medwireNews: The findings of a phase III trial pitting a second- against a first-generation 5-hydroxytryptamine 3 (5-HT3) receptor antagonist suggest that choosing the appropriate 5-HT3 inhibitor as part of a triplet regimen to prevent chemotherapy-induced nausea and vomiting (CINV) may not be straightforward.
The TRIPLE trial, in which patients undergoing highly emetogenic chemotherapy were given either the second-generation agent palonosetron or the first-generation compound granisetron alongside dexamethasone and aprepitant, did not show a significant difference between the agents with regard to the primary endpoint of complete response.
However, several of the secondary endpoints were significantly improved with palonosetron, prompting the Japanese researchers to remark that the clinical implications of their results need to be considered when selecting the 5-HT3 receptor antagonist for controlling CINV in patients using highly emetogenic drugs.
Complete response, defined as no vomiting or retching and no use of rescue medication, during the total observation period of 0–120 hours from the start of cisplatin (≥50 mg/m2) therapy was comparable for the 414 patients randomly assigned to receive palonosetron and for the 413 patients given granisetron, with rates of 65.7% and 59.1%, respectively.
Palonosetron significantly improved the complete response rate during the delayed period (24–120 h; 67.2 vs 59.1%), although not in the acute period (0–24 h), when the rates were identical (91.8%).
Moreover, the rates of complete and total control – defined as a complete response with no more than mild nausea or no nausea, respectively – were significantly better with palonosetron than granisetron, during the total observation period (63.8 vs 55.9% and 47.6 vs 40.7%, respectively) and the delayed period (65.2 vs 55.9% and 48.6 vs 41.4%, respectively).
In this double-blind trial, palonosetron and granisetron were administered on day 1 of the chemotherapy cycle at doses of 0.75 mg and 1.0 mg, respectively, and both agents were given alongside dexamethasone and aprepitant, report Nobuyuki Yamamoto, from Wakayama Medical University, and fellow investigators.
They conclude in the Annals of Oncology that “the present study did not show the superiority of palonosetron when compared with granisetron in the primary end point and should be concluded as a negative result.
“We, however, observed that palonosetron achieved the same efficacy as granisetron at the acute period as well as significantly higher [complete response, complete control, and total control] rates than granisetron at the delayed period”.
Therefore, the team believes that “palonosetron showed its efficacy over granisetron in terms of controlling CINV.”
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