Efficacy and Safety of Adding Olanzapine to the Standard Preventive Regimen for Chemotherapy-induced Nausea and Vomiting in Children: A Randomized Double-blind Controlled Trial

This study aimed to assess the additive value of olanzapine to a combination of ondansetron and dexamethasone to prevent chemotherapy-induced nausea and vomiting (CINV) in pediatric patients. A total of 40 patients between 4 to 18 years of age were enrolled in this randomized clinical trial. Both groups received a combination of ondansetron and dexamethasone, and 0.14 mg/kg olanzapine or matched placebo were administered for olanzapine and control groups, respectively. The primary end points were complete response and lack of nausea as far as three days after chemotherapy evaluated by the Common Terminology Criteria for Adverse Effects (CTCAE) v5.0 and the Multinational Association of Supportive Care in Cancer (MASCC) Anti-emesis Tool (MAT). Side effects of olanzapine were also analyzed. In patients receiving the standard regimen of ondansetron and dexamethasone, nausea was observed in 10.5% and 21% of patients according to MAT and CTCAE scales, respectively. In the olanzapine group, 37.5% (MAT scale) and 31.3% (CTCAE scale) of patients developed nausea. Complete response was observed in 84% (MAT scale) and 94.7% (CTCAE scale) of patients in the placebo group receiving ondansetron and dexamethasone. In comparison, it was observed in 87.5% (MAT scale) and 81.25% (CTCAE scale) for patients allocated to the olanzapine group. Neither acute nor delayed CINV was statistically different between placebo and olanzapine groups. The frequency of adverse effects was higher in the olanzapine group. Adding olanzapine to the standard regimen of CINV prophylaxis was only unhelpful in pediatric patients receiving moderately emetogenic chemotherapy but also associated with a higher rate of minor side effects.