Pharmacokinetics Of Imatinib Mesylate Research Articles

Pharmacokinetics of Imatinib Mesylate and Development of Limited Sampling Strategies for Estimating the Area under the Concentration-Time Curve of Imatinib Mesylate in Palestinian Patients with Chronic Myeloid Leukemia.

Imatinib is a tyrosine kinase inhibitor used in the treatment of chronic myeloid leukemia (CML). The area under the concentration-time curve (AUC) is a pharmacokinetic parameter that symbolizes overall exposure to a drug, which is correlated with complete cytogenetic and treatment responses to imatinib, as well as its side effects in patients with CML. The limited sampling strategy (LSS) is considered a sufficiently precise and practical method that can be used to estimate pharmacokinetic parameters such as AUC, without the need for frequent, costly, and inconvenient blood sampling. This study aims to investigate the pharmacokinetic parameters of imatinib, develop and validate a reliable and practical LSS for estimating imatinib AUC0-24, and determine the optimum sampling points for predicting the imatinib AUC after the administration of once-daily imatinib in Palestinian patients with CML. Pharmacokinetic profiles, involving six blood samples collected during a 24-h dosing interval, were obtained from 25 Palestinian patients diagnosed with CML who had been receiving imatinib for at least 7days and had reached a steady-state level. Imatinib AUC0-24 was calculated using the trapezoidal rule, and linear regression analysis was performed to assess the relationship between measured AUC0-24 and concentrations at each sampling time. All developed models were analyzed to determine their effectiveness in predicting AUC0-24 and to identify the optimal sampling time. To evaluate predictive performance, two error indices were employed: the percentage of root mean squared error (% RMSE) and the mean predictive error (% MPE). Bland and Altman plots, along with mountain plots, were utilized to assess the agreement between measured and predicted AUC. Among the one-timepoint estimations, predicted AUC0-24 based on concentration of imatinib at the eighth hour after administration (C8-predicted AUC0-24) demonstrated the highest correlation with the measured AUC (r2=0.97, % RMSE=6.3). In two-timepoint estimations, the model consisting of C0 and C8 yielded the highest correlation between predicted and measured imatinib AUC (r2=0.993 and % RMSE=3.0). In three-timepoint estimations, the combination of C0, C1, and C8 provided the most robust multilinear regression for predicting imatinib AUC0-24 (r2=0.996, % RMSE=2.2). This combination also outperformed all other models in predicting AUC. The use of a two-timepoint limited sampling strategy (LSS) for predicting AUC was found to be reliable and practical. While C0/C8 exhibited the highest correlation, the use of C0/C4 could be a more practical and equally accurate choice. Therapeutic drug monitoring of imatinib based on C0 can also be employed in routine clinical practice owing to its reliability and practicality. The LSS using one timepoint, especially C0, can effectively predict imatinib AUC. This approach offers practical benefits in optimizing dose regimens and improving adherence. However, for more precise estimation of imatinib AUC, utilizing two- or three-timepoint concentrations is recommended over relying on a single point.

Safety, tolerability, and pharmacokinetics of single and multiple topical ophthalmic administration of imatinib mesylate in healthy subjects.

For the long‐term efficacy of dry eye disease treatment, relieving underlying inflammation is necessary. Imatinib mesylate is a novel ophthalmic formulation of imatinib mesylate, which is expected to alleviate inflammation by inhibiting the discoidin domain receptor 1 activity. This study aims to evaluate the safety and pharmacokinetics of imatinib mesylate in healthy subjects. A randomized, double‐blind, placebo‐controlled study was conducted. In a single ascending dose, 16 subjects received a single eye drop of imatinib mesylate 0.1%, 0.3%, or matching placebo. In the multiple ascending dose (MAD), subjects received multiple eye drops of imatinib mesylate 0.1%, 0.3%, or matching placebo once daily for 7 days. Safety and tolerability were assessed by ophthalmic examination, including the visual analog scale (VAS) to monitor the burning sensation in the eyes. A total of four treatment‐emergent adverse events (TEAEs) occurred during the study. All TEAEs were mildly severe with no serious cases. VAS results in the 0.1% MAD group exhibited highest score of two points, whereas it was less than one point in others. Insignificant difference between the imatinib mesylate and placebo groups in the VAS results was seen. After a single dose administration of imatinib mesylate 0.1%, all plasma concentrations were below the lower limit of quantification. The peak plasma concentrations of imatinib were less than 0.54 µg/L in all groups. In conclusion, a single and multiple topical ophthalmic administration of imatinib mesylate was well‐tolerated in healthy subjects. Because there was minimal systemic exposure to imatinib, the adverse effect in the body seems to be insignificant.

