An FDA oncology view of juvenile animal studies in support of initial pediatric trials for anticancer drugs

Navigating the Regulatory Landscape to Develop Pediatric Oncology Drugs: Expert Opinion Recommendations

Regulatory changes have been enacted in the United States (US) and European Union (EU) to encourage the development of new treatments for pediatric cancer. Here, we review some of the factors that have hampered the development of pediatric cancer treatments and provide a comparison of the US and EU regulations implemented to address this clinical need. We then provide some recommendations for each stage of the oncology drug development pathway to help researchers maximize their chance of successful drug development while complying with regulations. A key recommendation is the engagement of key stakeholders such as regulatory authorities, pediatric oncologists, academic researchers, patient advocacy groups, and a Pediatric Expert Group early in the drug development process. During drug target selection, sponsors are encouraged to consult the Food and Drug Administration (FDA), European Medicines Agency (EMA), and the FDA target list, in addition to relevant US and European consortia that have been established to characterize and prioritize oncology drug targets. Sponsors also need to carefully consider the resourcing requirements for preclinical testing, which include ensuring appropriate access to the most relevant databases, clinical samples, and preclinical models (cell lines and animal models). During clinical development, sponsors can account for the pharmacodynamic (PD)/pharmacokinetic (PK) considerations specific to a pediatric population by developing pediatric formulations, selecting suitable PD endpoints, and employing sparse PK sampling or modeling/simulation of drug exposures where appropriate. Additional clinical considerations include the specific design of the clinical trial, the potential inclusion of children in adult trials, and the value of cooperative group trials.

Lack of value of juvenile animal toxicity studies for supporting the safety of pediatric oncology phase I trials

Toxicity studies in juvenile animals (JAS) are sometimes performed to support clinical trials in pediatric oncology patients, and there are differing conclusions on the value of JAS for pediatric drug development. This manuscript provides a review of the pediatric clinical data for 25 molecularly-targeted and 4 biologic anticancer therapeutics. Other publications that evaluated the value of JAS in pediatric drug development focus on differences in toxicity between juvenile animals and adult animals. The present paper examines pediatric-specific clinical findings to focus on dose setting in pediatric oncology patients and safety monitoring in terms of the potential value of JAS. Our assessment demonstrates that pediatric starting doses were safe for all 29 therapeutics examined in that no life-threatening toxicities occurred in the first cohort, and overall the ratio of the pediatric maximum tolerated dose (MTD) to the recommended adult dose was close to 1. In addition, the 4 serious adverse events (SAEs) that weren't detectable with standard monitoring plans for pediatric oncology trials would not have been detectable in a standard JAS. This review demonstrates that safe starting doses in pediatric oncology patients for these therapeutics could have been solely based on adult doses without any knowledge of findings in JAS.

Juvenile Animal Testing: Assessing Need and Use in the Drug Product Label

BACKGROUND

Juvenile animal testing has become an established part of drug development to support safe clinical use in the human pediatric population and for eventual drug product label use.

METHODS AND RESULTS

A review of European Paediatric Investigation Plan decisions showed that from 2007 to mid-2017, 229 drugs had juvenile animal work requested, almost exclusively incorporating general toxicology study designs, in rat (57.5%), dog (8%), mouse (4.5%), monkey (4%), pig (2%), sheep (1%), rabbit (1%), hamster (0.5%), and species not specified (21.5%). A range of therapeutic areas were found, but the most common areas were infectious diseases (15%), endocrinology (13.5%), oncology (13%), neurology (11%), and cardiovascular diseases (10%). Examination of major clinical indications within these therapeutic areas showed some level of consistency in the species of choice for testing and the pediatric age that required support. Examination of juvenile animal study findings presented in product labels raises questions around how useful the data are to allow prescribing the drug to a child.

CONCLUSION

It is hopeful that the new ICH S11 guideline "Nonclinical Safety Testing in Support of Development of Pediatric Medicines" currently in preparation will aid drug developers in clarifying the need for juvenile animal studies as well as in promoting a move away from toxicology studies with a conventional design. This would permit more focused testing to examine identified areas of toxicity or safety concerns and clarify the presentation/interpretation of juvenile animal study findings for proper risk assessment by a drug prescriber.

Bridging Adult Experience to Pediatrics in Oncology Drug Development

Pediatric drug development in the United States has grown under the current regulations made permanent by the Food and Drug Administration Safety and Innovation Act of 2012. Over 1200 pediatric studies have now been submitted to the US FDA, but there is still a high rate of failure to obtain pediatric labeling for the indication pursued. Pediatric oncology represents special problems in that the disease is most often dissimilar to any cancer found in the adult population. Therefore, the development of drug dosing in pediatric oncology patients represents a special challenge. Potential approaches to pediatric dosing in oncology patients include extrapolation of efficacy from adult studies in those few cases where the disease is similar, inclusion of adolescent patients in adult trials when possible, and bridging the adult dose to the pediatric dose. An analysis of the recommended phase 2 dose for 40 molecularly targeted agents in pediatric patients provides some insight into current practices. Increased knowledge of tumor biology and efforts to identify and validate molecular targets and genetic abnormalities that drive childhood cancers can lead to increased opportunities for precision medicine in the treatment of pediatric cancers.

Clinical trial enrollment of adolescents and young adults with sarcoma

More than half of all sarcomas occur in adolescents and young adults (AYAs) aged 15 to 39 years. After the publication of the AYA series in the April 1, 2016 issue of Cancer, several leaders in the field of sarcoma across disciplines gathered to discuss the status of sarcoma clinical research in AYAs. They determined that a focused effort to include the underrepresented and understudied AYA population in current and future sarcoma clinical trials is overdue. Trial enrichment for AYA-aged sarcoma patients will produce more meaningful results that better represent the disease's biology, epidemiology, and treatment environment. To address the current deficit, this commentary outlines changes believed to be necessary to expediently achieve an increase in the enrollment of AYAs in sarcoma clinical trials. Cancer 2017;123:3434-40. © 2017 American Cancer Society.

Enrolling Adolescents in Disease/Target-Appropriate Adult Oncology Clinical Trials of Investigational Agents

The enrollment of adolescents with cancer in clinical trials is much lower than that of younger pediatric patients. For adolescents with "adult-type" cancers, lack of access to relevant trials is cited as one of the reasons for this discrepancy. Adolescents are generally not eligible for enrollment in adult oncology trials, and initial pediatric trials for many drugs are conducted years later, often after the drug is approved. As a result, accrual of adolescents to these trials may be slow due to off-label use, prospectively collected safety and efficacy data are lacking at the time of initial approval, and, most importantly, these adolescents have delayed access to effective therapies. To facilitate earlier access to investigational and approved drugs for adolescent patients with cancer, and because drug exposure is most often similar in adolescents and adults, we recommend the inclusion of adolescents (ages 12-17) in disease- and target-appropriate adult oncology trials. This approach requires careful monitoring for any differential safety signals, appropriate pharmacokinetic evaluations, and ensuring that ethical requirements are met. Inclusion of adolescents in adult oncology trials will require the cooperation of investigators, cooperative groups, industry, institutional review boards, and regulatory agencies to overcome real and perceived barriers. Clin Cancer Res; 23(1); 9-12. ©2016 AACR.