Plasma Docetaxel Concentration Research Articles

A sub-pharmacological test dose does not predict individual docetaxel exposure in prostate cancer patients

PurposeDocetaxel is a cytotoxic drug used for first-line treatment of various malignancies. It has a narrow therapeutic index and shows wide interpatient variability in clearance and toxicity. Tools for individual dose optimization are needed to maximize efficacy and avoid toxicity.MethodsWe performed a proof-of-concept study (EudraCT 2016-003785-77) to evaluate whether pharmacokinetics after a sub-pharmacological test dose of 1000 µg docetaxel (millidose) could be used to predict therapeutic dose exposure. Thirty prostate cancer patients eligible for treatment with docetaxel as part of routine clinical care were included. An intravenous docetaxel millidose was administered 1–7 days prior to therapeutic docetaxel. After both doses plasma docetaxel concentrations were measured by ultra- high performance liquid chromatography-tandem mass spectrometry. The docetaxel clearance was estimated with non-linear mixed effects modeling.ResultsGeometric mean docetaxel clearance was 57.9 L/h (GCV 78.6%) after admission of a millidose and 40.3 L/h (GCV 60.7%) after admission of a therapeutic dose. The millidose and therapeutic dose in a single patient were not significantly correlated (Spearman’s rho R = 0.02, P = 0.92).ConclusionDocetaxel pharmacokinetics at milli- and therapeutic dose level showed insufficient correlation for individual dose optimization. However, the clearance of a docetaxel millidose and full dose are within the same order of magnitude. Therefore, docetaxel millidose pharmacokinetics could potentially facilitate prediction of docetaxel pharmacokinetics at a population level in situations where therapeutic dose levels are impractical, such as pharmacokinetic drug-drug interaction studies or pediatric studies.

ModraDoc006, an oral docetaxel formulation in combination with ritonavir (ModraDoc006/r), in metastasized castration-resistant prostate cancer (mCRPC): A multicenter phase I study.

79 Background: ModraDoc006 is a novel formulation of docetaxel and to enhance bioavailability, this tablet is co-administered with ritonavir (r), an inhibitor of cytochrome p450 3A4 and P-glycoprotein. The safety, anti-tumor activity and pharmacokinetics (PK) of ModraDoc006/r were investigated by dose-escalation in patients with mCRPC, to propose a recommended phase 2 dose (RP2D). Methods: Progressive mCRPC patients, who were treatment naïve or previously treated with either abiraterone or enzalutamide, received a maximum of 30 weekly cycles of ModraDoc006/r in a bi-daily once weekly (BIDW) schedule. Plasma docetaxel concentrations were determined at the first 2 cycles up to 48h after intake of ModraDoc006/r. Adverse events were evaluated using the Common Terminology Criteria for Adverse Events (CTCAE) version 4.03. Serum Prostate Specific Antigen (PSA) levels were assessed every 6 weeks. Results: 23 patients were included, of whom 20 were evaluable for safety and PK. In 5 patients, the initial 30-20/100-100 dose was explored, with observation of one dose limiting toxicity (DLT) (grade 3 alanine aminotransferase increase). The next dose level of 30-20/200-200 resulted in 2 DLTs in 6 patients (grade 3 diarrhea and mucositis). Subsequently, two intermediate dose levels: 30-20/200-100 and 20-20/200-100 were explored in 6 and 3 patients. At the 30-20/200-100 dose, an adequate docetaxel exposure was achieved and 1 DLT (grade 3 diarrhea) was observed, with no DLTs at the 20-20/200-100 dose. Common treatment-related AEs (occurring in > 30% of all patients) were diarrhea, nausea, vomiting, anorexia and fatigue. Five patients completed the maximum of 30 weekly treatments. In 10 patients, evaluable for anti-tumor activity after treatment with ≥9 cycles, 4 confirmed and 2 non-confirmed PSA responses ( > 50% decrease) were observed. Conclusions: The RP2D of BIDW ModraDoc006/r in mCRPC was established as 30-20/200-100 mg. These results are encouraging for further development of ModraDoc006/r as a convenient, safe and effective alternative to IV docetaxel for mCRPC patients. A phase 2b study is currently being conducted. Clinical trial information: NCT03136640.

