN stock stayed ‘neutral.’

BBIO stock has gained 19% year-to-date, compared to IONS’s 19% drop. 

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