A study at the Animal Cancer Center in the James L. Voss Veterinary Teaching Hospital is looking at a new way to treat cancer in animals and people. The study is investigating the impact of a drug on cells that suppress the immune system and allow growth. Initial results in mice and dogs show that the drug can reverse suppression of the immune system and halt tumor growth in dogs and, in some cases, even shrink tumors.
The class of drugs being evaluated, called bisphosphonates, has been used for years to diminish bone pain in bone cancer patients. The studies at the Animal Cancer Center are looking at bisphosphonate drugs in combination with liposomes to target cells that suppress the immune system around specific types of tumors.
“To date, nearly a dozen dogs have been treated in the study. The tumor response rate -- shrinkage of the tumor or suppression of growth -- has been very encouraging,” said Dr. Steve Dow, a researcher and veterinarian in the Animal Cancer Center. “We believe the results will provide important insights into a new way of fighting many different kinds of tumors.”
When the drugs are incorporated into liposomes, they target a population of white blood cells known as myeloid suppressor cells or MSC. When a person or animal develops cancer, the patient’s immune system may be suppressed by large numbers of MSC stimulated by the cancer. As tumors begin to grow, the number of MSC cells rises dramatically and the immune system becomes more suppressed. Liposome-incorporated bisphosphonates, called liposomal bisphosphonates, target myeloid suppressor cells in tumors and the bloodstream and spleen, reversing their crippling effects on the immune system.
Researchers are enrolling dogs that meet specific entry criteria into clinical studies designed to evaluate the safety and efficacy of a new drug delivery approach. For the current clinical studies, Dr. Dow is working with Drs. Scott Hafeman and Amanda Guth and Joe Sottnik in the Animal Cancer Center. The team is looking for dogs with soft tissue sarcomas and malignant histiocytosis to enroll in the clinical trial.
Dogs that meet certain criteria can be enrolled in the studies. The soft tissue sarcoma study pays $500 toward the cost of treatment, such as surgery, at the end of the study. The study consists of six treatments over seven to 13 weeks, depending upon the treatment option that is selected. Dogs enrolled in the MH study are eligible to receive the drug at no cost, though all other charges are supported by the owners. To discuss opportunities to enroll your dog in the study, contact Dr. Scott Hafeman at the Animal Cancer Center, 970-491-4535.
The MSC inhibitor studies are supported by the Morris Animal Foundation, the Canine Health Foundation and the National Institutes of Health.