目标:硫鸟嘌呤(TG),硫唑嘌呤(AZA),和巯基嘌呤(MP)是硫嘌呤前药常用于治疗疾病,如白血病和炎症性肠病(IBD)。6-硫鸟嘌呤核苷酸(6-TGN)通常用于监测治疗。红细胞(RBC)中高水平的6-TGN与白细胞减少症有关,预测这种副作用的截止水平仍然不确定。硫嘌呤被代谢并掺入白细胞DNA中。测量掺入DNA的硫鸟嘌呤(DNA-TG)的水平可能是预测临床反应和毒性(例如白细胞减少症)的更合适的方法。不幸的是,大多数测定6-TGN的方法无法确定NUDT15变体的影响,影响主要是种族人口(例如,中文,印度人,马来人,日本人,和西班牙裔)。DNA-TG通过直接测量DNA中的硫鸟嘌呤来解决这个问题,可受TPMT和NUDT15变体的影响。虽然RBC6-TGN浓度传统上用于优化硫嘌呤治疗,因为它们易于测量且可负担,液相色谱-串联质谱(LC-MS/MS)技术的最新发展使得淋巴细胞中DNA-TG浓度的测量更加准确,可重复,和负担得起的。本系统综述的目的是评估DNA-TG水平作为硫嘌呤治疗标志物的当前证据,特别是关于NUDT15变体。
方法:对DNA-TG作为硫嘌呤治疗监测指标的当前证据进行了系统评价和荟萃分析,包括测量方法以及DNA-TG和各种基因变体(如TPMT,NUDT15ITPA,NT5C2和MRP4)。截至2024年4月,PubMed和Embase对已发表的研究进行了系统搜索,使用带有MeSH术语和同义词的关键字“DNA-TG”。通过对文章中引用的参考文献进行手动检查,增强了电子搜索策略,最近的评论,社论,和荟萃分析。使用Rstudio4.1.3进行荟萃分析。研究DNA-TG和6-TGNs水平的系数(Fisherz变换相关系数)之间的差异。使用RevMan5.4版进行荟萃分析,以使用随机效应大小模型研究有或没有白细胞减少症的患者之间DNA-TG水平的差异。使用纽卡斯尔-奥托瓦质量评估量表评估偏倚风险。
结果:在本系统综述中,包括21项研究,这些研究测量了ALL(n=16)或IBD(n=5)患者白细胞中的DNA-TG水平。在我们的荟萃分析中,白细胞减少症(ALL+IBD)与非白细胞减少症患者之间的总体平均差异为134.15fmolTG/µgDNA[95%置信区间(CI)(83.78-184.35),P<0.00001;异质性卡方为5.62,I2为47%]。有和没有白细胞减少的IBD患者的DNA-TG水平存在显著差异[161.76fmolTG/µgDNA;95%CI(126.23-197.29),P<0.00001;异质性卡方为0.20,I2为0%]。在有或没有白细胞减少的ALL患者之间,DNA-TG水平没有显着差异(57.71fmolTG/µgDNA[95%CI(-22.93至138.35),P<0.80])。DNA-TG监测被发现是预测ALL患者复发率的一种有前途的方法。与RBC6-TGNs水平相比,DNA-TG水平可能是IBD患者白细胞减少的更好预测指标。DNA-TG水平已被证明与各种基因变异相关(TPMT,NUDT15ITPA,和MRP4)在各种研究中,指出了它作为指导不同遗传背景的硫代嘌呤治疗的更多信息标记的潜力。
结论:本系统综述强烈支持DNA-TG作为硫嘌呤治疗监测标志物的进一步研究。它与治疗结果的相关性,如ALL的无复发生存率和IBD的白细胞减少风险,强调了其在增强个性化治疗方法中的作用。DNA-TG有效地识别NUDT15变异并预测IBD患者的晚期白细胞减少症,无论其NUDT15变体状态如何。建议使用DNA-TG的IBD患者的晚期白细胞减少症预测阈值在320至340fmol/µgDNA之间。更多关于DNA-TG实施的临床研究是强制性的,以改善患者护理并改善硫代嘌呤治疗的包容性。
OBJECTIVE: Thioguanine (TG), azathioprine (AZA), and mercaptopurine (MP) are thiopurine prodrugs commonly used to treat diseases, such as leukemia and inflammatory bowel disease (IBD). 6-thioguanine nucleotides (6-TGNs) have been commonly used for monitoring treatment. High levels of 6-TGNs in red blood cells (RBCs) have been associated with leukopenia, the cutoff levels that predict this side effect remain uncertain. Thiopurines are metabolized and incorporated into leukocyte DNA. Measuring levels of DNA-incorporated thioguanine (DNA-TG) may be a more suitable method for predicting clinical response and toxicities such as leukopenia. Unfortunately, most methodologies to assay 6-TGNs are unable to identify the impact of NUDT15 variants, effecting mostly ethnic populations (e.g., Chinese, Indian, Malay, Japanese, and Hispanics). DNA-TG tackles this problem by directly measuring thioguanine in the DNA, which can be influenced by both TPMT and NUDT15 variants. While RBC 6-TGN concentrations have traditionally been used to optimize thiopurine therapy due to their ease and affordability of measurement, recent developments in liquid chromatography-tandem mass spectrometry (LC-MS/MS) techniques have made measuring DNA-TG concentrations in lymphocytes accurate, reproducible, and affordable. The objective of this systematic review was to assess the current evidence of DNA-TG levels as marker for thiopurine therapy, especially with regards to NUDT15 variants.
