Nonclinical safety evaluation plays a critical role in the process of new drug development.International Conference on Harmonization (ICH) guideline M3 (R2) provides a key direction for the nonclinical safety evaluation process.Proper strategies and toxicological studies should be considered together to move the drug candidates forward efficiently and quickly to support clinical plans and market registration.Updates on ICH guidelines,such as ICH S6 and ICH S9,have great impact on the direction of development.With the increasing cost of development and competition in the industry,elements like predictivity,animal models,and regulatory compliance are also very important in the process.Therefore,an insight into all these factors is essential to toxicologists in the safety evaluation process.The ability to use the overall knowledge will result in a quicker and better new drug development program.

Assessment of QTc prolongation is a critical step for small molecule drug development.ICH S7B continues to be the main frame to guide the assessment for this potential cardiovascular risk.The ICH guideline outlines a 3-step approach to QTc prolongation,including in vitro bERG inhibition,ex vivo action potential duration (APD),and in vivo animal telemetry approch.Dog,monkey,swine,rabbit,ferret,and guinea pig are the common laboratory animals used for in vivo electrophysiology studies,especially using conscious Beagle Dog. In addition to all these guideline standard studies,many newly developed approaches,such as receptor binding for hERG inhibition,ex vivo methods such as perfused rabbit heart or guinea pig heartare are useful models for this purpose.All these methods display good correlation to clinic outcomes,and are low cost and have rapid turn-around time in nature; so that,they can help rapidly and predict this potential cardiac liability,resulting into accelerating process for small molecule drug candidate development.

Bi-specific T-cell engagers (BiTEs) show great clinical outcomes for anti-cancer purposes. However, potential cytokine release syndrome (CRS) is notorious to all BiTEs. The mechanism underlying CRS is still not fully known, even though such toxicities are considered to be cytokine release related. Assessment of CRS is a key to non-clinical de-risk programs for BiTEs therapeutic development. In the present review, possible mechanisms are discussed, especially factors contributing to CRS develop?ment. T cell activation may be just an initiation of the CRS cascade, and other cell types can greatly contribute to CRS, such as a chain reaction triggered by downstream B-cells, monocytes, and endothe?lium cells. A non-clinical de-risk program can be designed based on these components in the CRS cascade. Combination of in vitro cytokine release assay, and in vivo mouse and non-human primates studies should be reliable enough to predict and mitigate CRS risk in the clinics. Further more, a good de-risk program should be able to provide ranking for candidates for further development and provide enough confidence to select a first-in-human dose.