Drug plasma monitoring in CML and GIST: A case-based discussion.

Drug plasma monitoring has emerged as an important tool to obtain optimal levels of a particular drug among individual patients. Plasma monitoring of imatinib levels would appear to be practical in cases where there is lack of response, heightened toxicity, or evidence of poor adherence to therapy. However, the potential role of monitoring plasma drug concentrations in guiding treatment decisions and optimizing patient therapy has yet to be established. Currently, there are no clinical recommendations regarding how to incorporate imatinib drug plasma monitoring in patients with either chronic myeloid leukemia or gastrointestinal stromal tumors, indications for which imatinib is approved. Here, the latest research and evidence regarding imatinib drug plasma monitoring is discussed. Three cases are presented to illustrate the most common examples where monitoring imatinib plasma concentrations may help to guide treatment decisions. These cases include a suboptimal response to imatinib treatment, lack of patient adherence to imatinib, and imatinib-related toxicity. By understanding the potential role of monitoring plasma imatinib concentrations in patients with chronic myeloid leukemia or gastrointestinal stromal tumors, physicians can identify patients who may benefit from drug plasma monitoring and consider incorporating the data in order to improve patient outcomes.