Trough plasma concentration of imatinib reflects BCR-ABL kinase inhibitory activity and clinical response in chronic-phase chronic myeloid leukemia: A report from the BINGO study

Abstract Abstract 4266 Introduction Imatinib, which is the most successful molecularly targeting drug, is the first-line agent for the treatment of chronic myeloid leukemia patients (CML) in chronic phase (CP). However, some patients show poor response against imatinib therapy, resulting in the progression to blastic phase. To date, several reports showed that imatinib trough plasma concentration (Cmin) was associated with the clinical response in CML patients, while it remains unclear whether Cmin reflects the actual inhibitory effect on the BCR-ABL kinase activity. In human plasma, imatinib binds to several plasma proteins, such as albumin (ALB) and alpha1-acid glycoprotein (AGP), and the protein-binding-imatinib lacks the kinase inhibitory activity. Especially, AGP is a major imatinib-binding protein, and the high plasma AGP concentration reportedly reduces the clinical efficacy of imatinib. These results indicate that the free-imatinib concentration is a more reliable surrogate marker for predicting the clinical efficacy than the total imatinib concentration. However, since routine measurements of the free-imatinib concentration is difficult, the inhibitory activity of the patient's plasma (PIA) against the BCR-ABL kinase is proposed to be a direct marker reflecting the actual inhibitory effects of the free-imatinib. In this study, we analyzed the association between Cmin of total imatinib and the clinical response in CML-CP patients in considering the AGP concentration. Furthermore, we evaluate the usefulness of PIA for predicting the clinical response in the CML patients treated with imatinib. Methods We measured Cmin of the total imatinib and AGP and ALB concentrations at the different two points in CML-CP patients who were treated with imatinib alone. The PIA was quantified by determining the de-phosphorylation levels of BCR-ABL and STAT5 in BCR-ABL-expressing Ba/F3 cells after the treatment with patients' plasma. We evaluated the association of these parameters with clinical response. Informed consent was obtained from all patients to use their samples for this study. This study was approved by the ethical committee of Nagoya university school of medicine. Results The study population included 65 CML-CP patients. The mean Cmin of imatinib was 1070 ± 362 ng/ml. Clinical response was evaluated by the achievement of the complete cytogenetic response (CCR) and major molecular response (MMR) at 12 months after the start of imatinib therapy. The CCR and MMR were achieved in 63 (96.9%) and 40 (61.5%) patients, respectively. The mean Cmin of the patients who achieved MMR was significantly higher than that of those who did not (1167 ± 386 ng/ml vs. 913 ± 257ng/ml, P=0.012). The differences of Cmin between the two different points (median interval 28 ± 20 days) in the same patient were not so little (median 123 ± 198 ng/ml, range 12 to 923 ng/ml), but were not associated with clinical outcomes. The PIA was statistically correlated with the Cmin (P=0.018). Although serum AGP level was within normal range (72.8 ± 13.9 mg/dl, range 44 to 106 mg/dl) in most patients, it was notable that the serum AGP level correlated with Cmin of imatinib and clinical outcomes. The Cmin of patients with high AGP level was significantly higher than that of low AGP level (1237 ± 379ng/ml vs. 907 ± 260ng/ml, P=0.0003) and the MMR rate was significantly higher in patients with high AGP level (78%) than in those with low AGP level (45%, P=0.007). Conclusions We demonstrate that the Cmin of imatinib predicts clinical response and reflects the actual kinase inhibitory effects in CML patients treated with imatinib. However, the Cmin is not necessarily stable during the treatment in a part of patients, suggesting that it is recommended to examine Cmin at more than two different points for evaluating its suitability. The serum AGP and ALB levels did not affect the relationship between Cmin and PIA. However, since the serum AGP level was correlated with Cmin and clinical response, the AGP level might influence the kinase inhibitory activity in the patients whose Cmin of imatinib were low. Disclosures: Kiyoi: Novartis Pharma : Research Funding; Kyowa Hakko Kirin Co., Ltd. : Consultancy. Naoe:Kyowa Hakko Kirin Co., Ltd. : Research Funding; Chugai Pharmaceutical Co.,Ltd.: Research Funding; Wyeth K.K.: Research Funding.