Pharmacogenetic Markers of Treatment Response of Imatinib Mesylate in Chronic Myeloid Leukemia Brazilian Patients

The treatment of chronic myeloid leukemia (CML) was revolutionized by the introduction of imatinib mesylate (IM). However, approximately 20% of patients are non-responsive and interpatient variability in response to IM is still a phenomenon lacking explanation. Single nucleotide polymorphisms (SNPs) located in genes encoding proteins involved in IM pharmacokinetics are potentially involved in the causes of this variation. In this study, we investigated the association of SNPs in the genes encoding IM metabolizing enzymes CYP3A4 (rs35599367 and rs2740574) and CYP3A5 (rs776746) and efflux transporter proteins ABCB1 (rs3213619, rs1128503, rs2032582 and rs1045642), ABCG2 (rs2231142) and ABCC4 (rs9561765) with response to treatment and with IM plasma through levels and hair concentrations. The analyzed sample was constituted of 182 CML patients on IM treatment. DNA samples were genotyped for the nine SNPs using real-time polymerase chain reaction. Hair and plasma trough IM concentrations were measured through liquid chromatography coupled to mass spectrometry methods. Clinical response was defined according to the European Leukemia Net guidelines. The number of responders to standard IM therapy was 104. A trend to a higher frequency of CYP3A4 *22 (rs35599367) allele carriers was observed among responders to IM (12.5 vs. 3.4% of non-responders, P = 0.087), although no significant differences in plasma or hair concentrations between genotypes were found. Pharmacogenetics may become a valuable approach to optimize therapy with IM in CML, but many factors still need to be clarified to make possible its application in clinical practice. DisclosuresNo relevant conflicts of interest to declare.

A dose-escalating phase I of imatinib mesylate with fixed dose of metronomic cyclophosphamide in targeted olid tumours

Background:Preclinical findings suggest that imatinib mesylate (IM) and metronomic cyclophosphamide (MC) combination provides synergistic antiangiogenic activity on both pericytes and endothelial cells.Methods:We have designed a 3+3 dose-escalating phase I trial with a fixed dose of MC (50 mg two times daily) plus IM (400 mg per day; 300 and 400 mg two times daily). Enrolled patients had IM- and sutininib-refractory advanced gastrointestinal stromal tumours (GIST) (n=17), chordoma (n=7) and mucosal melanoma (n=2). Dose-limiting toxicities were monitored for the first 6 weeks. Progression-free survival (PFS) and response assessment are based on RECIST 1.0 guidelines. Pharmacokinetics of IM were measured before and after exposure to MC.Results:No dose-limiting toxicity was observed. Fourteen patients of the expanded cohort received 400 mg two times daily of IM with MC. Apart from a case of possibly related acute leukaemia occurring after 4 years of treatment, we did not see unexpected toxicity. No drug–drug pharmacokinetic interaction was observed. There was no objective response. We have observed long-lasting stable disease in chordoma patients (median PFS=10.2 months; range, 4.2–18+) and short-term stable disease in heavily GIST pretreated patients (median PFS=2.3 months; range, 2.1–6.6).Conclusion:This combination is feasible and may warrant further exploration in refractory GIST or chordoma patients.

Phase I clinical trial combining imatinib mesylate and IL-2 in refractory cancer patients

Imatinib mesylate (IM) is a small molecule inhibitor of protein tyrosine kinases. In addition to its direct effect on malignant cells, it has been suggested IM may activate of natural killer (NK) cells, hence exerting immunomodulatory functions. In preclinical settings, improved antitumor responses have been observed when IM and interleukin-2 (IL-2), a cytokine that enhances NK cells functions, were combined. The goals of this study were to determine the maximum tolerated dose (MTD) of IL-2 combined with IM at a constant dose of 400 mg, the pharmacokinetics of IM and IL-2, as well as toxicity and clinical efficacy of this immunotherapeutic regimen in patients affected by advanced tumors. The treatment consisted in 50 mg/day cyclophosphamide from 21 d before the initiation of IM throughout the first IM cycle (from D-21 to D14), 400 mg/day IM for 14 d (D1 to D14) combined with escalating doses of IL-2 (3, 6, 9 and 12 MIU/day) from days 10 to 14. This treatment was administered at three week intervals to 17 patients. Common side effects of the combination were mild to moderate, including fever, chills, fatigue, nausea and hepatic enzyme elevation. IL-2 dose level II, 6 MIU/day, was determined as the MTD with the following dose-limiting toxicities: systemic capillary leak syndrome, fatigue and anorexia. Pharmacokinetic studies revealed that the area under the curve and the maximum concentration of IM and its main metabolite CGP74588 increased significantly when IM was concomitantly administered with IL-2. In contrast, IM did not modulate IL-2 pharmacokinetics. No objective responses were observed. The best response obtained was stable disease in 8/17 (median duration: 12 weeks). Finally, IL-2 augmented the impregnation of IM and its metabolite. The combination of IM (400 mg/day) and IL-2 (6 MIU/day) in tumors that express IM targets warrants further investigation.

