Purpose:Times above certain Paclitaxel(PTX)concentrations(Tcon)exceeding a particular threshold has been clearly shown to be related to both therapeutic efficacy and toxicity instead of traditional body surface area(BSA).Limited research has focused on the pharmacokinetic of Paclitaxel in Asian patients,especially in Nasopharyngeal Carcinoma(NPC)patients.So we conducted this prospective study to characterize the pharmacokinetic variability of PTX in Chinese NPC patients.Patients:A total of 98 NPC patients were enrolled between February 20,2014 to July 20,2015 at Sun Yat-Sen University Cancer Center.All patients received PTX and Carboplatin doublet regimen for up to 6 cycles.Blood samples were collected before and 24 hours after infusion of PTX.The pharmacokinetic analyses were carried out by examing PTX exposure expressed as Tcon.Results:PTX exposure varied greatly among patients ranging from 7 to 228μmol/L(SD 37.3μmol/L,%CV 36.1%),with Tcon ranging from 8 to 54 hours(SD 8.3 hours,%CV 21.4%),as well as different cycle of every individual patient.Based on the therapeutic PTX Tcon of 26 to 31 hours established by Jogger,the vast majority of patients(86.0%)exceeded the therapeutic range,only 8.6%patients had a Tcon within the therapeutic range and 5.4%patients had a Tcon < 26 hours in first cycle.Patients PTX exposure showed no correlation with BSA(p = 0.339).The incidence of leukopenia and neutropenia after first cycle of treatment is 79.6%(74 of 93 patients),73.1%(68 of 93 patients)respectively.In the 91 patients with evaluable imaging evaluations,percentage of patients with partial response,stable disease and disease progression were 28.6%,48.4%and 23.0%respectively.Dicussion:According to traditional BSA,patients PTX exposure varied greatly and the vast majority of patients exceeded the therapeutic range.Further study is needed to expore the correlation of PTX pharmacokinetics with toxicity and treatment response among East-Asian patients.