Preparation, characterization, and pharmacokinetics of liposomal docetaxel for oral administration

A docetaxel (DTX) liposomal formulation composed of egg phosphatidylcholine, sodium deoxycholate, and stearylamine was developed. Eudragit (0.5%) was coated to deliver the drug to the region between the distal small intestine and the colon. Lyophilized trehalose and mannitol were used as cryoprotectants because they preserve the particle integrity and good appearance. In vitro release studies showed that the amount of drug released from the coated liposomes was low in solution 1, which simulated the pH condition of the stomach. Especially during the average gastric emptying time, the amount of drug released decreased when Eudragit was added. The plasma DTX concentration was evaluated in pharmacokinetic studies. The plasma drug concentration after intravenous (i.v.) administration decreased rapidly within 120min. Free DTX formulated using Tween 80 and the lyophilized Eudragit-coated liposomal formulation were compared after oral administration. The oral liposomal formulation had a longer half-life (t1/2) and three-fold higher oral bioavailability. Thus, lyophilized Eudragit-coated liposomal DTX could be a promising therapy for various solid tumors to improve patient convenience and quality of life.

Clinical value of monitoring of plasma docetaxel concentration in patients with breast cancer in AC-T sequential chemotherapy

Objective To investigate the relationship between plasma docetaxel concentration and the efficacy as well as toxic and side effects in patients with breast cancer after chemotherapy. Methods Seventy-one patients with breast cancer who accepted AC sequential T chemotherapy regimen as first line treatment were selected from April 2015 to September 2015 in Hubei Provicial Tumor Hospital.The plasma concentration of docetaxel was detected by latex immunoturdidimetry after the docetaxel continuous infusion in each cycle.The three groups were assigned according to the concentration distribution of docetaxel: group A (plasma concentration docetaxel ≤ 2.0mg·h-1·L-1), group B (2.1-2.5mg·h-1·L-1) and group C (≥2.6 mg·h-1·L-1). The relationship between the drug plasma concentration, therapeutic efficacy and adverse reactions in different docetaxel plasma concentration was analyzed retrospectively by Chi-square tests. Results The average plasma concentrations of docetaxel of the three groups were (1.55±0.36)mg·h-1·L-1, (2.28±0.13)mg·h-1·L-1, (2.87±0.38)mg·h-1·L-1 respectively.The adverse reactions were enhanced with the increasing of docetaxel plasma concentration (χ2=5.169, 4.463, 3.630, P=0.023, 0.035, 0.047). The therapeutic efficacy of group C and group B was same(95.8%), which was higher than 87.0% of group A, but there was no statistically significant difference(χ2=1.559, P=0.24). Conclusion Breast cancer patients whose plasma concentration of docetaxel is between 2.1~2.5mg·h-1·L-1 has a better prognosis, and its adverse reactions are controlled in a certain extent. Key words: Breast Neoplasms; Docetaxel; Drug Monitoring

Oral delivery system prolongs blood circulation of docetaxel nanocapsules via lymphatic absorption

An original oral formulation of docetaxel nanocapsules (NCs) embedded in microparticles elicited in rats a higher bioavailability compared with the i.v. administration of the commercial docetaxel solution, Taxotere. In the present study, various animal studies were designed to elucidate the absorption process of docetaxel from such a delivery system. Again, the docetaxel NC formulation elicited a marked enhanced absorption compared with oral Taxotere in minipigs, resulting in relative bioavailability and Cmax values 10- and 8.4-fold higher, respectively, confirming the previous rat study results. It was revealed that orally absorbed NCs altered the elimination and distribution of docetaxel, as shown in the organ biodistribution rat study, due to their reinforced coating, while transiting through the enterocytes by surface adsorption of apoproteins and phospholipids. These findings were demonstrated by the cryogenic-temperature transmission electron microscopy results and confirmed by the use of a chylomicron flow blocker, cycloheximide, that prevented the oral absorption of docetaxel from the NC formulation in an independent pharmacokinetic study. The lipoproteinated NCs reduced the docetaxel release in plasma and its distribution among the organs. The improved anticancer activity compared with i.v. Taxotere, observed in the metastatic lung cancer model in Severe Combined Immune Deficiency-beige (SCID-bg) mice, should be attributed to the extravasation effect, leading to the lipoproteinated NC accumulation in lung tumors, where they exert a significant therapeutic action. To the best of our knowledge, no study has reported that the absorption of NCs was mediated by a lymphatic process and reinforced during their transit.