SLC22A1-ABCB1 Haplotype Profiles Predict Imatinib Pharmacokinetics in Asian Patients with Chronic Myeloid Leukemia

ObjectiveThis study aimed to explore the influence of SLC22A1, PXR, ABCG2, ABCB1 and CYP3A5*3 genetic polymorphisms on imatinib mesylate (IM) pharmacokinetics in Asian patients with chronic myeloid leukemia (CML).Patients and MethodsHealthy subjects belonging to three Asian populations (Chinese, Malay, Indian; n = 70 each) and CML patients (n = 38) were enrolled in a prospective pharmacogenetics study. Imatinib trough (C0h) and clearance (CL) were determined in the patients at steady state. Haplowalk method was applied to infer the haplotypes and generalized linear model (GLM) to estimate haplotypic effects on IM pharmacokinetics. Association of haplotype copy numbers with IM pharmacokinetics was defined by Mann-Whitney U test.ResultsGlobal haplotype score statistics revealed a SLC22A1 sub-haplotypic region encompassing three polymorphisms (rs3798168, rs628031 and IVS7+850C>T), to be significantly associated with IM clearance (p = 0.013). Haplotype-specific GLM estimated that the haplotypes AGT and CGC were both associated with 22% decrease in clearance compared to CAC [CL (*10−2 L/hr/mg): CAC vs AGT: 4.03 vs 3.16, p = 0.017; CAC vs CGC: 4.03 vs 3.15, p = 0.017]. Patients harboring 2 copies of AGT or CGC haplotypes had 33.4% lower clearance and 50% higher C0h than patients carrying 0 or 1 copy [CL (*10−2 L/hr/mg): 2.19 vs 3.29, p = 0.026; C0h (*10−6 1/ml): 4.76 vs 3.17, p = 0.013, respectively]. Further subgroup analysis revealed SLC22A1 and ABCB1 haplotypic combinations to be significantly associated with clearance and C0h (p = 0.002 and 0.009, respectively).ConclusionThis exploratory study suggests that SLC22A1-ABCB1 haplotypes may influence IM pharmacokinetics in Asian CML patients.

Phase I study of imatinib mesylate (IM) and sorafenib (S) in patients (pts) with refractory castration-resistant prostate cancer (CRPC).

146 Background: IM is an inhibitor of protein-tyrosine kinases including those that are over-expressed in bone metastases and primary prostatic adenocarcinoma. S is a potent inhibitor of wild-type and mutant BRAF, C-RAF, VEGFR2, VEGFR3, FLT3, and PDGFR-beta with modest activity in CRPC. We combined IM+S to determine the maximum tolerated dose (MTD) and the dose-limiting toxicity (DLT) in CRPC pts. Methods: CRPC pts with measurable disease and adequate organ function who failed chemotherapy were eligible. Dose escalation followed a 3+3 study design. Toxicity was scored following CTCAEv3. Responses were defined by RECIST1.0. IM pharmacokinetics (PK) were determined on day 15, 4 h post-dose with a validated LC-MS assay. Results: Seventeen pts were enrolled; 10 were evaluable. At dose level 0 (DL0), 6 pts received S at 400 mg S with 300 mg of IM both given daily. At DL1, 4 pts received 400 mg S twice/day with 300 mg IM daily; inevaluable pts received <1 cycle (5 withdrew consent, 1 rapid early progression, 1 non-compliant). Median age was 73 (57-89) and median PSA was 284 ng/ml (11.7–9027). Median number of prior non-hormonal therapies was 3 (1–12) and 12 pts had Gleason score ≥7 while 15 pts had bone as the major site of metastases. On DL0, 1/6 pts had DLT (gr 3 hand/foot). On DL1, 2/4 pts had DLT (1 gr 3 hand/foot, 1 gr 3 diarrhea). MTD was 300 mg IM and 400 mg S both qd. No biochemical responses were observed. Two pts on DL1 had stable disease radiographically by RECIST (overall clinical benefit for the entire cohort 20%). Median time to progression was 2 months (1-5) while median OS was 6 months (1-30+) with 3/17 patients (17%) remaining alive at a median follow-up of 21 months. Of patients enrolled, 10 had PK data, which suggested that S reduced IM clearance by 40%, resulting in 60% increased exposure (P = 0.009; two-tailed t-test on log-transformed values, compared to historic data). Conclusions: To our knowledge, this is the first report to show that IM+S can be safely combined in CRPC. The phase II recommended dose for future trials is 300 mg IM and 400 mg S, both given daily. The PK interaction might be of questionable clinical relevance because IM concentrations are within the commonly observed range.

