Key takeaways:
Camzyos is the first medication of its kind to treat obstructive hypertrophic cardiomyopathy (oHCM). It’s unique because it treats the cause of oHCM, not just the symptoms.
Camzyos can cause dizziness and fainting. It has a black box warning for worsening heart failure, and is part of a Risk Evaluation and Mitigation Strategy (REMS) program for this reason.
Camzyos has several potential drug interactions. Make sure to give your healthcare provider and pharmacist a list of all the medications and supplements you take before starting Camzyos.
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Hypertrophic cardiomyopathy (HCM) can happen when the walls of the left ventricle (one of the four chambers of the heart) become thicker. It’s most often caused by irregular (mutated) genes in the heart muscle.
In a type of HCM called obstructive HCM (oHCM), the wall between the left and right ventricle becomes thicker. This prevents blood from entering the heart as it normally would. It also makes it harder for the heart to pump blood to the rest of the body.
HCM can lead to other health problems. These include arrhythmias (like atrial fibrillation), blood clots, and heart failure. It can also lead to sudden cardiac death in rare cases.
Until recently, most medications for HCM simply treated the symptoms of the condition. But that changed in April 2022, when the FDA approved Camzyos (mavacamten) for oHCM. Camzyos is unique because it targets the underlying cause of oHCM, not just the symptoms.
In this article, we’ll discuss how Camzyos works, as well as its safety and effectiveness.
What is Camzyos?
Camzyos is a cardiac myosin inhibitor. It’s the only medication in its class. The FDA approved it to treat adults with symptomatic oHCM, in either class II or III of the New York Heart Association (NYHA) classification system.
The NYHA classification system classifies heart failure based on how severe your symptoms are. There are four different levels of symptom severity in the NYHA system. A person with NYHA Class II to III heart failure experiences limitations in their ability to comfortably exercise.
How does Camzyos work to treat hypertrophic cardiomyopathy?
To understand how Camzyos works, we need to understand how the heart pumps blood to the rest of the body.
The heart has to complete two actions to pump blood. These actions are squeezing (contracting) and relaxing. The heart pumps blood by alternating between these two phases.
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In HCM, the heart contracts too intensely. Camzyos allows the heart to relax by targeting one of the proteins responsible for how well the heart contracts. This protein is called myosin. The other protein that helps the heart contract is actin.
Camzyos minimizes the interaction between myosin and actin. This prevents the heart from contracting too hard. When the heart is able to relax, enough blood can enter the heart to be pumped out to the rest of the body.
How is Camzyos dosed?
Camzyos is FDA-approved for adults with obstructive HCM who have a left ventricular ejection fraction (LVEF) of at least 55% or higher. The LVEF measurement refers to how much blood is pumped out of the left ventricle each time it contracts.
The medication comes as a capsule in the following dosages:
2.5 mg
5 mg
10 mg
15 mg
You’ll usually start by taking 5 mg once a day. Your heart function will be assessed with an echocardiogram monthly for the first 3 months. An echocardiogram can help measure how well your heart is working. Depending on how you respond to Camzyos, your dose may be lowered or raised.
After the first 3 months, you’ll continue to follow up with your healthcare provider every 3 months. They’ll make sure you're taking the best dose for you.
How effective is Camzyos?
Camzyos is effective at improving oHCM symptoms.
The study that gained Camzyos FDA-approval was called the EXPLORER-HCM study. It was a randomized controlled trial (RCT). RCTs are the best type of clinical study to test cause-and-effect relationships.
The EXPLORER-HCM study included over 400 adults. It found that Camzyos improved HCM and symptoms of HCM more than placebo (a pill with nothing in it).
When compared to placebo, Camzyos improved the following outcomes:
How well the heart pumps blood (as measured by left ventricular outflow tract)
Exercise capacity (a measure of your ability to exert yourself during physical activity)
Heart failure symptoms
Improvement of at least one NYHA class
But, it’s important to note that the study only lasted about 7 months. So, we don’t know how effective Camzyos is long-term.
How does Camzyos compare to other medications for hypertrophic cardiomyopathy?
Beyond Camzyos, there are other medications that are used to treat HCM symptoms. In the EXPLORER-HCM study, over 90% of participants were already taking medication to improve their HCM symptoms.
