Novel cardiology therapy for cats is launched

Photo: dk_photo/Adobe Stock

A new therapy for managing ventricular hypertrophy in felines with subclinical hypertrophic cardiomyopathy (HCM) was officially launched Tuesday, June 17, 2025, by PRN Pharmacal, a Pegasus Laboratories brand. The drug, sirolimus delayed-release tablets (Felycin-CA1), is expected to be available on the veterinary market by late July 2025.¹

Sirolimus delayed-release tablets were developed by TriviumVet, which received the drug’s conditional approval from the FDA in March 2025. The acquisition of TriviumVet by PBI-Gordon Companies Inc., which is the parent company of Pegasus Laboratories, was announced in May 2025.²

The PRN Pharmacal launch was marked by a presentation on the drug at the Hermitage Farm in Goshen, Kentucky. It was a celebratory "best of Kentucky" experience for guests that included bourbon tasting, a stable visit with thoroughbred horses, and dinner prepared with locally sourced components. However, the main focus remained on the novel therapy.¹

“It is indeed a milestone that's been nearly a decade in the making, and we are so super excited about it. It's certainly, like most drugs, the result of a lot of collaboration, rigorous science, but also, fundamentally, that cats deserve the same level of innovation and care as humans do. They are animals we love. They deserve to be cared for,” Steve Clifford, president and CEO of PBI-Gordon Companies, told attendees.¹

In a public statement, Stuart Fitzgerald, MVB, MANZCVS, chief scientific officer at TriviumVet, noted that HCM is one of the most common and life-threatening feline diseases. “Increasing awareness, education, and access to treatment can contribute to earlier diagnosis and better management—ultimately helping cats live longer, healthier lives," he added.²

HCM reduces the heart’s ability to efficiently pump blood, which can lead to heart failure and other complications, including death. According to PRN Pharmacal, while some cats with the disease develop symptoms of congestive heart failure, many others remain subclinical for years.³

The cause of feline HCM is not fully understood, according to PRN Pharmacal, but investigators have found the condition more common in certain breeds such as British shorthair, Chartreux, Maine coon, Persian, ragdoll, and Sphynx. Mutations in some cardiac genes have been identified through research in several of the most commonly affected breeds.³

Held on the eve of the American College of Internal Veterinary Medicine (ACVIM) Forum—June 18-21, 2025, in nearby Louisville, Kentucky—the presentation at Hermitage Farm was delivered by Joshua Stern, DVM, PhD, DACVIM, associate dean for research and graduate studies at North Carolina State University College of Veterinary Medicine in Raleigh, as well as lead investigator for sirolimus delayed-release tablets. He provided an introduction of sirolimus delayed-release tablets and how the product manages HCM, a condition that causes a feline’s muscular walls to become abnormally thick.¹

Stern explained that sirolimus is a mammalian target of rapamycin (mTOR) inhibitor. “We have a reasonable expectation of effectiveness granted by the FDA because of some past literature and a lot of important work that we did along the way. And when we look into the past literature, it's really clear that overactivation of mTOR promotes left ventricular hypertrophy in hypertrophic cardiomyopathy across multiple species. Sirolimus as a compound is shown to reduce left ventricular hypertrophy, particularly in its maladaptive form,” Stern said.¹

“Veterinarians have long needed options beyond palliative care when it comes to feline HCM,” Stern said. “The [sirolimus] tablets come in 0.4-, 1.2-, and 2.4-mg tablets. And the combination of any of those tablets will dose just about any cat you can imagine from tiny to gigantic…and they're all delightfully small and dosed once weekly,” Stern said.¹

Heather Davis, DVM, PhD, DACVS-LA, director of clinical affairs and veterinary services at Pegasus Laboratories, noted in a news release that sirolimus delayed-release tablets signal a “turning point” in feline medicine because the drug provides veterinarians with a needed option to help slow the progression of HCM, which goes beyond only managing the disease. “For the first time, we’re changing the conversation around what’s possible in feline heart care,” Davis said.³

In his talk, Stern also provided insights about ongoing studies related to safety and efficacy. This includes the HALT Study, which currently has 210 enrolled cats, and aims to confirm the positive impact of reduced left ventricular wall thickness on clinical outcomes. If successful, the HALT Study could support full FDA approval, according to Stern.¹

“I really believe that Felycin-CA1 is a paradigm shift in how we think about treating cardiovascular disease in cats. It's charting a new course. And I think we're moving from looking at disease outcomes and how we go about scrambling to mitigate treatment for those disease outcomes, and really looking at the pathogenesis of this disease in a cellular event hole. That's super exciting as somebody who researches this disease,” Stern said.

References

1. Stern J. Presenting Felycin-CA1 (sirolimus delayed-release tablets). Presented at: Hermitage Farm; Goshen, KY. June 17, 2025.
2. Felycin-CA1 (sirolimus delayed-release tablets) redefines feline cardiac care. News release. Pegasus Laboratories and PRN Pharmacal. June 12, 2025.
3. PBI-Gordon Companies acquires TriviumVet, expanding portfolio of innovating treatments in pet health. News release. PBI-Gordon Companies. May 5, 2025. Accessed June 18, 2025. https://www.prnewswire.com/news-releases/pbi-gordon-companies-acquires-triviumvet-expanding-portfolio-of-innovative-treatments-in-pet-health-302445353.html