Adventures With the Fabulous mAb, Part Three

They can perform a lot of amazing tricks, those mAbs. Human beings are enjoying the vast majority of the mAb action, however, while pets have access to just four of these therapies. Conventional medicines developed for humans can often be adapted for use in dogs and cats; some examples are clopidogrel, furosemide, and fluoxetine. The monoclonal antibody, however, is way too fussy to cross species lines. Trying to use the human version in a dog would be (best case scenario) like throwing it at a wall. Its specific target is inside a human being. Only.

The mAb therapies developed especially for pets include Bedinvetmab (Librela, for dogs) and frunevetmab (Solensia, for cats).These act by targeting and binding nerve growth factor, blocking this molecule from irritating the patient’s nerve endings. The idea is to minimize chronic pain, specifically from arthritis. Lokivetmab, or Cytopoint, works in a similar way, sticking to a naturally-occurring itch protein called IL-31. In this scenario, the itch sensation never really gets a chance to bloom, and the skin remains comfortable, even in the face of allergies. A fourth compound has been successfully used to blockade infection with parvovirus, the notorious killer of puppies. It’s just called Canine Parvovirus Monoclonal Antibody (CPMA)—nothing fancy—and its target is simply the outer surface of the virus. Given early in the disease process (i.e., right away when the pup tests positive), this injection renders the virus incapable of locking onto its prey and limits damage done to the lining of the GI tract.

The superpower of mAbs is distinguishing between two almost identical things, and this keeps their actions inside the body from spilling over onto innocent bystanders. Side effects, therefore, are very rare. These therapies aren’t totally flawless, however. The FDA compiles individual reports of adverse effects for all sorts of drugs, and—of the four veterinary therapeutics listed above—we have the most detailed information on Librela (bedinvetmab). These reports help us recognize that if an untoward event were to occur after use of Librela, it could be weakness, stumbling, or urine leakage. Increased drinking and urination has also been occasionally observed. These things are most likely to occur in the first week after the first dose of Librela, often within 24 hours of the treatment. About a third of the events did not occur during the first month and were instead correlated with subsequent doses.

It’s worth noting that all of the “side effects” listed are relatively commonplace events among the population most likely to take Librela, which is old, painful dogs—which is to say, the cause-and-effect relationship here is a little murky. Further obscuring any solid connection is the fact that other medical treatments were often employed on the same day as the Librela. In real life, it’s difficult to say confidently that one thing caused another, but perhaps you recognize something in what I’ve described above. In that case, it might be better for your pet to try a different route to arthritis relief. Watch this space for ongoing developments in mAb therapy, since dozens of targets are currently being explored for veterinary use.

Dr M.S. Regan