Predictive value of topoisomerase IIα immunoreactivity in canine diffuse large B-cell lymphoma (DLBCL) and peripheral T-cell lymphoma (PTCL) treated with a doxorubicin-based chemotherapy protocol

Topoisomerase II alpha (TOPII alpha) plays a key role in DNA replication and is a molecular target for TOPII alpha inhibitor chemotherapy. A doxorubicin-based chemotherapy remains the most effective treatment for canine lymphoma, but there are no clear indications for its use in individual patients. The aim of this study was to assess the predictive value of TOPII alpha expression in the treatment of canine lymphomas with TOPII alpha inhibitors. Samples of formalin-fixed paraffin-embedded lymph nodes from 14 dogs with diffuse large B-cell lymphoma (DLBCL) and 5 dogs with peripheral T-cell lymphoma (PTCL) treated with a CHOP protocol were immunohistochemically labelled with anti-TOPII alpha. Progression-free survival time (PFS) and overall survival time (OS) were estimated and compared with TOPII alpha expression. Dogs with DLBCL had a higher level of TOPII alpha expression compared to dogs with PTCL. The median PFS for dogs with DLBCL was significantly longer (260 days) than it was for dogs with PTCL (60 days). In DLBCL dogs with a high TOPII alpha expression level, the median PFS was significantly longer (310 days) then it was in dogs with week or medium TOPII alpha expression (51 days). The results of the study indicate that the imm unohistochemical assessment of TOPII alpha expression may be a valuable predictive indicator for anth racycline-based treatment of dogs with malignant lymphoma.