Development and validation of a sensitive assay for the quantification of imatinib using LC/LC-MS/MS in human whole blood and cell culture

Imatinib treatment and longitudinal growth in pediatric patients with chronic myeloid leukemia: influence of demographic, pharmacological, and genetic factors in the German CML-PAED cohort

In children and adolescents, impaired growth due to tyrosine kinase inhibitor therapy remains an insufficiently studied adverse effect. This study examines demographic, pharmacological, and genetic factors associated with impaired longitudinal growth in a uniform pediatric cohort treated with imatinib. We analyzed 94 pediatric patients with chronic myeloid leukemia (CML) diagnosed in the chronic phase and treated with imatinib for >12 months who participated in the Germany-wide CML-PAEDII study between February 2006 and February 2021 (clinicaltrials gov. Identifier: NCT00445822). During imatinib treatment, significant height reduction occurred, with medians of -0.35 standard deviation score (SDS) at 12 months and -0.76 SDS at 24 months. Cumulative height SDS change (Δ height SDS) showed a more pronounced effect in prepubertal patients during the first year but were similar between prepubertal and pubertal subgroups by the second year (-0.55 vs. -0.50). From months 12 to 18 on imatinib, only 18% patients achieved individually longitudinal growth adequate to the growth standard (Δ height SDS ≥0). When patients were divided into two subgroups based on median Δ height SDS (classifier Δ height SDS > or ≤-0.37) after 1 year on imatinib therapy, cohort 1 (Δ height SDS ≤-0.37) showed younger age at diagnosis, a higher proportion of prepubertal children, but also better treatment response and higher imatinib serum levels. Exploring the association of growth parameters with pharmacokinetically relevant single nucleotide polymorphisms, known for affecting imatinib response, showed no correlation. This retrospective study provides new insights into imatinib-related growth impairment. We emphasize the importance of optimizing treatment strategies for pediatric patients to realize their maximum growth potential.

An Exploration of Advancement in Analytical Methodology for Quantification of Anticancer Drugs in Biomatrices

Significant numbers of newer anticancer drugs are regularly entering into the market worldwide to fight against different types of cancers. Analytical methodologies are being developed to quantitate those molecules in a variety of matrices during their drug development stages. Selection of biological matrices for developing bioanalytical methods is based on the mechanism of action, site of action, site of metabolism and route of excretion of the drugs or their metabolites. In this review, we have described the current scenario and advancements in bioanalytical techniques for quantification of different anticancer drugs in a variety of biomatrices with a special emphasis on sample preparation techniques. We have discussed and summarized different bioanalytical aspects for anticancer drugs, which can give direction to the researcher for choosing appropriate techniques for their quantification needs.

Imatinib quantification in human serum with LC-MS3 as an effective way of protein kinase inhibitor analysis in biological matrices

BACKGROUND

As imatinib gained a lot of attention in the field of medicine, appropriate methods are needed for drug analysis. LC-MS/MS combined with complex sample preparation and column enrichment is usually the method of choice when high sensitivity is necessary. The application of LC-MS3 in imatinib quantification has not been discussed in the literature.

METHODS

An LC-MS3 imatinib quantification method was developed and validated in human serum. The sample preparation was based on the liquid-liquid extraction of 50 μL human serum. Chromatographic separation was performed using a Luna 5 μm C18 (2) 100 A, 150 mm×2 mm column and the elution was done using a mobile phase consisting of A (H2O/methanol=95/5, v/v) and B (H2O/methanol=3/97, v/v), both with 10 mM ammonium acetate and 0.1% acetic acid.

RESULTS

The conditions applied resulted in a limit of detection/quantification value of 0.14/0.45 ng/mL reached without a sophisticated sample preparation technique or enrichment column application. It could be demonstrated that MS3 detection is a very effective way of sensitive imatinib quantification. Further, it could be stated that the strategy presented can be very useful for a sensitive analysis of other protein kinase inhibitors, because their molecule structure is appropriate for MS3 detection.

CONCLUSIONS

The presented analytical strategy is an effective way of protein kinase inhibitor analysis in human serum.

