Cancer drugs approved for use in children: Impact of legislative initiatives and future opportunities

Off-label prescribing of immune checkpoint inhibitor therapy at a single pediatric cancer center

BACKGROUND

Immune checkpoint inhibitors (ICI) have improved outcomes in a variety of adult cancers and are prescribed with increasing frequency across oncology. However, patterns of off-label use of ICI in pediatrics remain unclear.

METHODS

This is a single-institution, retrospective cohort study evaluating off-label ICI use in pediatric and young adult patients with cancer treated at our institution from 2014 to 2022. Response was based on clinician assessment derived from clinical records. Immune-related adverse events (iRAEs) were classified according to CTCAE v5.0.

RESULTS

We identified 50 unique patients treated with off-label ICI (28 with solid tumors, 20 with central nervous system (CNS) tumors, 2 with hematologic malignancies). At time of ICI initiation, only five patients (10%) had localized disease, and all but one patient was treated in the relapsed/refractory setting. All patients were treated with the FDA-approved weight-based dosing recommendations. Overall, there was disease control in 21 patients (42%), with best response including one complete response (melanoma), two partial responses (high-grade glioma, CNS nongerminomatous germ cell tumor), and 18 patients with stable disease. Forty-four patients (88%) eventually experienced disease progression. Among 22 patients (44%) experiencing iRAEs, 10 (20%) had a grade ≥3 irAE, 12 (24%) required corticosteroids, and 14 (28%) required ICI discontinuation. irAE occurrence was associated with significantly improved progression-free survival (HR 0.35; 95% CI: 0.18 to 0.68; p = 0.002) and overall survival (HR 0.33; 95% CI: 0.17 to 0.66; p = 0.002).

CONCLUSIONS

At our institution, ICI was most commonly prescribed in the relapsed/refractory setting to patients with metastatic disease. The treatment was generally well-tolerated in the pediatric population. The overall response rate was low, and the majority of patients eventually experienced disease progression. A few patients, however, had durable treatment responses. Further studies are needed to identify which pediatric patients are most likely to benefit from ICI.

Pediatric oncology drug development and dosage optimization

Oncology drug discovery and development has always been an area facing many challenges. Phase 1 oncology studies are typically small, open-label, sequential studies enrolling a small sample of adult patients (i.e., 3-6 patients/cohort) in dose escalation. Pediatric evaluations typically lag behind the adult development program. The pediatric starting dose is traditionally referenced on the recommended phase 2 dose in adults with the incorporation of body size scaling. The size of the study is also small and dependent upon the prevalence of the disease in the pediatric population. Similar to adult development, the dose is escalated or de-escalated until reaching the maximum tolerated dose (MTD) that also provides desired biological activities or efficacy. The escalation steps and identification of MTD are often rule-based and do not incorporate all the available information, such as pharmacokinetic (PK), pharmacodynamic (PD), tolerability and efficacy data. Therefore, it is doubtful if the MTD approach is optimal to determine the dosage. Hence, it is important to evaluate whether there is an optimal dosage below the MTD, especially considering the emerging complexity of combination therapies and the long-term tolerability and safety of the treatments. Identification of an optimal dosage is also vital not only for adult patients but for pediatric populations as well. Dosage-finding is much more challenging for pediatric populations due to the limited patient population and differences among the pediatric age range in terms of maturation and ontogeny that could impact PK. Many sponsors defer the pediatric strategy as they are often perplexed by the challenges presented by pediatric oncology drug development (model of action relevancy to pediatric population, budget, timeline and regulatory requirements). This leads to a limited number of approved drugs for pediatric oncology patients. This review article provides the current regulatory landscape, incentives and how they impact pediatric drug discovery and development. We also consider different pediatric cancers and potential clinical trial challenges/opportunities when designing pediatric clinical trials. An outline of how quantitative methods such as pharmacometrics/modelling & simulation can support the dosage-finding and justification is also included. Finally, we provide some reflections that we consider helpful to accelerate pediatric drug discovery and development.

