What’s Immunotherapy and Can It Help Dogs with Cancer

Immunotherapy is a buzzword in human medicine. Although there’s still more research to be done, this form of cancer treatment can also benefit dogs suffering from malignancies.

If you know someone with cancer, you may have heard them refer to immunotherapy as a potential form of treatment for their disease. While immunotherapy started out as a human treatment, more recent advancements now mean it can also be used to help dogs with cancer. But what exactly is it, and how does it work?

WORKING WITH THE IMMUNE SYSTEM

As the name suggests, immunotherapy revolves around the immune system, which is the body’s built-in ability to fight off ailments and destroy abnormal cells. Immunotherapy involves manipulating the immune system to either prevent or get rid of a malady in the body.

The history of immunotherapy can be traced as far as back as the Chinese Qin dynasty, when people were purposefully inoculated with the variola minor virus to boost the immune system and prevent smallpox. In 1718, another localized inoculation method was noticed by the wife of a British ambassador in Turkey, and reported back to Britain. However, the event largely accepted as the inception of immunotherapy as a valid treatment option occurred in 1796, when physician Edward Jenner successfully proved protective immunity against smallpox by using the common cowpox virus inoculation.

In the 1980s, the first vaccine based on specific portions of disease-causing agents became available — it was commonly known as the hepatitis B vaccine. This gave further impetus to the development of immunotherapy, which was now being looked on as a potential savior against many diseases, including cancer.

IMMUNOTHERAPY COMES OF AGE

Prior to the 1980s, in-depth research was already ongoing in the field of cancer immunotherapy. During the 1970s, an immuno-oncology professor, Loyd Old, predicted that immunotherapy would prove to be the fourth pillar of cancer treatment — the other three being chemotherapy, radiotherapy, and surgery.

With the accumulation of advanced knowledge about the immune system, immunotherapy has certainly come of age and can now be seen as an effective cancer treatment option. Its evolution has entailed many years of intensive research and carefully conducted clinical trials.

CANINE CANCERS AND IMMUNOTHERAPY

One in four dogs is likely to develop cancer, with the most common malignancies being:

• Melanoma
• Mast cell tumors
• Osteosarcoma (bone cancer)
• Lymphoma
• Soft-tissue sarcomas
• Hemangiosarcoma

While immunotherapy’s potential as an effective treatment for these canine cancers is promising, some road bumps need consideration. The canine immune system has not been studied as extensively as the human immune system, which means most of what we know about canine immunotherapy is derived from human studies. This makes it difficult to be sure how individual canine patients will respond to immunotherapy for different kinds of cancers.

A lot of research is being done, however, to make immunotherapy more precise and effective for canine cancers. Different dog breeds have variable genetic makeups, which means their innate responses to cancer will not be identical. And understanding how a certain body form reacts to an ailment is pivotal to comprehending the disease dynamics and developing efficacious treatments.

Currently, only a handful of immunotherapy options are available for canine cancer patients, and these products are not very well regulated. So you need to be aware of the authenticity and safety of commercially-available immunotherapy products. Your veterinarian can research and validate the efficacy and safety of these treatment choices.

WHICH CANINE CANCERS RESPOND BEST TO IMMUNOTHERAPY?

The immune system has the ability to detect abnormal cells, including many different kinds of cancers. The University of Wisconsin is using this knowledge to develop a universal vaccine against canine cancer. It targets about 30 proteins that are present on cancer cells as a result of mutations. This single vaccine can prime immune cells to counter a variety of cancers such as mast cell tumors, hemangiosarcoma, osteosarcoma, and lymphoma. This vaccine is still under clinical trial.

The nature of a cancer can also help decide an appropriate immunotherapy approach for successful remission.

• Hematological cancers can be treated with vaccines because the immunomodulatory agents can reach the site of the tumor and its cancerous cells.
• Solid cancers need a different approach because they create a microenvironment where blood flow gets distorted. Direct intra-tumor injections can prove to be a better option for these cancers. Autologous vaccines that constitute the patient’s own treated tumor cells have also shown promising results against solid cancers such as transitional cell carcinomas and anal sac adenocarcinomas.
• Studies on localized injections of natural killer cells have shown good results with locally advanced osteosarcoma.
• One study on checkpoint inhibitor drugs that stop cancer cells from deactivating the canine body’s immune cells shows this method can be effective treatment for oral melanoma.

It’s worth noting that immunotherapy can yield the best results when the cancer is already receding due to other therapies such as radiation and chemotherapy. So using immunotherapy as one of the pillars of the overall canine cancer treatment can yield better outcomes.

AVAILABLE CANINE CANCER IMMUNOTHERAPY OPTIONS

Most of the immunotherapy techniques mentioned above are still under development and not commercially available.

1. The first widely-used canine cancer vaccine was developed for second-stage melanoma. The recorded results indicate an almost 50-50 pattern; some dogs recovered, while others showed no positive effects. The canines with the best remission rates were those who received the vaccine as an additional treatment along with radiation and surgery.
2. Vaccines are not the only immunotherapies currently being used. The Penn Vet cancer center at the University of Pennsylvania has successfully used an approach that upgrades the immune system to produce an antibody that precisely targets the tumor. The center has also efficaciously used adoptive cell therapy, involving T cells, to treat leukemia. However, at this stage, dogs have to be enrolled in the center’s treatment programs to be able to benefit.
3. As mentioned earlier, only a handful of commercially-available immunotherapy products currently cater to canine cancer. Most are still under development and going through trial phases, but the day will come when more will be available. In the meantime, consult your veterinarian about the use of available immunotherapies if your dog has cancer.
4. Personalized adoptive cell therapy for canine osteosarcoma is available.
5. Immunity enhancer drugs to counter canine mammary cancer are also on the market.

Based on available clinical data, experts indicate that immunotherapy works best in conjunction with other cancer treatments. At the moment, there isn’t enough information to be sure the therapy will work in particular dogs of specific breeds. However, immunotherapy is certainly a good cancer treatment option, and research and clinical trials are underway to make it more refined and effective for canine patients.