Evaluating the use of olanzapine for prevention of chemotherapy-induced nausea and vomiting (CINV) for highly emetic chemotherapy regimens

Background: Pharmacological management of chemotherapy-induced nausea and vomiting (CINV) includes antagonizing serotonin, neurokinin, dopamine, and histamine receptors involved in the emetic response from the vomiting center. In addition to traditional antiemetic triplet therapy with dexamethasone, neurokinin-1 receptor antagonists and serotonin antagonists recommended by the National Comprehensive Cancer Network (NCCN) for highly emetic chemotherapy (HEC), olanzapine is an atypical antipsychotic that has seen increased utilization alongside triplet therapy due to its antagonistic effects on receptors involved in the CINV signaling pathways. Objective: The objective of this study was to evaluate the efficacy of olanzapine in reducing the severity and frequency of CINV due to HEC and provide real-world evidence of its use in clinical practice. Methods: This study was a multicenter, retrospective, electronic chart review of patients aged 18 years and older with a confirmed cancer diagnosis who received HEC at Wellstar Northwest Georgia Oncology Centers (NGOC) between January 1, 2021, and January 1, 2023. Patient-reported episodes of CINV were compared between 94 total patients who received traditional triplet therapy plus olanzapine (study group) and those who received traditional triplet therapy alone (comparator group). Cycles administered to the study group before the initiation of olanzapine were recorded in the comparator group to mitigate potential under- or overestimation of efficacy and safety. Data collection was performed using the SlicerDicer reporting tool in the electronic health record EpicÒ. Results: The addition of olanzapine to traditional triplet therapy significantly reduced the incidence of CINV in patients receiving HEC. Out of 159 cycles administered with olanzapine and 358 cycles without, a total of 10 (0.06 per cycle) and 242 (0.68 per cycle) episodes of CINV were documented, respectively. Additionally, HEC dose reductions secondary to CINV were significantly higher in the comparator group. Conclusion: Limiting the need for dose modifications due to toxicities attributed to chemotherapy provide clinicians the opportunity to achieve recommended doses with evidence-based survival benefits. The reduction of CINV episodes associated with HEC in this study provides additional real-word evidence supporting the efficacy of olanzapine for managing CINV.