Recent Use of Pediatric Extrapolation in Pediatric Drug Development in US

The regulatory standards of the United States Food and Drug Administration (FDA) require substantial evidence of effectiveness from adequate and well-controlled trials, for drugs developed in both adults and children. However, when scientifically justified, relying on extrapolation may be acceptable. Historically, the FDA's extrapolation approach was based on draft guidance published in 2014, which introduced the categories of full, partial, and no extrapolation. The European Medicines Agency (EMA) took a different view on pediatric extrapolation. To better understand the use of extrapolation to support pediatric drug development and approval, we reviewed the pediatric labeling changes published by the FDA, focusing on the labeling updates between 1/1/2015 and 7/31/2021, the period where the extrapolation approach is in transition to harmonize with the EMA. Within this time window, among the 265 drugs and biological products with pediatric labeling changes, 169 (63.8%) were identified where extrapolation was used. This includes 64 (24.2%) labeling changes, where full extrapolation was used, and 105 (39.6%) labeling changes, where partial extrapolation was used. The major disease areas that extrapolation was used include neuroscience (40/53, 75.5%) and infectious disease (20/28, 71.4%). The extrapolation approach was identified in terms of source population beyond the use of adult as well as extrapolation from clinical trials conducted in the same drug class. The use of extrapolation increased the rates of new and expanded pediatric indication in the period. This review gives the most recent landscape of pediatric labeling changes using extrapolation. With the released ICH (International Council for Harmonization) E11A guidance in April 2022, the paper also provides insights for future pediatric drug development programs.

Utility of propensity score-based Bayesian borrowing of external adult data in pediatric trials: A pragmatic evaluation through a case study in acute lymphoblastic leukemia (ALL)

A fully powered randomized controlled cancer trial can be challenging to conduct in children because of difficulties in enrollment of pediatric patients due to low disease incidence. One way to improve the feasibility of trials in pediatric patients, when clinically appropriate, is through borrowing information from comparable external adult trials in the same disease. Bayesian analysis of a pediatric trial provides a way of seamlessly augmenting pediatric trial efficacy data with data from external adult trials. However, not all external adult trial subjects may be equally clinically relevant with respect to the baseline disease severity, prognostic factors, co-morbidities, and prior therapy observed in the pediatric trial of interest. The propensity score matching method provides a way of matching the external adult subjects to the pediatric trial subjects on a set of clinically determined baseline covariates, such as baseline disease severity, prognostic factors and prior therapy. The matching then allows Bayesian information borrowing from only the most clinically relevant external adult subjects. Through a case study in pediatric acute lymphoblastic leukemia (ALL), we examine the utility of propensity score matched mixture and power priors in bringing appropriate external adult efficacy information into pediatric trial efficacy assessment, and present considerations for scaling fixed borrowing from external adult data.

The Battlefield of Chemotherapy in Pediatric Cancers

The survival rate for pediatric cancers has remarkably improved in recent years. Conventional chemotherapy plays a crucial role in treating pediatric cancers, especially in low- and middle-income countries where access to advanced treatments may be limited. The Food and Drug Administration (FDA) approved chemotherapy drugs that can be used in children have expanded, but patients still face numerous side effects from the treatment. In addition, multidrug resistance (MDR) continues to pose a major challenge in improving the survival rates for a significant number of patients. This review focuses on the severe side effects of pediatric chemotherapy, including doxorubicin-induced cardiotoxicity (DIC) and vincristine-induced peripheral neuropathy (VIPN). We also delve into the mechanisms of MDR in chemotherapy to the improve survival and reduce the toxicity of treatment. Additionally, the review focuses on various drug transporters found in common types of pediatric tumors, which could offer different therapeutic options.

The Development of New Agents for Post-Hematopoietic Stem Cell Transplantation Non-Infectious Complications in Children

Hematopoietic stem cell transplantation (HSCT) is often the only curative treatment option for patients suffering from various types of malignant diseases and some non-cancerous conditions. Nevertheless, it is associated with a high risk of complications leading to transplant-related mortality and long-term morbidity. An increasing number of therapeutic and prevention strategies have been developed over the last few years to tackle the complications arising in patients receiving an HSCT. These strategies have been mainly carried out in adults and some are now being translated into children. In this manuscript, we review the recent advancements in the development and implementation of treatment options for post-HSCT non-infectious complications in pediatric patients with leukemia and other non-malignant conditions, with a special attention on the new agents available within clinical trials. We focused on the following conditions: graft failure, prevention of relapse and early interventions after detection of minimal residual disease positivity following HSCT in acute lymphoblastic and myeloid leukemia, chronic graft versus host disease, non-infectious pulmonary complications, and complications of endothelial origin.

