One step closer to a dog longevity drug: What LOY-002’s safety milestone means to a practicing vet

Our North Star as a company is to bring to market the first drug approved by the FDA for lifespan extension in dogs. Today, we’re excited to share that we’re one step closer to achieving that goal: the FDA’s Center for Veterinary Medicine has accepted the Target Animal Safety (TAS) section of our Expanded Conditional Approval (XCA) application for LOY-002, Loyal’s lead drug candidate.

LOY-002 aims to address the metabolic dysfunction that all dogs experience as they age, delaying the start of many diseases that reduce quality of life for senior dogs and giving dogs, and their human family, more enjoyable time together. If we achieve approval and bring this drug to veterinarians, it will be a powerful new treatment for potentially millions of senior dogs. 

Our general strategy for extending healthy lifespan in dogs is to use our understanding of the fundamental biology of aging to target specific aging mechanisms (like metabolic dysfunction) that reduce the quality and length of life. Rather than waiting for aging to damage health and then reacting to the diseases that occur, we take a proactive approach. We aim to prevent the harm of aging before it happens and preserve function and health. This approach comes with many significant scientific and regulatory challenges. One of the most important is the issue of safety. 

All medicines have potential risks as well as benefits, and veterinarians routinely balance these to achieve a net-positive outcome for each patient. When a dog has disease that is causing significant suffering or is likely to be fatal, such as cancer, medicines that reduce suffering and prolong life can be beneficial even if they have significant negative effects. Chemotherapy is an example of this, and while it commonly causes undesired effects, such as nausea or a decrease in immune system function, these are worth coping with for a short while if the patient is likely to end up with a meaningful period of good quality life they couldn’t have had without treatment.

Preventative medicines are different. Since we are treating generally healthy dogs with the goal of preserving health, our tolerance for negative effects from the treatment has to be very low. Side-effects need to be minor or very rare if the treatment is to have a net benefit for most patients. This is a high bar, and for LOY-002 we have worked hard to meet the rigorous standards set by the FDA and to evaluate the safety of the drug in varied and realistic conditions of use.

Until the drug is approved by the agency^*, we are limited in how much detail we can provide about the testing process. The STAY study, our clinical trial testing LOY-002 against a placebo in 1,300 dogs across the U.S., promises to be a goldmine of information, not only about the drug but about canine aging. 

For now, we can share that the evidence we provided to the FDA in support of the safety portion of our application included data from multiple studies and over 400 dogs who have been given LOY-002, including:

• A safety study conducted at standard target dose multiples (1x, 3x, and 5x the intended clinical dose), with no clinically significant adverse events observed at these doses

• Field safety data from more than 400 companion animals on LOY-002 for varying durations, including for up to one year

We’ve studied LOY-002 in hundreds of dogs, including those with many of the health conditions and medical treatments senior dogs often experience, and we are extremely pleased the FDA agrees that these data support the safety of LOY-002 for its intended use. This is the same safety standard applied to all veterinary drugs, whether approved through XCA or the standard approval pathway.

XCA is a demanding process, scientifically and in terms of the regulatory requirements (Figure1). In February of last year, the FDA also accepted LOY-002’s Reasonable Expectation of Effectiveness (RXE) package. With the acceptance of our safety and efficacy packages, we have completed two of three critical elements of the XCA application. Acceptance of these submissions signals that the FDA finds our data support that the drug is likely to be effective and safe for its intended use to extend healthy lifespan in senior dogs.

We are diligently working on the manufacturing component of XCA, and we are also fully enrolled and charging ahead with the STAY study, the clinical trial necessary for eventual full approval of LOY-002.^* We’re excited by the progress we've made towards bringing veterinarians and dog owners a new tool to help address aging-related disease. While there’s still important work ahead, TAS completion is a major milestone towards delivering on our goal of meaningfully impacting the health and lifespan of our canine companions. 

We are also grateful to all the veterinarians, pet parents, and, of course, dogs who are participating in and following along on this journey towards the first longevity drug for dogs.