A pharmacometrics model to define docetaxel target in early breast cancer

The Efficacy Research of Prophylactic PEG-rhG-CSF in Preventing Neutropenia in Early-Stage Breast Cancer Patients Treated With Docetaxel-Based Chemotherapy: A Retrospective Analysis

PURPOSE

Docetaxel-based chemotherapy regimens (DBRs) are commonly used in the treatment of early-stage breast cancer (EBC). The prophylactic use of pegylated recombinant human granulocyte colony-stimulating factor (PEG-rhG-CSF) has been shown to reduce the incidence of neutropenia induced by DBRs. However, the clinical usage of PEG-rhG-CSF in EBC patients undergoing DBRs in China remains unclear.

METHODS

This retrospective study was conducted in 137 EBC patients receiving DBRs from September 2022 to February 2024. We compared the incidence of chemotherapy-induced neutropenia (CIN) between patients who was treated with prophylactic PEG-rhG-CSF or not by complete blood counts, evaluating the effectiveness of PEG-rhG-CSF in preventing CIN. Prophylactic PEG-rhG-CSF was given at 100 μg/kg body weight (maximum total dosage of 6 mg) once 24-48 h following chemotherapy. Meanwhile, we also collected basic patient information, the area under time-concentration curve of docetaxel, and liver and kidney function indicators. Multivariate logistic regression and Receiver operating characteristic (ROC) curve analysis were employed to explore independent factors influencing neutropenia.

FINDINGS

In this study, 87 of 137 EBC patients were administrated with prophylactic PEG-rhG-CSF, while 50 were not. Compared to patients who did not receive PEG-rhG-CSF, those who received prophylactic injections had a significantly lower incidence of grade 3-4 CIN (20% vs. 4.6%, P < 0.05). Higher body surface area (BSA), lower body mass index (BMI), elevated alanine aminotransferase (ALT), and nonprophylactic use of PEG-rhG-CSF were found to be positively correlated with CIN occurrence. ROC curve analysis indicated an area under the curve of 0.756 for predicting CIN in EBC patients when BSA was 1.66 m², BMI was 24.8 kg/m², and ALT was 41 U/L, with a sensitivity of 73.08% and specificity of 73.87%.

IMPLICATIONS

Prophylactic use of PEG-rhG-CSF significantly reduces the incidence of CIN, particularly grades 3 and 4. BSA, BMI, ALT, and PEG-rhG-CSF prophylaxis are independent influencing factors for the occurrence of neutropenia.

Oral docetaxel plus encequidar - A pharmacokinetic model and evaluation against IV docetaxel

The development of optimized dosing regimens plays a crucial role in oncology drug development. This study focused on the population pharmacokinetic modelling and simulation of docetaxel, comparing the pharmacokinetic exposure of oral docetaxel plus encequidar (oDox + E) with the standard of care intravenous (IV) docetaxel regimen. The aim was to evaluate the feasibility of oDox + E as a potential alternative to IV docetaxel. The article demonstrates an approach which aligns with the FDA's Project Optimus which aims to improve oncology drug development through model informed drug development (MIDD). The key question answered by this study was whether a feasible regimen of oDox + E existed. The purpose of this question was to provide an early GO / NO-GO decision point to guide drug development and improve development efficiency.

METHODS

 A stepwise approach was employed to develop a population pharmacokinetic model for total and unbound docetaxel plasma concentrations after IV docetaxel and oDox + E administration. Simulations were performed from the final model to assess the probability of target attainment (PTA) for different oDox + E dose regimens (including multiple dose regimens) in relation to IV docetaxel using AUC over effective concentration (AUCOEC) metric across a range of effective concentrations (EC). A Go / No-Go framework was defined-the first part of the framework assessed whether a feasible oDox + E regimen existed (i.e., a PTA ≥ 80%), and the second part defined the conditions to proceed with a Go decision.