Involvement of Wee1 in the Circadian Rhythm–Dependent Intestinal Damage Induced by Docetaxel

Docetaxel, a semisynthetic taxane, is effective for the treatment of some solid cancers; however, docetaxel-induced intestinal damage leads to poor prognosis in some patients. Although such adverse effects have been reported to depend on the dosing-time of docetaxel, the mechanisms involved remain unclear. Wee1 expression is controlled by the clock gene complex, clock/bmal1, and contributes to cell-cycle progression. The present study was undertaken to evaluate the potential role of Wee1 in the circadian rhythm-dependent profile of docetaxel. Male mice were maintained under a 12-hour light/dark cycle. Intestinal damage after repeated dosing of docetaxel (20 mg/kg) for 3 weeks was more severe at 14 hours after light on (HALO) than at 2 HALO. The intestinal protein expressions of Wee1, phosphorylated CDK1, and cleaved Caspase-3 were higher in the 14-HALO group than in the 2-HALO group, whereas that of survivin was lower in the 14-HALO group. Thus, it is speculated that elevated Wee1 expression inhibited CDK1 activity more by phosphorylation, which in turn caused the lower expression of survivin and consequently more activated Caspase-3 in the 14-HALO group. There were no significant differences in plasma docetaxel concentrations between the 2- and 14-HALO groups. Bindings of CLOCK and BMAL1 to the E-box regions at the wee1 gene promoter were not altered by docetaxel treatment at 2 and 14 HALO. These findings suggest that Wee1 is directly or indirectly involved in the mechanism of the circadian rhythm-dependent changes in docetaxel-induced intestinal damage. However, the mechanism for a circadian rhythm-dependent change in intestinal Wee1 expression by docetaxel remains to be determined.

Quantification of docetaxel plasma concentrations using a novel nanoparticle-based immunoassay.

e11545 Background: Docetaxel is a commonly used antineoplastic agent of the taxoid family. The pharmacokinetic profile of docetaxel has up to 10-fold inter-patient variability in total clearance and up to 7-fold in total exposure (AUC). This variability may result in severe toxicities and poor outcomes. Docetaxel AUC was shown to be a significant predictor of time to progression (TTP) and severe adverse events in non-small cell lung cancer. A new nanoparticle-based docetaxel immunoassay provides a rapid, simple and cost-effective drug concentration measurement as compared to current chromatographic methods. Methods: Novel antibodies to docetaxel were covalently linked to nanoparticles to develop a prototype automated, homogenous immunoassay. The assay was applied to the Beckman Coulter AU400 clinical analyzer. Total imprecision and linearity of the assay were evaluated by testing normal human plasma pools spiked with different levels of docetaxel. Background was determined by measuring >200 normal human plasma samples. Results: Within a quantitation range of 50 to 1000ng/mL and using instrument auto-dilution, plasma levels of docetaxel can be measured up to 10,000ng/mL with only 2µl sample size. This test range covers clinically relevant drug concentrations and can be used to calculate the systemic exposure (AUC) of docetaxel. Time-to-first result was < 9min, and 400 samples per hour could be measured. The total imprecision of plasma pools spiked with docetaxel at four concentrations across the assay range was <6% CV and the assay was linear from 50 to 1000ng/mL. Background of the assay was found to be < 10 ng/mL. The assay cross-reactivity to docetaxel hydroxy-tertbutyl carbamate, the major metabolite of docetaxel, was 20%, and <1% for 10-deacetylbaccatin, a degradation product of docetaxel. These were shown to have no significant impact on the quantitation of docetaxel. Conclusions: This rapid immunoassay is suitable for routine measurement of plasma docetaxel concentrations with only 2ul sample size and within ten minutes and could provide a tool for optimization of docetaxel blood levels for pharmacokinetic-guided dosing.

Interethnic differences in Cyp3A4 inhibition by ketoconazole on docetaxel pharmacokinetics (PK) and pharmacodynamics (PD)

