8046 Background: In a previous Phase I study, olanzapine (Zyprexa) was demonstrated to be a safe and effective agent for the prevention of delayed emesis in chemotherapy naïve cancer patients receiving cyclophosphamide, doxorubicin, and/or cisplatin. METHODS: Using the maximum tolerated dose of olanzapine in the Phase I trial, a Phase II trial was performed for the prevention of CINV in chemotherapy naive patients. The regimen was 5mg/day of oral olanzapine on the two days prior to chemotherapy, 10mg of olanzapine on the day of chemotherapy, day 1, (added to intravenous granisetron, 10 mcg/kg, and dexamethasone 20 mg) and 10 mg/day on days 2-4 after chemotherapy (added to dexamethasone, 8 mg p.o. BID, days 2,3, and 4 mg p.o. BID, day 4). Thirty patients (median age 58.5 yrs, range 25-84; 23 females; ECOG PS 0,1) consented to the protocol and all were evaluable. RESULTS: Complete response (CR) (no emesis, no rescue) was 100% for the acute period (24 hours post chemotherapy) and 80% for the delayed period (days 2-5 post chemotherapy) in 10 patients receiving highly emetogenic chemotherapy (HEC) (cisplatin, ≥ 70 mg/m2). CR was also 100% for the acute period and 85% for the delayed period in 20 patients receiving moderately emetogenic chemotherapy (MEC) (doxorubicin, ≥ 50 mg/m2). Nausea was well controlled in the patients receiving HEC with no patient having more than minimal nausea (≤2 on scale of 0-10, M.D. Anderson Symptom Inventory, MDASI) in the acute or delayed periods. Nausea was also well controlled in patients receiving MEC with minimal or no nausea in 85% of patients in the acute period and 70% in the delayed period. There were no Grade 3 or 4 toxicities and no significant pain, fatigue, disturbed sleep, memory changes, dyspnea, lack of appetite, drowsiness, dry mouth, mood changes or restlessness experienced by the patients. CR and control of nausea in subsequent cycles of chemotherapy (25 patients, cycle 2; 25 patients, cycle 3; 21 patients, cycle 4) were equal to or greater than cycle 1. CONCLUSIONS: Olanzapine is safe and highly effective in controlling acute and delayed CINV in patients receiving HEC and MEC. No significant financial relationships to disclose.