Breast Cancer Vaccine Shows Success for Treating Osteosarcoma in Dogs

When Sasha was diagnosed in March 2012 with osteosarcoma, a highly aggressive bone cancer, her owners were unsure if the 12-and-a-half-year-old American bulldog would be able to run, jump, swim, or catch frisbees. A year following her participation in a phase I clinical trial with a cancer vaccine, Sasha can still do what most dogs love to do—but with just three legs.

Nicola J. Mason, PhD, D.V.M., assistant professor of medicine and pathobiology at the University of Pennsylvania School of Medicine, has recently shown in a study funded by Advaxis Inc., a biotechnology company developing cancer immunotherapies, that a type of vaccine is effective in preventing osteosarcoma in dogs from coming back. This approach harnesses the power of the dog’s immune system, training it to “sniff out” and destroy cancer cells that remain after amputation and radiation or chemotherapy.

What’s unique about this vaccine is that it is a genetically modified vaccine that was originally created to target the Her2/neu gene, an antigen that is overexpressed in human breast cancer. Because this gene is similarly expressed in canine osteosarcoma, Mason identified the potential veterinary application and designed this trial to validate its usefulness in treating animals. She believes that the Advaxis immunotherapy is safe and effective in treating canine osteosarcoma, as most of the treated dogs in the study are living significantly longer than dogs that do not receive treatment.

Sasha was the first of six dogs that received the experimental vaccine so far. All dogs tolerated the vaccine well with no significant short or long-term side effects. To date, one dog that received a low dose of the vaccine has developed lung metastases. Four of the five canine patients, all of which enrolled in the clinical trial last year, including Sasha, are still tumor-free, with no complications.

While this isn’t the first time a vaccine has proven successful in treating animals with cancer, Merial’s ONCEPT vaccine has improved outcomes for melanoma in dogs. Jedd Wolchok, MD, PhD, associate director of CRI’s Scientific Advisory Council created and tested the vaccine, in collaboration with Phillip Bergman, D.V.M., in a CRI-funded study at the Animal Medical Center in New York City. It was approved in 2010, making it the first therapeutic cancer vaccine to be approved in either humans or animals.

Osteosarcoma can affect any breed, although it is more typical among middle to older-aged dogs and larger breeds. Any signs of bone cancer are subtle and can include swelling, lameness, joint or bone pain, and may occasionally exhibit a mass growth on their body around the site of the tumor. Current standard of care calls for limb amputation immediately after diagnosis, followed by chemotherapy and sometimes radiation to prevent the tumor cells from returning; unfortunately, sixty percent of dogs diagnosed with osteosarcoma die within 10 months. Therefore, this Advaxis study signifies a very exciting new approach to treating a disease in which patients for so long invariably faced a grim prognosis. As Mason continues to explore the merit of this immunotherapeutic approach in dogs, we are hopeful that this will not only improve the length and quality of our canine companions’ lives, but that this also could contribute to ongoing research efforts to treat people with immune-based medicines.

You can read Sasha’s blog or watch the CNN video to learn more about this exciting story.