遗传毒性早期初筛试验方法的研究进展

遗传毒性评价是药物临床前安全性评价研究的重要环节,目前ICH推荐的的标准试验组合基本能够满足新化学实体注册遗传毒理学实验数据的需求。然而随着全程式毒理学研究模式的推进,各制药公司越来越重视在创新药物研发早期进行遗传毒性初筛,及早发现具有潜在遗传毒性的候选化合物,降低新药开发的风险。作为在新药研发早期用于遗传毒性初筛的试验方法,除了要求灵敏、快速、经济外,还必须尽量减少化合物的用量,逐步实现高通量和自动化的要求。文中综述了目前研究比较广泛的早期体外遗传毒性初筛试验方法的原理、检测终点和应用进展,为候选化合物的早期遗传毒性初筛工作的深入开展提供技术指导。     

新药研发过程中的毒理学

目前在已形成体系的药物毒理学研究包括有发现毒理学、一般毒理学、安全性药理学、毒性病理学、生殖与发育毒理学、遗传毒理学、毒代动力学、临床病理学等。药物毒理学与药理学其实并没有本质的差别,都是关注药物在体内的药动学与药效动力学过程,只不过毒理学观察的范围更广泛,包括药物对各个系统的影响,大剂量药物对人体的影响等。然而在药物的发现阶段必须要建立短期高效毒性优化筛选系统,包括体内、体外毒性筛选,一般毒性筛选和特殊毒性筛选,涵盖原核和真核毒性筛选系统。通过早期毒性优化筛选,筛选出更合适研发的化合物,提高候选药物的质量,减少药物开发循环的时间;通过对(基因表达、蛋白质、代谢产物)数据系统性分析,建立更加适合于毒性预测的动物模型;选择更精确的剂量和确定安全域MOS(margin of safety),为新药研发中毒理学的检测提供可靠坚实依据。     

抗乙肝病毒新药Bay41-4109的发现毒理学研究

目的:利用发现毒理学中的临床前先导化合物优化技术(preclinical lead optimization technolo-gies,PLOTs)对抗乙肝病毒候选新药Bay41-4109的一般毒性、遗传毒性和生殖毒性进行研究,为早期发现候选新药的毒性提供实验依据.方法:一般毒性研究中分别以MTT比色法和上下法检测Bay41-4109的体外细胞毒性和小鼠LD50;遗传毒性研究中分别以Ames波动试验、SOS显色试验、双核细胞微核试验检测Bay41-4109诱发鼠伤寒沙门菌基因回复突变的能力、诱发大肠杆菌的原发DNA损伤效应以及对CHL细胞的染色体断裂效应;生殖毒性研究中以大鼠胚胎中脑细胞微团培养试验来检测Bay41-4109的致畸性.结果:Bay41-4109对CHL细胞的IC50为54.0 μmol·L-1,对雌性小鼠的LD50大于2 000 mg·kg-1.无论有无S9活化,Bay41-4109均不引起沙门菌回复突变,也不导致DNA损伤和染色体断裂.Bay41-4109对大鼠胚胎中脑细胞亦无致畸作用.结论:早期毒性筛选结果表明:Bay41-4109未表现明显的遗传毒性和生殖毒性.     

药物毒理学研究新进展

药物毒理学是现代毒理学中研究药物的毒副作用机制、评价新药安全性的分支学科,主要目的在于指导药物合成和临床合理用药,降低药物的毒副作用及减少因毒性导致的新药研发失败。现就药物毒理学研究的新思路、发现毒理学的发展和全程式新药安全性研究评价新模式的特征以及药物毒理学研究的新方法作简要阐述。     

新药评价中彗星试验方法学研究及发展趋势

彗星试验是一项检测单细胞损伤的试验方法,近年来在毒理学研究中发展很快。对彗星试验的原理和方法,及其在新药评价遗传毒性研究、生殖毒性研究和靶器官毒理学研究中的应用进行了分析和介绍,并提出了彗星试验技术的发展趋势。     

免疫毒理学在新药安全评价中的应用

新药对免疫系统毒性的研究一直是国内外的研究热点。本文从免疫毒理学的角度综述了这门学科在新药安全评价中的应用，包括新药对免疫系统的副作用、临床前研究中对免疫系统的检测方法和注意事项。     

TDAR在药物临床前毒理学研究中的应用

目的 TDAR试验被认为是检测药物潜在免疫毒性预测性较好的功能性试验,本文综述总结TDAR检测方法在药物临床前毒理学研究中应用的一般原则,以便同行参考。方法通过综合分析、对比,总结国内外文献资料中关于TDAR的实验方法和评价,得出在药物临床前毒理学研究中应用的一般原则。结果 T细胞依赖性抗体反应（TDAR）是检测免疫功能的主要试验。TDAR通过人为引入外来抗原,反映药物或化学物质对免疫系统整体的影响,目前在药物免疫毒理学研究中逐渐得到广泛应用。结论 TDAR试验是检测药物潜在免疫毒性预测性较好的功能性试验,该试验可以用来在临床前的反复给药毒性试验或者临床试验中检测免疫功能的改变,可以对候选药物的免疫调节和免疫毒性特点进行早期预测。     

