It has been proposed that serum TK1 levels (i) may indicate patients’ response to therapy, (ii) may serve as a prognostic indicator and (iii) may reflect the aggressiveness of leukemic cells.6 The mechanism of how TK1 enters the bloodstream is not yet fully understood; nevertheless, experimental evidence suggests that screening serum for elevated TK1 levels may prove to be a simple and effective means of detecting and monitoring malignant disease. The level of serum TK1 in patients with several types of cancer has been shown to correlate with the stage of the disease and repeated measurements also reflect relapses and remissions.
TK1 has also been shown to be of prognostic value in many solid tumors, including breast cancer, prostate cancer, bladder carcinoma and small-cell carcinoma of the lung.3,6 Serum TK1 levels correlate strongly with cancer stage and its aggressiveness. In this communication, we report that measuring the serum TK1 levels of ALL and AML patients would provide a method for monitoring patient response to treatment in acute leukemic diseases and potentially other non-solid tumors.
This study consists of several phases. In brief, we first compared the serum TK1 levels of ALL patients with non-cancer patients. Second, sera from the ALL patients were grouped according to clinical status (pre-treatment, relapse, remission) and analyzed against non-cancer controls. Finally, TK1 levels in sera from individual patients both ALL and AML were sequentially followed for over a year. In the initial study, TK1 levels were measured in serum samples from ALL patients (19 females/14 males) and healthy individuals (35 males/14 females; Figure 1). Sera samples from both sample groups were measured using a radioassay as well as an immunoassay employing a TK1-specific monoclonal antibody (mAb) developed in our laboratory.