Influence of CYP3A5 and drug transporter polymorphisms on imatinib trough concentration and clinical response among patients with chronic phase chronic myeloid leukemia

Imatinib mesylate (IM) trough concentration varies among IM-treated chronic myeloid leukemia (CML) patients. Although IM pharmacokinetics is influenced by several enzymes and transporters, little is known about the role of pharmacogenetic variation in IM metabolism. In this study, associations between IM trough concentration, clinical response and 11 single-nucleotide polymorphisms in genes involved in IM pharmacokinetics (ABCB1, ABCC2, ABCG2 CYP3A5, SLC22A1 and SLCO1B3) were investigated among 67 Japanese chronic phase CML patients. IM trough concentration was significantly higher in patients with a major molecular response than in those without one (P=0.010). No significant correlations between IM trough concentration and age, weight, body mass index or biochemical data were observed. However, the dose-adjusted IM trough concentration was significantly higher in patients with ABCG2 421A than in those with 421C/C (P=0.015). By multivariate regression analysis, only ABCG2 421A was independently predictive of a higher dose-adjusted IM trough concentration (P=0.015). Moreover, previous studies have shown that the ABCG2 421C>A (p.Q141K) variant is prevalent among Japanese and Han Chinese individuals and less common among Africans and Caucasians. Together, these data indicate that plasma IM concentration monitoring and prospective ABCG2 421C>A genotyping may improve the efficacy of IM therapy, particularly among Asian CML patients.

Influence of SLC22A1 (hOCT1) polymorphisms on imatinib mesylate pharmacokinetics in Asian patients with chronic myelogenous leukemia.

e13594 Background: This study aimed to explore the influence of SLC22A1 IVS2+797C>G (rs4646274) polymorphism on the pharmacokinetics of imatinib mesylate (IM) in Asian patients with chronic myelogenous leukemia (CML). Methods: A total of 37 patients were enrolled in a prospective pharmacogenetic study conducted in patients with CML, all receiving IM median dose 400 mg/day (range: 300-800 mg/day). The median age and weight of patients were 49 years (range: 24-71 years) and 68 kg (range: 47-135.5 kg) respectively. The majority of the patients were Chinese (86.5%) followed by Malays (10.8%) and Indians (2.7%). IM pharmacokinetics (C0h, C2h, and CL) were determined in the CML patients. SLC22A1 polymorphism IVS2+797C>G (rs4646274) was determined in all patients. The nonparametric Mann-Whitney U test and Kruskal-Wallis test were used to find the association between rs4646274 genotype status and IM pharmacokinetics in the CML patients. Results: The genotype frequencies of rs4646274 SNP were CC (37.8%); CG (40.5%...

The pharmacogenetics of imanitib

Imatinib mesylate (IM), a tyrosine kinase inhibitor, is one of the first molecularly targeted therapies to have been used in the clinic. It has proven to be efficient in the treatment of chronic myeloid leukemia and also in other malignancies that involve expression of a tyrosine kinase. However, some patients can develop resistance and others suffer from toxic side effects. The pharmacokinetics of IM depends on several enzymes and transporters, and several studies have attempted to identify genetic factors associated with variable drug levels and clinical responses using a candidate gene approach. Larger and more homogenous studies are still needed to replicate the findings obtained so far, or to analyze other genetic variations to get clearer insights into how IM treatment can be tailored to each patient's genetics. Here we summarize pharmacogenetic studies of IM and highlight the genetic markers that could be used to improve the treatment and management of diseases for which IM is used.