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BCR-ABL kinase domain mutation analysis in chronic myeloid leukemia patients treated with tyrosine kinase inhibitors: recommendations from an expert panel on behalf of European LeukemiaNet

Blood ◽

10.1182/blood-2010-12-326405 ◽

2011 ◽

Vol 118 (5) ◽

pp. 1208-1215 ◽

Cited By ~ 332

Author(s):

Simona Soverini ◽

Andreas Hochhaus ◽

Franck E. Nicolini ◽

Franz Gruber ◽

Thoralf Lange ◽

...

Keyword(s):

Chronic Myeloid Leukemia ◽

Tyrosine Kinase ◽

Tyrosine Kinase Inhibitors ◽

Mutation Analysis ◽

Myeloid Leukemia ◽

Kinase Inhibitors ◽

Direct Sequencing ◽

Chronic Phase ◽

Kinase Domain ◽

Abl Kinase

AbstractMutations in the Bcr-Abl kinase domain may cause, or contribute to, resistance to tyrosine kinase inhibitors (TKIs) in chronic myeloid leukemia patients. Recommendations aimed to rationalize the use of BCR-ABL mutation testing in chronic myeloid leukemia have been compiled by a panel of experts appointed by the European LeukemiaNet (ELN) and European Treatment and Outcome Study and are here reported. Based on a critical review of the literature and, whenever necessary, on panelists' experience, key issues were identified and discussed concerning: (1) when to perform mutation analysis, (2) how to perform it, and (3) how to translate results into clinical practice. In chronic phase patients receiving imatinib first-line, mutation analysis is recommended only in case of failure or suboptimal response according to the ELN criteria. In imatinib-resistant patients receiving an alternative TKI, mutation analysis is recommended in case of hematologic or cytogenetic failure as provisionally defined by the ELN. The recommended methodology is direct sequencing, although it may be preceded by screening with other techniques, such as denaturing-high performance liquid chromatography. In all the cases outlined within this abstract, a positive result is an indication for therapeutic change. Some specific mutations weigh on TKI selection.

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Utility of the trough plasma imatinib level monitoring at two time points in patients with the chronic myeloid leukemia-chronic phase

Journal of Cancer Research and Therapeutics ◽

10.4103/0973-1482.136583 ◽

2014 ◽

Vol 10 (2) ◽

pp. 305 ◽

Cited By ~ 6

Author(s):

Tulika Seth ◽

Pravas Mishra ◽

Manoranjan Mahapatra ◽

Sudha Sazawal ◽

T Velpandian ◽

...

Keyword(s):

Chronic Myeloid Leukemia ◽

Myeloid Leukemia ◽

Chronic Phase ◽

Time Points ◽

Level Monitoring ◽

Trough Plasma

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Allografting for Bosutinib, Imatinib, Nilotinib, Dasatinib, and Interferon Resistant Chronic Myeloid Leukemia without ABL Kinase Mutation

Case Reports in Hematology ◽

10.1155/2011/263725 ◽

2011 ◽

Vol 2011 ◽

pp. 1-4

Author(s):

B. Uz ◽

O. Bektas ◽

E. Eliacik ◽

H. Goker ◽

Y. Erbilgin ◽

...

Keyword(s):

Chronic Myeloid Leukemia ◽

Myeloid Leukemia ◽

Kinase Inhibitors ◽

Chronic Phase ◽

Kinase Domain ◽

Current Treatment ◽

Hematopoietic Stem ◽

Abl Kinase ◽

Kinase Domain Mutation ◽

Kinase Mutation

The current treatment of chronic phase chronic myeloid leukemia (CML) consists of oral tyrosine kinase inhibitors (TKIs). However, high-risk CML may present with an aggressive course which may result in blastic crisis or a “difficult-to-manage” state with available treatments. The aim of this paper is to report a patient with complicated CML resistant to treatment and progressed despite the administration of bosutinib, imatinib mesylate, nilotinib, dasatinib, interferon alpha 2a, cytotoxic chemotherapy, and allogeneic hematopoietic stem cell transplantation. The striking point of this case story is that no Abl kinase domain mutation against TKIs has been detected during this very complicated disease course of CML. Meanwhile, challenging cases will always be present despite the hope and progress in CML in the TKI era.

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Correlation between trough imatinib plasma concentration and clinical response in chronic myeloid leukemia

Leukemia Research ◽

10.1016/j.leukres.2009.03.002 ◽

2009 ◽

Vol 33 (8) ◽

pp. 1149-1150

Author(s):

Donna L. Forrest ◽

Shannon Trainor ◽

Ryan R. Brinkman ◽

Michael J. Barnett ◽

Donna E. Hogge ◽

...