The use of special approval medicines among pediatric patients in a tertiary care hospital: A reality check

Background

Special approval medicines (SAMs) are medicines used with approval from the Director General of Health Malaysia when the therapeutic options within regulatory and formulary boundaries appear unsuitable or ineffective to treat the patients.

Objectives

To examine and characterize the use of SAMs among children in a Malaysian tertiary care hospital.

Methods

The named-patient basis SAM application forms, cover letter, pharmacist review summary and patient monitoring forms available at the Pharmacy Department between 1st January 2019 and 31st December 2020 were reviewed. Unprocessed, unapproved and stock-basis applications were excluded. The outcome measures were categories, scope, off-label use and cost of SAM. Per-patient data were analyzed descriptively.

Results

Overall, 1010 patients (mean age of 8.7 ± 5.6 years) were involved in 328 SAMs applications. The most common SAMs pharmacological groups were nervous system (n = 371, 36.7%) and antineoplastic and immunomodulating agents (n = 332, 32.9%). Top three SAMs were melatonin (11.5%), scopolamine (7.6%) and cholecalciferol (7.1%). A total of 837 (82.9%) and 513 (50.8%) patients were involved in the SAMs applications for non-formulary and unregistered medicines, respectively. Unregistered, non-formulary medicines were applied for 47.3% (n = 478) of the patients. The majority of the scope for SAMs (64.7%) were to substitute the available alternatives in the national formulary which were ineffective or sub-optimal for the patients. Among the 262 patients with repeat applications, 93.8% reported disease or symptom improvement while 1.9% experienced side effects. Up to 17% of SAMs analyzed in this study were used for off-label indications. The total cost of the SAMs was RM8,748,358.38 (USD 2,090,418.86).

Conclusion

The use of SAMs among children in this hospital involved unregistered, non-formulary medicines used to substitute the available alternatives in the formulary. A concerted effort is warranted in exploring supplementary mechanisms to enhance the medicine registration process and formulary system towards facilitating enhanced provision of treatment for children.

The emerging role of pyroptosis in pediatric cancers: from mechanism to therapy

Pediatric cancers are the driving cause of death for children and adolescents. Due to safety requirements and considerations, treatment strategies and drugs for pediatric cancers have been so far scarcely studied. It is well known that tumor cells tend to progressively evade cell death pathways, which is known as apoptosis resistance, one of the hallmarks of cancer, dominating tumor drug resistance. Recently, treatments targeting nonapoptotic cell death have drawn great attention. Pyroptosis, a newly specialized form of cell death, acts as a critical physiological regulator in inflammatory reaction, cell development, tissue homeostasis and stress response. The action in different forms of pyroptosis is of great significance in the therapy of pediatric cancers. Pyroptosis could be induced and consequently modulate tumorigenesis, progression, and metastasis if treated with local or systemic therapies. However, excessive or uncontrolled cell death might lead to tissue damage, acute inflammation, or even cytokine release syndrome, which facilitates tumor progression or recurrence. Herein, we aimed to describe the molecular mechanisms of pyroptosis, to highlight and discuss the challenges and opportunities for activating pyroptosis pathways through various oncologic therapies in multiple pediatric neoplasms, including osteosarcoma, neuroblastoma, leukemia, lymphoma, and brain tumors.

Improving comprehension, recall and attention using multimedia-informed assent among pediatric oncology patients: A comparative randomized controlled trial

BACKGROUND

Assent should be obtained in all children involved in research in keeping with their level of maturity. Traditional assent forms contain too much information and are difficult to read. The study aimed to identify an effective tool to enhance children's comprehension during the assent process and focused on those with cancer who are likely more engaged in research involving greater than minimal risk.

METHODS

In all, 116 children with cancer were randomized to receive either a paper-based assent document or a multimedia-based assent document. Open-ended and multiple-choice questions were used to assess comprehension and recall. Time spent on the documents and children's behavior during the assent process was recorded to determine their attention and satisfaction.

RESULTS

Children randomized to a multimedia-based assent document achieved significant higher comprehension and recall assessment scores (p-values <.001). The high score achievement significantly correlated with the child's age with adjusted odds ratio (OR) of 1.90 (p-value <.001; 95% confidence interval [CI]: 1.35-2.66) for comprehension assessment and 1.59 (p-value .001; 95% CI: 1.20-2.12) for recall assessment. Children randomized to a multimedia-based assent document had significant longer time spent on the document (p-value .001) with less numbers of inattention (p-value <.001) and expressed more signs of enjoyment during the assent process (p-values <.001).