Imatinib Mesylate Pharmacokinetics Before and After Sleeve Gastrectomy in a Morbidly Obese Patient with Chronic Myeloid Leukemia

Abstract Imatinib is widely used to treat chronic myeloid leukemia and gastrointestinal stromal tumors. The agent, administered orally, has approximately 98% oral bioavailability, achieves maximum plasma concentration approximately 2-4 hours after ingestion, and has a plasma half-life of approximately 18 hours. As maintaining an adequate plasma imatinib concentration is essential to achieving a favorable therapeutic response, it is important to determine whether gastrointestinal surgery, pathologic conditions, or anatomic changes negatively affect imatinib absorption, and thereby result in subtherapeutic plasma imatinib concentrations. We describe a 36-year-old, morbidly obese woman with chronic myeloid leukemia who received treatment with alpha-interferon and cytarabine over 5 years. Her chemotherapy was then switched to imatinib 400 mg/day because she failed to achieve a molecular response with the other two agents. A complete molecular response was achieved with imatinib. Four years later, she underwent a sleeve gastrectomy while receiving imatinib. Imatinib plasma pharmacokinetic values were assessed before and on four occasions during the year after the sleeve gastrectomy. The patient's trough plasma concentration before surgery (1558 ng/ml) was consistent with those found in the literature (>/= 1000 ng/ml), whereas her trough concentrations after surgery were 46-60% lower (629-836 ng/ml) than the preoperative value. Despite this, the patient remained in complete molecular remission for 1 year after surgery. Monitoring plasma imatinib concentrations is recommended in morbidly obese patients with chronic myeloid leukemia or gastrointestinal stromal tumors who undergo gastric procedures. Additional pharmacokinetic studies, however, are needed in these patients.

Phase I/II Study of Imatinib Mesylate for Recurrent Malignant Gliomas: North American Brain Tumor Consortium Study 99-08

Phase I: To determine the maximum tolerated doses, toxicities, and pharmacokinetics of imatinib mesylate (Gleevec) in patients with malignant gliomas taking enzyme-inducing antiepileptic drugs (EIAED) or not taking EIAED. Phase II: To determine the therapeutic efficacy of imatinib. Phase I component used an interpatient dose escalation scheme. End points of the phase II component were 6-month progression-free survival and response. Fifty patients enrolled in the phase I component (27 EIAED and 23 non-EIAED). The maximum tolerated dose for non-EIAED patients was 800 mg/d. Dose-limiting toxicities were neutropenia, rash, and elevated alanine aminotransferase. EIAED patients received up to 1,200 mg/d imatinib without developing dose-limiting toxicity. Plasma exposure of imatinib was reduced by approximately 68% in EIAED patients compared with non-EIAED patients. Fifty-five non-EIAED patients (34 glioblastoma multiforme and 21 anaplastic glioma) enrolled in the phase II component. Patients initially received 800 mg/d imatinib; 15 anaplastic glioma patients received 600 mg/d after hemorrhages were observed. There were 2 partial response and 6 stable disease among glioblastoma multiforme patients and 0 partial response and 5 stable disease among anaplastic glioma patients. Six-month progression-free survival was 3% for glioblastoma multiforme and 10% for anaplastic glioma patients. Five phase II patients developed intratumoral hemorrhages. Single-agent imatinib has minimal activity in malignant gliomas. CYP3A4 inducers, such as EIAEDs, substantially decreased plasma exposure of imatinib and should be avoided in patients receiving imatinib for chronic myelogenous leukemia and gastrointestinal stromal tumors. The evaluation of the activity of combination regimens incorporating imatinib is under way in phase II trials.

The Influence of St. John's Wort on the Pharmacokinetics and Protein Binding of Imatinib Mesylate

To determine the effect of St. John's wort on the pharmacokinetics of imatinib mesylate. Open-label, complete crossover, fixed-sequence, pharmacokinetic study. Clinical research center. Ten healthy adult volunteers. Single 400-mg oral doses of imatinib were administered before and after 2 weeks of treatment with St. John's wort 300 mg 3 times/day. The pharmacokinetics of imatinib were significantly altered by St. John's wort, with reductions of 32% in the median area under the concentration-time curve from time zero to infinity (p=0.0001), 29% in maximum observed concentration (p=0.005), and 21% in half-life (p=0.0001). Protein binding ranged from 97.7-90.3% (mean 94.9%), was concentration independent, and was not altered by St. John's wort. Therapeutic outcomes of imatinib have been shown to correlate with both dose and drug concentrations. Coadministration of imatinib with St. John's wort may compromise imatinib's clinical efficacy.

Efficacy and pharmacokinetics of imatinib mesylate in a child with chronic myeloid leukemia

Efficacy and pharmacokinetics of imatinib mesylate in a child with chronic myeloid leukemia