Keyword(s):

Plasma Concentration ◽

Chronic Myeloid Leukemia ◽

Clinical Response ◽

Myeloid Leukemia

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Association Between CYP3A4 Polymorphisms, Trough Imatinib Plasma Concentration and Cytogenetic Response in Chronic Phase Chronic Myeloid Leukemia (CML-CP)

Blood ◽

10.1182/blood.v120.21.3788.3788 ◽

2012 ◽

Vol 120 (21) ◽

pp. 3788-3788 ◽

Cited By ~ 1

Author(s):

Vikram Gota ◽

Anupam Sharma ◽

Amey Paradkar ◽

Anand Patil ◽

Navin Khattry ◽

...

Keyword(s):

Plasma Concentration ◽

Roc Curve ◽

Chronic Phase ◽

Cytogenetic Response ◽

Molecular Response ◽

Complete Cytogenetic Response ◽

Trough Plasma Concentration ◽

Pcr Rflp ◽

Trough Levels ◽

Trough Plasma

Abstract Abstract 3788 Introduction: Imatinib mesylate has demonstrated excellent efficacy as first-line therapy for treatment of chronic phase chronic myelogenous leukemia (CML-CP). The drug has a high inter-patient variability in pharmacokinetics (PK), and several factors are presumed to influence its PK. Imatinib is a substrate of CYP3A4 and CYP3A5 enzymes. However, the clinical significance of its metabolism on pharmacokinetics and therapeutic response is still unclear. Significantly higher in vivo CYP3A activity was reported recently in patients achieving complete molecular response than those who did not in a small cohort study. Several investigators in the past have tried to optimize imatinib dosing based on trough levels after the fourth treatment week. Picard S et al (Blood, 2007) showed that threshold plasma concentration of 1002 ng/ml on day 29 was associated with higher incidence of major molecular response. The primary objective of this study was to evaluate the association between CYP3A4 polymorphisms, trough plasma concentration of imatinib on day 8 and day 29 of treatment, and cytogenetic response. The secondary objective was to evaluate the potential of early (day 8) trough level monitoring to discriminate between responders and non-responders. Methods: All patients received standard 400 mg OD dose of imatinib. A single blood sample was collected on day 8 and day 29 prior to imatinib dosing for the determination of trough plasma concentration. Imatinib level was determined using High Performance Liquid Chromatography (HPLC). Cytogenetic response was assessed at 3 monthly intervals by Fluorescence In Situ Hybridization (FISH). Complete cytogenetic response (CCR) was defined as 0% of Philadelphia chromosome–positive cells in the bone marrow aspirate. Pharmacogenetic sample was collected from each patient at the beginning of the study to look for CYP3A4 polymorphism. Genotyping was carried out for *4 (rs55951658), *5 (rs55901263) and *18 (rs28371759) variants by PCR-RFLP technique. About 10% samples were chosen randomly for direct sequencing to confirm the PCR-RFLP findings. Median imatinib concentration in the CCR and non CCR groups was compared using non-parametric Mann-Whitney test. Receiver Operating Characteristic (ROC) curve analysis was performed to assess the discrimination potential of trough imatinib plasma levels for complete cytogenetic response (CCR). Results: Ninety eight patients were enrolled on this study, 70 males and 28 females. The median age was 33 years (Range 6 – 71 years). High interpatient variability in the trough concentration of imatinib was observed (Coefficient of variation = 64% and 56% for day 8 and day 29 respectively). However, none of the patients were found to have *4, *5 or *18 variant alleles. Genotype–PK or genotype-response association could not be evaluated as a result. Data on cytogenetic response at 12 months was available for 75 patients (60 CCR, 15 without CCR), 46 of whom also had trough imatinib levels measured on day 8 and day 29 (36 CCR, 10 without CCR). Median day 8 and day 29 trough concentrations were not significantly different in the group with CCR (1.71 and 1.91 μg/mL respectively) and the group without (1.31 and 1.64 μg/mL respectively). Regarding the discrimination potential of trough levels for CCR, day 8 concentrations failed to discriminate between responders and non-responders, whereas for the Day 29 levels, the area under the ROC curve (AUC) was 0.554, with best sensitivity (75%) and specificity (61%) at plasma threshold of 1.69 μg/mL. Conclusion: In this cohort of patients, common CYP3A4 variants did not contribute to the high inter-patient variability of imatinib levels. Early monitoring on Day 8 failed to discriminate responders from non-responders. Day 29 levels are a better predictor of complete cytogenetic response as shown in previous studies. Disclosures: No relevant conflicts of interest to declare.

