FDA conditionally approves first drug for feline subclinical hypertrophic cardiomyopathy

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The FDA announced it was conditionally approved sirolimus delayed-release tablets (Felycin-CA1; TriviumVet). The conditionally approved medication is for management of ventricular hypertrophy in feline patients with subclinical hypertrophic cardiomyopathy (HCM), making it the first product to receive approval for use in cats with this condition for any indication.

HCM in feline patients

Feline HCM is a condition that causes the muscular walls of a feline patient’s heart to thicken, which decreases the heart’s efficiency, and can create other symptoms within other parts of the body. Currently, there is no cause of HCM clearly identified, but it is prevalent in certain breeds, including British shorthair, Chartreux, Maine coon, Persian, and Sphynx cats. Mutations of several cardiac heart genes has also been identified in some cats with HCM, suggesting genetics play a role.²

Feline patients with HCM may not show any signs of being ill and can live for years in this subclinical phase. Others may present with congestive heart failure, including labored or rapid breathing, open-mouthed breaking, and lethargy. The presenting symptoms occur when fluid accumulates around or in the patient’s lungs. When it comes to HCM, a serious and life-threatening consequences is the formation of blood clots in the heart. The clots could move through the blood stream, causing thromboembolism. Although rare, feline patients with HCM are also at risk of sudden death.²

Feline HCM Is extremely common in cats, affecting 1 in 1 of all pet cats, and for cats over 9-years-old, the prevalence is 1 in 3, making it the leading cause of mortality in adult cats.³

Felycin-CA1

Sirolimus, the active ingredient in Felycin-CA1, at a higher dose is used as an immunosuppressant in human patients receiving organ transplants. Felycin-CA1 is given to cats at a target dose of 0.3 mg/kg orally once a week and is not expected to be an immunosuppressive in patients.

In order for an animal drug to be eligible for conditional approval, it must address a serious or life-threatening disease or address an unmet need in animal or human health. The drug would also need to demonstrate effectiveness, requiring a complex or particularly difficult study or studies. Felycin-CA1 met this requirement because subclinical HCM progresses to clinical HCM, impacting daily functioning in cats and could be fatal. Felycin-CA1 also addresses an unmet animal need because there were no other drugs approved for use in feline patients with ventricular hypertrophy due to subclinical HCM.

“Felycin-CA1 is the first and only medication shown to reduce the ventricular hypertrophy that is the principal feature of subclinical HCM. It provides a valuable treatment option for veterinarians and pet owners and will transform the way feline HCM is managed’ said Stuart Fitzgerald, Chief Scientific Officer at TriviumVet, in an organizational release.⁴

For Felycin-CA1, demonstrating effectiveness required a complex or particularly difficult study or studies because the detection of subclinical HCM requires advanced diagnostic tests, which makes it difficult to enroll enough eligible cats.

Felycin-CA1 is only available by prescription from a licensed veterinarian, and cats should be screened for pre-existing live disease before starting the medication. This medication should also not be used in feline patients with diabetes mellitus or a pre-existing liver condition.

Felycin-CA is available in 0.4 mg, 1.2 mg, and 2.4 mg tablet sizes.

Refernce

1. FDA Conditionally Approves Drug for Management of Ventricular Hypertrophy in Cats. News release. US Food and Drug Administration. March 14, 2025. Accessed March 14, 2025. https://www.fda.gov/animal-veterinary/cvm-updates/fda-conditionally-approves-drug-management-ventricular-hypertrophy-cats?utm_medium=email&utm_source=govdelivery
2. Cornell University. Hypertrophic Cardiomyopathy. Cornell University College of Veterinary Medicine. Accessed March 14, 2025. https://www.vet.cornell.edu/departments-centers-and-institutes/cornell-feline-health-center/health-information/feline-health-topics/hypertrophic-cardiomyopathy
3. Kaplan JL, Rivas VN, Walker AL, et al. Delayed-release rapamycin halts progression of left ventricular hypertrophy in subclinical feline hypertrophic cardiomyopathy: results of the RAPACAT trial. J Am Vet Med Assoc. 2023;261(11):1628-1637. Published 2023 Jul 26. doi:10.2460/javma.23.04.0187
4. TriviumVet Secures FDA Conditional Approval for Feline Cardiology Disease. News release. TriviumVet. March 14, 2025. Accessed March 14, 2025. https://www.triviumvet.com/blog/triviumvet-secures-fda-conditional-approval-for-feline-cardiology-disease