Effect of olanzapine for breast cancer patients resistant to triplet antiemetic therapy with nausea due to anthracycline-containing adjuvant chemotherapy

Triplet antiemetic therapy with neurokinin 1 receptor blocker, 5-hydroxytryptamine receptor blocker and steroids is commonly used in patients who are highly emetic after chemotherapy. However, an alternative antiemetic therapy for patients who are resistant to triplet antiemetic therapy is not established. Olanzapine is recommended in the guidelines as an optional antiemetic drug. However, the effectiveness of adding olanzapine to triplet antiemetic therapy is unknown. In this study, the effectiveness and safety of adding olanzapine to triplet antiemetic therapy with aprepitant, palonosetron and dexamethasone as highly emetic anthracycline-containing adjuvant chemotherapy for primary breast cancer patients were prospectively investigated. Forty-five patients with breast cancer who experienced >Grade 1 nausea or any vomiting after the first cycle of chemotherapy using both epirubicin and cyclophosphamide were included. Low-dose olanzapine (2.5 mg/day) was administered orally from the first day of chemotherapy for 4 days, and the number of episodes of vomiting, scale of nausea, dietary intake and somnolence were compared with the symptoms after the first cycle. As the primary endpoint, the nausea grade was significantly improved by adding olanzapine (P < 0.05). As the secondary endpoints, mean nausea scale (3.2→1.9, Day 1; 3→1.3-1, Days 2-6) and dietary intake (33.6→53.8%, Day 1; 42.0→60.7-78.1%, Days 2-6) were improved by adding olanzapine. Only four patients withdrew due to somnolence and/or dizziness. This study demonstrated the effectiveness and tolerability of adding low-dose olanzapine for patients with insufficient nausea relief with triplet antiemetic therapy consisting of palonosetron, steroid and aprepitant.