RESUMEN
Objective To conduct a prospective phase Ⅱ clinical study to explore the distribution of CYP2D6 gene polymorphism in Chinese population and its relationship with the metabolism of tamoxifen in early-stage hormonal receptor-positive breast cancer. Methods CYP2D6 genotype was tested by Sanger sequencing using the ABI 3500 Genetic Analyzer. Plasma concentrations of tamoxifen and endoxifen were measured using the HPLC-MS/MS(API 2000)assay. We downloaded the data of CYP2D6 allele from the CPIP database. Results In Chi-nese patients,the most common alleles were CYP2D6*1,*2,and *10;the predominant diplotypes were *1/*10 (38.3%)and*10/*10(18.8%). The distribution of metabolic phenotype,plasma concentration of endoxifen,and endoxifen:tamoxifen plasma concentration ratio were inconsistent between the normal metabolic phenotype(EM) and the intermediate phenotype(IM)under different CYP2D6 activity prediction criteria.The differences in the ratios and endoxifen plasma concentrations were statistically significant between the three groups by cluster analysis. Conclusions The CYP2D6 genotype distribution in Chinese population is different from that in the Western popu-lation. There is considerable variation of serum endoxifen concentration in Chinese breast cancer patients possess-ing the phenotype previously known as the intermediate active metabolizers of CYP2D6. Therefore,in the current era of precision medicine,the standard CYP2D6 genotype-phenotype classification system cannot properly stratify the Chinese population with different levels of endoxifen plasma concentration.
RESUMEN
Objective To compare the efficacy and safety of everolimus combined with endocrine therapy and fulvestrant in patients with estrogen receptor-positive advanced breast cancer progressed after endocrine thera-py. Methods Ninety-three breast cancer patients were selected from January 2014 to February 2017. The primary end points were progression-free survival and clinical benefit rate and the secondary end points was tolerability. Re-sults The progression-free survival in fulvestrant group was slightly higher than that in the everolimus group(13.4 months vs 12.2 months,P = 0.297). The clinical benefit rates were 46.15% and 31.71% in fulvestrant group and everolimus group,respectively. Patients treated with fewer than 2 lines and endocrine resistant patients benefited more from fulvestrant but without statistical difference. The main adverse events related to everolimus were stomati-tis,with a prevalence rate of about 26% and a localized pneumonia with a prevalence rate of about 10%. The main adverse reaction of fulvestrant was the injection site reaction. Conclusions The efficacy of everolimus in combina-tion with endocrine therapy is not superior to that of fulvestrant for the treatment of advanced breast cancer pro-gressed after endocrine therapy. After weighing the clinical benefits and quality of life,fulvestrant may be better for patients treated with fewer than 2 lines and endocrine resistance.