Medications used for HCM include:
Beta blockers like propranolol (Inderal) and metoprolol (Lopressor)
Non-dihydropyridine calcium channel blockers like verapamil and diltiazem (Cardizem)
Antiarrhythmic medication disopyramide (Norpace)
Propranolol is the only medication that’s FDA-approved to treat HCM. The other medications are used off-label for HCM. There are currently no clinical studies comparing Camzyos to these medications. But in a recent study of 29 people with oHCM, metoprolol didn’t improve exercise capacity. As discussed above, Camzyos did improve exercise capacity in the EXPLORER-HCM study.
What are the side effects of Camzyos?
Dizziness, fainting, and decreased LVEF are the most common side effects of Camzyos.
In the EXPLORER-HCM trial, 27% of people taking Camzyos experienced dizziness. And 6% of people experienced fainting.
Some people (6%) also experienced a decrease in their LVEF. This means the heart isn’t pumping blood effectively. But this was reversible — when Camzyos was stopped, LVEF increased.
Still, lower than normal LVEF can lead to heart failure. Camzyos has a black box warning for its potential to cause heart failure. A black box warning is the FDA’s strictest medication warning. Camzyos also has a Risk Evaluation and Mitigation Strategy (REMS) program. A REMS program is an FDA-required drug safety program. It ensures that the benefits of a medication outweigh the risks.
The risk for heart failure is greater in people taking Camzyos who develop a serious infection. The risk is also greater in people with a new or worsening arrhythmia.
Seek immediate medical attention if you notice any heart failure symptoms, including:
Uncomfortable laying down
Gasping for air, especially at night
Shortness of breath
Tiredness
Leg and belly swelling
Pitting in the area of swelling (when there's an indentation after pressing down on a swollen area)
Can I take Camzyos if I’m pregnant?
No, you shouldn’t take Camzyos if you’re pregnant.
If you could become pregnant while taking Camzyos, take a pregnancy test before starting treatment to confirm you’re not pregnant.
You should use a form of birth control during treatment and 4 months after the last dose of Camzyos. Birth control pills with estrogen and progestin aren’t recommended. Camzyos can lower their effectiveness. These are called "combination pills."
Does Camzyos interact with other medications?
Camzyos should be avoided with certain medications. For example, if you’re taking disopyramide along with verapamil or diltiazem, you shouldn’t take Camzyos. This could lead to a higher risk of decreased LVEF and heart failure.
Camzyos is broken down (metabolized) by enzymes in the liver. These enzymes, called cytochrome P450 (CYPS), are involved in metabolizing many medications. The specific CYP enzymes involved in Camzyos metabolism are CYP2C19 and CYP3A4. Other medications that also affect these enzymes can interact with Camzyos. The medications discussed below should be avoided with Camzyos:
Moderate or strong CYP2C19 inhibitors: Examples include fluconazole (Diflucan) and fluoxetine (Prozac).
Strong CYP3A4 inhibitors: These include ritonavir (Norvir) and ketoconazole. Grapefruit juice also blocks CYP3A4. You should avoid drinking it when taking Camzyos.
Moderate or strong CYP219 inducers: Examples include rifampin and phenytoin (Dilantin, Phenytek).
Moderate or strong CYP3A4 inducers: Examples include carbamazepine (Tegretol) and St. John's wort.
This isn’t a complete list of medications that interact with Camzyos. Before starting Camzyos, create a list of the medications you take. Your healthcare provider or pharmacist can help you check for drug interactions.
How much will Camzyos cost?
The cash price of Camzyos could be over $7,000 for a month’s supply. The company that makes Camzyos offers a free trial for people to get started with the medication.
If you have commercial insurance, you may be eligible for a copay program. You could pay as little as $10 per month for Camzyos, and you may be able to get help paying for your required echocardiograms. Call 855-226-9967 to learn more.
If you have government insurance, check with your plan to see what they cover. This includes Medicare or Medicaid. If you don’t have insurance, BMS encourages you to call the number above to learn about your options.
When will Camzyos be available?
Camzyos is available now, but you won’t find it at your local pharmacy. Your healthcare provider will send the prescription to a specialty pharmacy. Camzyos will be mailed to you from this pharmacy.
The bottom line
Camzyos is the first medication of its kind to be FDA-approved to treat oHCM. It treats the underlying cause of oHCM, not just the symptoms. It’s more effective than placebo at treating oHCM. But it can have drug interactions and side effects. In serious cases, Camzyos can cause heart failure.
Make sure your healthcare provider and pharmacist are aware of your full medical history. You should also provide them with a list of the medications and supplements you take before starting Camzyos.
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References
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