Lymphoma and Lymphoma Vaccine in Dogs
Lymphoma, one of the most common neoplasms in the dog, can arise in any tissue in the body but tends to appear in lymphoid tissues, such as lymph nodes, spleen and bone marrow. It primarily occurs in middle-aged dogs (6-9 years of age). Lymphoma is classified by where it is located, the histologic criteria, and the immunophenotypic characteristics of the lymphocytes, of which the two most common phenotypes are B-cell and T-cell, with 75-80% of those reported as B-cell. These classifications are important in determining prognosis and treatment options. The oncologist will explain all of this at your oncology consultation.
Prognosis depends on many different factors. Untreated lymphoma typically progresses rapidly, going from presentation to terminal stages within 1 to 2 months. Lymphoma is rarely curable (less than 10% of cases), however considerable improvement in duration and quality of life can be seen in dogs treated with chemotherapy. A common chemotherapeutic protocol for treating canine B-cell lymphoma, CHOP or modified CHOP, typically results in an 80-90% remission rate with a median survival time of 12 months. However, only approximately 25% of dogs that respond to this protocol will be long-term survivors (>2 years). Therefore, a majority of dogs require repeated chemotherapeutic intervention, with highly variable response rates to maintain remission state.
The development of an exogenous antibody vaccine that targets native surface antigens on B-cells has sparked a revolution in the treatment of B-cell lymphoma in humans. The antibody is directed against an antigen found on the surface of B cells, and has been shown to be an excellent target for passive immunotherapy. Thus, a vaccine to induce antibodies that target the same antigen has been produced for canine patients. DNA cancer vaccines offer a safe adjunct to existing therapies with the potential to induce longer term remissions.
Canine Lymphoma Vaccine, DNA, is indicated for the therapeutic immunization of dogs diagnosed with Large B-cell Lymphoma upon achieving remission through chemotherapy. The challenge with many cancers is that the host does not recognize the neoplastic cells as “foreign”, so the immune system is not elicited to defend the body against the neoplastic cells. Upon vaccination with the lymphoma vaccine, the antigen is taken up by the host cells and is then transcribed in the host and actively presented to the immune system. The immune system recognizes the form as foreign and procedures an immune response thus leading to destruction of the neoplastic B-cells. Studies of the vaccine have shown significantly improved survival times (>734 days) over dogs treated with chemotherapy alone (approximately one year).
Initial treatment with the canine lymphoma vaccine is four doses of vaccine at two-week intervals, followed by a booster dose at six-month intervals.