Correlation between paclitaxel Tc > 0.05 and its therapeutic efficacy and severe toxicities in ovarian cancer patients

Aim: Although paclitaxel (PTX) is a widely used chemotherapeutic agent across many cancer types, the correlation between its concentration and treatment efficacy and toxicity is yet to be clarified. Hence, the study aims to determine the correlation between PTX Tc > 0.05 and its therapeutic efficacy and toxicity. Methods: Using MyPaclitaxel™, we measured the blood concentration of PTX in 96 ovarian cancer (stage IIIB to IV) patients, who were admitted to the Cancer Hospital of Shantou University Medical College in Chaoshan, China. PTX Tc > 0.05, the time during which PTX plasma concentration exceed 0.05 μmol/L, is calculated using nonlinear mixed effect model. Results: (1) The PTX Tc > 0.05 was constant and significantly correlated with treatment response and the range of Tc > 0.05 of PTX was 14-36 h. (2) There was no correlation between relative PTX dose and the PTX Tc > 0.05. (3) There was a statistically significant difference in the PTX Tc > 0.05 between complete remission (CR) + partial remission (PR) and stable disease (SD) + progressive disease (P = 0.00185). The PTX Tc > 0.05 in most patients with CR and PR was in the range of 26-30 h. (4) The PTX Tc > 0.05 significantly correlated with the occurrence of leukopenia (P = 0.0002) and leukopenic fever (P = 0.0211), and higher PTX Tc > 0.05 correlated with increased incidence of severe leukopenia and leukopenic fever. (5) Occurrence and severity of peripheral neuropathy significantly correlated with the level of PTX Tc > 0.05 (P = 0.0003, 0.0118). Conclusion: These results indicated that the PTX Tc > 0.05 correlated with therapeutic efficacy and drug toxicity. Therefore, monitoring the PTX Tc > 0.05 other than blood concentration of PTX is necessary to optimize individual treatment.