RESUMO
OBJECTIVES: Vorinostat, a histone deacetylase inhibitor being actively evaluated in solid tumors, is metabolized by UGT2B17. UGT2B17 null genotype (UGT2B17*2) has been shown in vitro to reduce UGT2B17 activity. This variant is common in Asians but rare in Caucasians, and we studied its impact on vorinostat pharmacokinetics and pharmacodynamics in a clinical study in Asian patients with metastatic breast cancer. METHODS: Eligible patients received 400 mg of vorinostat monotherapy daily in a lead-in phase I followed by a phase II study. Patients were genotyped for UGT2B17*2, which was correlated with vorinostat pharmacokinetics and clinical outcomes. RESULTS: Twenty-six patients were treated with no complete response, one partial response, six stable disease lasting for 12 weeks or more, and 19 progressive disease. Sixteen patients (62%) were UGT2B17*2 homozygotes and had significantly lower mean area under the curve ratio of vorinostat-O-glucuronide/vorinostat (1.84 vs. 2.51 on day 1, P=0.02; 1.63 vs. 2.38 on day 15, P=0.028), and trended toward having higher vorinostat area under the curve (399.02 vs. 318.40, P=0.188), more serious adverse events (31 vs. 0%, P=0.121), higher clinical benefit rate (40 vs. 10%, P=0.179), and longer median progression-free survival (3.0 vs. 1.5 months, P=0.087) than patients with at least one wild-type allele. CONCLUSION: UGT2B17*2 genotype reduces vorinostat glucuronidation and may increase vorinostat efficacy and toxicity. These observations are important in the development of vorinostat, and may have clinical implications on other cancer and noncancer drugs that are UGT2B17 substrates such as exemestane and ibuprofen.
Assuntos
Antineoplásicos/metabolismo , Povo Asiático/genética , Neoplasias da Mama/tratamento farmacológico , Neoplasias da Mama/enzimologia , Glucuronosiltransferase/genética , Ácidos Hidroxâmicos/metabolismo , Ácidos Hidroxâmicos/uso terapêutico , Adulto , Antineoplásicos/efeitos adversos , Antineoplásicos/farmacocinética , Antineoplásicos/uso terapêutico , Neoplasias da Mama/genética , Neoplasias da Mama/patologia , Demografia , Intervalo Livre de Doença , Feminino , Genótipo , Humanos , Ácidos Hidroxâmicos/efeitos adversos , Ácidos Hidroxâmicos/farmacocinética , Pessoa de Meia-Idade , Antígenos de Histocompatibilidade Menor , Metástase Neoplásica , Fatores de Tempo , Resultado do Tratamento , VorinostatRESUMO
PURPOSE: This study (EGF20009) assessed the efficacy and tolerability of two lapatinib administration schedules as first-line monotherapy in women with ErbB2-amplified locally advanced or metastatic breast cancer. PATIENTS AND METHODS: Patients with ErbB2-amplified, locally advanced or metastatic breast cancer previously untreated in the metastatic setting were randomly assigned to one of two lapatinib dose cohorts and received either 1,500 mg once daily or 500 mg twice daily. Clinical response was assessed at weeks 8 and 12 and every 12 weeks thereafter. RESULTS: A total of 138 patients were treated with lapatinib for a median of 17.6 weeks. The overall response rate (complete response [CR] plus partial response [PR]) was 24% in the intent-to-treat population, and 31% of patients derived clinical benefit (CR, PR, or stable disease for >or= 24 weeks). The median time to response was 7.9 weeks, and the progression-free survival rates at 4 and 6 months were 63% and 43%, respectively. The most common lapatinib-related adverse events (AEs) were diarrhea, rash, pruritus, and nausea, and these events were primarily grade 1 or 2. There were no significant differences in clinical activity or the AE profile between the dosing schedules. CONCLUSION: Lapatinib demonstrated clinical activity and was well tolerated as first-line therapy in ErbB2-amplified locally advanced or metastatic breast cancer. This study supports further evaluation of lapatinib in first-line and early-stage ErbB2-overexpressing breast cancer.
