00613: The Prognostic Significance of Chromosome Aneuploidy in Canine Lymphoma
Grant Status: Closed
In the USA it is estimated than over 300,000 dogs each years are diagnosed with lymphoma. Despite improvements in veterinary medicine, the response to treatment for canine lymphoma continues to be highly variable, with no reliable means to predict duration of remission. In human lymphoma the presence of characteristic chromosome aberrations has been shown to have both diagnostic and prognostic significance. With previous funding from the AKC-CHF, the investigators identified a series of recurrent chromosome aberrations in canine lymphoma, some of which also correlate with different sub-types of lymphoma. In particular they identified that specific regions of the canine genome differ in copy number in lymphoma patients compared to healthy individuals. In a healthy individual all genes are present as two copies, while in cancer cells the number may vary from zero copies to numerous copies. The investigators proposed that copy number of select regions of the canine genome might be associated with response to therapy and thus correlate with duration of remission. For this study they used a population of archival tumor (lymph node) specimens from canine lymphoma patients that had been recruited as part of a clinical trial. The patient samples were of numerous breeds, both genders, from across the USA and had a wide range of ages. At the time of diagnosis, each patient has a lymph node biopsy taken that was fixed in formalin and embedded in paraffin blocks. These formed the archival sample population used for the present study. All patients were subsequently treated for their lymphoma with single agent doxorubicin and were clinically monitored during the course of their treatment and beyond. As part of the clinical follow-up the duration of first remission was noted. Cells of lymphoma patients were extracted from the FFPE specimens and prepared on glass slides. A series of DNA probes was developed to assess copy number of four select regions of the genome using multicolor fluorescence in situ hybridization (FISH). Using this process they determined the mean copy number of each of the four regions in each patient sample. Statistical analysis of the data reveled that the mean copy number of one of the four regions evaluated was significantly correlated with the duration of disease free interval in the study population. This region may thus be considered to have prognostic significance. By combining these data with data from a parallel project (funded by Morris Animal Foundation), they identified two regions of the canine genome that together provided the means to predict duration of first remission of lymphoma patients treated with single agent doxorubicin with 95% confidence. Over the past year, during a no cost extension, they have developed a cytogenetic test that allows for these two regions to be evaluated routinely. The merged data from both projects (CHF-613 and MAFDO5CA019) were used to support a patent application and the resulting test has been licensed to a large biomedical company to bring to market. In addition they have evaluated the efficacy of this test to be able to predict duration of remission in canine lymphoma patients that were subsequently treated with multi-agent (CHOP) chemotherapy. These data are pending but early indications suggest that the region identified as part of CHF-613 is also significant in such cases. In summary the outcome of this project is the development of the first cytogenetic test to predict treatment response in a canine cancer. The test should become widely available to the within the next year and will provide owners and veterinarians a new source of added data as they decide on the most appropriate treatment options for dogs diagnosed with lymphoma. This work will now move forward to investigate the genes within these two regions and determine their possible candidacy for new therapies.
Seiser, E. L., Thomas, R., Richards, K. L., Kathryn Kelley, M., Moore, P., Suter, S. E., & Breen, M. (2013). Reading between the lines: molecular characterization of five widely used canine lymphoid tumour cell lines. Veterinary and Comparative Oncology, 11(1), 30–50. https://doi.org/10.1111/j.1476-5829.2011.00299.x
Thomas, R., Seiser, E. L., Motsinger-Reif, A., Borst, L., Valli, V. E., Kelley, K., … Breen, M. (2011). Refining tumor-associated aneuploidy through ‘genomic recoding’ of recurrent DNA copy number aberrations in 150 canine non-Hodgkin lymphomas. Leukemia & Lymphoma, 52(7), 1321–1335. https://doi.org/10.3109/10428194.2011.559802
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