Wainua’s Failed Heart Trial Hands ATTR-CM to Oral Pills

AstraZeneca and Ionis said Friday that Wainua failed to cut heart deaths and repeat events in 1,432 people with ATTR-CM. The once-monthly gene silencer did lower transthyretin, the protein that gums up the heart in this disease. It still missed the main goal of the largest ATTR-CM trial ever run.

Full results at the European Society of Cardiology meeting in Munich, and in the New England Journal of Medicine, split the two drug classes that treat the condition. Oral stabilizer pills came out stronger. Injectable silencers were left with a narrower job: patients who are not already on those pills.

The Largest Heart Amyloid Trial Came Up Empty

CARDIO-TTRansform tested eplontersen, sold as Wainua in the United States, against placebo on top of usual care. Patients got 45 mg under the skin every four weeks for 140 weeks. AstraZeneca enrolled 1,432 participants across 130 sites in 20 countries, the biggest ATTR-CM study to date.

The New England Journal of Medicine paper, with Marianna Fontana as first author, assigned 715 people to eplontersen and 717 to placebo. Mean age was 76.4 years, and 90.6% were men. ESC press materials listed a mean age of 72; the journal figure is the published record. Women made up 9.4% of the cohort in both accounts.

The main endpoint was a mix of cardiovascular death and recurrent heart events. There were 381 of those events in 210 people on eplontersen (29.4%) versus 392 events in 231 people on placebo (32.2%). The rate ratio was 0.89 (95% CI 0.73 to 1.09). The p value was 0.28 in the journal and 0.277 in the Hot Line session, a miss either way.

Cardiovascular deaths, counted on their own, went the other way: 74 on eplontersen and 70 on placebo, according to the journal abstract. Recurrent heart events were 307 versus 322. Serious side effects were similar, 57.8% versus 59.4%. The drug did what a silencer is built to do. Circulating TTR fell and stayed down through week 140.

Dr. Mathew Maurer of Columbia University Irving Medical Center presented the Hot Line. He has reported grant support and fees from Alnylam, Ionis, Pfizer, BridgeBio, and AstraZeneca, the companies that sell or are testing these drugs.

CARDIO-TTRANSFORM VERSUS HELIOS-B

Alnylam’s earlier HELIOS-B study reduced death and recurrent heart events with vutrisiran. That trial was smaller, and far fewer people walked in already taking a stabilizer. CARDIO-TTRansform asked a harder question in a treated population, and it did not clear the bar.

The 1.14 Rate Ratio in the Pill Group

AstraZeneca designed the study to test a silencer on top of today’s usual care. At the start, 57% of patients in each arm were already on a TTR stabilizer, mainly Pfizer’s tafamidis (Vyndamax or Vyndaqel). Another 24% in each arm started a stabilizer during the trial, so about four in five people were on a pill at some point.

That mix sank the study. In people not on a stabilizer at the start, eplontersen as a single drug cut primary events by about 29%, a result the companies called nominally significant. Stifel mapped that monotherapy signal to a rate ratio of about 0.71. In people already on a stabilizer, the companies said they saw no added benefit. Stifel told clients the combination group’s ratio was 1.14, meaning 14% more cardiovascular deaths and repeat events than the comparison arm.

THE SPLIT THAT MOVED THE MARKET

• Overall study: Rate ratio 0.89, confidence interval crossing 1.0, primary miss.
• Already on a pill: Rate ratio 1.14, the figure Stifel called clearly worse than expected.
• No pill at the start: About a 29% drop in events, nominally significant, ratio near 0.71.
• The protein target: Serum TTR fell as planned, so the miss was not a failure to hit the gene.

Jefferies analyst Michael Leuchten wrote that the negative combo result raises the chance that extra benefit from stacking a silencer on a stabilizer is smaller than HELIOS-B had implied. Evercore’s Cory Kasimov, quoted Friday by STAT’s Adam Feuerstein, said the 1.14 ratio looks less like a design glitch and more like a limit on dual therapy. Slides from the Hot Line, circulated by cardiologists at the meeting, also listed a 19.7-meter edge on the six-minute walk test and a 4.0-point edge on the Kansas City Cardiomyopathy Questionnaire, both nominal because the main endpoint failed.

The protein went down. The people already protected by a daily pill did not get a second win from a monthly shot. That is a therapeutic ceiling, not a surprise about trial math.

Pills From Pfizer and BridgeBio Keep the Front Line

Jefferies told clients Friday that oral stabilizers from Pfizer and BridgeBio remain the preferred first treatment for ATTR-CM. Stabilizers bind TTR so the protein is less likely to fall apart and form amyloid. They are swallowed. Silencers shut down TTR production in the liver and are injected.

Pfizer got there first. Tafamidis won U.S. approval for ATTR-CM after ATTR-ACT showed fewer deaths and hospital stays than placebo. BridgeBio followed in 2024 with acoramidis, sold as Attruby, a second oral stabilizer. Alnylam’s Amvuttra later became the only silencer cleared for the heart form of the disease. Wainua was the candidate meant to join that silencer shelf.