METHODS: A systematic review and meta-analysis were performed on the current evidence for DNA-TG as a marker for monitoring thiopurine therapy, including methods for measurement and the illustrative relationship between DNA-TG and various gene variants (such as TPMT, NUDT15, ITPA, NT5C2, and MRP4). PubMed and Embase were systematically searched up to April 2024 for published studies, using the keyword \"DNA-TG\" with MeSH terms and synonyms. The electronic search strategy was augmented by a manual examination of references cited in articles, recent reviews, editorials, and meta-analyses. A meta-analysis was performed using R studio 4.1.3. to investigate the difference between the coefficients (Fisher\'s z-transformed correlation coefficient) of DNA-TG and 6-TGNs levels. A meta-analysis was performed using RevMan version 5.4 to investigate the difference in DNA-TG levels between patients with or without leukopenia using randomized effect size model. The risk of bias was assessed using the Newcastle-Ottowa quality assessment scale.
RESULTS: In this systematic review, 21 studies were included that measured DNA-TG levels in white blood cells for either patients with ALL (n = 16) or IBD (n = 5). In our meta-analysis, the overall mean difference between patients with leukopenia (ALL + IBD) versus no leukopenia was 134.15 fmol TG/µg DNA [95% confidence interval (CI) (83.78-184.35), P < 0.00001; heterogeneity chi squared of 5.62, I2 of 47%]. There was a significant difference in DNA-TG levels for patients with IBD with and without leukopenia [161.76 fmol TG/µg DNA; 95% CI (126.23-197.29), P < 0.00001; heterogeneity chi squared of 0.20, I2 of 0%]. No significant difference was found in DNA-TG level between patients with ALL with or without leukopenia (57.71 fmol TG/µg DNA [95% CI (- 22.93 to 138.35), P < 0.80]). DNA-TG monitoring was found to be a promising method for predicting relapse rates in patients with ALL, and DNA-TG levels are likely a better predictor for leukopenia in patients with IBD than RBC 6-TGNs levels. DNA-TG levels have been shown to correlate with various gene variants (TPMT, NUDT15, ITPA, and MRP4) in various studies, points to its potential as a more informative marker for guiding thiopurine therapy across diverse genetic backgrounds.
CONCLUSIONS: This systematic review strongly supports the further investigation of DNA-TG as a marker for monitoring thiopurine therapy. Its correlation with treatment outcomes, such as relapse-free survival in ALL and the risk of leukopenia in IBD, underscores its role in enhancing personalized treatment approaches. DNA-TG effectively identifies NUDT15 variants and predicts late leukopenia in patients with IBD, regardless of their NUDT15 variant status. The recommended threshold for late leukopenia prediction in patients with IBD with DNA-TG is suggested to be between 320 and 340 fmol/µg DNA. More clinical research on DNA-TG implementation is mandatory to improve patient care and to improve inclusivity in thiopurine treatment.