Enhanced platelet adhesion in essential thrombocythemia after in vitro activation

Objective: Essential thrombocythemia (ET) is a chronic myeloproliferative disorder characterized by elevated platelet counts and increased risk of thrombosis. Ex vivo data suggest increased platelet reactivity in agreement with the increased thrombosis risk, while in vitro tests often detect decreased platelet activity. The present study aimed to investigate adhesion of ET-platelets in vitro, which is an aspect of platelet function that has been addressed in only a few studies on ET patients. Material and Methods: The study included 30 ET patients and 14 healthy controls. Platelet adhesion was measured with a static platelet adhesion assay. Results: The main finding was that ET-platelets were more readily activated by adhesion-inducing stimuli in vitro than control platelets. This was particularly evident in elderly patients and when using multiple stimuli, such as surfaces of collagen or fibrinogen combined with addition of adenosine 5’-diphosphate or ristocetin. Such multiple stimuli resulted in adhesion above the control mean +2 standard deviations for approximately 50% of the patients.Conclusion: The results are in accordance with the concept of increased platelet activity in ET, but opposite to most other in vitro studies. We suggest that the conditions in the adhesion assay might mimic the in vivo situation regarding the presence of chronic platelet activation

Tyrosine kinase inhibitor therapy-induced changes in humoral immunity in patients with chronic myeloid leukemia

Purpose Tyrosine kinase inhibitors (TKIs) have well-characterized immunomodulatory effects on T and NK cells, but the effects on the humoral immunity are less well known. In this project, we studied TKI-induced changes in B cell-mediated immunity. Methods We collected peripheral blood (PB) and bone marrow (BM) samples from chronic myeloid leukemia (CML) patients before and during first-line imatinib (n = 20), dasatinib (n = 16), nilotinib (n = 8), and bosutinib (n = 12) treatment. Plasma immunoglobulin levels were measured, and different B cell populations in PB and BM were analyzed with flow cytometry. Results Imatinib treatment decreased plasma IgA and IgG levels, while dasatinib reduced IgM levels. At diagnosis, the proportion of patients with IgA, IgG, and IgM levels below the lower limit of normal (LLN) was 0, 11, and 6% of all CML patients, respectively, whereas at 12 months timepoint the proportions were 6% (p = 0.13), 31% (p = 0.042) and 28% (p = 0.0078). Lower initial Ig levels predisposed to the development of hypogammaglobulinemia during TKI therapy. Decreased Ig levels in imatinibtreated patients were associated with higher percentages of immature BM B cells. The patients, who had low Ig levels during the TKI therapy, had significantly more frequent minor infections during the follow-up compared with the patients with normal Ig values (33% vs. 3%, p = 0.0016). No severe infections were reported, except recurrent upper respiratory tract infections in one imatinib-treated patient, who developed severe hypogammaglobulinemia. Conclusions TKI treatment decreases plasma Ig levels, which should be measured in patients with recurrent infections.Peer reviewe

Linköping University Post Print

Optimization and evaluation of electroporation delivery of siRNA in the human leukemic CEM cell lin

CYP3A activity influences imatinib response in patients with chronic myeloid leukemia: a pilot study on in vivo CYP3A activity

Imatinib is currently used for the treatment of chronic myeloid leukemia (CML). The main metabolite CGP74588 has similar potency to that of imatinib and is a product of CYP3A4 and CYP3A5 metabolism. However, the clinical significance of the metabolism on therapeutic response and pharmacokinetics is still unclear. We designed this study to investigate the role of the CYP3A activity in the response to imatinib therapy. Fourteen CML patients were phenotyped for in vivo CYP3A activity using quinine as a probe drug. The plasma concentration ratio of quinine and its CYP3A metabolite was used for assessing CYP3A activity. The patients were divided into complete molecular responders with undetectable levels of BCR-ABL transcripts after 12 months of therapy and into partial molecular responders who had failed to achieve a complete molecular response. Patients that achieved complete molecular response showed significantly (Mann-Whitney U-test, p = 0.013) higher in vivo CYP3A activity (median quinine metabolic ratio = 10.1) than patients achieving partial molecular response (median = 15.9). These results indicate a clinical significance of the CYP3A activity and its metabolic products in CML patients treated with imatinib.The original publication is available at www.springerlink.com: Henrik Green, Karin Skoglund, Franz Rommel, Rajaa A Mirghani and Kourosh Lotfi, CYP3A activity influences imatinib response in patients with chronic myeloid leukemia: a pilot study on in vivo CYP3A activity, 2010, EUROPEAN JOURNAL OF CLINICAL PHARMACOLOGY, (66), 4, 383-386. http://dx.doi.org/10.1007/s00228-009-0772-y Copyright: Springer Science Business Media http://www.springerlink.com/</p

Summary Recent findings have indicated...

Irreversible pan-ERBB inhibitor canertinib elicits anti-leukaemic effects and induces the regression of FLT3-ITD transformed cells in mic

In Vivo Cytochrome P450 3A Isoenzyme Activity and Pharmacokinetics of Imatinib in Relation to Therapeutic Outcome in Patients With Chronic Myeloid Leukemia

Background: Cytochrome P450 3A (CYP3A) isoenzyme metabolic activity varies between individuals and is therefore a possible candidate of influence on the therapeutic outcome of the tyrosine kinase inhibitor imatinib in patients with chronic myeloid leukemia (CML). The aim of this study was to investigate the influence of CYP3A metabolic activity on the plasma concentration and outcome of imatinib in patients with CML. Methods: Forty-three patients with CML were phenotyped for CYP3A activity using quinine as a probe drug and evaluated for clinical response parameters. Plasma concentrations of imatinib and its main metabolite, CGP74588, were determined using liquid chromatography-mass spectrometry. Results: Patients with optimal response to imatinib after 12 months of therapy did not differ in CYP3A activity compared to nonoptimal responders (quinine metabolic ratio of 14.69 and 14.70, respectively; P = 0.966). Neither the imatinib plasma concentration nor the CGP74588/imatinib ratio was significantly associated with CYP3A activity. Conclusions: The CYP3A activity does not influence imatinib plasma concentrations or the therapeutic outcome. These results indicate that although imatinib is metabolized by CYP3A enzymes, this activity is not the rate-limiting step in imatinib metabolism and excretion. Future studies should focus on other pharmacokinetic processes so as to identify the major contributor to patient variability in imatinib plasma concentrations.Funding Agencies|Swedish Research Council; Swedish Cancer Society; Medical Research Council of Southeast Sweden; Novartis</p