Slow Uptake of an Effective Therapy: Patterns of Olanzapine Prescribing for Those Receiving Highly Emetogenic Chemotherapy

For the past 5 years, most major antiemesis guidelines have included olanzapine-containing regimens among the recommended options for prophylaxis with highly emetogenic chemotherapy (HEC). We analyzed the uptake of olanzapine in clinical practice and the changing composition of multidrug antiemetic regimens.A retrospective analysis was performed using an OptumLabs deidentified database of medical and pharmacy claims, which was filtered for patients starting HEC in the interval of 2006 to Q2 of 2021. Descriptive statistics were used to analyze patient characteristics and year-by-year antiemetic prescribing patterns, coinciding with cycles 1 and 2 of chemotherapy.A total of 63,154 distinct patients were included. The median age was 58 years (range, 18-88). Breast (45.2%) and hematologic (20.8%) cancers were the most common diagnoses. In 2016, olanzapine was prescribed to 1.4% of patients with cycle 1 of HEC. Prescriptions increased modestly each year, and by 2021, 13.9% of patients received olanzapine with their first cycle of chemotherapy. An additional 5.7% of patients received olanzapine for breakthrough symptoms or enhanced prophylaxis during cycle 2. In 2021, more than three-quarters of patients were prescribed antiemetics in a guideline-concordant manner, with an olanzapine-containing quadruplet (12.2%), an NK1-receptor antagonist triplet (64.5%), or an olanzapine triplet (suppressed for small sample size).Despite inclusion in major antiemesis guidelines, there has been relatively slow uptake of olanzapine for prophylaxis with HEC. This finding highlights the challenges of disseminating information and keeping prescribing systems updated with the newest evidence in supportive oncology.