Antineoplastic drugs and their analysis: a state of the art review

We provide an overview of the analytical methods available for the quantification of antineoplastic drugs in pharmaceutical formulations, biological and environmental samples.

Plasma and intracellular imatinib concentrations in patients with chronic myeloid leukemia

BACKGROUND

Imatinib (Gleevec, STI-571), a 2-phenylaminopyrimidine-type competitive inhibitor of Bcr-Abl kinase, is the current frontline therapy for patients with chronic myeloid leukemia, and it induces durable responses and prolonging event-free and progression-free survival. Monitoring imatinib trough plasma concentration is a simple and rapid way to determine if the drug exposure exceeds the clinical efficacy threshold (1 mcg/mL). Because the target enzyme is located within cells, adequate drug intracellular concentrations are needed to inhibit its function.

METHODS

Chromatographic methods were used to quantify imatinib concentrations in both plasma and peripheral blood mononuclear cells collected from adult patients with chronic myeloid leukemia at the Department of Hematology. Samples were collected at steady state, and trough concentrations (24 ± 2 hours after last drug intake) were evaluated. Associations between variables were tested using the Pearson test; results are presented as mean (±SD).

RESULTS

Thirty-five samples from 24 patients were collected; patients were mainly men (16, 66.7%), aged 60 years old (±13.1) and with a body mass index of 24.8 (±4.4). A positive and significant correlation (r = 0.203; P = 0.027) was found between imatinib plasma and intracellular concentrations.

CONCLUSIONS

The observed correlation between plasma and intracellular imatinib concentrations suggests that they may be used to monitor drug exposure and treatment efficacy.

Dasatinib

Dasatinib (Sprycel®), a second-generation TKI, has been shown to be effective as an anticancer drug in the treatment of patients with chronic myeloid leukemia or Philadelphia chromosome-positive acute lymphoblastic leukemia who are resistant or intolerant to imatinib. Several methods of gefitinib synthesis are included in this review. UV spectroscopy of dasatinib showed a λmax of approximately 320-330nm, and IR spectroscopy principal peaks were observed at 3418 (NH), 3200 (OH), 1620 (CO), 1582 (CC and CN), 1513 (CHCH) cm(-1). Characteristic NH peaks were observed in nuclear magnetic resonance (NMR) spectroscopy at 11.47 and 9.88ppm. The molecular mass was observed at m/z=487.3((35)Cl) and 488.9((37)Cl) (molecular weight=487.15) and the fragmentation pattern was studied using ion trap mass spectrometry. In addition, different analytical methods for determination of dasatinib are also described in this review. Pharmacokinetically, dasatinib is rapidly absorbed after oral administration where the solubility is dependent on pH. Dasatinib extensively binds to human plasma proteins by approximately 96%. In leukemic patient, the calculated apparent volume of distribution for dasatinib was 2502L and the estimated elimination half-life was approximately 3-5h. Dasatinib is metabolized in humans markedly by CYP3A4 to active metabolites and by phase II drug-metabolizing enzymes, such as UDP glucuronosyltransferase. Dasatinib is mainly eliminated via the feces (85%), of which relatively small amount of dasatinib is excreted unchanged as intact drug (19%). Most of the adverse effects associated with dasatinib therapy are mild to moderate in severity and are usually reversible and manageable with appropriate intervention, such as cardiac failure, hypertension, and coronary artery disease.

Inhibition of calcineurin combined with dasatinib has direct and indirect anti-leukemia effects against BCR-ABL1(+) leukemia

