Effects of adding a neurokinin-1 receptor antagonist to 5 mg olanzapine, a 5-hydroxytryptamine-3 receptor antagonist, and dexamethasone for preventing carboplatin-induced nausea and vomiting: a propensity score-matched analysis.

Background: Olanzapine has been reported to be an effective antiemetic in patients receiving carboplatin-based chemotherapy. However, the efficacy of a neurokinin-1 receptor antagonist (NKRA) added to olanzapine, a 5-hydroxytryptamine-3 receptor antagonist (5-HTRA), and dexamethasone (DEX) has not been proven. This study aimed to assess the efficacy and safety of NKRA, in combination with three-drug antiemetic regimens containing olanzapine, in preventing nausea and vomiting induced by carboplatin-based chemotherapy.

Methods: Data were pooled for 140 patients receiving carboplatin-based chemotherapy from three multicenter, prospective, single-arm, open-label phase II studies that evaluated the efficacy and safety of olanzapine for chemotherapy-induced nausea and vomiting. The propensity score of the co-administration of NKRA was estimated for each patient using a logistic regression model that included age, sex, and carboplatin dose. We analyzed a total of 62 patients, who were treated without NKRA (non-NKRA group: 31 patients) and with NKRA (NKRA group: 31 patients). The patients were selected using propensity score matching.

Results: The complete response rate (without emetic episodes or with no administration of rescue medication) in the overall period (0-120 h post carboplatin administration) was 93.5% in the non-NKRA group and 96.8% in the NKRA group, with a difference of -3.2% (95% confidence interval, -18.7% to 10.9%; P = 1.000). In terms of safety, there was no significant difference between the groups in daytime sleepiness and concentration impairment, which are the most worrisome adverse events induced by olanzapine.

Conclusions: The findings suggest that antiemetic regimens consisting of olanzapine, 5HTRA, and DEX without NKRA may be a treatment option for patients receiving carboplatin-based chemotherapy.