Evaluation of Juvenile Animal Studies for Pediatric CNS-Targeted Compounds: A Regulatory Perspective.

Central nervous system (CNS)-targeted products are an important category of pediatric pharmaceuticals. In view of the significant postnatal maturation of the CNS, juvenile animal studies (JAS) are performed to support pediatric development of these new medicines. In this project, the design and results of juvenile toxicity studies from 15 drug compounds for the treatment of neurologic or psychiatric conditions were analyzed. Studies were conducted mostly in rats; sometimes in addition in dogs and monkeys. The study design of the pivotal JAS was variable, even for compounds with a similar therapeutic indication. Age of the juvenile animals was not consistently related to the starting age of the intended patient population. Of 15 compounds analyzed, 6 JAS detected more severe toxicities and 6 JAS evidenced novel CNS effects compared to their adult counterparts. The effects of CNS on acoustic startle and learning and memory were observed at high dosages. Reversibility was tested in most cases and revealed some small effects that were retained or only uncovered after termination of treatment. The interpretation of the relevance of these findings was often hampered by the lack of matching end points in the adult studies or inappropriate study designs. Detailed clinical observation and motor activity measures were the most powerful end points to detect juvenile CNS effects. The need for more detailed behavioral examinations in JAS, for example, on learning and memory, should, therefore, be decided upon on a case-by-case basis, based on specific concerns in order to avoid overloading the studies.

Implementation of mechanism of action biology-driven early drug development for children with cancer.

An urgent need remains for new paediatric oncology drugs to cure children who die from cancer and to reduce drug-related sequelae in survivors. In 2007, the European Paediatric Regulation came into law requiring industry to create paediatric drug (all types of medicinal products) development programmes alongside those for adults. Unfortunately, paediatric drug development is still largely centred on adult conditions and not a mechanism of action (MoA)-based model, even though this would be more logical for childhood tumours as these have much fewer non-synonymous coding mutations than adult malignancies. Recent large-scale sequencing by International Genome Consortium and Paediatric Cancer Genome Project has further shown that the genetic and epigenetic repertoire of driver mutations in specific childhood malignancies differs from more common adult-type malignancies. To bring about much needed change, a Paediatric Platform, ACCELERATE, was proposed in 2013 by the Cancer Drug Development Forum, Innovative Therapies for Children with Cancer, the European Network for Cancer Research in Children and Adolescents and the European Society for Paediatric Oncology. The Platform, comprising multiple stakeholders in paediatric oncology, has three working groups, one with responsibility for promoting and developing high-quality MoA-informed paediatric drug development programmes, including specific measures for adolescents. Key is the establishment of a freely accessible aggregated database of paediatric biological tumour drug targets to be aligned with an aggregated pipeline of drugs. This will enable prioritisation and conduct of early phase clinical paediatric trials to evaluate these drugs against promising therapeutic targets and to generate clinical paediatric efficacy and safety data in an accelerated time frame. Through this work, the Platform seeks to ensure that potentially effective drugs, where the MoA is known and thought to be relevant to paediatric malignancies, are evaluated in early phase clinical trials, and that this approach to generate pre-clinical and clinical data is systematically pursued by academia, sponsors, industry, and regulatory bodies to bring new paediatric oncology drugs to front-line therapy more rapidly.

Juvenile animal studies and pediatric drug development: a European regulatory perspective.

During the workshop organized by ILSI/HESI on May 5-6, 2010 on the value of juvenile animal toxicity studies, the implementation of the European Pediatric Regulation and in particular the review process of the nonclinical part of the Pediatric Investigation Plan (PIP) were described. A PIP is intended to outline the development of a medicinal product in the pediatric population (i.e. quality, safety, efficacy of the medicine and timing of studies); it is reviewed and agreed by the Pediatric Committee (PDCO) of the European Medicines Agency (EMA). The Nonclinical Working Group (NcWG) supports the PDCO in the review process of the nonclinical part of a PIP and is composed of members from the PDCO, the EMA Safety Working Party, additional experts from national competent authorities and the FDA. This article summarizes the NcWG review process and outcomes of 97 approved or ongoing PIPs, from the establishment of the NcWG in November 2008 to May 2010, as presented during the workshop. Juvenile animal studies were proposed by the applicant in 33% or required by the NcWG in 26% of the PIPs. The requirements were mainly motivated by concerns regarding potential developmental toxicities, in view of the young age of the pediatric population to be investigated, the lack of knowledge concerning the maturation of the pharmacological target, the lack of sufficient (non)clinical data, observed toxicities in the adult (non)clinical studies and the long duration of the intended treatments. Most juvenile animal studies were in the therapeutic areas of oncology, infectious diseases and endocrinology. In about 14% of the PIPs submitted, the NcWG requested either justifications of, or amendments to the study designs proposed by the applicants (e.g. justification of endpoints, study duration, species selection and timing with regards to clinical pediatric studies). Generally, only one species was selected or proposed for the juvenile studies, the rat being the most prevalent. The number of juvenile studies initially proposed by the applicant plus those requested by the NcWG was higher than the number of studies included in the "key binding elements" of the PIP opinions. This apparent discrepancy was mainly due to additional information or justifications submitted by the applicant during the clock stop. It was noted that the PIPs initially submitted often lacked information relevant to the nonclinical evaluation. Therefore, during the workshop, the need to provide scientifically based justifications when no juvenile animal studies are proposed in the initial PIP submission was stressed.

Juvenile animal studies for the development of paediatric medicines: a description and conclusions from a European Medicines Agency workshop on juvenile animal testing for nonclinical assessors.

A workshop organised by the European Medicines Agency involved assessors and experts present in a Nonclinical Working Group evaluating juvenile animal studies for Paediatric Investigation Plans in collaboration with the Paediatric Committee and the Safety Working Party of the Committee for Human Medicinal Products. The objective of the workshop was to analyse which juvenile animal studies proposals were received and agreed by the Paediatric Committee, to check consistency and how to apply the existing European guideline on juvenile animal studies. A comparison of main organ system development in man vs. animal species was presented to guide the review and to support species selection and protocol design. An analysis of juvenile animal studies included in finalised PIP's was also presented. Out of 109 paediatric investigation plans finalised between November 2008 and March 2009, 43 included one or more juvenile animal studies. In most cases the preferred species was the rat; one species only was requested to be studied (20/22), but in a minority two species were required (2/22). When deciding on the characteristics of the juvenile animal studies, such as age of animals at study start, the age of the children targeted by the medicine was considered. It is expected that the increasing experience gained by Applicants and Regulators will allow further refining the criteria for these juvenile animal studies. Further research on this topic is highly encouraged in the European Regulatory framework.