Treatment of BCR-ABL1(+) leukemia has been revolutionized with the development of tyrosine kinase inhibitors. However, patients with BCR-ABL1(+) acute lymphoblastic leukemia and subsets of patients with chronic myeloid leukemia are at high risk of relapse despite kinase inhibition therapy, necessitating novel treatment strategies. We previously reported synthetic lethality in BCR-ABL1(+) leukemia cells by blocking both calcineurin/NFAT signaling and BCR-ABL1, independent of drug efflux inhibition by cyclosporine. Here, using RNA-interference we confirm that calcineurin inhibition sensitizes BCR-ABL1(+) cells to tyrosine kinase inhibition in vitro. However, when we performed pharmacokinetic and pharmacodynamic studies of dasatinib and cyclosporine in mice, we found that co-administration of cyclosporine increases peak concentrations and the area under the curve of dasatinib, which contributes to the enhanced disease control. We also report the clinical experience of two subjects in whom we observed more hematopoietic toxicity than expected while enrolled in a Phase Ib trial designed to assess the safety and tolerability of adding cyclosporine to dasatinib in humans. Thus, the anti-leukemia benefit of co-administration of cyclosporine and dasatinib is mechanistically pleiotropic, but may not be tolerable, at least as administered in this trial. These data highlight some of the challenges associated with combining targeted agents to treat leukemia.

Low-salt diet and cyclosporine nephrotoxicity: changes in kidney cell metabolism

Cyclosporine (CsA) is a highly effective immunosuppressant used in patients after transplantation; however, its use is limited by nephrotoxicity. Salt depletion is known to enhance CsA-induced nephrotoxicity in the rat, but the underlying molecular mechanisms are not completely understood. The goal of our study was to identify the molecular effects of salt depletion alone and in combination with CsA on the kidney using a proteo-metabolomic strategy. Rats (n = 6) were assigned to four study groups: (1) normal controls, (2) low-salt fed controls, (3) 10 mg/kg/d CsA for 28 days on a normal diet, (4) 10 mg/kg/d CsA for 28 days on low-salt diet. Low-salt diet redirected kidney energy metabolism toward mitochondria as indicated by a higher energy charge than in normal-fed controls. Low-salt diet alone reduced phospho-AKT and phospho-STAT3 levels and changed the expression of ion transporters PDZK1 and CLIC1. CsA induced macro- and microvesicular tubular epithelial vacuolization and reduced energy charge, changes that were more significant in low-salt fed animals, probably because of their more pronounced dependence on mitochondria. Here, CsA increased phospho-JAK2 and phospho-STAT3 levels and reduced the phospho-IKKγ and p65 proteins, thus activating NF-κB signaling. Decreased expression of lactate transport regulator CD147 and phospho-AKT was also observed after CsA exposure in low-salt rats, indicating a decrease in glycolysis. In summary, our study suggests a key role for PDZK1, CD147, JAK/STAT, and AKT signaling in CsA-induced nephrotoxicity and proposes mechanistic explanations on why rats fed a low-salt diet have higher sensitivity to CsA.

Development of imatinib and dasatinib resistance: dynamics of expression of drug transporters ABCB1, ABCC1, ABCG2, MVP, and SLC22A1

About 20% of patients with chronic myeloid leukemia (CML) do not respond to treatment with imatinib either initially or because of acquired resistance. To study the development of CML drug resistance, an in vitro experimental system comprising cell lines with different resistance levels was established by exposing K562 cells to increasing concentrations of imatinib and dasatinib anticancer agents. The mRNA levels of BCR- ABL1 and of genes involved in drug transport or redistribution (ABCB1, ABCC1, ABCC3, ABCG2, MVP, and SLC22A1) were measured and the ABL1 kinase domain sequenced. Results excluded BCR- ABL1 overexpression and mutations as relevant resistance mechanisms. Most studied transporters were overexpressed in the majority of resistant cell lines. Their expression pattern was dynamic: varying with resistance level and chronic drug exposure. Studied efflux transporters may have an important role at the initial stages of resistance, but after prolonged exposure and for higher doses of drugs other mechanisms might take place.

A non-radioactive assay for precise determination of intracellular levels of imatinib and its main metabolite in Bcr-Abl positive cells