WHERE FRIDAY LEFT EACH DRUG

• Tafamidis (Pfizer): Still the background drug most trial patients were already taking, and the combo data give cardiologists little reason to layer a silencer on top of it.
• Attruby (BridgeBio): Same oral class, later to market, now sitting in a first-line group that Friday made harder to challenge.
• Wainua (Ionis/AstraZeneca): Stifel said it is hard to see a path to a heart-failure approval after a failed primary endpoint and a combo ratio on the wrong side of 1.0.
• Amvuttra (Alnylam): Still the only silencer approved for ATTR-CM, but the add-on case that helped sell combination care is now the open question hanging over the class.

Oppenheimer has put the ATTR-CM market in a $15 billion to $20 billion range. Combination therapy was supposed to claim a slice of that by stacking a shot on a pill. Friday’s numbers argue that slice may not exist. Eric Schmidt, speaking on the Biotech Hangout podcast after the session, said patients on the combination did a little bit worse, and that less combination use is the logical market response until someone proves otherwise.

Sharon Barr, AstraZeneca’s executive vice president for BioPharmaceuticals R&D, said in the company’s July statement that the trial was built to test a gene silencer on top of today’s standard of care. “Although the trial did not meet its primary objective, we believe the results support greater scientific understanding of treatment approaches for the hundreds of thousands of patients worldwide suffering from this progressive and often fatal condition,” Barr said.

Why Alnylam’s Stock Still Fell

A rival’s failure should have been a gift. Amvuttra would have been the last silencer standing in ATTR-CM. Instead Alnylam shares dropped as much as 5% Friday morning, then closed roughly flat. They were already down about 30% since the July 9 topline miss, a slide that also included a late-July cut of about $200 million in TTR product sales guidance.

The read-through is the next-generation shot, nucresiran, now in the Phase 3 TRITON-CM study. That trial is enrolling in a market where tafamidis and Attruby are common. If most recruits are already on a pill, TRITON-CM could walk into the same ceiling CARDIO-TTRansform hit. Stifel said the combo data could push Alnylam to steer more patients toward monotherapy and make that group the main outcome, which is what investors have wanted.

FROM TOPLINE MISS TO THE MUNICH AUTOPSY

1. July 9, 2026: AstraZeneca and Ionis announce CARDIO-TTRansform missed its primary endpoint. AstraZeneca shares fall about 9% to 13% in London. Ionis falls as much as 15% to 21%.
2. July 30, 2026: Alnylam cuts TTR sales guidance by about $200 million after slower ATTR-CM growth, and the stock drops sharply in that session.
3. August 28, 2026: Fontana, Maurer, and colleagues present the full dataset in a Hot Line at ESC Congress in Munich and publish in the New England Journal of Medicine. The 1.14 combination ratio is the number that travels.

Stifel’s Paul Matteis wrote that a modest combo benefit was largely expected, and that a 1.14 ratio was an incremental surprise. He does not see a large hit to current Amvuttra sales, because few patients use that shot with tafamidis today. The damage is to the story that two mechanisms stacked together would keep winning as pills spread.

Some investors argue HELIOS-B and CARDIO-TTRansform are not the same experiment. People in the Ionis study may have been on pills longer. More of them may have been on Attruby, which binds TTR more tightly than older tafamidis. Those are plausible reasons the combo curves diverged. They do not rescue a failed primary endpoint in 1,432 people.

ATTR-CM Stiffens the Heart With Misfolded Protein

ATTR-CM is transthyretin amyloid cardiomyopathy. The liver makes TTR, a carrier protein. When TTR misfolds, it dumps amyloid fibrils in heart muscle. The walls get thick and stiff. The heart fills poorly, then fails. AstraZeneca estimates 300,000 to 500,000 people live with ATTR-CM worldwide. A 2024 JAMA review put U.S. heart-failure cases from ATTR in a 50,000 to 150,000 range, with median survival of about five years if the disease is not treated.

There are two main forms. Wild-type ATTR shows up with age, without a family mutation. Mayo Clinic notes that wild-type ATTR amyloidosis in older men often targets the heart and can also cause carpal tunnel syndrome. Hereditary, or variant, ATTR comes from a TTR gene change passed through families. It can hit nerves, heart, and kidneys. People of African descent have a higher chance of carrying a TTR version tied to heart disease. The Val122Ile variant is present in about 3.4% of African American people in the United States, according to that JAMA review.

Symptoms are easy to miss. Shortness of breath, ankle swelling, palpitations, dizziness, weakness, and fatigue all show up in other kinds of heart failure. Diagnosis now often uses bone-avid nuclear scans plus blood tests that rule out AL amyloidosis, the light-chain form that starts in bone marrow and needs a different treatment. Getting that distinction wrong is dangerous, because ATTR pills and shots do not treat AL disease.

Until tafamidis, doctors mostly managed fluid with diuretics and hoped. Targeted drugs changed the outlook. Harvard cardiologist Dr. Sarah Cuddy has said most people on these therapies now live well past the old three-to-five-year life expectancy after diagnosis. Friday’s result does not erase that progress. It says the next increment, a silencer on top of a working pill, did not show up in the largest test of that idea.

