01344-A: Comparison of percentage of T regulatory cells in dogs with spontaneously occurring lymphoma following oral versus intravenous cyclophosphamide

Grant Amount: $11,362.57

Kimberly A. Selting, DVM; University of Missouri, Columbia

June 1, 2009 - May 31, 2011

Sponsor(s): Nova Scotia Duck Tolling Retriever Club (USA)

Breed(s): -All Dogs

Research Program Area: Oncology - Lymphoma

Project Summary

Lymphoma, a cancer of the lymph nodes, is among the most common cancers seen in dogs. Although highly responsive to chemotherapy, almost all dogs ultimately relapse and die of this disease. A subset of immune cells called T regulatory cells (Tregs) determines what cells belong in your body. Tregs can prevent other immune cells from attacking cancer in the body, and are therefore thought to be detrimental to the body's ability to fight off cancer. They have not been evaluated in dogs with lymphoma. Additionally, some drugs that treat lymphoma, such as cyclophosphamide, can decrease Tregs. We attempted to characterize the population of Tregs in dogs with lymphoma before they are treated, and then after they receive cyclophosphamide. We also planned to compare injected to oral cyclophosphamide. By considering the effects on Tregs, the side effects and the efficacy, we had hoped to be able to recommend the best way to use this drug, and to better understand Tregs in lymphoma so that future studies could focus on incorporating this knowledge to our advantage when we treat dogs. We partnered with Comparative Internal Medicine Laboratory at the University of Missouri and arranged to use the flow cytometer in the Cell and Immunology Core at MU to approach this clinical question. We recruited dogs with lymphoma from our hospital population and measured Tregs as discussed above. Based upon statistical evaluation, we anticipated the need to recruit 40 dogs (20 each with oral vs. intravenous cyclophosphamide). Unfortunately we encountered a series of obstacles that precluded the successful completion of this project. Foremost, the recruitment was slow enough that the resident in charge of the project completed her program and left before many dogs were enrolled. This meant that the cost of processing samples increased dramatically. In an effort to recruit dogs more rapidly, some money was reallocated to increase the incentive in addition to our contribution of internal funds in an attempt to properly complete this trial. This was a minimally funded trial as most of the money from the grant was used for the cost of flow cytometry to identify the Tregs. Therefore pet owners were often not motivated to return at the needed time intervals. When we had accrued 8 cases, we evaluated the preliminary data and found that the results were variable enough that more than 40 cases would likely be needed to adequately satisfy our objectives. Around that time, a fully funded competing trial was opened and there was no further interest by pet owners in enrolling in this trial. The trial was then closed and unused money returned to the sponsor. Our group of 8 dogs will be used as pilot data to help secure funding in the future so in that sense, this grant served the purpose of an ACORN to provide preliminary data. We did see a decrease in absolute Treg percent and in percent of circulating lymphocytes that were Tregs. This would suggest that we are on the right track. We just need to formulate a larger trial to fully satisfy the original aims.

Publication(s)

None at this time.