Henry H, Sobhi HR, Scheibner O, Bromirski M, Nimkar SB, Rochat B. "Rapid Commun Mass Spectrom. 2012 Mar"
The capabilities of a high-resolution (HR), accurate mass spectrometer (Exactive-MS) operating in full scan MS mode was investigated for the quantitative LC/MS analysis of drugs in patients' plasma samples. A mass resolution of 50 000 (FWHM) at m/z 200 and a mass extracted window of 5?ppm around the theoretical m/z of each analyte were used to construct chromatograms for quantitation. The quantitative performance of the Exactive-MS was compared with that of a triple quadrupole mass spectrometer (TQ-MS), TSQ Quantum Discovery or Quantum Ultra, operating in the conventional selected reaction monitoring (SRM) mode.
The study consisted of 17 therapeutic drugs including 8 antifungal agents (anidulafungin, caspofungin, fluconazole, itraconazole, hydroxyitraconazole posaconazole, voriconazole and voriconazole-N-oxide), 4 immunosuppressants (ciclosporine, everolimus, sirolimus and tacrolimus) and 5 protein kinase inhibitors (dasatinib, imatinib, nilotinib, sorafenib and sunitinib). The quantitative results obtained with HR-MS acquisition show comparable detection specificity, assay precision, accuracy, linearity and sensitivity to SRM acquisition.
Importantly, HR-MS offers several benefits over TQ-MS technology: absence of SRM optimization, time saving when changing the analysis from one MS to another, more complete information of what is in the samples and easier troubleshooting. Our work demonstrates that U/HPLC coupled to Exactive HR-MS delivers comparable results to TQ-MS in routine quantitative drug analyses. Considering the advantages of HR-MS, these results suggest that, in the near future, there should be a shift in how routine quantitative analyses of small molecules, particularly for therapeutic drugs, are performed.
Vigilant monitoring of a patient's response to current treatment is imperative to the management of chronic myeloid leukemia (CML). Early identification of treatment failure may increase the probability that alternative therapy will be effective. This review discusses the use of molecular monitoring in the timely detection of failure of imatinib treatment. Changes in the levels of BCR-ABL transcripts are predictive of response or relapse.
Patients achieving a major molecular response (MMR) within 12 months of treatment may experience longer cytogenetic remission. Accumulating evidence also suggests that lower transcript levels observed under 6 months after the start of treatment are associated with improved patient outcomes. For patients with primary or secondary imatinib resistance (or intolerance), dasatinib or nilotinib may be prescribed. These agents have demonstrated activity in patients harboring imatinib-resistant BCR-ABL mutations, except for the T315I substitution.
The introduction of the tyrosine kinase inhibitors (TKIs) imatinib, dasatinib, and nilotinib has dramatically improved the treatment of chronic myeloid leukemia (CML). However, a minority of CML patients in chronic phase (CP) and a substantial proportion of patients in advanced phase are either initially refractory to TKIs or eventually develop resistance. Rates of resistance and relapse directly correlate with disease progression. The most frequently identified mechanism of acquired TKI resistance is BCR-ABL1 kinase domain (KD) mutations that impair TKI binding by disrupting the drug contact sites or causing conformational changes that make the contact sites inaccessible.
The underlying mechanisms of disease progression are heterogeneous and only poorly understood. So far the most frequent and best characterized include genomic instability, loss of tumor-suppressor functions, and differentiation arrest. Clinical data indicate that both development of a BCR-ABL1 KD mutation during TKI treatment and/or disease progression are associated with a poorer outcome. Thus, therapeutic strategies are needed for the treatment or prevention of resistance and disease progression. They include, for example, TKI dose escalation, treatment interruption to stop selection of resistant cells, and allogeneic stem cell transplantation in eligible patients, as well as the use of novel TKIs with activity against resistant mutations and/or inhibition of alternative pathways.
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