CONCLUSION

Multimedia-based assent document successfully enhanced comprehension, recall, and attention with more satisfaction compared with a traditional paper-based document among children with cancer. This approach may be considered as an alternative format for children engaging in research involving greater than minimal risk.

The RACE for children act at one year: progress in pediatric development of molecularly targeted oncology drugs

BACKGROUND

The Research to Accelerate Cures and Equity (RACE) for Children Act of 2017 authorized the Food and Drug Administration (FDA) to require pediatric clinical trials for new oncology drugs with relevant molecular targets. This study reviewed oncology drug approvals within the first year after the new legislation came into effect, to evaluate the impact on development of molecularly targeted oncology drugs for pediatric cancers.

RESEARCH DESIGN AND METHODS

For new oncology drugs approved by the FDA between 08/18/2020-08/18/2021, drug approval packages, letters and prescribing information were reviewed for the submission and approval dates, indication and molecular target of the drug, and post-marketing requirements that included pediatric clinical trials.

RESULTS

Within the 1-year period, 17 new oncology drugs were approved, but only 5 had been submitted after 08/18/2020. Three of the 5 (60.0%) had requirements for pediatric trials under the RACE Act. None of the 12 submitted prior to 08/18/2020 had pediatric trial requirements, but 11 (91.7%) had molecular targets that would have made them candidates under the RACE Act. Nine of the 17 approvals (52.9%) had pediatric trials registered on clinicaltrials.gov.

CONCLUSIONS

Early evidence suggests that while some pediatric development of oncology drugs was initiated without FDA request, the RACE Act was effective at closing the loopholes of previous legislation and creating new opportunities for innovation in developing therapies for childhood cancers.

Childhood cancer drugs in China: An overview and comparison of regulatory approvals in China and the United States

Different from less developed countries, 80% of children with cancers in the United States are cured. Traditional chemotherapy drugs are the mainstay of therapies; new targeted medications have become available recently. Using publicly available data, we created a database of cancer drugs with paediatric malignancy indications approved by 31 October 2020 in China and the United States. We compared numbers, type, indications and listing on the World Health Organization Model List of Essential Medicines for Children (WHO EMLc) between the two countries, assessed the correlation between paediatric indications and cancer incidences, and described evidence supporting approvals of targeted medications in the two settings. Our study showed that by 31 October 2020, 31 and 39 cancer drugs available in China and the United States were approved for use in children, corresponding to 137 and 102 paediatric cancer indications, respectively. About half of these drugs (17 in China and 18 in the United States) were listed on the WHO EMLc. The correlation between indications and burden of disease was higher in the United States (r = 0.68) than China (r = 0.59). More traditional chemotherapy drugs were approved in China (n = 27) than the United States (n = 19). Of 20 targeted childhood anticancer medicines approved in the United States, mainly on the basis of single arm trials (27/32 indications, 84.4%), only four were approved for paediatric indications in China, at a median of 2.8 years after US Food and Drug Administration approval. A harmonised, evidence-based regulatory framework is needed to ensure approvals of needed, safe and efficacious childhood cancer drugs across the world.

Precision Medicine: An Emerging Paradigm for Improved Diagnosis and Safe Therapy in Pediatric Oncology

Cancer is a lethal disease that kills a great number of people each year. Standard treatments such as chemotherapy or radiation are only effective in a small percentage of individuals due to illness variability. Tumors can be caused by a variety of genetic factors and express a variety of proteins depending on the individual. Because of developments in high-throughput technology, there has been a flood of large-scale biological data produced in recent decades. As a result, the focus of medical research has evolved. It was a once-in-a-lifetime chance for translational research to explore molecular alterations across the entire genome. In this setting, precision medicine was developed, and the possibility of better diagnostic and treatment tools became a reality. This is especially true in the case of cancer, which is becoming more prevalent around the world. The goal of this study is to look at precision medicine technology and its applications to cancer, with a focus on children. The inherent diversity of cancer lends itself to the rapidly expanding field of precision and personalized medicine.

Multicenter study of risk factors of unplanned 30-day readmissions in pediatric oncology

Background

Pediatric oncology patients have high rates of hospital readmission but there is a dearth of research into risk factors for unplanned 30‐day readmissions among this high‐risk population.