Multidrug resistance (MDR) is often associated with overexpression of the P-glycoprotein (P-gp, ABCB1). It was demonstrated that the P-gp mediated efflux decreases the drug concentration in cancer cells which results in the failure of chemotherapy. However, the MDR phenotype in cancer cells obviously involves various mechanisms. Therefore, if we want to estimate a contribution of the P-gp expression to the MDR phenotype, a clear quantitative relationship between the intracellular drug level and cell sensitivity must be established. To achieve this goal, a sensitive and non-radioactive assay for precise determination of intracellular levels of imatinib and its main metabolite N-desmethyl imatinib (CGP 74588) has been developed. The assay is based on an optimised extraction of cells with 4% formic acid after their separation from the growth medium by centrifugation through a layer of silicone oil. Cell extracts are subsequently analyzed by LC/MS/MS. Calibration curves were linear from 1 to 500 nmol/l for imatinib and from 2 to 500 nmol/l for CGP 74588, with correlation coefficients (r(2)) better than 0.998 and 0.996, respectively. The limit of quantitation (LOQ) was 1 nmol/l for imatinib and 2 nmol/l for CGP 74588. Our method has been successfully applied to the determination of intracellular levels of imatinib in sensitive K562 and their resistant variant, K562/Dox cells.

Synergistic proapoptotic effects of the two tyrosine kinase inhibitors pazopanib and lapatinib on multiple carcinoma cell lines

Pazopanib and lapatinib are two tyrosine kinase inhibitors that have been designed to inhibit the VEGF tyrosine kinase receptors 1, 2 and 3 (pazopanib), and the HER1 and HER2 receptors in a dual manner (lapatinib). Pazopanib has also been reported to mediate inhibitory effect on a selected panel of additional tyrosine kinases such as PDGFR and c-kit. Here, we report that pazopanib and lapatinib act synergistically to induce apoptosis of A549 non-small-cell lung cancer cells. Systematic assessment of the kinome revealed that both pazopanib and lapatinib inhibited dozens of different tyrosine kinases and that their combination could suppress the activity of some tyrosine kinases (such as c-Met) that were not or only partially affected by either of the two agents alone. We also found that pazopanib and lapatinib induced selective changes in the transcriptome of A549 cells, some of which were specific for the combination of both agents. Analysis of a panel of unrelated human carcinoma cell lines revealed a signature of 52 genes whose up- or downregulation reflected the combined action of pazopanib and lapatinib. Indeed, pazopanib and lapatinib exerted synergistic cytotoxic effects on several distinct non-small-cell lung cancer cells as well as on unrelated carcinomas. Altogether, these results support the contention that combinations of tyrosine kinase inhibitors should be evaluated for synergistic antitumor effects. Such combinations may lead to a 'collapse' of pro-survival signal transduction pathways that leads to apoptotic cell death.

Metabolic characteristics of imatinib resistance in chronic myeloid leukaemia cells

BACKGROUND AND PURPOSE

Early detection of resistance development is crucial for imatinib-based treatment in chronic myeloid leukaemia (CML) patients. We aimed to distinguish metabolic markers of cell resistance to imatinib.

EXPERIMENTAL APPROACH

Two human imatinib-sensitive CML cell lines: LAMA84-s and K562-s, and their resistant counterparts: LAMA84-r and K562-r (both resistant to 1 microM imatinib), and K562-R (5 microM) were analysed by nuclear magnetic resonance spectroscopy to assess global metabolic profiling, including energy state, glucose and phospholipid metabolism.

KEY RESULTS

We found, by Western blotting and flow cytometry, that the levels of Bcr-Abl tyrosine kinase and multi-drug resistance p-glycoprotein were inconsistent among resistant clones. On the other hand, phospholipid metabolism and lactate production were highly predictive for cell response to imatinib. As previously reported, sensitive cells showed significantly decreased glycolytic activity (lactate) and phospholipid synthesis (phosphocholine) as well as increased phospholipid catabolism (glycerophosphocholine) after 24 h of 1 microM imatinib treatment, which correlated with inhibition of cell proliferation and induction of apoptosis. In contrast to their sensitive counterparts, the K562-r, K562-R and LAMA84-r maintained increased phospholipid synthesis and glycolytic lactate production in the presence of 1 microM (K562-r and LAMA84-r) and 5 microM (K562-R) imatinib.

CONCLUSIONS AND IMPLICATIONS

Specific metabolic markers for early detection of imatinib resistance, including increased glycolytic activity and phospholipid turnover, can be identified in resistant clones. Once validated in human isolated leukocytes, they may be used to monitor the responsiveness of CML patients to treatment.