Colorado State’s Animal Cancer Center Investigates Promising Drug Combination to Treat Bone Cancer

The Colorado State University Animal Cancer Center is studying a promising combination of a new and an old cancer drug that may increase chemotherapy effectiveness without increasing unwanted side effects. The study may eventually be useful for the treatment of both human and animal cancer.

The center, which is seeking pet owners with dogs diagnosed with bone cancer to participate in the study, is combining a common chemotherapy drug, called doxorubicin or Adriamycin, with valproic acid, also called Depakote, a drug that previously has been used to treat seizures in dogs and humans. An enzyme called histone deacetylase, which may reduce the sensitivity of cancer cells to chemotherapy, can be inhibited with valproic acid.

"By combining these drugs, we think we may make chemotherapy more effective. We think they are stronger together," said Dr. Douglas Thamm, professor and researcher at the Animal Cancer Center. "Both of these drugs are available in generic forms and are widely available, making them affordable to humans and dogs. Our current study will help identify the optimal dose of valproic acid for use in dogs, and we hope it will lead to providing these drugs as a viable, affordable option for pets and humans facing bone cancer treatment choices."

Dogs in the study will receive valproic acid for several days before receiving a standard dose of doxorubicin. Veterinarians will be looking for common side effects of the drug such as liver issues and sleepiness to help identify the right combination. They’ll also look at the impacts of the drug on the histone deacetylase enzyme and the effects of the drug combination on the size and spread of tumors.

Valproic acid has been shown in previous tests to "open up" the DNA of cancer cells by inhibiting the histone deacetylase enzyme. The drug may change the actual structure of the cancer cell’s DNA, allowing chemotherapy drugs like doxorubicin to cause more damage.

While this combination of drugs has shown much promise in the laboratory, it’s sometimes difficult to get drug combinations into human trials without years of additional research, Thamm said. "This study will allow us to help dogs with cancer and provide information that may be helpful in future human trials. Both of these drugs have been approved by the Food and Drug Administration for use in humans for many years, but we hope our research into their use in combination will help develop the information needed for the drugs to be considered as a treatment together."

People interested in getting their dog involved in the drug trial should contact the Animal Cancer Center at (970) 297-4195. Dogs much undergo testing prior to the study to ensure that they are eligible and must meet certain other requirements. All treatments must be performed at Colorado State.