Mirtazapine plus granisetron and dexamethasone for carboplatin-induced nausea and vomiting in patients with thoracic cancers: A prospective multicenter phase II trial

•We studied antiemetic therapy consisting of MTZ, 5-HT3 RA, and DEX in CBDCA-based chemotherapy.•CR rate during the delayed period was 83.3 % for prophylaxis using MTZ, 5-HT3 RA, and DEX combination therapy.•No grade 3 or higher treatment-related adverse events were observed except for one patient with grade 3 dry mouth. Mirtazapine blocks 5-hydroxytryptamine type (5-HT)2A, 5-HT2C, 5-HT3 and histamine H1 receptors, similarly to olanzapine. This study aimed to investigate the efficacy and safety of mirtazapine plus granisetron and dexamethasone for carboplatin (CBDCA)-induced nausea and vomiting in patients with thoracic cancers. We conducted a prospective, open‐label, single‐arm, multicenter, phase II trial in four institutions in Japan. Registered patients were moderately to highly emetogenic chemotherapy-naïve, and were scheduled to receive CBDCA at area under the curve (AUC) ≥ 4 mg/mL per minute. Patients received mirtazapine 15 mg/day orally at bedtime for four consecutive days, in combination with granisetron and dexamethasone. Primary endpoint was complete response (CR; no emesis and no use of rescue medication) rate during the delayed period (24–120 h). Between July 2022 and July 2023, 52 patients were enrolled, and 48 patients were evaluated. CR rates in the delayed (24–120 h), overall (0–120 h), and acute periods (0–24 h) were 83.3%, 83.3%, and 100%, respectively. No grade 3 or higher treatment-related adverse events were observed except for one patient who had grade 3 dry mouth as evaluated by Common Terminology Criteria for Adverse Events version 5.0. Prophylactic antiemetic therapy with mirtazapine plus granisetron and dexamethasone shows promising efficacy and an acceptable safety profile. This three‐drug combination appears to be a reasonable treatment approach in patients with thoracic cancers receiving a CBDCA‐based regimen at AUC ≥ 4 mg/mL per minute.