A multicenter, randomized, double-blind, placebo-controlled, phase 3 trial of olanzapine plus triple antiemetic regimen for the prevention of multiday highly emetogenic chemotherapy-induced nausea and vomiting (OFFER study)

BACKGROUND: Evidence supports prophylactic use of olanzapine for the treatment of chemotherapy-induced nausea and vomiting (CINV). However, most studies to date have focused on patients with single-day highly emetogenic chemotherapy (HEC). Currently, administration of antiemetic therapies for nausea and vomiting induced by multiday chemotherapy regimens remains a challenge. In this study, we evaluated the efficacy of olanzapine combined with triple antiemetic therapy for the prevention of CINV in patients receiving multiday chemotherapy. METHODS: We performed a randomized, double-blind, placebo-controlled phase 3 trial in 22 hospitals. Eligible patients were between 18 and 75 years old, were diagnosed with malignant solid tumors, and they had an Eastern Cooperative Oncology Group (ECOG) performance status of 0–2. All the study participants were scheduled to be treated with chemotherapy regimens containing 3-day cisplatin (3-day total dose ≥75 mg/m(2)). Randomization was computer generated and stratified by gender and chemotherapy treatment history. Allocation was done via an interactive web response system. Enrolled patients were randomly assigned 1:1 to receive either 5 mg olanzapine or placebo orally before bedtime for 5 days combined with intravenous fosaprepitant (150 mg) 1 h before the administration of cisplatin on day 1, ondansetron hydrochloride intravenously, and dexamethasone orally 30 min before cisplatin from days 1 to 3. Dexamethasone was also administered at the same time on days 4 and 5. The primary endpoint was the proportion of subjects with complete response (no vomiting and no rescue therapy) within the overall phase (days 1–8) after starting chemotherapy. Baseline plasma concentrations of P-substance and 5-HT were measured for exploratory analysis. This study was registered at ClinicalTrials.gov, number NCT04536558. FINDINGS: Between December 2020 and September 2021, 349 patients with malignant solid tumors were enrolled in the study, with 175 participants randomly assigned to receive olanzapine and 174 participants assigned to receive placebo. The proportion of patients who achieved a complete response in the overall phase was significantly higher in the olanzapine group than in the placebo group (69% vs. 58%, P = 0.031). A complete response benefit was observed in the olanzapine group versus the placebo group in almost all the subgroups. Four factors were considered significantly associated with complete response in multivariable analysis: treatment group, gender, baseline plasma concentration of 5-HT, and prior radiotherapy. All the reported adverse events associated with olanzapine administration were grades 1 and 2. INTERPRETATION: Olanzapine (5 mg) combined with fosaprepitant, ondansetron, and dexamethasone was better than triple antiemetic therapy alone for patients receiving multiday chemotherapy regimens. Based on these results, the four-drug combination should be recommended as the best antiemetic regimen given to patients receiving multiday cisplatin-based chemotherapy and baseline plasma concentration of 5-HT may be used to identify individuals who are prone to CINV. However, all these findings need to be further validated in future studies. FUNDING: Jiangsu Hansoh Pharmaceutical Group Co., Ltd. provided research grant and study drugs for this investigator-initiated study.