Abstract: Objective To investigate the maximum tolerated dose of olanzapine for preventing emesis and nausea during chemotherapy in cancer patients. Methods This study was designed with olanzapine，using a six-cohort dose escalation of at least 3 patients per cohort，combining granisetron and dexamethasone for the prevention of chemotherapyinduced emesis and nausea in cancer patients. The initial dose cohort of olanzapine was 25mg； the terminal one was 20mg. Olanzapine was administered from one day before experiment to 14th day of experiment（d-1-d14） per night. If no dose-limiting toxicity was observed， the study could escalate to the next cohort. Results Eighteen patients were enrolled in the protocol and fifteen patients completed it. Two patient experienced a doselimiting toxicity（grade 3） of dry mouth and somnolence in 15mg cohort. Thus the study stopped on this cohort. In this study adverse events above grade 2 were somnolence， sedation， dizziness， akathisia， constipation， fatigue and bone marrow suppression.
Conclusion Olanzapine is well tolerated and safe in using recommended dose 15mg on d-1 to d14 per night.