A randomized, double-blind, placebo-controlled study of the safety and efficacy of olanzapine for the prevention of chemotherapy-induced nausea and vomiting in patients receiving moderately emetogenic chemotherapy: Results of the Korean South West Oncology Group (KSWOG) study

Purpose Data on the efficacy of olanzapine in patients receiving moderately emetogenic chemotherapy (MEC) are limited. This study aimed to evaluate and compare the efficacy of olanzapine versus placebo in controlling nausea and vomiting in patients receiving MEC. Materials and Methods We conducted a randomized, double-blind, placebo-controlled study to determine whether olanzapine can reduce the frequency of chemotherapy-induced nausea and vomiting (CINV) and improve the quality of life (QOL) in patients receiving palonosetron and dexamethasone as prophylaxis for MEC-induced nausea and vomiting. The primary end point was complete response for the acute phase (0-24 hours after chemotherapy). The secondary end points were complete response for the delayed (24-120 hours) and overall phase (0-120 hours), proportion of significant nausea (visual analogue scale 25 mm), use of rescue medications, and effect on QOL. Results Fifty-six patients were randomized to the olanzapine (n=29) and placebo (n=27) groups. Complete response rates were not significantly different between the olanzapine and placebo groups in the acute (96.5% vs. 88.0%, p=0.326), delayed (69.0% vs. 48.0%, p=0.118), and overall phases (69.0% vs. 48.0%, p=0.118). However, the percentage of patients with significant nausea (17.2% vs. 44.0%, p=0.032) and the use of rescue medications (0.03±0.19 vs. 1.88±2.88, p=0.002) were lower in the olanzapine group than in the placebo. Furthermore, the olanzapine group demonstrated better QOL (p=0.015). Conclusion Olanzapine combined with palonosetron and dexamethasone significantly improved QOL and vomiting control among previously untreated patients receiving MEC, although the efficacy was limited to the reduction of the frequency of CINV.