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

Lineage-dependence of the neuroblastoma surfaceome defines tumor cell state-dependent and independent immunotherapeutic targets

Background

Neuroblastoma is a heterogeneous disease with adrenergic (ADRN)- and therapy resistant mesenchymal (MES)-like cells driven by distinct transcription factor networks. Here, we investigate the expression of immunotherapeutic targets in each neuroblastoma subtype and propose pan-neuroblastoma and cell state specific targetable cell-surface proteins.

Methods

We characterized cell lines, patient-derived xenografts, and patient samples as ADRN-dominant or MES- dominant to define subtype-specific and pan-neuroblastoma gene sets. Targets were validated with ChIP- sequencing, immunoblotting, and flow cytometry in neuroblastoma cell lines and isogenic ADRN-to-MES transition cell line models. Finally, we evaluated the activity of MES-specific agents in vivo and in vitro .

Results

Most immunotherapeutic targets being developed for neuroblastoma showed significantly higher expression in the ADRN subtype with limited expression in MES-like tumor cells. In contrast, CD276 (B7-H3) and L1CAM maintained expression across both ADRN and MES states. We identified several receptor tyrosine kinases (RTKs) enriched in MES-dominant samples and showed that AXL targeting with ADCT-601 was potently cytotoxic in MES-dominant cell lines and showed specific anti-tumor activity in a MES cell line-derived xenograft.

Conclusions

Immunotherapeutic strategies for neuroblastoma must address the potential of epigenetic downregulation of antigen density as a mechanism for immune evasion. We identified several RTKs as candidate MES-specific immunotherapeutic target proteins for the elimination of therapy-resistant cells. We hypothesize that the phenomena of immune escape will be less likely when targeting pan-neuroblastoma cell surface proteins such as B7-H3 and L1CAM, and/or dual targeting strategies that consider both the ADRN- and MES-cell states.

Key Points

Cellular plasticity influences the abundance of immunotherapeutic targets.Subtype-specific targets may be susceptible to epigenetically-mediated downregulation.Immunotherapeutic targets in development, B7-H3 and L1CAM, show "pan-subtype" expression.

Importance of Study

Neuroblastoma is a lethal childhood malignancy that shows cellular plasticity in response to anti-cancer therapies. Several plasma membrane proteins are being developed as immunotherapeutic targets in this disease. Here we define which cell surface proteins are susceptible to epigenetically regulated downregulation during an adrenergic to mesenchymal cell state switch and propose immunotherapeutic strategies to anticipate and circumvent acquired immunotherapeutic resistance.

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.

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 development of new drugs for adults and children with cancer, 2010-2020

BACKGROUND

Many new molecular entities enter clinical development to evaluate potential therapeutic benefits for oncology patients. We characterized adult and pediatric development of the set of new molecular entities that started clinical testing in 2010-2015 worldwide.

METHODS

We extracted data from AdisInsight, an extensive database of global pharmaceutical development, and the FDA.gov website. We followed the cohort of new molecular entities initiating first-in-human phase I clinical trials in 2010-2015 to the end of 2020. For each new molecular entity, we determined whether it was granted US Food and Drug Administration (FDA) approval, studied in a trial open to pediatric enrollment, or stalled during development. We characterized the cumulative incidence of these endpoints using statistical methods for censored data.

RESULTS

The 572 new molecular entities starting first-in-human studies in 2010-2015 were studied in 6142 trials by the end of 2020. Most new molecular entities were small molecules (n = 316, 55.2%), antibodies (n = 148, 25.9%), or antibody-drug conjugates (n = 44, 7.7%). After a mean follow-up of 8.0 years, 173 new molecular entities did not advance beyond first-in-human trials, and 39 were approved by the FDA. New molecular entities had a 10.4% estimated probability (95% confidence interval = 6.6% to 14.1%) of being approved by the FDA within 10 years of first-in-human trials. After a median of 4.6 years since start of first-in-human trials, 67 (11.7%) new molecular entities were tested in trials open to pediatric patients, and 5 (0.9%) were approved for pediatric indications.

CONCLUSIONS

More efficient clinical development strategies are needed to evaluate new cancer therapies, especially for children, and incorporate approaches to ensure knowledge gain from investigational products that stall in development.

Actionable Tumor Alterations and Treatment Protocol Enrollment of Pediatric and Young Adult Patients With Refractory Cancers in the National Cancer Institute-Children's Oncology Group Pediatric MATCH Trial

PURPOSE

The National Cancer Institute-Children's Oncology Group Pediatric MATCH trial aimed to facilitate evaluation of molecular-targeted therapies in biomarker-selected cohorts of childhood and young adult patients with cancer by screening tumors for actionable alterations.

PATIENTS AND METHODS

Tumors from patients age 1-21 years with refractory solid tumors, lymphomas, or histiocytic disorders were subjected to cancer gene panel sequencing and limited immunohistochemistry to identify actionable alterations for assignment to phase II treatment arms. The rates of treatment arm assignment and enrollment were compared between clinical and demographic groups.

RESULTS

Testing was completed for 94.7% of tumors submitted. Actionable alterations were detected in 31.5% of the first 1,000 tumors screened, with treatment arm assignment and enrollment occurring in 28.4% and 13.1% of patients, respectively. Assignment rates varied by tumor histology and were higher for patients with CNS tumors or enrolled at Pediatric Early Phase Clinical Trials Network sites. A reported history of prior clinical molecular testing was associated with higher assignment and enrollment rates. Actionable alterations in the mitogen-activated protein kinase signaling pathway were most frequent (11.2%). The most common reasons provided for not enrolling on treatment arms were patients receiving other treatment or poor clinical status.

