Striving to end canine cancer with vaccinations

dvm360dvm360 October 2023
Volume 54
Issue 10
Pages: 41

A clinical trial study aims to prevent oncologic disease in dogs with a vaccine

Georgii /

Georgii /

Calviri, a research development company aimed at ending cancer with new diagnostic and therapeutic products, is also working on developing a preventive vaccine that can stop oncologic disease in canines before it starts. The company recently announced the beginning of the long development journey and clinical trial stages with dogs, but once a canine cancer vaccine is successfully created, the company aims to extend its research into human health. With the 5-year study currently in the last year, Calviri is already seeing several positive results, according to company officials.

The clinical trial

Calviri is currently studying 804 dogs from owners at 3 clinical sites: Colorado State University, College of Veterinary Medicine and Biomedical Sciences in Fort Collins; University of California, Davis, School of Veterinary Medicine; and University of Wisconsin–Madison, School of Veterinary Medicine. The study, Vaccine Against Canine Cancer Study (VACCS), is funded by a $6.4 million grant from the Open Philanthropy Project and Calviri, Inc.1

Stephen Albert Johnston, PhD, CEO of Calviri and principal investigator of VACCS, told dvm360 in an interview that vaccine development began as a challenge. He stated, “I'm an inventor and quite a few years ago, we decided to see if we could invent a vaccine to prevent cancer, partly as a challenge, because everybody said we couldn't do it. So, we thought it would be interesting to try. We showed that it was feasible, at least in mouse models, but we couldn't get anybody in the human oncology space to work with us to try and develop the vaccine. So, we turned to dogs and [veterinary] oncologists, and they were more than willing to work with us.”

After 15 years of preclinical work in mice, Calviri developed a vaccine for testing in dogs. One half of the canine participants were administered the vaccine, while the other half of the study pool received a placebo to act as the control group. To qualify for this study, dogs were between the ages of 5 and 11 years and were screened to detect any existing cases of cancer, to make sure all participants did not currently have any type of cancer disease.1 From there, the dogs were split randomly and given either the test vaccine or the placebo, blinded to owners and clinical sites. According to Johnston, both groups also got adjuvants.

“And then we simply brought the dogs in every 6 months and gave them a standard checkup to see any occurrence of tumors. And the endpoint of the trial, the primary endpoint, was to see if there were fewer tumors, malignant tumors, occurring in the vaccine group than the control group,” Johnston told dvm360. Johnston also explained that both groups got a booster vaccine after 1 year of the initial dose and each year following.

Impacting the future of veterinary medicine

With the trial still in progress, the VACCS data is still continuously being collected, however it has shown positive outlooks for veterinary medicine. Johnston stated that the vaccine is working. It’s not perfect, and the research team plans to improve the development of the vaccine even more, but overall, the vaccine is improving the dogs’ health. The vaccine is showing current signs of reducing the number of malignant tumors and reducing the deaths caused by these tumors. According to the data the control group had 85 tumor incidences, while the vaccine group had 30 after subtracting vaccine non-responding dogs.1 In terms of vaccine non-responding dogs, Johnston stated, “Only about 65% of the vaccinated dogs had a vaccine take, as measured by their immune response 6 months after vaccination. So, the dogs without an immune response were not counted in the totals for the vaccine group. Another way to look at this is that dogs with a good immune response were much less likely to have a tumor than those that were vaccinated and did not have an immune response. There were technical problems with the delivery system which we have now corrected so we should get a much better take rate.”

Johnston also added, “The vaccine also seems to be substantially reducing the non-tumor deaths. So, deaths from heart disease, arthritis, metabolic diseases, dementia, all of the deaths from those things seem to be being reduced. So that's another positive aspect of the of the trial and we should get more numbers on that effect.”

The challenges the study has faced thus far include only about 65% of the dogs got a good immune response to the vaccine and some tumors were missed. Johnston stated that with these challenges, the team will work on refining the vaccine.

Moving forward, the team is hoping to get a conditional license from the United States Department of Agriculture, and from there, get this product out to veterinarians across the country. They also aim to have no age restrictions on the vaccine.

For more information and updates on this study go to the Calviri website at 


Let’s end cancer. Calviri. Presented August 6, 2023. Accessed August 21, 2023.

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