Introduction

Diffuse large B-cell lymphoma (DLBCL) is frequently treated with CHOP-based chemotherapy, which induces remission in 80–95% of cases. However, not all dogs derive meaningful benefit from CHOP and prognostic factors for dogs with DLBCL are poorly defined. Serum thymidine kinase 1 (TK1) activity, a marker of tumor cell proliferation, has shown promising initial results as a prognostic biomarker in dogs with multicentric lymphomas. The purpose of this study was to determine if baseline serum TK1 activity is associated with clinical outcome in dogs with CHOP-treated DLBCL.

Methods

Baseline serum TK1 activity was measured in banked sera from 100 dogs with CHOP-treated DLBCL using a commercially available ELISA kit. Data on other potential prognostic factors were obtained retrospectively from electronic medical records. Multivariable statistical methods were used to find associations between potential prognostic factors and progression-free survival (PFS) and attainment of complete remission.

Results

TK1 activity at baseline was not associated with reduced PFS (P=0.299) or attainment of complete remission (P=0.910) following CHOP chemotherapy. Of the other prognostic factors analyzed, only purebred (vs. mixed breed) status (HR 8.81, 95% CI 1.68–46.30, P=0.010), attainment of complete (vs. partial) remission (HR 0.09, 95% CI 0.02–0.49, P=0.006), and baseline serum C-reactive protein concentration (HR 1.19, 95% CI 1.07–1.32, P=0.001) were independently associated with PFS.

Conclusion

Based on these findings, baseline serum TK1 activity does not appear to be a useful prognostic biomarker in dogs with CHOP-treated DLBCL.

Funding Information

Veterinary Cancer Society—Gordon Theilen Resident Research Grant.