Olanzapine is effective for refractory chemotherapy-induced nausea and vomiting irrespective of chemotherapy emetogenicity.

PURPOSE: The role of olanzapine added to a dopamine antagonist and benzodiazepine for the treatment of refractory chemotherapy-induced nausea and vomiting (CINV) is incompletely characterized in all levels of chemotherapy emetogenicity. This retrospective study evaluated the efficacy of the addition of olanzapine in adults experiencing refractory CINV stratified by chemotherapy emetogenicity.
METHODS: Thirty-three adults who experienced CINV refractory to guideline-recommended prophylaxis and breakthrough antiemetics (dopamine antagonists and benzodiazepines) and received at least one dose of olanzapine 5-10 mg per os were evaluated. Failure was defined as >5 emesis events in 24 h or more than 10 cumulative doses of rescue antiemetics following first olanzapine dose per treatment cycle. Post hoc analyses investigated variables impacting olanzapine efficacy.
RESULTS: The addition of olanzapine demonstrated an overall success rate of 70 %. This success rate did not differ between chemotherapy regimens of high versus low-to-moderate emetogenicity (p = 0.79), prophylaxis with serotonin antagonist plus corticosteroid and aprepitant versus serotonin antagonist alone (p = 0.77), or age over 50 versus ≤50 years (p > 0.99). A trend toward greater benefit was seen in women (p = 0.08).
CONCLUSIONS: The addition of olanzapine to a dopamine antagonist and benzodiazepine demonstrated high efficacy rates for refractory CINV irrespective of chemotherapy emetogenicity. The high success rates among all groups suggests that incomplete resolution of CINV with prophylactic serotonin antagonists and breakthrough dopamine antagonists plus benzodiazepine may benefit from the addition of olanzapine regardless of gender, degree of chemotherapy emetogenicity, number of prophylactic antiemetics, or age. The trend toward greater control of emesis in women merits further investigation.