Dogs With Non-Hodgkin's Lymphoma May Benefit From New Vaccine. Photo credit: Martin L.
The results of a pilot study of a vaccine designed to aid in treatment of non-Hodgkin’s lymphoma in dogs suggest that the vaccine may increase the length of time this deadly cancer remains in remission. In addition, based on this limited study, the vaccine seems to be well-tolerated by most dogs.
Further clinical trials will be needed as the number of dogs in the study was small, but the RNA-loaded CD40-B vaccine, when used in conjunction with chemotherapy, had a 40% durable (long term) second remission rate versus only 3% for dogs receiving chemotherapy alone. Given the similarity between non-Hodgkin’s lymphoma in dogs and humans, this vaccine/chemotherapy combination may also prove to be of value for people with non-Hodgkin’s lymphoma.
What is Canine Non-Hodgkin’s Lymphoma?
Lymphocytes protect the body from infection. Image courtesy of the National Cancer Institute
Canine non-Hodgkin’s lymphoma is a cancer originating within the lymphatic system, specifically the white blood cells called lymphocytes which normally protect the body from infection. These abnormal lymphocytes accumulate in the lymph nodes or other organs rather than circulating throughout the body to fight disease. Non-Hodgkin’s lymphoma is the most common form of lymphoma in people, ranking fifth as the cause of cancer deaths.
In dogs, the death rate is much higher. As a result, there is a great deal of interest in finding better ways to deal with this disease. Other researchers are looking at genetic aspects of the disease and the use of NBD peptide to inhibit tumor progression.
Present Standard Treatment for Non-Hodgkin’s Lymphoma in Dogs
The standard treatment for Non-Hodgkin’s lymphoma has been chemotherapy, generally using multiple drugs, but dogs treated with combination chemotherapy rarely remain in remission for more than a year. Once a dog starts showing clinical signs of cancer again, a second round of chemotherapy may be given, using different drugs to counteract the resistance that the cancer cells often develop to the first medications. The second round of chemotherapy, termed salvage therapy, generally results in remission of a much shorter duration, often only half as long as the initial remission.
How the RNA-loaded CD40-B Vaccine Helps in Treatment of Non–Hodgkin’s Lymphoma
The RNA-loaded CD40-B vaccine, developed from canine B cells (lymphocytes which produce antibodies) and tumor RNA, stimulates the immune system and, because it has some of the RNA of the cancer in it, helps the body to recognize the cells which need to be destroyed. By first treating the cancer with standard chemotherapeutic drugs, the tumor mass is decreased. The vaccine is given when the dogs are in remission and the immunosuppressive impact of the chemotherapy is reduced, allowing the immune system to function more effectively.
Vaccine Shows Promise for Dogs With Non-Hodgkin's Lymphoma. Photo Credit:Jason McELweenie
RNA-loaded CD40–Activated B Cell Cancer Vaccine May Improve Remission Rates
At this stage, the vaccine appears to be effective in improving the chance of a durable (long term) second remission. In the control group, which did not receive the vaccine, only 3% of the dogs who received salvage therapy achieved durable second remission as compared to the vaccinated dogs where 40% achieved durable second remission.
The number of dogs in the study, conducted by Dr. Karin Sorenmo, et al. of the University of Pennsylvania’s School of Veterinary Medicine was small, so further clinical research will be necessary to better understand how chemotherapy and the RNA-loaded CD40-B vaccine work synergistically to improve remission rates and to ensure that the results achieved in this study are transferrable to a larger population.According to Dr. Soremno, the next phase of clinical trials has not yet begun. The preliminary study does, however, suggest that the addition of the RNA-loaded CD40-B vaccine to the treatment protocol for dogs in remission from non-Hodgkin’s lymphoma may result in longer remission for some dogs.
Sources:
Sorenmo KU, Krick E, Coughlin CM, Overley B, Gregor TP, et al. (2011) CD40-Activated B Cell Cancer Vaccine Improves Second Clinical Remission and Survival in Privately Owned Dogs with Non-Hodgkin’s Lymphoma. PLoS ONE 6(8): e24167. doi:10.1371/journal.pone.0024167. accessed online 10.20.11
Mayo Clinic. 2011. Non-Hodgkin’s Lymphoma. http://www.mayoclinic.com/health/non-hodgkins-lymphoma/DS00350 Accessed online 10.20.11
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