Prospective evaluation of flow cytometric characteristics, histopathologic diagnosis and clinical outcome in dogs with naïve B‐cell lymphoma treated with a 19‐week CHOP protocol

Abstract

Canine B‐cell lymphoma is a clinically heterogenous disease; however, it is generally treated as a single disease entity. The purpose of this clinical trial was to prospectively evaluate naïve canine B‐cell lymphoma patients using histopathology, flow cytometry (FC) and a standardized chemotherapy protocol to better define subsets of this disease that may respond differently to treatment. Sixty‐four dogs with naïve multicentric B‐cell lymphoma were treated with a standardized 19‐week CHOP (cyclophosphamide, doxorubicin, vincristine, and prednisone) chemotherapy protocol. Most of the dogs (84.3%) were diagnosed with diffuse large B‐cell lymphoma (DLBCL), followed by nodal marginal zone (7.8%), small B‐cell (4.7%), Burkitt‐like (1.6%) and follicular lymphoma (1.6%). FC confirmed the diagnosis of B‐cell lymphoma in all cases. There were no clear phenotyping differences between the subtypes of B‐cell lymphoma detectable by our FC panel. The histologic subtypes in this study exhibited a range of forward scatter values on flow cytometry, but all of the DLBCL cases were higher than a value of 469, while the only cases with a lower forward scatter value were follicular lymphoma and diffuse small B‐cell lymphoma. Dogs with DLBCL had a significantly better objective response rate to the CHOP protocol (96.3%) than the non‐DLBCL subtypes (70%, P = .024). The median progression‐free survival time for patients with DLBCL (233 days) was significantly longer than that of all other histopathologic subgroups combined (163 days, P = .0005).

Clinical outcome and prognostic factors in dogs with B‐cell chronic lymphocytic leukemia: A retrospective study

“…Those BCLL cases presenting with clinical signs had significantly shorter survival, which is an important prognostic factor in other types of lymphoma in dogs. 29,30 20 Age was not prognostic in our study as it was in a prior study. 3 Most cases in our study were middle-aged to older (only 7/121 [6%] were <6 years old), and perhaps too few young cases were available to detect a difference in survival.…”

Flow Cytometry in the Diagnosis of Canine B-Cell Lymphoma

“…Other non-specific markers for B-cells may be added to FC panels to discriminate their activation or maturation status. Among these, the pan-leukocytic markers CD45 and CD18 are generally expressed with lower intensity in B-cells than in other leukocytes (7). CD25 is generally expressed by activated B-cells and MHC II is expressed by mature B-cells.…”

The Genetic and Molecular Basis for Canine Models of Human Leukemia and Lymphoma

“…cDLBCL affects dogs over a wide range of ages, with the median age of 7-9 years (10,30,31). It is not clear if there is a breed-specific predilection for this disease, but several studies of histologically confirmed cDLBCL indicate Golden retrievers, Labrador retrievers, Bernese mountain dogs and German shepherds are commonly affected breeds (10,30,31). Dogs are typically treated with CHOP, with overall survival times varying between studies, from 300 to 500 days (31)(32)(33).…”

“…It is not clear if there is a breed-specific predilection for this disease, but several studies of histologically confirmed cDLBCL indicate Golden retrievers, Labrador retrievers, Bernese mountain dogs and German shepherds are commonly affected breeds (10,30,31). Dogs are typically treated with CHOP, with overall survival times varying between studies, from 300 to 500 days (31)(32)(33). Although a number of clinical trials of anti-CD20 therapy in dogs with B cell lymphoma are in progress, to date clinically efficacious antibody therapy is not available for dogs with BCL.…”