Not yet recruitingRare disease

Serum Transthyretin Levels in Patients with Transthyretin Amyloid Cardiomyopathy Treated with Tafamidis and Acoramidis: A Within‑Patient Pilot Crossover Study

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What is this trial about?

A plain-language summary of the goals, design and what participants do

The condition being studied is Transthyretin Amyloid Cardiomyopathy, a rare heart disease in which an abnormal protein builds up in the heart muscle, causing it to become stiff and work less efficiently. The trial compares two oral medicines: the approved drug tafamidis, which helps stabilize the abnormal protein, and the experimental compound acoramidis, which is designed to work in a similar way.

The purpose of the study is to see how each medication changes the amount of a blood protein called serum transthyretin, which carries vitamin A and thyroid hormone and can reflect disease activity.

Participants will take one of the medicines for about four weeks, during which blood samples are collected to measure protein levels, then they will switch to the other medicine for another four‑week period with similar testing. This “crossover” design lets each person serve as their own comparison, providing information on how the two drugs affect the protein levels over short treatment periods.

The research process

The trial runs in 4 steps – from screening to follow-up. Each step says what happens and what the team monitors.

Step 1
Baseline assessment
On the first day of the study (day 0), a blood sample is taken to measure serum transthyretin levels. This measurement serves as the baseline for comparison with later results.
A brief medical evaluation is performed to confirm eligibility and to record any current medications or health conditions.
Step 2
First treatment period
The patient begins taking the first study medication for a period of 28 days. The medication is taken once each day.
If the first medication is tafamidis, the patient takes one soft capsule containing 61 mg of the drug daily.
If the first medication is acoramidis, the patient takes enough film‑coated tablets to provide a total of 1424 mg of the drug each day.
At the end of the 28‑day period (day 28 ±5 days), another blood sample is collected to determine the change in serum transthyretin from the baseline measurement.
Step 3
Crossover to second medication
After completing the first 28‑day treatment, the patient stops the first medication and immediately starts the second medication for another 28 days, continuing the once‑daily dosing schedule.
If the second medication is tafamidis, the patient takes one soft capsule containing 61 mg each day.
If the second medication is acoramidis, the patient takes enough film‑coated tablets to provide a total of 1424 mg each day.
A blood sample is taken at the end of this second 28‑day period (day 28 of the second period) to measure serum transthyretin again.
Step 4
Final evaluation
The two sets of blood results are compared to determine the difference in serum transthyretin levels between the tafamidis and acoramidis treatment periods.
The primary outcome is the absolute change in serum transthyretin concentration from baseline to the end of each 28‑day treatment period.

Who can join the trial?

9 criteria

Age between 18 and 99 years.
Confirmed diagnosis of transthyretin amyloid cardiomyopathy (ATTR-CM), a rare heart disease caused by abnormal protein deposits.
Kidney function test called eGFR (estimated glomerular filtration rate) at least 30 mL/min/1.73 m², which shows the kidneys are working well enough.
Blood test for NT‑proBNP (a marker that rises when the heart is under stress) greater than 300 pg/mL and not higher than 7,000 pg/mL.
Must be in a clinically stable condition, meaning no recent severe worsening of heart symptoms or serious infection.
Must be treatment‑naive for TTR‑targeted medicines – no prior use of tafamidis, acoramidis, diflunisal, doxycycline + TUDCA, patisiran, vutrisiran, inotersen, eplontersen, or similar drugs.
Women who could become pregnant must have a negative pregnancy test and use a highly effective form of birth control.
Ability and willingness to attend study visits, have repeated blood draws, and accept a short break from treatment during a washout period.
Provide written informed consent, agreeing to take part in the study.

Who cannot join the trial?

14 criteria

Been in the hospital for heart failure (HF) or transthyretin amyloid cardiomyopathy (ATTR‑CM) within the last three months.
Having unstable health that would make stopping the study medicine unsafe, as judged by the doctor.
Having an active infection or a flare‑up of inflammation when the study starts.
Having already had a heart or liver transplant, or planning to have one within the next year.
Having a current or planned ventricular assist device (VAD), a machine that helps the heart pump.
Being pregnant now or planning to become pregnant during the study.
Having a life expectancy of less than one year.
Having heart failure that is mainly caused by blocked coronary arteries (ischemic heart disease).
Having confirmed AL amyloidosis, a different type of protein buildup in the body.
Being on dialysis (a treatment that cleans the blood) or having a urine test result called UACR higher than 300 mg per gram, which shows significant kidney problems.
Having had major surgery within the past 90 days.
Having serious liver disease, shown by liver enzymes (ALT or AST) at three times the normal upper limit, or bilirubin at three times the normal upper limit.
Taking any other medicines that are not allowed because they also treat ATTR‑CM.
Having a known allergy (hypersensitivity) to the study drug or any of its inactive ingredients (excipients).

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Medical University Of Vienna
Vienna, Austria

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Investigated drugs

Tafamidis
is an oral medication taken as a soft capsule. It works by binding to the transthyretin protein and keeping it from breaking apart and forming amyloid deposits in the heart. In this study each participant took tafamidis for a 28‑day period, and the researchers measured the amount of transthyretin in the blood to see how the drug affected its level.
Acoramidis
is an experimental oral tablet. It is designed to increase the production of normal transthyretin protein, which can raise the amount of this protein in the bloodstream. In the trial participants also took acoramidis for a 28‑day period, and the same blood tests were done to compare its effect with that of tafamidis.

What is already known about the treatment

Acoramidis
Acoramidis is taken as a 356 mg film‑coated tablet swallowed with water. It is still an investigational drug being studied in clinical trials and has not received regulatory approval for general use. The medication is being tested for transthyretin amyloid cardiomyopathy, a rare heart disease caused by abnormal protein buildup. It works by binding to the transthyretin protein and keeping its four‑part structure together, which helps prevent harmful protein clumps; it belongs to the class of transthyretin stabilizers.
Tafamidis
Tafamidis is provided as 61 mg soft capsules that are swallowed whole. It is an approved treatment for transthyretin amyloid cardiomyopathy and has been described in the medical literature for many years. The drug is used to manage this rare heart condition caused by abnormal transthyretin protein. Tafamidis works by attaching to the transthyretin protein and preventing it from breaking apart, thereby reducing amyloid deposits; it is classified as a transthyretin kinetic stabilizer.

Investigated diseases

Transthyretin Amyloid Cardiomyopathy - This disease occurs when a protein called transthyretin builds up as amyloid deposits in the heart muscle. The deposits make the walls of the heart stiff and less able to relax. Over time the heart’s ability to pump blood can become reduced, leading to symptoms such as shortness of breath, tiredness, and swelling of the ankles. The condition usually develops slowly, with changes becoming noticeable over months to years.