The antiemetic efficacy of oral ondansetron plus intravenous dexamethasone in patients with gynecologic malignancies receiving carboplatin-based chemotherapy

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.

5-HT(3)-receptor antagonists in the management of nausea and vomiting in cancer and cancer treatment

The 5-HT(3)-receptor antagonists, considered as 'gold standard' therapy for cancer patients, are generally perceived to have similar efficacy and safety profiles, andmost antiemetic guidelines do not distinguish between agents. However, important pharmacological differences exist between agents, which may translate into potential benefits for some patients. In particular, 5-HT(3)-receptor antagonists vary in the nature of their receptor antagonism and plasma half-lives, possibly leading to differences in duration of action. Agents with a longer duration of action provide antiemetic protection throughout the acute emetic period (24 h) with a single daily dose, whereas shorter-acting agents, e.g. ondansetron, may require multiple dosing for full efficacy. Differences also exist between agents in their hepatic metabolism and cardiovascular safety, which may present particular problems for elderly patients who often receive additional medications for comorbid conditions, increasing the risk of drug-drug interaction. Recent antiemetic guidelines from the National Comprehensive Cancer Network recommend preferential use of palonosetron for moderately emetogenic chemotherapy; however, this agent is newly approved and key clinical questions remain unanswered by clinical trial data. Selection of an appropriate 5-HT(3)-receptor antagonist should be based on proven efficacy and safety, as well as on the individual characteristics of the patient.

Toxicities of the platinum antineoplastic agents

The platinum agents (cisplatin, carboplatin and oxaliplatin) are among the most useful anticancer agents available to oncologists. The drugs have the potential to produce both mild and more serious side effects. However, in general, the platinum agents can be delivered with acceptable toxicity, even when used in combination chemotherapy regimens. Furthermore, with appropriate dose modifications, the large majority of patients who may benefit from this class of cytotoxic pharmaceutical drugs will be able to complete a planned therapeutic programme.

Effectiveness of serotonin-receptor antagonist antiemetic therapy over successive courses of carboplatin-based chemotherapy

PURPOSE

There are extremely limited data available in the general oncology or gynecologic cancer literature to document the effectiveness of antiemetic therapy over multiple courses of cytotoxic chemotherapy.

METHODS

To examine this highly clinically relevant issue, we analyzed the complete treatment course of patients with gynecologic cancers receiving carboplatin-based chemotherapy regimens who had participated in one of four institutional serotonin-receptor antagonist antiemetic trials, which had specifically evaluated the benefits of such therapy during only the first treatment course. Medical records were reviewed to examine the development of emesis during subsequent chemotherapy treatment cycles.

RESULTS

The 91 patients included in this analysis received a median of 6 courses (range 1-18) of carboplatin (initial AUC dose 4, 5, and 6 in 29, 29, and 32 patients, respectively). All received ondansetron or granisetron plus dexamethasone with every treatment course. Complete control of emesis (no acute or delayed nausea or vomiting) was experienced by 56 (62%) patients during every cycle. Conversely, 20% of women noted one or more episodes of nausea without vomiting and 19% developed at least one incidence of vomiting. In no case was emesis considered to be severe (grade 3), and no patient required either discontinuation of carboplatin or a dose reduction due to the development of emesis.

CONCLUSION

In the large majority of patients, serotonin-receptor antagonist antiemetic therapy, administered in combination with dexamethasone, is highly effective over multiple courses in preventing significant carboplatin-induced nausea and vomiting.