RESULTS

 The overall population pharmacokinetic model consisted of a 3-compartment model with linear elimination, constant bioavailability, constant binding mechanics, and a combined error model. Simulations revealed that single dose oDox + E regimens did not achieve a PTA greater than 80%. However, two- and three-dose regimens at 600 mg achieved PTAs exceeding 80% for certain EC levels.

CONCLUSION

 The study demonstrates the benefits of MIDD using oDox + E as a motivating example. A population pharmacokinetic model was developed for the total and unbound concentration in plasma of docetaxel after administration of IV docetaxel and oDox + E. The model was used to simulate oDox + E dose regimens which were compared to the current standard of care IV docetaxel regimen. A GO / NO-GO framework was applied to determine whether oDox + E should progress to the next phase of drug development and whether any conditions should apply. A two or three-dose regimen of oDox + E at 600 mg was able to achieve non-inferior pharmacokinetic exposure to current standard of care IV docetaxel in simulations. A Conditional GO decision was made based on this result and further quantification of the "effective concentration" would improve the ability to optimise the dose regimen.

Bicalutamide Enhances Conventional Chemotherapy in In Vitro and In Vivo Assays Using Human and Canine Inflammatory Mammary Cancer Cell Lines

Human inflammatory breast cancer (IBC) and canine inflammatory mammary cancer (IMC) are highly aggressive neoplastic diseases that share numerous characteristics. In IBC and IMC, chemotherapy produces a limited pathological response and anti-androgen therapies have been of interest for breast cancer treatment. Therefore, the aim was to evaluate the effect of a therapy based on bicalutamide, a non-steroidal anti-androgen, with doxorubicin and docetaxel chemotherapy on cell proliferation, migration, tumor growth, and steroid-hormone secretion. An IMC-TN cell line, IPC-366, and an IBC-TN cell line, SUM149, were used. In vitro assays revealed that SUM149 exhibited greater sensitivity, reducing cell viability and migration with all tested drugs. In contrast, IPC-366 exhibited only significant in vitro reductions with docetaxel as a single agent or in different combinations. Decreased estrogen levels reduced in vitro tumor growth in both IMC and IBC. Curiously, doxorubicin resulted in low efficacy, especially in IMC. In addition, all drugs reduced the tumor volume in IBC and IMC by increasing intratumoral testosterone (T) levels, which have been related with reduced tumor progression. In conclusion, the addition of bicalutamide to doxorubicin and docetaxel combinations may represent a potential treatment for IMC and IBC.

A Cross-sectional Comparative Analysis of Eleven Population Pharmacokinetic Models for Docetaxel in Chinese Breast Cancer Patients

OBJECTIVE

Various population pharmacokinetic (PPK) models have been established to help determine the appropriate dosage of docetaxel, however, no clear consensus on optimal dosing has been achieved. The purpose of this study is to perform an external evaluation of published models in order to test their predictive performance, and to find an appropriate PPK model for Chinese breast cancer patients.

METHODS

A systematic literature search of docetaxel PPK models was performed using PubMed, Web of Science, China National Knowledge Infrastructure, and WanFang databases. The predictive performance of eleven identified models was evaluated using prediction-based and simulation-based diagnostics on an independent dataset (112 docetaxel concentrations from 56 breast cancer patients). The -2×log (likelihood) and Akaike information criterion were also calculated to evaluate model fit.

RESULTS

The median prediction error of eight of the eleven models was less than 10%. The model fitting results showed that the three-compartment model of Bruno et al. had the best prediction performance and that the three compartment model of Wang et al. had the best simulation effect. Furthermore, although the covariates that significantly affect PK parameters were different between them, seven models demonstrated that docetaxel PK parameters were influenced by liver function.

CONCLUSIONS

Three compartment PPK models may be predictive of optimal docetaxel dosage for Chinese breast cancer patients. However, for patients with impaired liver function, the choice of which model to use to predict the blood concentration of docetaxel still requires great care.