Approximately 70% of EBV-positive NPC expressed PD-L1, but this did not correlate with patient survival or clinicopathologic features. The findings of this study represent the immune biomarker profile of confirmed EBV-associated NPC in an endemic region. Since the current clinical development of immune checkpoint inhibitor for NPC is mostly focusing on an EBV-associated tumor, differences in immune biomarker profiles and EBV status of endemic and nonendemic regions should be further explored.

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BackgroundPharmacogenetic study of cytochrome P450 (CYP) gene CYP2D6 and tamoxifen outcomes remain controversial. Apart from CYP2D6, other drug-metabolizing enzymes and transporters also play a role in tamoxifen metabolic pathways. The aim of this study is to investigate the impact of CYP3A4/5, ABCB1, and ABCC2 polymorphisms on the risk of recurrence in Thai patients who received tamoxifen adjuvant therapy.MethodsPatients with early-stage breast cancer who received tamoxifen adjuvant therapy were recruited in this study. All six single-nucleotide polymorphisms (SNPs), including CYP3A4*1B (−392 A>G)/*18(878 T>C), CYP3A5*3(6986 G>A), ABCB1 3435 C>T, ABCC2*1C(−24 C>T), and ABCC2 68231 A>G, were genotyped using real-time polymerase chain reaction assays. The impacts of genetic variants on disease-free survival (DFS) were analyzed using the Kaplan–Meier method and Cox regression analysis.ResultsThe ABCB1 3435 C>T was found to have the highest allele frequency among other variants; however, CYP3A4*1B/*18 could not be found in this study. Patients with heterozygous ABCB1 3435 CT genotype showed significantly shorter DFS than those with homozygous 3435 CC genotype (P = 0.041). In contrast, patients who carried homozygous 3435 TT genotype showed no difference in DFS from wild-type 3435 CC patients. Cox regression analysis showed that the relative risk of recurrence was increased by five times (P = 0.043; hazard ratio = 5.11; 95% confidence interval: 1.05–24.74) in those patients carrying ABCB1 3435 CT genotype compared to those with ABCB1 3435 CC.ConclusionABCB1 3435 C>T is likely to have a clinically significant impact on recurrence risk in Thai patients with breast cancer who receive tamoxifen adjuvant therapy.