Explore the Individual Treatment of Docetaxel and Paclitaxel in NSCLC, NPC and BRC by PK-guided Dosing Strategy

Overview

As cytotoxic agents, DTX and PTX have a narrow therapeutic window. BSA dosing leads to great inter-individual PK variability, which is a major contributor for severe toxicity, especially in East-Asian populations. DTX exposures measured by area under plasma concentration-time curve (AUC), PTX exposures measured by the time above a plasma concentration of 0.05 µmol/L (TC\>0.05), are the most biologic effects associated PK parameters for DTX and PTX, respectively, which could positively predict related toxicities such as neutropenia, peripheral neuropathy, etc. So, we conducted a randomized clinical trial to compare the effect on related toxicities and efficacy of PK-guided dosing strategy and BSA dosing strategy.

3 populations were included: advanced NSCLC patients receive a single-agent docetaxel regimen palliative chemotherapy without restriction of lines; NPC patients receive paclitaxel and carboplatin doublet regimen whether as induction chemotherapy for local advanced patients or palliative chemotherapy for metastatic patients; BRC patients receive a single-agent docetaxel regimen after 4 cycles of adriamycin and cyclophosphamide for adjuvant chemotherapy. Patients are randomly assigned into the BSA-based dosing group and pharmacokinetically-guided dosing group. In the BSA-based dosing group, NPC patients receive paclitaxel (175mg/m2) and carboplatin (AUC=5) treatment, NSCLC and BRC patients receive docetaxel (75mg/m2) treatment, 3-weekly and for up to 6 cycles. BSA group and PK-guided group are with a same starting dose. DTX exposure (AUC) and PTX exposure (TC\>0.05) are calculated from a published PK model with an established limited sampling strategy. Dose of subsequent cycles of PK-guided group patients is calculated base on the previous cycle PK results, according to optimal target algorithm. The optimal target for DTX exposure is 2.5 - 3.7 µg•h/mL. Dose reductions were permitted in both arms according to instructions. The study had a power of 80% to detect a 23% reduction of grade \>3 neutropenia with PK-guided arm for DTX sub-study in NSCLC. A sample size of 100 NSCLC patients was estimated by using Fisher's exact test to provide a 5% two-sided alpha significance level to observe a decrease in the hematological toxicity with a power of 0.8. This is based on the reported toxicity rates of 85% with dose of 75mg/m2 and 63% with 60mg/m2. Objective response rate is evaluated by imaging examination (CT or MR scan) every 2 cycles. Toxicities are evaluated by patients' diary for toxicity reports and physician's evaluation at day 10 and day 21 at every cycle. Blood samples are collected every cycle. And survival information is collected by clinic and telephone follow-up. Research Hypothesis: 1. The concentrations variability dosed by BSA, and the limitation of BSA- and MTD-based dosing. 2. Verify that paclitaxel TC\>0.05 and docetaxel AUC are the most relevant predictor of related toxicities and clinical outcomes. 3. Verify the feasibility of dosing algorithm based on paclitaxel TC\>0.05 and docetaxel AUC, quantify its effect on both reducing toxicity and improving Effectiveness. 4. The effect of using dose modification and administration of G-CSF based on toxicity determined by paclitaxel TC\>0.05 and docetaxel AUC measurement. 5. Prove the ability of PK-guided dosing strategy in reducing DTX and PTX related hematologic and non-hematologic toxicities, and the effect on treatment efficacy.