How a Monthly Shot Differs From a Daily Pill

Stabilizers and silencers attack the same protein from opposite ends. A stabilizer, taken by mouth, holds TTR in its proper four-piece shape so it is less likely to break into amyloid. A silencer, given as a shot, tells the liver to make less TTR in the first place. Wainua is an antisense oligonucleotide. Amvuttra is an RNA-interference drug. Both cut TTR production. Both require vitamin A supplements, because TTR carries vitamin A in the blood.

Wainua is already approved for nerve damage, not for the heart. The U.S. label covers adults with polyneuropathy of hereditary transthyretin-mediated amyloidosis. The dose is 45 mg once a month from an autoinjector. The most common listed side effects are lower vitamin A and vomiting. That nerve approval does not move because a heart trial missed. It also does not become a heart approval on a failed primary endpoint.

ESC’s own Hot Line summary said there was no difference in cardiovascular mortality and recurrent events with eplontersen versus placebo up to 140 weeks, even though serum TTR fell. Maurer closed the session on that split.

In CARDIO-TTRansform, the largest ATTR-CM trial to date, eplontersen achieved reductions in circulating serum TTR, although the trial did not demonstrate a significant reduction in the primary endpoint in the overall population. Baseline stabilizer use appeared to influence the primary results. No additional benefit was observed in patients receiving background stabilizer therapy, while fewer primary endpoint events were observed with eplontersen in patients not receiving a stabilizer.

Dr. Mathew Maurer, Columbia University Irving Medical Center, ESC Congress 2026 Hot Line, Munich

For someone already taking tafamidis or Attruby, Friday is a reason to ask whether a monthly silencer is worth adding, not a reason to stop a pill that is working. For someone who cannot take a stabilizer, the monotherapy signal is the remaining case for a shot. Wainua stays on pharmacy shelves for hereditary nerve disease. The heart file is now a published record, and the pills are the drugs that Friday treated as standard care.

Frequently Asked Questions

What Is the Difference Between ATTR-CM and AL Amyloidosis?

ATTR-CM is caused by misfolded transthyretin made in the liver. AL amyloidosis is caused by abnormal light-chain proteins from plasma cells in bone marrow, and it is often tied to multiple myeloma. The two can look alike on a heart scan, so doctors use blood and urine tests to exclude AL before starting an ATTR stabilizer or silencer. AL is treated with plasma-cell drugs, not with tafamidis, Attruby, Wainua, or Amvuttra.

How Is ATTR-CM Usually Diagnosed?

After AL is ruled out with a serum free light-chain assay and immunofixation, many centers confirm ATTR-CM with cardiac nuclear scintigraphy that shows a typical uptake pattern, sometimes without a heart biopsy. Genetic testing then sorts wild-type disease from a hereditary TTR variant. Carpal tunnel syndrome, spinal stenosis, and biceps-tendon rupture are extracardiac clues that often appear years before heart failure.

Does Wainua Still Treat Nerve Damage From Hereditary Amyloidosis?

Yes. The Food and Drug Administration approved Wainua on December 21, 2023, for polyneuropathy of hereditary transthyretin-mediated amyloidosis in adults, under NDA 217388, and that indication was not part of Friday’s heart readout. It is the only approved ATTRv-PN therapy designed for monthly self-injection with an autoinjector. People on the drug are told to take the recommended daily allowance of vitamin A and to see an eye doctor if night blindness or other vitamin A deficiency symptoms appear.

Who Has a Higher Risk of Hereditary ATTR Heart Disease?

Risk rises with age and is higher in men. The Val122Ile (pV142I) TTR variant, with origins in West African populations, is found in about 3.4% of African American people in the United States, or roughly 1.5 million people who carry the allele. Carrying the variant is not the same as having amyloid heart disease, but it raises lifetime risk and is a reason some heart-failure clinics now offer targeted genetic testing.

Can a Patient Stay on Both a Stabilizer and a Silencer?

Nothing in Friday’s dataset tells a person to stop a prescribed drug without talking to an amyloid specialist. The practical change is upstream: cardiologists now have less evidence that starting a silencer on top of a working stabilizer prevents deaths or repeat heart events, and they have a 1.14 rate ratio that argues against assuming the combo is additive. Combination care is likely to be individualized, and in many clinics it will be harder to justify as a default.

Disclaimer: This article is news reporting and analysis of a published clinical trial and related drug labels. It is for information only and is not medical advice, a treatment recommendation, or a substitute for care from a licensed clinician. It does not tell anyone to start, stop, or combine tafamidis, acoramidis, eplontersen, vutrisiran, or any other medicine. Readers who have ATTR amyloidosis, heart failure, or a related diagnosis should talk with a cardiologist or amyloidosis specialist before changing therapy. Figures, approvals, and trial statuses reflect the sources available as of August 29, 2026, and may change if companies file new data or regulators act.