计算毒理学与中药毒性预测的研究进展

计算毒理学近几年受到美国及欧盟相关立法及研究机构的重视,被越来越多地应用于新药毒性预测及环境化合物的安全评价。化合物毒性预测方法可分为两大类:一类是以化合物本身为基础的计算方法,主要是研究结构与毒性的定量关系;另一类是以毒性靶分子结构为基础的方法,又被称为分子机理法。我国在环境化合物的毒性预测、算法及建立构效模型上取得进展,将计算毒理学应用于新药研发已经起步,但尚未见到计算毒理学用于中药及其化合物毒性的研究。而国外在天然化学成分的毒性预测、结构毒性关系的研究上取得了一些进展。由于中药化学成分与人工合成化合物在化学空间的差别,同时中药是多组分的混合物,毒性预测有较大的挑战性。随着组学技术被更多地应用于化合物毒性的研究,计算毒理学在中药毒性研究中的应用也有新的机遇。     

药物毒理学研究的发展现状与趋势

药物毒理学是现代毒理学中研究药物的毒副作用机制,评价在研新药安全性的分支学科;其主要目的在于指导临床合理用药,降低药物的副作用及减少因药物毒性导致的新药开发失败。自上世纪90年代通过药代动力学和药物代谢的优化改进药物的吸收和生物利用度之后,药物的毒性因素已成为新药研发失败或撤市的主要原因之一,如替马沙星引起的溶血性贫血和肾衰,调脂药西立伐他汀所产生的横纹肌溶解,非甾体抗炎药罗非昔布所导致的心脏病和卒中等。为了应对毒性因素对新药研发过程(尤其是临床前阶段)中的制约,近十年来药物毒理学家在新药发现阶段的发现毒理…     

发现毒理学的研究进展

发现毒理学又称为开发前毒理学(Predevelopmental Toxicology),是指在创新药物的研发早期,对所合成的系列新化合物实体(New Chemical Entities, NCEs)进行毒性筛选,以发现和淘汰因毒性问题而不适于继续研发的化合物,指导合成更安全的同类化合物.发现毒理学的研究既可加快药物研发进程,提高研发成功率,又减少资源消耗.笔者就发现毒理学研究的定义、必要性、研究内容、研究方法和我国当前的研究现状作一简述.     

Pathway analysis tools and toxicogenomics reference databases for risk assessment

The pharmaceutical industry has begun to leverage a range of new technologies (proteomics, pharmacogenomics, metabolomics and molecular toxicology [e.g., toxicogenomics]) and analysis tools that are becoming increasingly integrated in the area of drug discovery and development. The approach of analyzing the vast amount of toxicogenomics data generated using molecular pathway and networks analysis tools in combination with analysis of reference data will be the main focus of this review. We will demonstrate how this combined approach can increase the understanding of the molecular mechanisms that lead to chemical-induced toxicity and application of this knowledge to compound risk assessment. We will provide an example of the insights achieved through a molecular toxicology analysis based on the well-known hepatotoxicant lipopolysaccharide to illustrate the utility of these new tools in the analysis of complex data sets, both in vivo and in vitro. The ultimate objective is a better lead selection process that improves the chances for success across the different stages of drug discovery and development.     

药物毒理学技术方法研究进展

药物是否安全和有效是药物研发成功与否的决定性因素。就药物研发的整个流程而言,毒性是终止药物研发的重要原因之一。药物毒理学研究贯穿于新药发现阶段、临床前安全性评价和上市后跟踪监督的全过程,因此药物的毒理学研究至关重要。简要综述了药物毒理学研究过程中所涉及的技术方法以及研究新动向,并主要介绍了组学技术的发展。     

High‐Content Analysis in Toxicology: Screening Substances for Human Toxicity Potential,Elucidating Subcellular Mechanisms and In Vivo Use as Translational Safety Biomarkers

High‐content analysis (HCA) of in vitro biochemical and morphological effects of classic (small molecule) drugs and chemicals is concordant with potential for human toxicity. For hepatotoxicity, concordance is greater for cytotoxic effects assessed by HCA than for conventional cytotoxicity tests and for regulatory animal toxicity studies. Additionally, HCA identifies chronic toxicity potential, and drugs producing idiosyncratic adverse reactions and/or toxic metabolites are also identified by HCA. Mechanistic information on the subcellular basis for the toxicity is frequently identified, including various mitochondrial effects, oxidative stress, calcium dyshomeostasis, phospholipidosis, apoptosis and antiproliferative effects, and a fingerprinting of the sequence and pattern of subcellular events. As these effects are frequently non‐specific and affect many cell types, some toxicities may be detected and monitored by HCA of peripheral blood cells, such as for anticancer and anti‐infective drugs. Critical methodological and interpretive features are identified that are critical to the effectiveness of the HCA cytotoxicity assessment, including the need for multiple days of exposure of cells to drug, use of a human hepatocyte cell line with metabolic competence, assessment of multiple pre‐lethal effects in individual live cells, consideration of hormesis, the need for interpretation of relevance of cytotoxicity concentration compared to efficacy concentration and quality management. Limitations of the HCA include assessment of drugs that act on receptors, transporters or processes not found in hepatocytes. HCA may be used in a) screening lead candidates for potential human toxicity in drug discovery alongside of in vitro assessment of efficacy and pharmacokinetics, b) elucidating mechanisms of toxicity and c) monitoring in vivo toxicity of drugs with known toxicity of known mechanism.     

