A new study conducted in the US demonstrated ability of Swedish biotech company Biovica’s DiviTum biomarker assay in testing efficacy of breast cancer drug palbociclib (Ibrance).
DiviTum measures the activity of the enzyme thymidine kinase (TK) in serum or cell cultures which otherwise is hardly detectable, but in proliferating cells, it increases more than 20-fold in late G1/S-phase.
The TK is hugely dependent on an active cell cycle which consequently makes it a suitable biomarker for cell proliferation.
Its expression in serum or cell cultures is highly associated with cell proliferation and tumour aggressiveness.
In the biomarker assay, thymidine is replaced by bromodeoxyuridine (BrdU), which is accepted by TK as an analogous substrate.
The TK activity determines the amount of BrdU built into a DNA strand which is then detected using an ELISA technique.
The DiviTum technology operates by amplifying the signal thereby enabling the assay to determine TK activity with high-sensitivity.
The study conducted by Washington University School of Medicine, St Louis, US used the DiviTum assay to measure TK activity in blood samples collected before and after treatment from 50 women with clinical stage II or III estrogen receptor positive, HER2 negative breast cancer who were treated with anastrozole in combination with palbociclib before surgery.
DiviTum assisted in suggesting the anti-proliferative effect of palbociclib which thereby validated the assay as an early indicator of treatment response by CDK 4/6 inhibitors.
Biovica CEO Anders Rylander said: “These first results correlating DiviTum to palbociclib efficacy are highly promising since there are no other biomarkers available for CDK 4/6 inhibitors today.
“We aim to provide DiviTum as a tool for clinicians to optimise the survival and quality-of-life benefits gained by patients treated with this new class of drugs.”