Proposal for Classifying the Emetogenicity of Oral Anticancer Agents with a Focus on PARP Inhibitors: A Prospective,...

Background: Olaparib and niraparib (poly adenosine diphosphate [ADP]-ribose polymerase [PARP] inhibitors) have significant antitumor action in patients with ovarian cancer. However, the incidence of nausea and vomiting among patients on these drugs in clinical trials is rather high. There are no guidelines on antiemetic treatment for nausea caused by oral anticancer agents. This study aimed to investigate the incidence of nausea and vomiting caused by PARP inhibitors and the actual situation of antiemetic therapy in patients with gynecologic cancer. Methods: Patients with gynecologic cancer who were scheduled to receive PARP inhibitors were enrolled. Data on PARP inhibitor-induced nausea and vomiting were collected from patient diaries for 21 days. The primary endpoint was the incidence of vomiting during the 21 days after starting olaparib and niraparib. Results: Overall, between January 2020 and March 2023, 134 patients were enrolled. Of the 129 patients who were evaluated, 28 (21.7%) received prophylactic antiemetics for 21 days, and 101 (78.3%) did not. The overall incidence of PARP inhibitor-induced vomiting was 16.3%. The incidence of vomiting in the group that did not receive antiemetic prophylaxis was 13.9%. On dividing the group that did not receive antiemetic prophylaxis into the olaparib and niraparib subgroups, the incidence of vomiting was found to be 18.6% for the olaparib group and 10.3% for the niraparib group. Conclusion: The incidence of emesis without antiemetic prophylaxis among patients on olaparib and niraparib ranged from 10% to 30%. Therefore, olaparib and niraparib can be classified in the low emetogenic risk and prophylactic antiemetic therapy at the time of treatment initiation may be unnecessary.