Regulatory perspectives of Type II prodrug development and time-dependent toxicity management: nonclinical Pharm/Tox analysis and the role of comparative toxicology

Many therapeutic agents are prepared in prodrug forms, which are classified into Type I, II and subtypes A, B based on their sites of conversion. Recently, an increasing number of INDs have appeared as Type II prodrugs that often contain dual tracks of toxicity profile exploration, one on the prodrug and another on the active drug. A comparative toxicology analysis is introduced here to assist reviewers to evaluate the dual toxicity profiles effectively. The analysis helps determine which toxicity is contributed by the prodrug itself, its intermediates, or the active drug itself. As prodrug INDs, or any other new molecular entity (NME) INDs progress into advanced phases of toxicology development, analysis of time-dependent component of toxicity expression, regarding the emergence of new target organs over time, becomes more significant. A strategy is developed to address Pharm/Tox issues such as what duration is required for a toxicity to emerge at the exposure level achieved or dose studied, how many animals in the group are affected, whether the toxicity is a cross-species phenomenon, and whether it is reversible, etc. In conclusion, dual-track comparative toxicology can be useful in the understanding of Type II prodrug's mechanism of toxicity, and that time-dependent toxicology analysis offers means to detecting new toxicity emergence over time. Both approaches could significantly facilitate secondary and tertiary review processes during IND development of a prodrug or NME.     

Use of high-content analysis for compound screening and target selection

High-content analysis (HCA) has rapidly established itself as a core technology in drug discovery for secondary cell-based screening. When combined with our knowledge of genetics, HCA can provide a powerful tool for target validation, but excitingly, HCA may also enable the increased use of cellular assays in high-throughput screening for novel drug leads.     

Putting the fun into functional toxicogenomics.

The term "toxicogenomics" was first coined in 1999 to describethe marriage of toxicology and genomics (Nuwaysir et al., 1999).Since then, the field of toxicogenomics has undergone a rapidand uneven surge of growth. Driven by the promise of whole-genomegene expression analysis by microarray, toxicogenomics has beenadvanced as the tool for improved mechanistic toxicology screens,more sensitive and earlier toxicity discovery, drug and chemicalsafety assessments, and new drug discovery assays (Hayes andBradfield, 2005). However, it quickly became evident to scientistsconducting toxicogenomic studies that making sense of enormousdata sets from microarray studies would require new tools andnew approaches in order to     

Informed toxicity assessment in drug discovery: systems-based toxicology

Technological advances in the biological, chemical and in silico sciences have transformed many scientific disciplines, including toxicology. A vast new palate of toxicity testing tools is now available to investigators, enabling the generation of enormous amounts of data using only small amounts of test sample and at relatively low cost. In addition to these tools, the pharmaceutical industry has an urgent need for toxicity testing earlier in the process, based on the recognition that safety issues are the single largest cause of drug candidate attrition from development portfolios and the marketplace. However, along with the opportunity provided by new testing tools comes the dilemma of deciding which tools to use and, equally as important, when and why to use them. It may well be unwise to apply a new toxicity test or screening system simply because one can, as both false positive and false negative outcomes can quickly negate the value of a toxicity test system and may even have a net negative impact on drug discovery productivity. This can be true even of test systems that are considered to be 'validated' in the traditional sense. How then is an investigator or drug discovery organization to decide which of the new tools to use, and when to use them? Proposed herein is a strategy for identifying high-value toxicity testing systems and strategies based on program knowledge and informed decision-making. The decision to apply a certain toxicity testing system in this strategy is informed by knowledge of the pharmacological target, the chemical features of molecules active at the pharmacological target, and existing public domain or institutional learning. This 'fit-for-purpose' approach limits non-targeted or 'uninformed' toxicity screening to only those few test systems with high specificity, strong outcome concordance and molecular relevance to frequently encountered toxicity risks (eg, genotoxicity). Additional toxicity testing and screening is then conducted to address specific known or potential toxicity risks, based on existing knowledge of the target pharmacology and secondary pharmacology or chemical attributes with known or suspect risk, and by active 'interrogation' of both the target and active chemical moieties during the drug discovery process. This model for toxicity testing decision-making is illustrated by two case studies from recent experience.     

Proteomics: a major new technology for the drug discovery process

Proteomics is a new enabling technology that is being integrated into the drug discovery process. This will facilitate the systematic analysis of proteins across any biological system or disease, forwarding new targets and information on mode of action, toxicology and surrogate markers. Proteomics is highly complementary to genomic approaches in the drug discovery process and, for the first time, offers scientists the ability to integrate information from the genome, expressed mRNAs, their respective proteins and subcellular localization. It is expected that this will lead to important new insights into disease mechanisms and improved drug discovery strategies to produce novel therapeutics.