Objective: To evaluate the efficacy and safety of the addition of olanzapine to ondansetron and dexamethasone for chemotherapy-induced nausea vomiting (CINV) prevention in patients receiving highly emetogenic chemotherapy (HEC).
Methods: In this randomized, double-blind, placebo-controlled, crossover study, we randomly assigned chemotherapy-naïve patients receiving HEC to receive olanzapine or placebo in addition to ondansetron and dexamethasone. All subjects were crossed over to another treatment arm on second-cycle chemotherapy. The primary endpoint was complete response (CR) rate defined as no vomiting and no use of rescue drugs.
Results: At the first cycle, there were significantly more patients with CR in the olanzapine group than in the placebo group in overall phase (68.7% vs. 25.0%, p < 0.001), acute phase (0-24 h) (75.0% vs. 31.2%, p < 0.001) and delayed phase (24-120 h) (68.7% vs. 43.7%, p = 0.038). After crossover, there were significantly more patients with CR in the olanzapine group than in the placebo group in overall phase (67.2% vs. 25.0%, p < 0.001), acute phase (71.9% vs. 32.8%, p < 0.001) and delayed phase (67.2% vs. 37.5%, p < 0.001). In crossover analysis, the olanzapine group had significantly lower mean nausea (1.28 vs. 3.05, p < 0.001) and fatigue (3.5 vs. 4.58, p < 0.001) scores but higher mean appetite (2.5 vs. 1.55, p = 0.003) and sleepiness (3.26 vs. 2.2, p < 0.001) scores. There were no grade 3 and 4 anti-emetic-drug-related toxicities. Mean QT interval changes did not different between two groups (-4.30 vs. -1.86, p = 0.69).
Conclusion: The addition of olanzapine to ondansetron and dexamethasone significantly improved CINV prevention and was safe in patients receiving HEC.
Keywords: CINV prevention; HEC; Olanzapine; Ondansetron.