Aim

In this study, we built a statistical model to provide insight into risk factors of unplanned readmissions in this pediatric oncology.

Methods

We retrieved 32 667 encounters from 10 418 pediatric patients with a neoplastic condition from 16 hospitals in the Cerner Health Facts Database and built a mixed‐effects model with patients nested within hospitals for inference on 75% of the data and reserved the remaining as an independent test dataset.

Results

The mixed‐effects model indicated that patients with acute lymphoid leukemia (in relapse), neuroblastoma, rhabdomyosarcoma, or bone/cartilage cancer have increased odds of readmission. The number of cancer medications taken by the patient and the administration of chemotherapy were associated with increased odds of readmission for all cancer types. Wilms Tumor had a significant interaction with administration of chemotherapy, indicating that the risk due to chemotherapy is exacerbated in patients with Wilms Tumor. A second two‐way interaction between recent history of chemotherapy treatment and infections was associated with increased odds of readmission. The area under the receiver operator characteristic curve (and corresponding 95% confidence interval) of the mixed‐effects model was 0.714 (0.702, 0.725) on the independent test dataset.

Conclusion

Readmission risk in oncology is modified by the specific type of cancer, current and past administration of chemotherapy, and increased health care utilization. Oncology‐specific models can provide decision support where model built on other or mixed population has failed.

A review of the experience with pediatric written requests issued for oncology drug products

BACKGROUND

Pediatric anticancer drug development has numerous challenges. The Pediatric Research Equity Act (PREA) and the Best Pharmaceuticals for Children Act (BPCA) were passed to address pediatric drug development deficiencies in general. Until recently, the requirements for pediatric evaluation of most oncology products developed for adult cancers have been waived. Because children typically do not have the same type of cancers, which occur commonly in adults, or the indication or drug had been granted an orphan designation, PREA therefore has had no impact. Pediatric studies for labeling updates are largely done through BPCA by a written request (WR) issued by the Food and Drug Administration (FDA). Because the cancers that occur in pediatric and adult populations do not share the same etiology or natural history, there are limited opportunities to extrapolate adult efficacy and safety to the pediatric population. The characteristics of individual pediatric studies included in WRs have varied greatly over time.

PROCEDURE

In this study, we searched WRs that were issued by the FDA since 2001. We found 40 such requests issued for oncology drugs and biologics, which had been accepted by sponsors.

RESULTS

Clinical trials included in 23 of the WRs have been concluded, 19 have resulted in exclusivity, and three drugs that were studied have been approved for use in pediatric populations. Herein, we present the spectrum of WRs from a regulatory, study design, dosing, formulation, analysis plan, evidentiary standard of efficacy, and safety perspective.

CONCLUSIONS

This provides information on requests issued in the past nearly 20 years and studies that are completed. As WRs have provided the only regulatory mechanism to assure pediatric cancer drug development, this can potentially provide insight on how pediatric cancer drug development may change in the future.

Use of Antiangiogenic Therapies in Pediatric Solid Tumors

Cancer is an important cause of death in childhood. In recent years, scientists have made an important effort to achieve greater precision and more personalized treatments against cancer. But since only a few pediatric patients have identifiable therapeutic targets, other ways to stop the neoplastic cell proliferation and dissemination are needed. Therefore, the inhibition of general processes involved in the growth and behavior of tumors can be a relevant strategy for the development of new cancer therapies. In the case of solid tumors, one of these processes is angiogenesis, essential for tumor growth and generation of metastases. This review summarizes the results obtained with the use of antiangiogenic drugs in the main pediatric malignant solid tumors and also an overview of clinical trials currently underway. It should be noted that due to the rarity and heterogeneity of the different types of pediatric cancer, most studies on antiangiogenic drugs include only a small number of patients or isolated clinical cases, so they are not conclusive and further studies are needed.

Landscape of phase 1 clinical trials for minors with cancer in the United States

OBJECTIVES

Understanding trends in characteristics of early phase trials that allow minors with cancer to participate may inform additional efforts to improve cancer drug development for young people.

METHODS

We accessed data for oncology phase 1 or phase 1/2 trials in the United States from ClinicalTrials.gov with lower age bound for eligibility <18 years. Descriptive statistics were calculated and trends over time evaluated using logistic and multinomial logistic regression.

