Assessing a patient's levels of P-glycoprotein soon after they start receiving Glivec therapy will help to predict their long-term response to the leukaemia drug, according to new research from South Australia (Eadie LN, Dang P, Saunders VA et al. The clinical significance of ABCB1 overexpression in predicting outcome of CML patients undergoing first-line imatinib treatment. Leukemia 2016 Jun 24 [Epub ahead of print]).
Researchers from the South Australian Health and Medical Research Institute (SAHMRI) and the University of Adelaide found that having multiple polymerase chain reaction (PCR) tests allowed them to calculate an increase in P-glycoproteins, which are drug-resistant proteins that pump biological treatments such as imatinib (Glivec) out of leukaemia cells.
Lead author Dr Laura Eadie (pictured) said they found the greater the increase in P-glycoprotein in patients, the greater the risk of them becoming resistant and not responding to the leukaemia drug. “Our new test is looking at expression levels and how much P-glycoprotein is present at diagnosis, and then again three weeks later. Then we compared the difference between them at those two points in time. Previously people have either just looked at one time point – at diagnosis or at 12 months after they began therapy.”
Everyone has P-glycoprotein in their cells but Dr Eadie’s research found that the levels increase in response to the leukaemia drugs that patients are taking. About 20% of patients had a poor response to Glivec, which reduces their chances of survival.
Dr Eadie said she hopes this new test would allow doctors around the world to change treatment strategies for patients with chronic myeloid leukaemia (CML) at high risk of developing a resistance to Glivec.