The relationship between carboplatin AUC and serum thrombopoietin kinetics in patients with lung cancer

To clarify the relationship between the carboplatin AUC and the extent of damage to thrombopoiesis, we monitored both endogenous serum TPO kinetics and carboplatin pharmacokinetics after single-agent carboplatin administration. Previously untreated 12 patients with stage IV non-small-cell lung cancer were enrolled. The actual carboplatin AUC showed a significant positive correlation with the maximum increase ratio of TPO (TPO(max)/TPO(day1) (r = 0.74, p = 0.014). Furthermore, the increase ratio of TPO at one week after administration of carboplatin (TPO(day8)/TPO(day1) showed a significant negative correlation with the following platelet nadir around day 19 (r = -0.84, p = 0.005). By monitoring the changes in endogenous TPO concentration, we could estimate the degree of thrombocytopenia and determine the indication, and thus the optimal timing of prophylactic administration of TPO before platelets are markedly reduced.