Ethical issues regarding study designs used in serotonin-antagonist drug development

Employment of substandard antiemetic prophylaxis in recent trials of chemotherapy-induced nausea and vomiting

OBJECTIVE

To determine the prevalence of substandard antiemetic therapy among recently published trials conducted in patients with cancer who received emetogenic chemotherapy.

DATA SOURCES

A MEDLINE search was conducted (2000-July 2004) using the key words 5-HT(3) antagonists, ondansetron, granisetron, dolasetron, tropisetron, ramosetron, palonosetron, NK-1 antagonists, and aprepitant.

STUDY SELECTION AND DATA EXTRACTION

All antiemetic trials in patients receiving chemotherapy that were published from January 2000 to July 2004 were evaluated. Standard prophylactic antiemetic therapy was derived from contemporary antiemetic guidelines published by oncology professional organizations and expert panels. The number of patients and studies in which patients received standard and substandard antiemetic therapy was determined for both the acute and delayed phases of chemotherapy-induced nausea and vomiting (CINV). Separate determinations were made for severely and moderately emetogenic chemotherapy. The annual percentage of studies in which substandard antiemetic prophylaxis was given and the percentage of patients who received substandard prophylaxis also were determined.

DATA SYNTHESIS

Fifty-six studies were reviewed, which included a total of 10 274 patients and 125 study arms. The percentage of patients who received substandard antiemetic prophylaxis was 30% (n = 3063) for acute CINV and 33% (n = 3413) for delayed CINV. The average annual percentage of studies that employed substandard prophylaxis during this time period was 54%.

CONCLUSIONS

In recent antiemetic trials for CINV, the employment of substandard antiemetic therapy is common. These results raise important ethical questions regarding contemporary antiemetic trial design.

Double-blind, randomized, parallel-group study on the efficacy and safety of oral granisetron and oral ondansetron in the prophylaxis of nausea and vomiting in patients receiving hyperfractionated total body irradiation

The efficacy and safety of granisetron and ondansetron for the prophylaxis of nausea and vomiting resulting from hyperfractionated total body irradiation (TBI) were assessed. Thirty-four patients randomly received double-blind, oral granisetron (2 mg, 1 h before first daily fraction of radiation) or ondansetron (8 mg, 1.5 h prior to each fraction of TBI). Ninety patients who received the same TBI regimen prior to bone marrow transplantation (BMT), but no 5-HT3-receptor antagonist, were identified and comprised the historical control group. By design, this study was only powered to show a difference between each of the active treatment groups and the historical control group. Significantly more patients given granisetron (33.3%) or ondansetron (26.7%) had zero emetic episodes over 4 days, the primary efficacy end point, than those in the historical control group (0%) (P < 0.01; intent-to-treat). Secondary efficacy end points were also evaluated. During the first 24 h, significantly more patients taking granisetron (61.1%) or ondansetron (46.7%) had zero emetic episodes than patients in the historical control group (6.7%) (P < 0.01). Complete emetic control (no emesis or rescue antiemetic) over 4 days was more frequent in patients taking granisetron (27.8%) or ondansetron (26.7%) compared with the historical control group (0%) (P < 0.01). Significantly fewer patients taking granisetron (18/18), but not those taking ondansetron (12/15), experienced more than five emetic episodes during the 4 days of the study compared with the historical control group (40/90; P < 0.01). Oral granisetron and ondansetron are safe and effective for the prevention of nausea and vomiting resulting from TBI.