Abstract 2618: The thymidine kinase 1 (TK1) protein concentration in sera from Hodgkin lymphoma patients: A marker for cell death and disruption of malignant cells

Abstract

TK activity measurements have been used for many years to monitor cancer disease activity. However, what the blood concentrations of TK1 protein reflect is still uncertain. A TK1 immunoassay, the AroCell TK 210 ELISA, has been developed based on specific monoclonal antibodies against the C-terminal region of TK1. We utilized this assay to monitor the blood concentrations of TK1 in a cohort of patients with Hodgkin lymphoma (HL) before and after conventional treatment. TK1 concentrations in serum or plasma were measured using the AroCell TK 210 ELISA. For comparison, a large number of other biomarkers and cells were measured in blood such as C-reactive protein (CRP), Lactate dehydrogenase (LDH), hemoglobin, WBC, platelet counts, erythrocyte sedimentation rates (ESR), albumin, liver enzymes, creatinine. Fifty-eight patients with HL were included before start of treatment. Seventy three percent had the nodular sclerosis subtype and 52% stages I-II and 48% stages III-IV disease. Blood was sampled before treatment, during treatment and twice after completion of treatment. The upper normal TK1 concentration of healthy subjects (n=250) was 0.45 μg/L with a median of 0.25 μg/L (range 0.15-0.66 μg/L) as compared to HL, which was 0.26 μg/L (range 0.03-17 μg/L). The differences in ranges were significant (p<0.0001, F-statistics). Nodular sclerosis patients had higher TK1 levels as compared to the other subtypes (p=0.03). TK1 increased after treatment (p=0.001) in patients with normal concentrations from start i.e. <0.45 μg/L, whereas the concentrations decreased in 5/6 patients with TK1 >0.45 μg/L. TK1 concentrations before start of treatment was correlated to high CRP (p=0.01), low Hemoglobin (p=0.03), high WBC (p<0.001) and high platelet counts (p<0.01), but not to albumin or ESR or any other of the measured biomarkers. In a multivariate regression analysis, TK1 was correlated to LDH as the only independent variable (p<0.0001). In Hodgkin lymphoma patients, serum or plasma concentrations of TK1 may reflect malignant cell death and cell disruption rather than cell proliferation during treatment. Our results and hypothesis may help to interpret TK1 protein measurements as clinical tools in cancer management. Citation Format: Jagarlamudi Kiran Kumar, Staffan Eriksson, Johan Mattsson Ulfstedt, Per Venge, Daniel Molin. The thymidine kinase 1 (TK1) protein concentration in sera from Hodgkin lymphoma patients: A marker for cell death and disruption of malignant cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 2618.