2526 Background: Use of concomitant medications that inhibit drug metabolizing enzymes such as Cyp3A4 is common and may affect chemotherapy PK/PD. We studied the effects of Cyp3A4 inhibition with ketoconazole on docetaxel PK/PD in 3 Asian ethnic groups. Methods: Two cohorts of chemonaive breast cancer patients were compared. The first cohort comprised of 95 patients (62 Chinese, 26 Malay, 7 Indian) treated with 75mg/m2 docetaxel unmodulated by ketoconazole, while the second cohort comprised of 31 patients (14 Chinese, 14 Malay, 3 Indian) treated with docetaxel 70mg flat dose modulated by oral ketoconazole, a regimen we previously reported to result in comparable docetaxel AUC as 75mg/m2 docetaxel. Plasma docetaxel concentrations were obtained at 0, 0.5, 1, 2, 5, 7 and 24 hours, and blood counts monitored on days 8 and 15 of cycle 1. Results: No significant differences in docetaxel PK or neutropenia between the races were observed in response to 75mg/m2 docetaxel unmodulated by ketoconazole (docetaxel clearance 36.4±16.9, 34.3±12.5, 44.2±27.7L/h, p=0.702; docetaxel AUC 3.6±2.7, 3.5±1.2, 2.9±1.3mg/L h, p=0.418; day 8 neutrophil count 0.5±0.6, 0.8±0.8, 0.4±0.3x109/L, p=0.138; grade 4 neutropenia 66%, 50%, 86%, p=0.157). In contrast, when docetaxel was administered with ketoconazole to inhibit Cyp3A4, inter-ethnic differences in docetaxel PK/PD were observed, with Chinese having the lowest docetaxel clearance and highest docetaxel AUC, followed by Malays and Indians (docetaxel clearance 18.6±5.7, 23.7±9.3, 30.6±6.7L/h, p=0.048; p=0.017 trend test; docetaxel AUC 4.2±1.4, 4.1±3.9, 2.4±0.5 mg/L h, p=0.048, p=0.017 trend test), although there were no statistically significant differences in body weight or surface area between the races. In concordance, Chinese patients experienced greatest degree of myelosuppression, followed by Malays and Indians (day 8 neutrophil count 0.8±0.8, 1.5±1.1, 1.7±1.1x109/L, p=0.046, p=0.013 trend test), and were more likely to develop grade 4 neutropenia (57%, 14%, 0%, p=0.024) from docetaxel + ketoconazole. Conclusions: Inter-ethnic differences in CYP3A inhibition by ketoconazole exist, and are important when evaluating the impact of concomitant medications with chemotherapy that may inhibit Cyp3A4. No significant financial relationships to disclose.

Clinical pharmacodynamic factors in docetaxel toxicity

Neutropenia is the main dose-limiting toxicity occurring in docetaxel treatment. The objective of this study was to identify pharmacodynamic (PD) factors responsible for the neutropaenia caused by docetaxel. Data were obtained from 92 patients treated with docetaxel as a monochemotherapy in two different treatment centres. A semiphysiological population pharmacokinetic–pharmacodynamic (PK/PD) model was applied to describe the time course of neutrophils and the neutropaenic effect of docetaxel. The plasma docetaxel concentration was assumed to inhibit the proliferation of neutrophil precursors through a linear model: Drug effect=Slope × Conc. Slope corresponds to the patients’ sensitivity to the neutropaenic effect of docetaxel. Covariate analysis was performed by testing the relationship between the patients’ characteristics and Slope using the program NONMEM. The neutropaenic effect of docetaxel showed a high interindividual variability. Three significant PD covariates were identified: serum α1-acid glycoprotein levels (AAG), level of chemotherapy pretreatment, and treatment centre. Extensive pretreatment was associated with an increase in Slope values meaning a higher haematotoxicity. An increase in AAG was associated with a decrease of both Slope and docetaxel plasma clearance. Patients treated in one centre had both higher Slope and docetaxel clearance. The centre effect (most likely due to a bias in the PK part of the study between the two centres) reveals the robustness of the PK/PD model. Individual dosing of docetaxel should be based on previous chemotherapy but not on the AAG level since it has a similar influence on PD and PK docetaxel parameters. This methodology should be applied to further investigate elderly patients and to identify more precisely the characteristics of previous chemotherapy that contribute to the cumulative myelotoxicity.

A Comparison of the Pharmacokinetics and Pharmacodynamics of Docetaxel between African-American and Caucasian Cancer Patients: CALGB 9871

Increased clearance of drugs, such as oral cyclosporine, that are CYP3A and/or ABCB1 (P-gp/MDR1) substrates was reported in African-American compared with Caucasian patients. We hypothesized that the pharmacokinetics and pharmacodynamics of docetaxel, an i.v. administered cytotoxic and substrate for CYP3A4, CYP3A5, and ABCB1, would differ between African-American and Caucasian patients. We investigated population pharmacokinetics and pharmacodynamics and the pharmacogenetics of CYP3A4, CYP3A5, and ABCB1 in African-American and Caucasian cancer patients who received docetaxel 75 or 100 mg/m(2) as a 1-h i.v. infusion. Plasma docetaxel concentrations were measured by high-performance liquid chromatography. Clinical toxicity and absolute neutrophil count (ANC) were monitored on days 8, 15, and 22 postadministration of docetaxel. Using a limited sampling strategy and nonlinear mixed-effects modeling, each patient's docetaxel clearance was estimated. Genotyping for known polymorphisms in CYP3A4, CYP3A5, and ABCB1 was done. We enrolled 109 patients: 40 African-Americans (26 males; 14 females), with a median age of 61 years (range, 29-73), and 69 Caucasians (43 males; 26 females), with a median age of 63 years (range, 38-81). There was no difference in the geometric mean docetaxel clearance between African-American patients [40.3 L/h; 95% confidence interval (95% CI), 19.3-84.1] and Caucasian patients (41.8 L/h; 95% CI, 22.0-79.7; P = 0.6). We observed no difference between African-American and Caucasian patients in the percentage decrease in ANC nor were docetaxel pharmacokinetic parameters related to the genotypes studied. Docetaxel clearance and its associated myelosuppression were similar in African-American and Caucasian cancer patients.

