Gene therapy demonstrates benefit to dogs with myxomatous mitral valve disease


Study results for RJB-01 (Rejuvenate Bio) were announced at the 26th Annual Meeting of the American Society of Gene and Cell Therapy.

Cavalier King Charles spaniel

Photo: Happy Monkey/Adobe Stock

New data show benefit for gene therapy RJB-01 (Rejuvenate Bio) in treating myxomatous mitral valve disease (MMVD) in canines. These pilot study results were announced today the 26th Annual Meeting of the American Society of Gene and Cell Therapy (ASGCT) in Los Angeles, California.

In the pilot study of Cavalier King Charles (CKC) spaniels with MMVD, a delay in disease progression was demonstrated. The study also showed RJB-01, in conjunction with pimobendan (Vetmedin; Boehringer Ingelheim) for MMVD in canines, helped reduce heart enlargement in the studied dogs, according to Rejuvenate Bio.

MMVD, a common disease in dogs, eventually leads to congestive heart failure. Of all dogs afflicted with MMVD, CKC spaniels have one of the highest breed incidences, with rates approaching 80%, according to Rejuvenate Bio.

“Mitral valve disease is often fatal for canines at the advanced stage, with no current treatments that can provide a cure,” said Noah Davidsohn, PhD, chief scientific officer for Rejuvenate Bio, in an organizational release. “The current standard of care is [pimobendane], paired with ACE inhibitors, but this only treats symptoms and does not address the underlying disease.”

RJB-01, expresses the genes FGF21 and sTGFßR2 with an adeno-associated virus delivery system in order to upregulate FGF21 and downregulate TGFß1 for the treatment of heart failure. This therapy was administered to 17 canines approaching 3 years of durable expression and bioactivity of genes with a favorable safety profile. The studied dogs were monitored hourly during administration when given RJB-01. Four CKC spaniels have been on the therapy for greater than 2 years with no safety signals.

Twelve CKC spaniels administered RJB-01 and pimobendan, the current best in class medication to treat dogs with congestive heart failure, experienced a delay in progression of over 1.5 years when compared with the reported time to progression in all breeds treated with standard of care, according to the release. When compared to a historical control of pimobendan alone in all breeds, CKC spaniels treated with RJB-01 and pimobendan saw an increase in time to progression of ~600 days, and over 800 compared to placebo.

Dogs with MMVD often see an enlargement in the left atrium of their heart due to damage caused by a malfunctioning mitral valve. Pimobendan limited the increase in heart size to 0.8 units over 28 months. RJB-01 with pimobendan was able to reduce left atrium size by 0.3 over a similar timeframe with some dogs enrolled in the study reverting to an earlier stage of the disease, according to the release.

Davidsohn noted that officials with Rejuvenate Bio are excited for the initial results from the pilot study, and to share them at ASGCT 2023. “We will continue to provide updates as the study progresses,” Davidsohn said.


Rejuvenate Bio Announces Data for Gene Therapy RJB-01 in Mitral Valve Disease at 2023 Meeting of the American Society of Gene and Cell Therapy (ASGCT). News release. May 18, 2023. Accessed May 18, 2023.

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