Optimal exposure to docetaxel in adjuvant chemotherapy for early-stage breast cancer.

WHAT IS KNOWN AND OBJECTIVE: Drug-induced neutropenia is the main reason for the dose limitation of docetaxel in patients with breast cancer. The area under the drug concentration-time curve (AUC) of docetaxel is associated with neutropenia. However, the optimal exposure to docetaxel for receiving postoperative adjuvant chemotherapy remains unclear. Therefore, we aimed to evaluate the relationship between the docetaxel AUC and neutropenia, identify potential influencing factors, and explore the best monitoring target for docetaxel when treating patients with early-stage breast cancer using a population pharmacokinetic (PopPK) model. METHODS: Docetaxel plasma concentration, demographics, clinical data, and related laboratory data were collected. PopPK analyses were performed using a nonlinear mixed-effect modelling program. The docetaxel AUC was determined using the maximum a posteriori Bayesian (MAPB) method. The docetaxel exposure-toxicity threshold measured from the AUC for neutropenia was determined using the receiver operating characteristic (ROC) curve. The correlation between docetaxel exposure and neutropenia was analysed using multivariable logistic regression. RESULTS: Among the 70 participants, 47 (67.1%) developed severe neutropenia. The PopPK analysis showed that the typical drug clearance (CL) rate was 37.4 L/h. Age was a significant covariate of CL rate, and aspartate aminotransferase and albumin levels were covariables of the volume of distribution. The multivariable regression analysis showed that AUC >3.0 mg.h/L (odds ratio [OR], 5.940; 95% confidence interval [CI], 1.693-20.843; P = 0.005), platinum use (OR, 0.156; 95% CI, 0.043-0.562; P = 0.005) and baseline haemoglobin level (OR, 0.938; 95% CI, 0.887-0.993; P = 0.027) were significant factors influencing the occurrence of grade 3/4 neutropenia. The AUC of first cycle may not predict the occurrence rates of grade 3/4 neutropenia in later cycles. WHAT IS NEW AND CONCLUSION: We developed a docetaxel PopPK model for patients with early-stage breast cancer. Age and AST and ALB levels were significant covariates. AUC estimated using the MAPB method can predict the toxicity of docetaxel in patients with breast cancer. Docetaxel AUC >3.0 mg.h/L, absence of platinum use and low baseline haemoglobin level were risk factors for docetaxel-induced grade 3/4 neutropenia. STUDY REGISTRATION: Chinese Clinical Trial Center Registry (ChiCTR2200056460).

Prognostic Value of Two Polymorphisms, rs1045642 and rs1128503, in ABCB1 Following Taxane-based Chemotherapy: A Meta-Analysis.

OBJECTIVE: Genetic polymorphisms can influence the chemotherapeutic response; however, previous studies have produced conflicting results, and have failed to identify the most relevant polymorphisms for predicting the response to treatment in patients with cancer. The present meta-analysis was conducted to determine the correlation between two polymorphisms (rs1045642 and rs1128503) in ATP-binding cassette transporter B subfamily member 1 (ABCB1), which is associated with multidrug resistance, and the survival of patients treated with taxane-containing chemotherapy. METHODS: Several databases, including PubMed and Embase, were used to retrieve articles evaluating the association between the ABCB1 rs1045642 and rs1128503 polymorphisms and survival, published prior to August 2019. The meta-analysis was conducted using R software to determine the pooled hazard ratio (HR) and 95% confidence intervals (95% CIs). RESULTS: Fifteen studies involving 3320 patients were included in the meta-analysis. The effect of the rs1128503 polymorphism on progression-free survival remained significant in the heterozygote (HR 0.81; 95% CI: 0.67-0.98) and homozygote (HR 0.71; 95% CI: 0.58-0.88) models. The TT genotype rs1128503 was associated with better overall survival (HR 0.72; 95% CI: 0.53-0.97). CONCLUSION: Carriers of the rs1128503 T allele of ABCB1 showed a survival benefit after taxane-containing chemotherapy.

Vancomycin-induced severe thrombocytopenia in a young infant

Abstract Vancomycin is a first-line drug for treating methicillin-resistant Staphylococcus aureus. Thrombocytopenia is a rare adverse reaction to vancomycin treatment, and there are no reports of vancomycin-induced thrombocytopenia (VIT) in infants. We describe the case of a 3-month-old girl who was diagnosed with purulent meningitis. After 13 days of treatment with vancomycin, her platelet count reduced to 8 × 109/L. Vancomycin was discontinued, and intravenous methylprednisolone was administered. The platelet count returned to normal after 4 days. Patients, especially young children, receiving vancomycin for a long clinical course should undergo careful monitoring of laboratory indicators and blood tests.