Single-center phase 3 trial of low-dose versus standard-dose olanzapine for prevention of CINV in patients with solid tumors

Olanzapine is an effective antiemetic agent, but it can result in substantial daytime somnolence when administered at the standard dose. A phase 3 trial at Tata Memorial Centre (Mumbai, India) compare efficacy of low-dose versus standard-dose olanzapine for prevention of highly emetogenic chemotherapy-induced nausea and vomiting (CINV) in patients with solid tumors. Patients were randomized 1:1 to receive low-dose (2.5 mg) or standard-dose (10.0 mg) for four days, in combination with a triple antiemetic regimen. The primary endpoint was complete control (no emetic episodes, no rescue medications, and no or mild nausea in the overall phase of 0-120 hours). Complete control in the overall phase was seen in 45% of patients in the low-dose group versus 44% of patients in the standard-dose group (p=0.87). Daytime solomnence of any grade (65% versus 90%; p<0.0001) in the overall phase and severe grade (5% versus 40%; pxtagstartz0.0001) on day 1 was significantly less frequent in the low-dose group when compared with the standard-dose group. The authors conclude that olanzapine 2.5 mg is non-inferior to 10.0 mg in antiemetic efficacy and results in reduced occurrence of daytime somnolence among patients receiving highly emetogenic chemotherapy.