Phase I and pharmacokinetic evaluation of the combination of orally administered docetaxel and cyclosporin A in tumor-bearing dogs

To determine the maximum tolerated dose and characterize the pharmacokinetic disposition of an orally administered combination of docetaxel and cyclosporin A (CSA) in dogs with tumors. 16 client-owned dogs with metastatic or advanced-stage refractory tumors. An open-label, dose-escalation, single-dose, phase I study of docetaxel administered in combination with a fixed dose of CSA was conducted. Docetaxel (at doses of 1.5, 1.625, or 1.75 mg/kg) and CSA (5 mg/kg) were administered concurrently via gavage twice during a 3-week period. Plasma docetaxel concentrations were quantified by use of high-performance liquid chromatography, and pharmacokinetic disposition was characterized by use of noncompartmental analysis. Dogs' clinical signs and results of hematologic and biochemical analyses were monitored for evidence of toxicosis. No acute hypersensitivity reactions were observed after oral administration of docetaxel. Disposition of docetaxel was dose independent over the range evaluated, and pharmacokinetic variables were similar to those reported in previous studies involving healthy dogs, with the exception that values for clearance were significantly higher in the dogs reported here. The maximum tolerated dose of docetaxel was 1.625 mg/kg. Gastrointestinal signs of toxicosis were dose limiting. The absence of myelosuppression suggested that the docetaxel-CSA combination may be administered more frequently than the schedule used. Further studies are warranted to evaluate combination treatment administered on a biweekly schedule in dogs with epithelial tumors.

Pharmacokinetics and tissue distribution of intraperitoneal docetaxel with different carrier solutions

Background Intraperitoneal chemotherapy administration results in high drug concentration locally with low systemic toxicity. Using a rat model we compared the pharmacokinetics and tissue absorption of docetaxel infused intraperitoneally in two isotonic carrier solutions; 1.5% dextrose peritoneal dialysis solution (peritoneal dialysis solution) and hetastarch (6% hydroxyethyl starch), a high molecular weight solution. Materials and methods Sixty Sprague–Dawley rats were randomized into groups according to the carrier solution administered. Rats were given a single dose of intraperitoneal docetaxel (80 mg/m 2) in 0.1 ml/g body weight of each carrier solution. Each group was further randomized according to the intraperitoneal dwell period (3, 6, 12, 18, and 24 h). At the end of the procedure the rats were killed, the peritoneal fluid was withdrawn completely and the volume recorded. Blood and tissues were sampled using a standardized protocol. Drug concentrations in peritoneal fluid, plasma, and tissues were determined by high-performance liquid chromatography. Results Hetastarch clearance from the peritoneal cavity was reduced when compared to peritoneal dialysis solution. The mean volumes remaining in the peritoneal cavity were significantly higher with hetastarch at 6 h ( P = 0.022) and 12 h ( P = 0.0012). Plasma docetaxel concentrations were similar for both carrier solutions. The mean total amount of docetaxel remaining in the peritoneal cavity was significantly greater with hetastarch at 3 h ( P = 0.0022), 6 h ( P = 0.0043), and 12 h ( P = 0.0023). There was a 39% increase in the area under the curve ratio of peritoneal fluid to plasma docetaxel concentrations with hetastarch (227) versus peritoneal dialysis solution (163). Docetaxel concentrations were significantly greater with hetastarch in colonic tissue at 18 and 24 h, and in gastric tissue at 6, 12, and 18 h. Conclusion The use of intraperitoneal docetaxel with a hetastarch carrier solution provides a pharmacologic advantage for a local-regional killing of residual intraperitoneal tumor cells without increasing systemic toxicity.