A U.S. study, performed by Dr. Cynthia Ma, Associate Professor of Medicine at Washington University School of Medicine, investigated 50 women with clinical stage II or III estrogen receptor positive HER2 negative breast cancer treated with anastrozole in combination with palbociclib prior to surgery.
DiviTum was used to measure levels of thymidine kinase (TK) activity, an enzyme closely linked to cell proliferation rate, in blood samples collected before and after treatment. Results demonstrate a highly significant correlation between the anti-proliferative effect of palbociclib and the reduction in TK levels measured by DiviTum after two weeks of adding palbociclib and at the time of surgery. The assay may serve as an early indicator of treatment response by CDK 4/6 inhibitors like palbociclib.
Breast cancer is the most common form of cancer among women today, affecting approximately 362,000 individuals in Europe and 233,000 in the U.S. each year. Around 1,600 new cases are diagnosed every day and 136,000 deaths occur annually in Europe and the U.S.
Palbociclib was FDA-approved in Feb. 2015. In the drug’s first year on the U.S. market, more than 20,000 women were prescribed the medicine, whose sales are estimated to exceed $2B in 2016. In Nov. 2016, palbociclib was approved in Europe.