Systematic target actionability reviews of preclinical proof-of-concept papers to match targeted drugs to paediatric cancers

Advancing European paediatric research - the contribution of the Innovative Health Initiative

Children deserve health solutions, including medicines, medical devices and diagnostics, that are adapted to their needs. They should not be left behind when it comes to benefitting from innovations. The introduction of paediatric legislation in the EU and US in the 2000s dramatically changed the regulatory environment by fostering the development of medicines for children. However, the development of paediatric medicines remains challenging, and many needs remain unmet. When it comes to medical devices and in vitro diagnostics (IVDs), very few are designed and intended specifically for use in children, leading doctors to use adult devices and adapt them to fit children. To address the scientific, technical, and operational challenges related to paediatric development, multi-stakeholder collaboration is key. The European public-private partnerships the Innovative Health Initiative (IHI), and its predecessor the Innovative Medicines Initiative (IMI), contribute to advancing paediatric research by bringing together the private health industry sectors and public partners including academia, healthcare providers, patients and carers, regulators, and health technology assessment bodies. Several of their large collaborative research projects have already produced significant results that are optimising the development of paediatric medicines. This article looks at these achievements and discusses opportunities for further public-private collaborative research to boost the development of innovative health solutions that address specifically all children's needs.

Timing for First-in-Minor Clinical Trials of New Cancer Drugs

OBJECTIVES

To describe the delay for first-in-minor cancer clinical trials and its relationship with the Food and Drug Administration (FDA) approval.

STUDY DESIGN

We used ClinicalTrials.gov to create a sample of pediatric-relevant cancer drugs starting efficacy testing in adults from 2006 through 2011. We characterized the delay between first-in-adult efficacy trials and first-in-minor trials. We also assessed the proportion of drugs evaluated in minors that failed to gain approval, the proportions that were not evaluated in minors before receiving the FDA approval, and whether shorter delay was associated with larger effect sizes or greater probability of regulatory approval.

RESULTS

Thirty-four percent of the 185 drugs in our cohort were evaluated in minors; the median delay to clinical trials was 4.16 years. Of all drugs, 17% received the FDA approval, 41% of which were never tested in minors before licensing. Of the 153 drugs not attaining approval, 78% were not evaluated in minors. Earlier testing did not significantly predict greater response rates (P = .13). Drugs not attaining regulatory approval were evaluated significantly earlier (3.0 for drugs not approved vs 5.4 years delayed testing for approved drugs, P = .019).

CONCLUSIONS

New cancer drugs were typically evaluated in minors years after adult efficacy evaluation. This delay likely eliminated some drugs lacking desirable pharmacology before pediatric testing. However, some drugs that were eliminated may have had activity in pediatric indications. Approaches for prioritizing drugs for pediatric testing warrants further consideration.

Clinical research with targeted drugs in paediatric oncology

The development of targeted drugs in paediatric oncology has been notoriously slow, in part due to the peculiarities of this rare and highly heterogeneous population. To provide therapeutic breakthroughs for the highest risk subgroups of childhood cancer, innovative research solutions have been implemented in the last several years by different international collaborative groups and regulators. Here, we discuss and summarise some of these approaches, as well as challenges and unmet needs that are still being addressed. A wide range of topics were covered in this review including molecular diagnosis optimisation, innovative research methodologies, big data approaches, trial enrolment strategies, and improvements in regulation and preclinical research platforms.

Drug sensitivity profiling of 3D tumor tissue cultures in the pediatric precision oncology program INFORM

The international precision oncology program INFORM enrolls relapsed/refractory pediatric cancer patients for comprehensive molecular analysis. We report a two-year pilot study implementing ex vivo drug sensitivity profiling (DSP) using a library of 75-78 clinically relevant drugs. We included 132 viable tumor samples from 35 pediatric oncology centers in seven countries. DSP was conducted on multicellular fresh tumor tissue spheroid cultures in 384-well plates with an overall mean processing time of three weeks. In 89 cases (67%), sufficient viable tissue was received; 69 (78%) passed internal quality controls. The DSP results matched the identified molecular targets, including BRAF, ALK, MET, and TP53 status. Drug vulnerabilities were identified in 80% of cases lacking actionable (very) high-evidence molecular events, adding value to the molecular data. Striking parallels between clinical courses and the DSP results were observed in selected patients. Overall, DSP in clinical real-time is feasible in international multicenter precision oncology programs.

Target actionability review to evaluate CDK4/6 as a therapeutic target in paediatric solid and brain tumours

BACKGROUND

Childhood cancer is still a leading cause of death around the world. To improve outcomes, there is an urgent need for tailored treatment. The systematic evaluation of existing preclinical data can provide an overview of what is known and identify gaps in the current knowledge. Here, we applied the target actionability review (TAR) methodology to assess the strength and weaknesses of available scientific literature on CDK4/6 as a therapeutic target in paediatric solid and brain tumours by structured critical appraisal.

METHODS

Using relevant search terms in PubMed, a list of original publications investigating CDK4/6 in paediatric solid tumour types was identified based on relevancy criteria. Each publication was annotated for the tumour type and categorised into separate proof-of-concept (PoC) data modules. Based on rubrics, quality and experimental outcomes were scored independently by two reviewers. A third reviewer evaluated and adjudicated score discrepancies. Scores for each PoC module were averaged for each tumour type and visualised in a heatmap matrix in the publicly available R2 data portal.

