Clinicians should be aware that the control of emesis has the greatest impact on quality of life during chemotherapy. With the correct use of antiemetics, chemotherapy-induced nausea and vomiting can be prevented in 70% to 80% of patients. Twenty years ago, nausea and vomiting were common adverse events associated with certain types of chemotherapy, forcing up to 20% of patients to postpone or refuse potentially curative treatment. Clinical and basic research over the past 25 years has led to steady improvements in the control of chemotherapy-induced nausea and vomiting.
The development of the 5-hydroxytryptamine (HT)3 receptor antagonists in the early 1990s was one of the most significant advances in chemotherapy of cancer patients. Another group of antiemetics, the neurokinin-1-receptor antagonists, has recently been developed, and the first drug in this class, aprepitant (Emend), has been incorporated in updated antiemetic guidelines. In 1998, the first international antiemetic guidelines from the Multinational Association for Supportive Care in Cancer (MASCC), based on the results of the Perugia consensus conference, were published. These were followed by the American Society for Clinical Oncology (ASCO) guidelines in 1999. Last year, these two sets of guidelines, as well as those from the National Comprehensive Cancer Network (NCCN), were updated.[1-3]
In this issue of ONCOLOGY, Schwartzberg has reviewed the latest findings in the field of antiemesis as well as the updated antiemesis guidelines. In particular, the author summarizes the results of a recently published study by Grote et al, which deserves closer attention. In this small phase II study, patients with moderately to highly emetogenic chemotherapy received a combination of palonosetron(Drug information on palonosetron)
(Aloxi), dexamethasone(Drug information on dexamethasone)
, and aprepitant on day 1 followed by aprepitant and dexamethasone on days 2 and 3. The intent-to-treat analysis demonstrated an overall response rate of 78% in the delayed phase. These very promising results raised two questions.
First, could the combination of dexamethasone and aprepitant in the delayed phase be responsible for the good response rate achieved in this study? In the updated guidelines, only aprepitant monotherapy is recommended in the delayed phase for patients receiving moderately emetogenic chemotherapy (doxorubicin/cyclophosphamide [AC]-based regimens), when aprepitant was part of the antiemesis prophylaxis in the acute phase. In the study by Warr et al, which formed the basis for the updated guidelines in this setting, patients with moderately/highly emetogenic chemotherapy (AC) received prophylaxis with aprepitant monotherapy alone in the delayed phase. Dexamethasone was used for the prevention of acute, but not for delayed, prophylaxis. In this study, a complete response rate of 55% in the delayed phase was achieved. It might be asserted that the combination of dexamethasone and aprepitant in the delayed phase would have enhanced the antiemetic efficacy rate.
Second, what impact does palonosetron—the so-called second-generation 5-HT3 receptor antagonist—have in the delayed phase? Without doubt, 5-HT3 receptor antagonists are the most important agents in the prevention of chemotherapy-induced nausea and vomiting. Whereas they have excellent activity in the acute phase, they show little activity in the delayed phase. In a recently published meta-analysis, it was demonstrated that the addition of a 5-HT3 receptor antagonist did not significantly improve control of delayed emesis, as compared with dexamethasone monotherapy. However, a patient might benefit from the additional use of 5-HT3 receptor antagonists in the delayed setting.
Indeed, palonosetron demonstrated antiemetic activity in the delayed period, as shown in several studies. However, no steroids were permitted in one study, and in another, only 5% of patients received a steroid as a late treatment modification. Thus, further investigation with different study designs will be necessary to explore the actual role of palonosetron in this setting. Although the results from the phase II study by Grote et al are promising, the use of palonosetron, aprepitant, and dexamethasone should be validated in a large randomized trial.