aprepitant and Breast-Neoplasms--Male

The prodrug cyclophosphamide is metabolized by cytochrome P450(CYP)2B6 to the active metabolite, 4-hydroxycyclophosphamide (4-OH), and by CYP3A4/5 to toxic chloracetaldehyde and 2-dechloroethylcyclophosphamide (DCE). Since aprepitant is a moderate inhibitor of CYP3A4, the study was designed to determine whether its concurrent use alters the pharmacokinetics (PK) of cyclophosphamide. In addition, we sought to determine the effect of race and pharmacogenomics on cyclophosphamide PK.. Eighteen patients with localized breast cancer were randomized in this double-blinded cross-over study to receive aprepitant or placebo in addition to cyclophosphamide 600 mg/m(2) and doxorubicin 60 mg/m(2). Blood samples were collected for both PK analysis of cyclophosphamide and metabolites and pharmacogenomic analysis. Single nucleotide polymorphisms genotyped were CYP3A4*1B, CYP3A5*3, and CYP2B6*6.. The geometric mean area under concentration-time curve (AUC(0-t) μg/mL h) for cyclophosphamide was 282 following aprepitant and 230 following placebo (ratio 1.23; 90% CI 1.13, 1.33). 4-OH AUC(0-t) (μg/mL h) was 6.80 following aprepitant and 6.96 following placebo (ratio 0.98; 90% CI 0.88, 1.08). DCE AUC(0-t) (μg/mL h) was 6.76 following aprepitant and 9.37 following placebo (ratio 0.72; 90% CI 0.64, 0.81). Genotype analysis was confounded by race. Race was a significant predictor of DCE lnAUC(0-t) (P = 0.0169) as African Americans had approximately a 2-fold higher DCE AUC than Caucasians.. Aprepitant altered the exposure of cyclophosphamide and DCE but not the active 4-OH metabolite, making it unlikely that aprepitant would change the clinical efficacy of cyclophosphamide. African Americans were also found to have altered PK compared with Caucasian patients.

Topics: Adult; Aged; Antiemetics; Antineoplastic Combined Chemotherapy Protocols; Aprepitant; Area Under Curve; Aryl Hydrocarbon Hydroxylases; Black or African American; Breast Neoplasms; Breast Neoplasms, Male; Cross-Over Studies; Cyclophosphamide; Cytochrome P-450 CYP2B6; Cytochrome P-450 CYP3A; Double-Blind Method; Doxorubicin; Drug Interactions; Female; Humans; Male; Middle Aged; Morpholines; Oxidoreductases, N-Demethylating; Pharmacogenetics; Polymorphism, Single Nucleotide; White People

A number of prognostic factors have been identified as risk factors for chemotherapy-induced emesis. This post-hoc analysis addressed whether: (1) these prognostic factors can identify a low-risk group for whom ondansetron plus dexamethasone alone provide a high level of protection (≥80% no emesis); (2) the NK1 receptor antagonist aprepitant improves antiemetic outcome regardless of emetic risk.. Breast cancer patients in a phase III double-blind, placebo-controlled trial were randomized to antiemetic regimens including ondansetron and dexamethasone, or aprepitant, ondansetron, and dexamethasone. Multivariate logistic regression models were used to assess the impact on emesis (but not nausea) of the regimen with aprepitant, and previously reported risk factors, including age (<55 and ≥55 years), ethanol use (0-4 or ≥5 drinks/week), history of pregnancy-related morning sickness, and history of motion sickness, using a modified intent-to-treat approach.. Treatment with aprepitant (P < 0.0001), older age (P = 0.006), ethanol use (P = 0.0048), and no history of morning sickness (P = 0.0007) were all significantly associated with reduced likelihood of emesis. The proportion of patients with one, two, or three risk factors who remained emesis free was significantly higher with the aprepitant-containing regimen than with the active control (70.2-82.8% vs. 38.6-66.4%, respectively).. Aprepitant markedly improved control of emesis in patients with one or more risk factors. This analysis did not support using risk factors for modifying the antiemetic approach. A low-risk group with zero risk factors for whom aprepitant provided little benefit was of questionable clinical utility, since they comprised less than 3% of patients.

Topics: Antiemetics; Antineoplastic Combined Chemotherapy Protocols; Aprepitant; Breast Neoplasms; Breast Neoplasms, Male; Cyclophosphamide; Dexamethasone; Double-Blind Method; Doxorubicin; Drug Therapy, Combination; Female; Humans; Logistic Models; Male; Middle Aged; Morpholines; Multivariate Analysis; Nausea; Neurokinin-1 Receptor Antagonists; Ondansetron; Prognosis; Risk Factors; Vomiting

Chemotherapy-induced nausea and vomiting includes both Acute (0-24 h) and Delayed (24-120 h) components with different physiologic mechanisms. A combination of a serotonin antagonist, a corticosteroid, and an NK-1 antagonist has proven effective against this problem. However, standard antiemetic regimens require administration over 3-4 days after chemotherapy. The present study evaluated a more convenient single-day three-drug antiemetic regimen for patients receiving moderately emetogenic chemotherapy.. Chemotherapy-naïve patients with solid tumors receiving cyclophosphamide and/or doxorubicin were eligible. Patients could not have pre-existing etiologies for vomiting. Prior to chemotherapy, patients received a single dose of aprepitant 285 mg p.o., dexamethasone 20 mg p.o., and palonosetron 0.25 mg i.v. A daily patient diary recording episodes of emesis and severity of nausea was then kept for 5 days. Any further antiemetics were considered rescue medication.. Forty-one eligible and evaluable patients (40 women, one man) with breast cancer were entered on study. Most were receiving adjuvant chemotherapy. Complete Response (no vomiting, no rescue medication) was seen in 51% of patients, including 76% with Complete Response for the Acute period and 66% for the Delayed period. No emesis was reported for 100% of patients in the Acute period and 95% in the Delayed period. No Nausea was seen in 32% of patients. No untoward toxicities were seen.. A single-day three-drug antiemetic regimen is feasible and effective for protection against both Acute and Delayed vomiting after moderately emetogenic chemotherapy. Formal comparison to a standard multi-day antiemetic regimen is warranted.

Topics: Adult; Aged; Antiemetics; Antineoplastic Agents; Aprepitant; Breast Neoplasms; Breast Neoplasms, Male; Chemotherapy, Adjuvant; Cyclophosphamide; Dexamethasone; Doxorubicin; Drug Administration Schedule; Drug Therapy, Combination; Female; Humans; Isoquinolines; Male; Middle Aged; Morpholines; Nausea; Palonosetron; Quinuclidines; Time Factors; Vomiting