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ABCB1 Haplotypes Are Associated With Lower P-Gp Activity and Major Molecular Response But Do Not Affect Imatinib Plasma Levels In Chronic Myeloid Leukemia Patients

Blood ◽

10.1182/blood.v122.21.3860.3860 ◽

2013 ◽

Vol 122 (21) ◽

pp. 3860-3860

Author(s):

Douglas Vivona ◽

Luciene Terezina Lima ◽

Alice C Rodrigues ◽

Carolina Tosin Bueno ◽

Cristiane M Gaitani ◽

...

Keyword(s):

Plasma Concentration ◽

Chronic Myeloid Leukemia ◽

Functional Activity ◽

Plasma Levels ◽

Myeloid Leukemia ◽

Standard Dose ◽

Chronic Phase ◽

Molecular Response ◽

Wild Type ◽

Major Molecular Response

Abstract Background Despite the high efficacy of IM treatment in chronic myeloid leukemia (CML), some patients fail to achieve optimal response. Several studies demonstrated that IM is a substrate of membrane transporters, such as ABCB1 (P-gp, MDR1) and variations in protein expression or activity could affect the pharmacokinetics of IM by reducing or increasing its bioavailability. These alterations could be related with single nucleotide polymorphisms in ABCB1 gene. Previous data confirms that haplotypes containing the mutated alleles for ABCB1 c.1236C>T, c.3435C>T and c.2677G>T showed major structural modifications that result in changes in the conformation of the binding sites of P-gp. These modifications could affect the pharmacokinetics of IM. Aim The aim of this study was to evaluate the influence of the different haplotypes for ABCB1 c.1236C>T, c.3435C>T and c.2677TG>T polymorphisms in IM plasma concentration, P-gp activity and IM response from CML patients treated with standard dose of IM (400 mg/day). Methods Twenty eight patients in chronic phase of CML were selected according to the haplotypes for ABCB1 c.1236C>T, c.3435C>T and c.2677G>T polymorphisms at two health centers in São Paulo, Brazil. Ten patients with ABCB1 1236CC/3435CC/2677GG haplotype comprised the wild-type group and 18 carriers of haplotypes with at least one mutated allele in each genotype for three ABCB1 polymorphisms (10 patients with 1236CT/3435CT/2677GT and 8 with 1236TT/3435TT/2677TT) comprised the mutated group. Patients were matched for IM time of use. All patients were in chronic phase of CML, treated with a standard dose of IM (400 mg/day) for a median time of 63.5±12.6 months and with complete cytogenetic response (CCyR). Major molecular response (MMR) was defined as a reduction of BCR-ABL1 transcripts levels to ≤ 0.1% in the peripheral blood standardized on the International scale. Complete molecular response (CMR) was defined as a reduction ≤0.0032% of BCR-ABL1 transcripts levels. Real-Time PCR was performed to evaluate ABCB1 mRNA expression to control gene GAPDH. P-gp functional activity was determinated by rhodamine123 efflux assay. Analysis of P-gp expression and functional activity were performed by flow cytometry. The determination of plasma concentration of IM was performed by capillary electrophoresis. Results Patients without MMR had lower plasma concentration of IM when compared to those that achieved this response (0.51 µg/mL vs. 1.42 µg/mL, P=0.001) but no association was found between the different haplotypes and IM plasma levels or ABCB1 mRNA/P-gp expression. The median of Rh123 efflux in wild-type and mutated groups was 59.1 (54.8 - 69.5) and 38.3 (27.4 - 47.9) (P<0.05), respectively. Patients who did not achieve MMR showed a higher rate of efflux mediated by P-gp compared to individuals who did not achieve this response (64.7% vs. 45.7%, P =0.001). All patients who did not achieve MMR showed efflux above 60%.There was a strong and positive correlation between ABCB1 mRNA expression and P-gp expression (r=0.747, P=0.001). P-gp activity was positive and moderate correlated with BCR-ABL1 transcripts (r=0.570; P=0.001). Conclusion ABCB1 1236CT/3435CT/2677GT and 1236TT/3435TT/2677TT haplotypes are associated with lower P-gp activity and higher frequency of MMR but not with IM plasma concentration in chronic phase CML patients treated with standard-dose of IM (400 mg/day) Disclosures: No relevant conflicts of interest to declare.

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