BACKGROUND Chemotherapy-induced nausea and vomiting occurs in up to 80% of patients undergoing chemotherapy treatment and is associated with a deterioration in quality of life. Olanzapine is an atypical antipsychotic antagonist blocking a variety of neurotransmitters in the nausea and vomiting pathophysiology. OBJECTIVES The primary objective of this study is to determine whether olanzapine is associated with improved breakthrough nausea
and vomiting in patients undergoing hematopoietic stem cell transplant. Secondary outcomes include number of documented emesis episodes, an evaluation of patient oral intake, and number of rescue antiemetic agents administered after olanzapine initiation. METHODS This is a retrospective cohort review examining the effects of olanzapine for the treatment of breakthrough nausea and vomiting following hematopoietic stem cell transplant. Patients undergoing autologous or allogeneic hematopoietic stem cell transplant between January 2014 and October 2017 were included. RESULTS A total of 150 patients were included in the study. Olanzapine use was associated with a complete response in 30% of patients for breakthrough chemotherapy-induced nausea and vomiting (p < 0.0001). An improvement in nausea (p < 0.0001) and vomiting (p = 0.02) was also observed in patients. Olanzapine administration was associated with lower as needed antiemetic usage (p < 0.0001) as well as fewer emesis episodes (p < 0.0001) but had no effect on oral intake (p = 0.13). CONCLUSIONS Olanzapine was associated with significant improvements in breakthrough nausea and vomiting control while reducing the number of emesis episodes and required antiemetic doses in the hematopoietic stem cell transplant population. Olanzapine may be beneficial in optimizing antiemetic regimens for breakthrough chemotherapy-induced nausea and vomiting control in patients undergoing hematopoietic stem cell transplant.