Veterinarians at the University of Missouri’s College of Veterinary Medicine in the USA have worked with a medical technology company to implement a trial for a new cancer treatment in dogs. The treatment involves immunotherapy (helping the patient’s own immune system to recognise and kill tumour cells) and appears to offer a chemotherapy-free treatment option for osteosarcoma, a common bone tumour of dogs.
What is osteosarcoma?
Osteosarcoma is the most common type of bone cancer in dogs. It is mostly seen in middle-aged to older, large to giant breed dogs, such as rottweilers, dobermans, saint bernards, german shepherds and great danes. Bones affected by osteosarcoma are often swollen, and are generally very painful, causing dogs to limp. The cancer can also weaken affected bones, leading to a risk of sudden bone breakage with activities that would generally be harmless, such as jumping off a step or out of the car.
Osteosarcoma is a malignant tumour, meaning that it is a type of cancer that is very likely to aggressively spread around the body, usually to the lungs.
How is osteosarcoma currently treated?
Treatment options for osteosarcoma most frequently involve one of several options:
- Palliative care - This involves keeping affected dogs comfortable with pain relief and special care, and then if their condition deteriorates, and they become too unwell or painful, euthanasia is considered.
- Amputation (surgical removal) of the affected bones or limb - This usually provides ~4 months of extra survival time, as in most cases, the cancer will have already spread to the lungs.
- Amputation plus chemotherapy - This involves amputation and then administration of chemotherapy (a schedule of drugs to poison the tumour cells). This allows an average survival time of just over a year, although the drugs can cause potential side effects such as gastrointestinal upset, heart damage, and weakening of the immune system. It also may require owners to wear protective gloves for the handling of their dog’s urine and faeces for five days after chemotherapy drug administration.
What does immunotherapy treatment of osteosarcoma involve?
Dogs in the osteosarcoma immunotherapy trial still required amputation of their affected bones/limbs to remove the bulk of the cancer. Tumour cells were then collected to create a “vaccine” specific to that patient - when administered, this vaccine helped the dog’s immune system learn to recognise the remaining cancer cells in their body (e.g. in their lungs or bloodstream), and produce targeted white blood cells to destroy them. Researchers assisted this process by collecting these special white blood cells from the dogs, multiplying them, and then infusing them back into the dog’s bloodstream in higher numbers for greater effect.
Is immunotherapy effective for osteosarcoma?
Of the ten dogs in the immunotherapy treatment trial, the average survival rate was 415 days (which is comparable to chemotherapy survival times), and five dogs survived for more than two years!
A larger, follow-up trial is being conducted based on these promising results so far, and the usage of this technology for other types of animal cancers will likely follow. Additionally, this important veterinary research may also transfer to the human medical field, with plans for its usage in an upcoming treatment trial for glioblastoma (an aggressive form of brain cancer).