Background: Docetaxel (DTX) is a widely used anti-tumour drug, and its dosage is solely determined by body surface area (BSA). Adverse events, such as neutropenia or unsatisfied efficacy, likely occur because of differences in the pharmacokinetics (PK) and pharmacodynamics of patients. Thus, a feasible dosage adjustment method is needed.
Methods: A total of 209 eligible patients who provided consent were enrolled and randomised into two groups to receive the BSA- and PK-guided dosage adjustments of DTX-based chemotherapy (3 weeks per cycle). The AUC of DTX was detected, and the therapeutic window for Chinese patients was determined. The proportion of patients within the therapeutic window was evaluated. Neutropenia was examined in accordance with the toxicity grading standard suggested by the World Health Organisation. Tumour response was assessed in accordance with Response Evaluation Criteria in Solid Tumors version 1.1. The primary endpoint was the incidence of neutropenia, and the secondary endpoints were disease control rate (DCR) and 3-year survival rate.
Results: The therapeutic window for Chinese patients was 1.7-2.5 mg·h/L. The proportion of patients within the therapeutic window was 63.89% versus 28.33% (P < 0.0001), and the incidence of neutropenia was 68.33% versus 38.89% (P = 0.001) in the experimental group versus the control group in the sixth cycle, respectively. DCR was 72% versus 85% (P = 0.018) in the control group versus the experimental group. The 3-year survival rate of the PK group was significantly higher than that of the BSA group (P = 0.034).
Conclusions: The PK-guided dosage adjustment of DTX could significantly increase the proportion of patients within the therapeutic window, decrease the incidence of neutropenia and increase the DCR and the 3-year survival rate. The PK-guided dosage adjustment based on the dynamic monitoring of AUC could be a useful method for oncologists to improve individualised treatment options, optimise drug efficacy and reduce drug toxicity.
Keywords: Body surface area; Docetaxel; Dosage; Pharmacokinetics.