A multicenter, phase II trial of triplet antiemetic therapy with palonosetron, aprepitant, and olanzapine for highly emetogenic chemotherapy in breast cancer (PATROL-II).

Dexamethasone is an antiemetic drug widely used to prevent nausea and vomiting caused by anticancer drugs. However, dexamethasone can cause several side effects even after short-term administration. Therefore, the development of dexamethasone-free antiemetic therapies has been recognized as an important challenge. The objective of this study was to investigate the efficacy and safety of palonosetron, aprepitant, and olanzapine. Patients who were chemotherapy-naïve and scheduled to receive highly emetogenic chemotherapy for breast cancer were enrolled and assessed for nausea and vomiting occurring within 120 h after the start of chemotherapy. The primary endpoint was the total control (TC) rate of overall phases. Secondary endpoints included the complete response (CR) rate, which was evaluated during the acute, delayed, and overall phases. A total of 88 patients were enrolled from eight centers in Japan, of whom 84 were included in the analysis. The proportion of patients achieving TC throughout the overall period was 17.1%. Similarly, CR and CC rates for the overall period were 43.4% and 39.5%, respectively. Frequently reported adverse events were loss of appetite and constipation, with rates of 52.4% and 50.0%, respectively. The primary endpoint was not achieved. Therefore, antiemetic therapy without dexamethasone shows an inadequate effect on nausea, and it is generally advisable to avoid omitting dexamethasone. However, in the overall period, both CR and CC were comparable to conventional three-drug combination therapy. Thus, in patients unable to use dexamethasone, replacing it with olanzapine could be an option.Trial registration number: UMIN 000038644, November 20, 2019. The date of first trial registration: 13/03/2020.