BACKGROUND: Olanzapine, neurokinin-1-receptor-antagonists (NK-1-RA), and thalidomide added to palonosetron + dexamethasone (PALO-DEX) have been evaluated in separate studies as prophylaxis for chemotherapy-induced nausea and vomiting (CINV) due to highly emetogenic chemotherapy (HEC). We conducted a Bayesian network meta-analysis to compare the prophylactic efficacy of these agents in combination with PALO-DEX.
METHODS: PubMed, Medline/Ovid, Embase, and Clinicaltrials.gov were searched from inception through 22 Mar 2018. Study quality was assessed using the Cochrane methodology. A Bayesian network meta-analysis using random-effects models was used to asses complete response (CR) and rate of no nausea (RNN) in acute, delayed, and overall phases and were expressed as odds ratios (OR) and 95% credible interval (95% CrI). Ranking probabilities of treatments were calculated using the surface under the cumulative ranking curve (SUCRA) to identify the probability of a given treatment as the best option against the worst option.
RESULTS: Nine RCTs involving two thousand nine hundred fifty-nine patients were included. The olanzapine-based regimen showed greater CR in the acute, delayed, and overall-phases versus the PALO-DEX regimen (OR = 3.97, 95% CrI = 1.02-19.13; OR = 5.62, 95% CrI = 1.66-28.58; OR = 4.79, 95% CrI = 1.40-24.02, respectively). Additionally, it showed greater RNN than the NK-1-RA-based and the PALO-DEX regimens in the delayed phase only (OR = 2.90, 95% CrI = 1.34-5.15; OR = 4.53, 95% CrI = 1.89-10.55, respectively). Olanzapine-, NK-1-RA-, and thalidomide-based regimens did not differ in CR in the three phases. SUCRA probabilities ranked the olanzapine-based regimen as the best option in terms of CR and RNN, while ranking the NK-1-RA-based regimens as the second best option in terms of CR throughout the three phases.
CONCLUSION: Based on the data included in the analyses, there is insufficient evidence to support adding thalidomide or NK-1-RA to PALO-DEX in preventing CINV induced by HEC. However, adding olanzapine to PALO-DEX achieves better CR and RNN. Olanzapine side-effects and the absence of direct comparisons explain why some guidelines are cautious in suggesting the use of olanzapine.