Chanthawong, S., Subongkot, S., & Sookprasert, A. (2014). Effectiveness of olanzapine for the treatment of breakthrough chemotherapy induced nausea and vomiting. Journal of the Medical Association of Thailand = Chotmaihet Thangphaet, 97, 349–355.

To evaluate the safety and efficacy of olanzapine for breakthrough emesis in addition to standard antiemetic regimen in patients with cancer receiving highly emetogenic chemotherapy

All patients were treated with the institutional standard for HEC: ondansetron 24 mg IV BID and dexamethasone 10 mg IV BID on day 1. Oral metoclopramide 10 mg TID plus dexamethasone 10 mg po BID were given on days 2 and 3. Oral olanzapine 5 mg was given after the first vomiting episode. Twelve hours later, the second dose was given concurrently with the standard prevention regimen. 

• N = 46  
• AGE: 89.1% younger than 50 years, 10.9% were 50 years or older
• MEDIAN AGE = 33.5 years 
• MALES: 69.5%, FEMALES: 30.5% 
• KEY DISEASE CHARACTERISTICS: Patients with solid tumors to receive at least one cycle of chemotherapy. No nausea or vomiting reported for at least 12 hours prior to chemotherapy 

• SITE: Single site    
• SETTING TYPE: Not specified    
• LOCATION: Khon Kaen, Thailand

• PHASE OF CARE: Active antitumor treatment
• APPLICATIONS: Pediatrics, elder care 

• Phase II prospective open-labeled clinical trial

• CINV measured by the Index of Nausea, Vomiting, and Retching (INVR tool) every 12 hours. Adverse drug reactions were evaluated by using the Naranjo’s algorithm to estimate the occurrence probability. CTCAE V. 4.03 was used.

Complete response of breakthrough emesis was 60.9%, retching was 71.7%, and nausea was 50.0%. Adverse events were mild, including dizziness, fatigue, and dyspepsia. 

The study demonstrated the effectiveness and safety of olanzapine in the treatment of nausea and vomiting in HEC patients. Olanzapine could be considered for treatment of patients at high risk for breakthrough emesis despite standard prevention. Olanzapine 5 mg every 12 hours for at least 24 hours could be recommended per the study.

• Small sample (< 100)
• Risk of bias (no control group)
• Other limitations/explanation
  • The “standard antiemetic” is not recommended by NCCN, ONS, MASCC, and ASCO for HEC.   
  • The medications used in the delayed phase were not recommendations by NCCN, MASCC, ONS, and ASCO guidelines.   
  • Olanzapine was only used for 24 hours at 5 mg (2 doses). Other olanzapine studies and guidelines recommend 3 days at 10 mg. 

Olanzapine is a drug that could be extremely helpful in treatment of CINV. Studies have shown olanzapine to be a safe and effective medication in acute and delayed CINV. The reviewed study attempted to show effectiveness in the breakthrough setting but many limitations were reported and are listed above. The researchers should not conduct CINV studies for “breakthrough” if the patient is given suboptimal treatment upfront.