RESULTS

Six hundred twelve trials met inclusion criteria. Sixty-five percent of trials were for older adults that also allowed minors, while 9% were exclusively for patients ≤18 years of age. Eighty-three percent of trials included at least one novel agent, while 17% studied only conventional therapies. Fifty-eight percent of trials studied treatments not yet Food and Drug Administration (FDA) approved (48% if exclusively for patients ≤18 years). Fifteen percent of trials for which dose-escalation method could be determined, utilized a model-based design. Eighteen percent of all trials were industry sponsored (48% if exclusively for patients ≤18 years). Forty-nine percent of all trials were multicenter (69% if exclusively for patients ≤18 years). There was an increase in trials exclusively focused on patients with central nervous system (CNS) tumors over the study period (P ≤ .02). No other temporal trends were seen. The median times from first-in-adult to first-in-pediatric for monotherapy and combination trials were 5.7 and 3.3 years, respectively.

CONCLUSION

The paucity of clear temporal trends highlights the need for innovation in early drug development for young people. Our analysis serves as a benchmark against which to evaluate initiatives to improve pediatric cancer drug development.

Guideline concordant care for prevention of acute chemotherapy-induced nausea and vomiting in children, adolescents, and young adults

PURPOSE

Prescribing guideline-recommended anti-emetics is an effective strategy to prevent CINV. However, the rate of guideline-concordant care is not well-understood. The purpose of this study was to describe the proportion of pediatric, adolescent, and young adult patients receiving HEC or MEC who received guideline-concordant antiemetic prophylaxis for acute CINV and to identify potential predictors of guideline-concordant antiemetic prophylaxis.

METHODS

Using electronic health record data from 2016 through 2018, a retrospective single-institution cohort study was conducted to investigate how often patients less than 26 years of age receiving moderately or highly emetogenic chemotherapy receive guideline-concordant prophylaxis for acute CINV. Guideline-concordant care was defined according to guidelines from the Pediatric Oncology Group of Ontario for patients < 18 years and the American Society of Clinical Oncology for those ≥ 18 years. Independent variables included: sex, age, insurance status, race, ethnicity, cancer type, chemotherapy regimen, clinical setting, chemotherapy emetogenicity, and patient location. Predictors of receiving guideline-concordant care were determined using multiple logistic regression.

RESULTS

Of 180 eligible patients, 65 (36.1%) received guideline-concordant care. In multivariable analysis, being treated in adult oncology setting (aOR 14.3, CI95 5.3-38.6), with a cisplatin-based regimen (aOR 3.5, CI951.4-9.0), solid tumor diagnosis (aOR 2.2, CI95 1.0-4.8), and commercial insurance (aOR 2.4, CI95 1.1-5.2) were associated with significantly higher likelihood of receiving guideline-concordant care.

CONCLUSIONS

Multi-level factors were associated with receiving guideline concordant care for prevention of CINV in children, adolescents, and young adults receiving emetogenic chemotherapy. These findings can inform current efforts to optimize implementation strategies for supportive care guidelines.

Pediatric Trials for Cancer Therapies With Targets Potentially Relevant to Pediatric Cancers

The Research to Accelerate Cures and Equity (RACE) for Children Act was enacted in 2017 to authorize the US Food and Drug Administration (FDA) to require pediatric studies for new cancer drugs that have a molecular target relevant to the growth or progression of a pediatric cancer. To assess the possible scope of this new policy, we examined all 78 adult cancer drugs approved by the FDA from 2007 to 2017. Only 17 (21.8%) drugs received any pediatric labeling information. Based on the FDA's Pediatric Molecular Target List, we found that the RACE Act could have increased the proportion of cancer drugs potentially subject to pediatric study requirements from 0% to 78.2%. However, the actual effect of the legislation will depend on how often regulators require pediatric trials and on timely completion of such trials.

Off-label prescribing of targeted anticancer therapy at a large pediatric cancer center

Background

Off‐label drug prescribing is common in pediatric clinical medicine, though the extent and impact of this practice in pediatric oncology has not yet been characterized.

Methods

We completed a retrospective single‐institution cohort study evaluating prevalence, characteristics, and clinical outcomes of off‐label prescribing of 108 FDA‐approved targeted anticancer drugs in patients < 30 years old treated for cancer from 2007 to 2017. Dosing strategies were adjusted for body size and compared to FDA‐approved adult dosing regimen. A composite toxicity endpoint was defined as a patient having unplanned clinic visits, emergency department visits, or unplanned hospital admissions that were at least possibly related to the off‐label treatment.

