A narrative review of tropisetron and palonosetron for the control of chemotherapy-induced nausea and vomiting
Review the clinical evidence of tropisetron or palonosetron, an old- and new-generation serotonin (5-hydroxytryptamine) type 3 (5-HT3) receptor antagonist (RA), respectively, for the prevention of chemotherapy-induced nausea and vomiting (CINV) in patients with cancer, and evaluate any difference in efficacy trends. A literature search of the EMBASE and PubMed databases was performed to identify publications of intravenous (IV) tropisetron (generic forms or Navoban®) for the treatment of CINV in patients with various cancers. Data from the pivotal clinical studies evaluating the IV formulation of Aloxi® (palonosetron HCl) were also considered. The effectiveness and safety of each antiemetic was summarized. Sixteen papers for tropisetron fulfilled the inclusion criteria and were extracted for full analysis; publications from six pivotal palonosetron clinical trials were considered. No direct data comparisons could be made between the two drugs, due to the varying definitions of efficacy endpoints between studies. For tropisetron, the rates of no emesis were lower in patients receiving highly emetogenic chemotherapy (HEC) versus moderately emetogenic chemotherapy (MEC). For palonosetron, the rates of complete response (no emesis, no rescue medication) were comparable in the MEC and HEC settings, demonstrating the effectiveness of this agent in patients receiving HEC. Both antiemetics offered some protection against nausea, although lower rates of no nausea were achieved compared with rates of no emesis. Two trials that evaluated the efficacy of palonosetron and tropisetron within the same study reported that palonosetron was more effective than tropisetron in controlling delayed vomiting in the HEC and MEC settings, with significantly higher rates of no emesis observed (P≤0.01). Palonosetron was non-inferior or more efficacious in controlling CINV compared with other older 5-HT3RAs, such as dolasetron, ondansetron, and granisetron. Conversely, tropisetron was no more efficacious than ondansetron or granisetron. Both tropisetron and palonosetron were generally well tolerated, with adverse event profiles consistent with drugs of this class (e.g., headache, constipation, and diarrhea). These data suggest that palonosetron is a highly selective prophylactic agent that may have an improved therapeutic profile compared with tropisetron, and is a feasible treatment option for controlling CINV in patients with cancer.