Episode 40: How immunotherapy is changing the face of veterinary cancer treatment

When a pet owner is told their dog has cancer, often their mind goes first to the adverse effects wrought by traditional cancer therapies in humans. In fact, a 2017 Canadian study revealed that 58% of dog and cat owners would not pursue chemotherapy for their pet, largely due to their previous experience with it.

According to Michael Lucroy,DVM, MS, DACVIM (oncology), the answer for many of these owners may lie in immunotherapy.

In this episode of The Vet Blast Podcast, Lucroy talks with Adam Christman, DVM, MBA, about how immunotherapy works and why it might be a good option for pets whose owners are anxious about chemotherapy, radiation, or surgery.

Adverse event rates are comparatively quite low with immunotherapeutics, according to Lucroy, so immunotherapy has a lot to offer for owners who are fearful about that. It is also good for owners who want to pursue every treatment option, he says—those who are “in it to win it”—because immunotherapy works well in concert with radiation therapy and chemotherapy.

There are a couple of ways the immune response can be altered to fight cancer. “With immunotherapy, [we’re] trying to use the body’s own innate defenses to our advantage,” Lucroy says, “whether that’s stimulating an immune response to go and fight cancer or…trying to deal with the immunosuppression cancer can create.”

One of the things cancer does is recruit T-regulatory cells that are immunosuppressive. In health, these T cells are supposed to moderate the immune response, but in the case of cancer, the cancer recruits the T cells and makes a nice environment for them to grow and thrive, preventing the rest of the immune system from fighting the cancer. “So sometimes the way you come at it is to get rid of that immunosuppression,” he says.

Metronomic therapy in human cancers is an example. Lucroy breaks down the process: “You give low doses daily of an alkylating agent like cyclophosphamide or chlorambucil, along with a COX-2 inhibitor NSAID, and what those do is actually deplete the body of T-regulatory cells. So, it overcomes that immune suppression that the cancer is driving.” This process allows the rest of the immune system, like the cytotoxic T cells, to come in and kill the cancer.

Listen below to learn more about the forms of immunotherapy used in veterinary medicine, how it works, the benefits it may offer, and the options for administering immunotherapy in general practice.