title: Preclinical models for pediatric solid tumor drug discovery: current trends, challenges and the scopes for improvement.
abstract: BACKGROUND
  The enhancement in pediatric cancer survival achieved in the past few decades has been confined to low- and moderate-risk cancers, whereas no notable improvement in survival was observed in high-risk and advanced-stage childhood cancers. High attrition rate of candidate drugs in clinical trials is a major hurdle in the development of effective therapies for pediatric solid tumors. In order to reduce the failure rate of candidate drugs in clinical trials, more effective strategies are needed to enhance the predictability of preclinical testing.
  
  
  METHODS
  The authors have described the current trends in preclinical drug development for treating pediatric solid tumors. Furthermore, the authors review their limitations and the available remedies, with regards to choice of models, pharmacokinetic considerations and the criteria for assessing the long-term efficacy of a candidate drug.
  
  
  CONCLUSIONS
  In many solid tumors, common differences between pediatric and adult cancers have been observed, and therefore, clinical trials for pediatric solid tumors must be conducted on the basis of preclinical observations in pediatric solid tumor models. There is a need to invest in extensive preclinical testing on pediatric solid tumor models. None of the preclinical models can fully recapitulate the human cancers. Therefore, these limitations must be considered while conducting a preclinical trial. The dose and schedule of drugs used for preclinical testing must be clinically relevant. While testing the efficacy of drugs, the markers of apoptosis, drug resistance, hypoxia and tumor-initiating cells can inform us about the long-term therapeutic response of a cancer.
authors.affiliation: Hospital for Sick Children, Department of Hematology/Oncology, Toronto, Ontario, Canada.
authors.forename: Sushil
authors.initials: S
authors.lastname: Kumar
authors.forename: Reza Bayat
authors.initials: RB
authors.lastname: Mokhtari
authors.forename: Herman
authors.initials: H
authors.lastname: Yeger
authors.forename: Sylvain
authors.initials: S
authors.lastname: Baruchel
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents / Q000737:chemistry / Q000494:pharmacology*; D002648:Child; D004195:Disease Models, Animal; D004353:Drug Evaluation, Preclinical / Q000379:methods*; D006801:Humans; D008954:Models, Biological; D009369:Neoplasms / Q000188:drug therapy*
chemical_list: D000970:Antineoplastic Agents