Leading Off: Veterinary clinical trials offer cancer patients more options

General practitioners may be hesitant to offer referral for the possibility of enrolling a pet with cancer into a clinical trial. While they may be aware of the possibilities, they do not wish for the owners to see their pets as experiments rather than cherished pets. However, clinical trials have several benefits and should be included in the discussion when talking to owners about treatment options for pets with cancer.

Kim A. Selting, DVM, MS, DACVIM

When general practitioners include this option, they are often viewed as practicing on the cutting edge of veterinary medicine. Owners feel that they have truly been given all the options and that nothing has been withheld or overlooked in their quest to consider all of their options for their pets. The reality is that once a pet is diagnosed with cancer, owners want options.

WHY CONSIDER A CLINICAL TRIAL?

Clinical trials can occur as dose-finding or pharmacodynamic studies or later-phase studies that compare a new treatment to the standard of care, if one exists. Trials involve treatments that have shown promise in preclinical studies. Benefits include availability of a promising treatment that would not otherwise be obtained, financial subsidy, treatment options when all others have failed, and the opportunity to contribute to the greater good.

This last point should not be undervalued. Many pet owners realize that the cancer may lead to the death of their pets, but they enjoy tremendous peace of mind knowing that their pets did not die in vain and that their participation in the trial will benefit dogs or cats in the future—and possibly people as well—in the fight against cancer.

Some veterinarians may avoid clinical trials. Referring cases elsewhere can lead to a loss of connection with the pet and owner. The learning curve to become acquainted with the details of trials may be daunting. Also, trials are typically either partially or fully subsidized, and the attraction of free cancer care may lure a pet owner away from standard therapy for which the veterinarian may have garnered income. Medically, this can be a concern for fear that owners will forego known effective therapy for an alternative of unknown benefit.

However, consider the fact that pets undergoing therapy will live longer and have more opportunities for extended care than those that are euthanized early in the course of disease. Many trials require some follow-up care at the referring clinic. The teamwork between the referring veterinarian and specialist has tremendous value to the pet owner. Also, when presented with all options, owners will ultimately choose what is right for them and their pets, and they may feel betrayed if they find a clinical trial that was not offered by their veterinarian.

HOW CAN I ENSURE MY PATIENTS ARE GOOD CANDIDATES?

Developing good habits can greatly facilitate offering clinical trials to pet owners. Many trials will exclude pets that have had certain treatments, and some require that a mass be measurable for enrollment. Examples include avoiding prednisone (unless medically necessary) until trials have been discussed for lymphoma and considering taking an incisional biopsy first (instead of removing everything possible at the time of biopsy) of solid tumors such as oral melanoma or sarcomas to confirm the diagnosis. Once a diagnosis is obtained, trials can be identified and further treatment can be planned properly. While imaging tests may be repeated at the clinical trials center, bloodwork often can determine basic eligibility and sometimes does not need to be repeated for trial enrollment.

HOW DO I FIND OUT ABOUT OPEN TRIALS?

While many veterinarians may have good intentions, it can be challenging to stay abreast of the current clinical trials. Each trial involves a novel and unfamiliar therapy, and it takes time to digest the ins and outs, the why and how, and the benefits and requirements of a trial. A central database for veterinary clinical trials has been developed at vetcancertrials.org, which is available and in the process of being populated. Through this site, pet owners, referring veterinarians or support staff, or others may search by species, tumor type, and location. If there are questions about the use or content of the site, please contact me at seltingk@missouri.edu.

In addition to this site, many academic centers maintain trial information on individual websites. The Comparative Oncology Trials Consortium initiates clinical trials intended to evaluate promising treatments for people with cancer first in dogs with spontaneous cancer. At a minimum, practitioners should contact the closest veterinary oncologist and academic institution to request a list of current trials on a regular basis, perhaps quarterly. Even if veterinarians are not abreast of clinical trial updates, resources can be provided for the owners to investigate details. These points and resources will help facilitate the discussion with pet owners when cancer is diagnosed.

Kim A. Selting, DVM, MS, DACVIM (oncology)

Department of Veterinary Medicine and Surgery

College of Veterinary Medicine

University of Missouri Columbia, MO 65211