Results

The overall prevalence of off‐label use of targeted therapies was 9.2% (n = 374 patients). The prevalence increased significantly over the study period (P < .0001). Patients treated off‐label were more likely to have neuro‐oncology diagnoses compared to patients not treated off‐label (46% vs 29%; P < .0001). Of the 108 potential agents, 38 (35%) were used by at least one patient. The median starting dose was below the FDA‐approved normalized dose for 44.4% of agents. Fifteen percent of patients had a complete response while receiving off‐label therapy, 38% experienced toxicity as defined, and 13% discontinued off‐label therapy due to toxicity.

Conclusions

In this real‐world evaluation of prescribing at a large pediatric cancer center, off‐label prescribing of FDA‐approved targeted therapies was common, increasing in prevalence, encompassed a broad sample of targeted agents, and was tolerable. Clinicians commonly start dosing below the equivalent FDA‐approved dose.

A Bayesian approach in design and analysis of pediatric cancer clinical trials

It is well recognized that cancer drug development for children and adolescents has many challenges, from biological and societal to economic. Pediatric cancer consists of a diverse group of rare diseases, and the relatively small population of children with multiple, disparate tumor types across various age groups presents a significant challenge for drug development programs as compared to oncology drug development programs for adults. Due to the different types of cancers, limited opportunities exist for extrapolation of efficacy from adult cancer indications to children. Thus, innovative study designs including Bayesian statistical approaches should be considered. A Bayesian approach can be a flexible tool to formally leverage prior knowledge of adult or external controls in pediatric cancer trials. In this article, we provide in a case example of how Bayesian approaches can be used to design, monitor, and analyze pediatric trials. Particularly, Bayesian sequential monitoring can be useful to monitor pediatric trial results as data accumulate. In addition, designing a pediatric trial with both skeptical and enthusiastic priors with Bayesian sequential monitoring can be an efficient mechanism for early trial cessation for both efficacy and futility. The interpretation of efficacy using a Bayesian approach is based on posterior probability and is intuitive and interpretable for patients, parents and prescribers given limited data.

Compare and contrast: pediatric cancer versus adult malignancies

Cancer is a leading cause of death in both adults and children, but in terms of absolute numbers, pediatric cancer is a relatively rare disease. The rarity of pediatric cancer is consistent with our current understanding of how adult malignancies form, emphasizing the view of cancer as a genetic disease caused by the accumulation and selection of unrepaired mutations over time. However, considering those children who develop cancer merely as stochastically "unlucky" does not fully explain the underlying aetiology, which is distinct from that observed in adults. Here, we discuss the differences in cancer genetics, distribution, and microenvironment between adult and pediatric cancers and argue that pediatric tumours need to be seen as a distinct subset with their own distinct therapeutic challenges. While in adults, the benefit of any treatment should outweigh mostly short-term complications, potential long-term effects have a much stronger impact in children. In addition, clinical trials must cope with low participant numbers when evaluating novel treatment strategies, which need to address the specific requirements of children.

New approaches to therapeutic drug development for childhood cancers

PURPOSE OF REVIEW

We provide an overview of the current landscape of drug development relevant to childhood cancers. We present recent and ongoing efforts to identify therapeutic targets in pediatric cancers. We describe efforts to improve the approach to clinical trials and highlight the role regulatory changes and multistakeholder platforms play in advancing pediatric cancer drug development.

RECENT FINDINGS

Expanding knowledge of the genetic landscape of pediatric malignancies through clinical genomics studies has yielded an increasing number of potential targets for intervention. In parallel, new therapies for children with cancer have shifted from cytotoxic agents to targeted therapy, with examples of striking activity in patients with tumors driven by oncogenic kinase fusions. Innovative trial designs and recent governmental policies provide opportunities for accelerating development of targeted therapies in pediatric oncology.

SUMMARY

Novel treatment strategies in pediatric oncology increasingly utilize molecularly targeted agents either as monotherapy or in combination with conventional cytotoxic agents. The interplay between new target identification, efforts to improve clinical trial design and new government regulations relevant to pediatric cancer drug development has the potential to advance novel agents into frontline care of children with cancer.