Immunoassay Quantifies Cancer Cell Loss During Treatment

The quantification of cell loss in breast cancer during neoadjuvant treatment (NACT) can be assessed by serum thymidine kinase protein concentrations (sTK1). TK1 has a key function in DNA synthesis and repair responsible for maintaining the nucleoid pool balance by salvage and recycle thymidine from extracellular sources.

A new technology is based on patented methods to measure Thymidine Kinase 1 (TK1) protein levels in a blood sample. The TK 210 enzyme-linked immunosorbent assay (ELISA) test provides valuable information mainly about the condition of cancer patients. This may help clinicians to optimize treatment strategies and estimate the risk of recurrence of the tumor disease during the monitoring of the disease.


Scientists at AroCell AB (Uppsala, Sweden) quantified cell loss using the AroCell TK 210 ELISA kit to measure serum TK1 in serial samples from 145 breast cancer patients undergoing chemotherapy before surgery. Serum TK1 levels correlated to clinical/radiologically determined tumor response after cycles 2, 4 and 6, as well as pathologically determined response and disease-free survival.

The investigators found that base-line sTK1 increases considerably 48 hours after treatment to plateau levels, but declines during the three weeks rest between courses. The level of sTK1 measured after treatment arrest periods correlated, after four cycles of treatment, significantly with clinical/radiological response during treatment and pathologic response at surgery. Surprisingly, the 48 hour plateau values are highest in pT0 (no evidence of breast tumor), followed by pT3 (tumor >50 mm in greatest dimension), pT2 (tumor >20 mm, but ≤50 mm in greatest dimension) and lowest in pT1 (Tumor ≤ 20 mm in greatest dimension). Disease free survival (median follow-up 49 months) ranged between 29.7% in pT0 and 5.7% in pT1 and is significantly related to sTK1.

The authors concluded that in their study TK1 has been proven to be a significant predictor of treatment response in NACT, and sTK1 is a promising method for treatment related response and clinical drug development. Jan Stålemark, AroCell’s CEO, said, “Our product TK 210 ELISA was used in this study to investigate whether or not TK1 concentration can be a significant predictor of treatment response during chemotherapy of breast cancer. This is another study showing that serum TK1 measured with TK 210 ELISA is a promising biomarker for monitoring treatment response and possibly as a tool in clinical drug development. It gives a prompt signal on whether the new therapy works or not”. The study was presented on November 18, 2017, at the European Society for Medical Oncology 2017 Congress held in Singapore.

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