RESULTS AND CONCLUSIONS

This CDK4/6 TAR, generated by analysis of 151 data entries from 71 publications, showed frequent genomic aberrations of CDK4/6 in rhabdomyosarcoma, osteosarcoma, high-grade glioma, medulloblastoma, and neuroblastoma. However, a clear correlation between CDK4/6 aberrations and compound efficacy is not coming forth from the literature. Our analysis indicates that several paediatric indications would need (further) preclinical evaluation to allow for better recommendations, especially regarding the dependence of tumours on CDK4/6, predictive biomarkers, resistance mechanisms, and combination strategies. Nevertheless, our TAR heatmap provides support for the relevance of CDK4/6 inhibition in Ewing sarcoma, medulloblastoma, malignant peripheral nerve sheath tumour and to a lesser extent neuroblastoma, rhabdomyosarcoma, rhabdoid tumour and high-grade glioma. The interactive heatmap is accessible through R2 [r2platform.com/TAR/CDK4_6].

Target Actionability Review: a systematic evaluation of replication stress as a therapeutic target for paediatric solid malignancies

BACKGROUND

Owing to the high numbers of paediatric cancer-related deaths, advances in therapeutic options for childhood cancer is a heavily studied field, especially over the past decade. Classical chemotherapy offers some therapeutic benefit but has proven long-term complications in survivors, and there is an urgent need to identify novel target-driven therapies. Replication stress is a major cause of genomic instability in cancer, triggering the stalling of the replication fork. Failure of molecular response by DNA damage checkpoints, DNA repair mechanisms and restarting the replication forks can exacerbate replication stress and initiate cell death pathways, thus presenting as a novel therapeutic target. To bridge the gap between preclinical evidence and clinical utility thereof, we apply the literature-driven systematic target actionability review methodology to published proof-of-concept (PoC) data related to the process of replication stress.

METHODS

A meticulous PubMed literature search was performed to gather replication stress-related articles (published between 2014 and 2021) across 16 different paediatric solid tumour types. Articles that fulfilled inclusion criteria were uploaded into the R2 informatics platform [r2.amc.nl] and assessed by critical appraisal. Key evidence based on nine pre-established PoC modules was summarised, and scores based on the quality and outcome of each study were assigned by two separate reviewers. Articles with discordant modules/scores were re-scored by a third independent reviewer, and a final consensus score was agreed upon by adjudication between all three reviewers. To visualise the final scores, an interactive heatmap summarising the evidence and scores associated with each PoC module across all, including paediatric tumour types, were generated.

RESULTS AND CONCLUSIONS

145 publications related to targeting replication stress in paediatric tumours were systematically reviewed with an emphasis on DNA repair pathways and cell cycle checkpoint control. Although various targets in these pathways have been studied in these diseases to different extents, the results of this extensive literature search show that ATR, CHK1, PARP or WEE1 are the most promising targets using either single agents or in combination with chemotherapy or radiotherapy in neuroblastoma, osteosarcoma, high-grade glioma or medulloblastoma. Targeting these pathways in other paediatric malignancies may work as well, but here, the evidence was more limited. The evidence for other targets (such as ATM and DNA-PK) was also limited but showed promising results in some malignancies and requires more studies in other tumour types. Overall, we have created an extensive overview of targeting replication stress across 16 paediatric tumour types, which can be explored using the interactive heatmap on the R2 target actionability review platform [https://hgserver1.amc.nl/cgi-bin/r2/main.cgi?option=imi2_targetmap_v1].

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.

International Consensus on Minimum Preclinical Testing Requirements for the Development of Innovative Therapies For Children and Adolescents with Cancer

Cancer remains the leading cause of disease-related death in children. For the many children who experience relapses of their malignant solid tumors, usually after very intensive first-line therapy, curative treatment options are scarce. Preclinical drug testing to identify promising treatment elements that match the molecular make-up of the tumor is hampered by the fact that (i) molecular genetic data on pediatric solid tumors from relapsed patients and thus our understanding of tumor evolution and therapy resistance are very limited to date and (ii) for many of the high-risk entities, no appropriate and molecularly well-characterized patient-derived models and/or genetic mouse models are currently available. However, recent regulatory changes enacted by the European Medicines Agency (class waiver changes) and the maturation of the RACE for Children act with the FDA, will require a significant increase in preclinical pediatric cancer research and clinical development must occur. We detail the outcome of a pediatric cancer international multistakeholder meeting whose output aims at defining an international consensus on minimum preclinical testing requirements for the development of innovative therapies for children and adolescents with cancer. Recommendations based on the experience of the NCI funded PPTP/C (www.ncipptc.org) and the EU funded ITCC-P4 public private partnership (www.itccp4.eu) are provided for the use of cell-based and mouse models for pediatric solid malignancies, as well as guidance on the scope and content of preclinical proof-of-concept data packages to inform clinical development dependent on clinical urgency. These recommendations can serve as a minimal guidance necessary to jumpstart preclinical pediatric research globally.