Department of Microbiology, Vall d'Hebron University Hospital, PROSICS Barcelona, Pº Vall d'Hebron 119-129, 08035 Barcelona, Spain.
Laboratorio de Biología Molecular de la Enfermedad de Chagas, Instituto de Investigaciones en Ingeniería Genética y Biología Molecular "Dr. Hector Torres" (INGEBI-CONICET), Vuelta de Obligado 2490; Second Floor, Ciudad de Buenos Aires, ZIP code 1428 Argentina.
Acta Trop. 2019 Nov;199:105120. doi: 10.1016/j.actatropica.2019.105120. Epub 2019 Jul 31.
Chagas disease has become a global health problem due to migration of infected people out of Latin America to non-endemic countries. For more than 40 years, only the nitroimidazole compounds Benznidazole and Nifurtimox, have been used for specific treatment of Trypanosoma cruzi infection with disappointing results, specially due to the long duration of treatment and adverse events in the chronic phase. In the last years, ergosterol inhibitors have been also proposed for specific treatment. Different randomized clinical trials were performed for evaluating their treatment efficacy and safety. One of the greatest concerns in clinical trials is to provide an early surrogate biomarker of response to trypanocidal chemotherapy. Serological response is slow and the classical parasitological tests have poor sensitivity and are time-consuming. Nowadays, PCR is the most helpful tool for assessing treatment response in a short period of time. Different protocols of PCR have been developed, being quantitative real time PCR based on amplification of repetitive satellite or minicircle DNA sequences plus an internal amplification standard, the mostly employed strategies in clinical trials. Standardized protocols and the use of an external quality assessment ensure adequate technical procedures and reliable data. Clinical trials have shown a significant reduction in parasite loads, reaching undetectable DNA levels in bloodstream after specific treatment, however events of treatment failure have also been reported. Treatment failure could be due to inadequate penetrance of the drugs into the affected tissues, to the presence of primary or secondary drug resistance of the infecting strains as well as to the existence of dormant parasite variants reluctant to drug action. The early diagnosis of drug resistance would improve clinical management of Chagas disease patients, allowing dictating alternative therapies with a combination of existing drugs or new anti-T. cruzi agents. The aim of this review was to describe the usefulness of detecting T.cruzi DNA by means of real time PCR assays, as surrogate biomarker in clinical trials for evaluating new drugs for CD or new regimens of available drugs and the possibility to detect treatment failure.
由于感染该病的人从拉丁美洲移民到非流行地区，因此，恰加斯病已成为全球健康问题。四十多年来，只有硝基咪唑类化合物苯并硝唑和硝呋替莫被用于治疗克氏锥虫感染，但效果不佳，特别是由于治疗时间长且在慢性期出现不良反应。在过去的几年中，也提出了固醇抑制剂用于特异性治疗。已经进行了不同的随机临床试验来评估其治疗效果和安全性。临床试验中最大的关注点之一是提供对杀锥虫化疗有早期反应的替代生物标志物。血清学反应缓慢，经典的寄生虫学检测方法敏感性差且耗时。如今，PCR 是在短时间内评估治疗反应最有用的工具。已经开发了不同的 PCR 方案，基于扩增重复卫星或微环 DNA 序列加内部扩增标准的定量实时 PCR 是临床试验中最常用的策略。标准化方案和外部质量评估的使用可确保适当的技术程序和可靠的数据。临床试验表明寄生虫负荷显著降低，在特定治疗后血液中可检测到的 DNA 水平达到不可检测水平，但也有治疗失败的报道。治疗失败可能是由于药物不能充分渗透到受影响的组织中，感染株存在原发性或继发性耐药性以及存在对药物作用不敏感的休眠寄生虫变异体。早期诊断耐药性将改善对恰加斯病患者的临床管理，允许用现有药物的组合或新的抗 T. cruzi 药物替代治疗。本文综述的目的是描述实时 PCR 检测 T.cruzi DNA 作为临床试验中评价治疗 CD 的新药或现有药物新方案的替代生物标志物的有用性，以及检测治疗失败的可能性。
