Background To determine the feasibility and efficacy of olanzapine, which is approved by the Pharmaceuticals and Medical Devices Agency as multi acting receptor targeted antipsychotic agent of the thienobenzodiazepine class, for prevention of chemotherapy-induced nausea and vomiting (CINV) in patients undergoing continuous five-day chemotherapy. Patients and methods This study was a prospective dose escalation study at a single center (UMIN ID: UMIN000015386). Patients received a combination of adriamycin and ifosfamide (AI) or a combination of bleomycin, etoposide, and cisplatin (BEP). On days 1–5, all patients received intravenous granisetron (1 mg) and intravenous dexamethasone sodium phosphate (24 mg). Olanzapine was administrated on day-1 to day5 at bedtime. The dose of olanzapine followed a dose-escalation scheme, with monitoring of safety and tolerability at each dose. A 3 + 3 cohort design was used, with three to six patients per cohort. Results Nine patients were enrolled (three for each cohort). No patients experienced dose-limiting toxicity (DLT). The most frequent adverse events were dry mouth and constipation. In each cohort, the maximum severity of nausea was Grade 2, and no patients experienced a vomiting episode. Conclusion A 2.5 mg/day dosage of olanzapine is sufficient to prevent from CINV in Japanese patients receiving continuous five-day chemotherapy. A dose of 10 mg/day, which is recommended by international CINV guidelines, is also tolerated. If CINV is not controlled by an initial dose of 2.5 mg/day of olanzapine, dosage escalation is encouraged. Future studies should compare olanzapine with aprepitant.
