Efficacy of Olanzapine-Triple Antiemetic Regimen in Patients with Gastrointestinal Tumor and High Risk of Chemotherapy-Induced Nausea and Vomiting Receiving Moderately Emetogenic Chemotherapy: A Retrospective Study

Purpose: Dexamethasone combined with 5-hydroxytryptamine type 3 receptor antagonists (5-HT3 RA) dual regimen is the standard prophylaxis regimen for patients receiving moderately emetogenic chemotherapy (MEC). However, it has been found in real-world practice that chemotherapy-induced nausea and vomiting (CINV) remains poorly controlled among patients with gastrointestinal tumor, especially in those with high-risk factors for vomiting, such as female, young, and non-alcoholic individuals. Hence, we aimed to evaluate the efficacy of an olanzapine-containing triple regimen in this clinical setting. Patients and Methods: We retrospectively reviewed the clinical records of gastrointestinal tumor patients who received mFOLFOX6, XELOX, or FOLFIRI chemotherapy at two institutions. All patients included were female and less than 55 years old, with no history of drinking. The patients were divided into two groups for olanzapine-containing triple therapy (olanzapine, tropisetron, and dexamethasone) and non-olanzapine dual therapy (tropisetron and dexamethasone). The study outcomes were complete response (CR), complete control (CC), nausea control, and quality of life (QoL) by the functional living index-emesis (FLIE) questionnaire. Results: A total of 93 patients were included in the study (olanzapine: 40; control: 53). The CR rate in the olanzapine group was significantly higher than that in the control group in delayed and overall phase (75.0% vs 54.7%, p=0.044; 70.0% vs 47.2%; p=0.028). The CC rate in the overall phase was also better in the olanzapine group (62.5% vs 39.6%, p=0.029). The control of nausea in the overall phase showed a superior trend in the olanzapine group (p=0.059). The olanzapine group exhibited higher FLIE scores, which demonstrated better QoL. More patients in the olanzapine group exhibited somnolence and dizziness. Conversely, the incidence of insomnia and anorexia in the olanzapine group was lower. Conclusion: This retrospective study indicates that in gastrointestinal tumor patients with high-risk factors for CINV who were receiving MEC, olanzapine-containing triple antiemetic regimen exhibit better efficacy and QoL as compared to non-olanzapine dual regimen. Further randomized studies are required to confirm these results.