Posted November 14, 2013
In Fall 2012 the CWCCA donated $2500 from our AKC CHF account to help fund a study regarding Canine Lymphoma. During the course of the grant period, AKC CHF reports progress to supporting organizations. Below is the latest report.
Grant 01787: Clinical advancement of RNA-transfected CD40-B cell vaccine technology for cancer therapy
Original Project Description:
Canine lymphoma is the most common hematopoeitic cancer in dogs with an estimated annual incidence of 30/100,000. Chemotherapy induces remission in 75-85% of patients; however, the majority relapse with drug-resistant lymphoma within 8-10 months of diagnosis and most dogs die of their disease shortly thereafter. Cell-based vaccine strategies that stimulate anti-tumor immunity have shown promise in the treatment of many different cancer types including non- Hodgkin’s lymphoma (NHL) in humans. We have used a cell-based vaccine to induce antitumor immunity in dogs with NHL. This vaccine given three times after successful induction chemotherapy significantly prolonged overall survival. However, in the majority of dogs the vaccine did not prevent relapse but significantly prolonged second remission duration induced by rescue chemotherapy when compared to unvaccinated controls. These findings suggest that the lymphoma vaccine stimulated anti-tumor immunity but that this was insufficient to prevent relapse and only upon immunological boosting (through a poorly defined but previously recognized chemotherapy effect) could prolonged cancer free survival be realized. Here we aim to optimize our cell-based vaccine approach to induce functional, long lasting tumor-specific immune responses that aim to prevent relapse and prolong survival in dogs with NHL. This cellular vaccine will be generated in the presence of a potent immune stimulant and will be given every 2 months to dogs with NHL. The effects on tumor specific immunity will be evaluated.
The goal is to optimize our vaccine/protocol to stimulate more effective anti-tumor immunity that will prevent relapse and prolong overall survival in dogs with NHL.
Report to Grant Sponsor from Investigator:
The goal of this proposal is to build on our previous work developing a cell-based vaccine that aims to stimulate potent tumor specific immune responses that will kill lymphoma cancer cells. Our previous work has shown that white blood cells known as B cells found in the peripheral blood can be activated and grown outside of the body using special “feeder cells” that express an important molecule known as CD40L. The stimulated B cells (known as CD40-B cells) can be loaded with genetic material (RNA) that has been extracted from the patient’s tumor. When re-injected back into the patient, the CD40-B cells are able to present the tumor material to the body’s immune system and stimulate an anti-tumor immune response. We have shown in a phase I clinical trial that this approach has produce promising results with respect to prolonging overall survival in dogs with lymphoma. We now aim to improve on this vaccine in two main areas; 1) we aim to improve the ease of vaccine production since our current methods are time consuming and require specialized laboratory equipment. This will enable us and other researchers with access to basic laboratory equipment to generate this vaccine and treat more patients, 2) we aim to improve the vaccine’s ability to stimulate anti-tumor immunity.
Our current methods of generating the vaccine from lymphoma patients are labor-intensive and require specialized laboratory equipment that is not available in most facilities. Therefore, we are evaluating second-generation feeder cells that stably express CD40L (either the human or canine CD40L) as well as non cell-based techniques for canine B cell culture. Success in either of these areas will improve on our current process and ideally will enable vaccine production to occur in any basic laboratory without the need for expensive equipment.
We are also testing the hypothesis that the vaccine’s ability to stimulate anti-tumor immunity could be improved by altering the culture conditions used to generate the canine B cells (ie. the vaccine), through the use of a potent immune adjuvant (CpG DNA). In the first 6 months of this work, we have made progress towards these goals. Our progress to date is summarized in the following bullet points:
- We have employed more stable, second generation “feeder” cells that express human CD40L (KTCD40L) and have shown that these cells can activate canine B cells and cause them to proliferate in the same way as our first generation feeder cells. However, these second generation feeder cells are easier to grow and maintain in culture since they do not require antibiotic selection and are less sensitive to alterations in culture media acidity.
- We are in the final stages of generating a different stable “feeder” cell that expresses the canine form of CD40L, rather than our current human CD40L system, and in the next 6 months we will test the hypothesis that these canine CD40L expressing cells are superior to human CD40L expressing cells in generating canine B cells for cancer vaccines.
- We have initiated experiments to evaluate a soluble form of CD40L that may be able to replace the requirement to use feeder cells for B cell culture altogether. If successful this would eliminate the need for a gamma irradiator (these are not readily available to many institutions and clinics) and for regular technical maintenance of feeder cell cultures.
- We have begun experiments to evaluate the effects of bacterial DNA, known as CpG, to our CD40L stimulated B cell cultures and our preliminary results suggest that CpG promotes the production of greater number of B cells and induces greater expression of B cell surface molecules that are necessary to stimulate anti-tumor immunity. These early results suggest that the addition of CpG to our B cell cultures may improve vaccine production and efficacy.
Together, this optimization work will direct the protocol we will use for a second generation B cell vaccine that will be utilized in our next CD40-B cell clinical trial. We aim to start recruitment for this trial in the Fall of 2013.