CONCLUSION

The Pediatric MATCH trial has proven the feasibility of a nationwide screening Protocol for identification of actionable genetic alterations and assignment of pediatric and young adult patients with refractory cancers to trials of molecularly targeted therapies. These data support the early use of tumor molecular screening for childhood patients with cancer whose tumors have not responded to standard treatments.

Targeted inhibitors and antibody immunotherapies: Novel therapies for paediatric leukaemia and lymphoma

Despite improved outcomes achieved in the last decades for children with newly diagnosed leukaemia and lymphoma, treatment of patients with refractory/relapsed disease remains a challenge. The cure rate is still unsatisfactory and often achieved at the cost of significant morbidity. Exploring treatment with novel agents should offer less toxic therapeutic options, without compromising efficacy. Bispecific and antibody-drug conjugates targeting CD19 and CD22 (blinatumomab and inotuzumab ozogamicin) play an important role in the treatment of relapsed and refractory B-cell precursor acute lymphoblastic leukaemia (BCP-ALL); antibodies targeting CD123 and CD38 are also under investigation for acute myeloid leukaemia (AML) and T-ALL, respectively. Targeted therapy with small molecules is of primary importance for specific genetic subtypes, such as BCR-ABL-positive ALL, FLT3-ITD AML and anaplastic lymphoma kinase (ALK)-positive anaplastic large cell lymphoma. KMT2A-directed targeted therapy with menin inhibitors holds promise to be of relevance in KMT2A-rearranged leukaemias, known to have dismal prognosis. Target inhibition in cellular pathways such as BCL-2, RAS, MEK, Bruton's tyrosine kinase, JAK-STAT or CDK4/CDK6 inhibition may be suitable for different diseases with common mutated pathways. Nevertheless, development and approval of new agents for paediatric cancers lags behind adult therapeutic options. New regulations were implemented to accelerate drug development for children. Considering the number of oncology medicinal products available for adults and the rarity of paediatric cancers, prioritisation based on scientific evidence and medical need, as well as international collaboration, is critical. Herein, we review the current status of drug development for children with leukaemia and lymphoma, excluding cellular therapy despite its well-known significance.

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.

Multicenter Analysis of Genomically Targeted Single Patient Use Requests for Pediatric Neoplasms

PURPOSE

The US Food and Drug Administration-expanded access program (EAP) uses a single patient use (SPU) mechanism to provide patient access to investigational agents in situations where no satisfactory or comparable therapy is available. Genomic profiling of de novo and relapsed or refractory childhood cancer has led to increased identification of new drug targets in the last decade. The aim of this study is to examine the SPU experience for genomically targeted therapies in patients with pediatric cancer.

PATIENTS AND METHODS

All genomically targeted therapeutic SPUs obtained over a 5-year period were evaluated at four large pediatric cancer programs. Data were collected on the type of neoplasm, agents requested, corresponding molecularly informed targets, and clinical outcomes.

RESULTS

A total of 45 SPUs in 44 patients were identified. Requests were predominantly made for CNS and solid tumors (84.4%) compared with hematologic malignancies (15.6%). Lack of an available clinical trial was the main reason for SPU initiation (64.4%). The median time from US Food and Drug Administration submission to approval was 3 days (range, 0-12 days) and from Institutional Review Board submission to approval was 5 days (range, 0-50 days). Objective tumor response was seen in 39.5% (15 of 38) of all evaluable SPUs. Disease progression was the primary reason for discontinuation of drug (66.7%) followed by toxicity (13.3%).

CONCLUSION

SPU requests remain an important mechanism for pediatric access to genomically targeted agents given the limited availability of targeted clinical trials for children with high-risk neoplasms. Furthermore, this subset of SPUs resulted in a substantial number of objective tumor responses. The development of a multi-institutional data registry of SPUs may enable systematic review of toxicity and clinical outcomes and provide evidence-based access to new drugs in rare pediatric 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.

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.

Recent Developments in Nanomedicine for Pediatric Cancer

Cancer is the second biggest cause of death in children in the US. With the development of chemotherapy, there has been a substantial increase in the overall survival rate in the last 30 years. However, the overall mortality rate in children with cancer remains 25%, and many survivors experience a decline in overall quality of life and long-term adverse effects caused by treatments. Although cancer cells share common characteristics, pediatric cancers are different from adult cancers in their prevalence, mutation load, and drug response. Therefore, there is an urgent unmet need to develop therapeutic approaches specifically designed for children with cancer. Nanotechnology can potentially overcome the deficiencies of conventional methods of administering chemotherapy and ultimately improve clinical outcomes. The nanoparticle-based drug delivery systems can decrease the toxicity of therapy, provide a sustained or controlled drug release, improve the pharmacokinetic properties of loading contents, and achieve a targeted drug delivery with achievable modifications. Furthermore, therapeutic approaches based on combining nanoformulated drugs with novel immunotherapeutic agents are emerging. In this review, we discussed the recently developed nanotechnology-based strategies for treating blood and solid pediatric cancers.

The Best Pharmaceuticals for Children Act and Pediatric Research Equity Act reach the age of majority-An oncology perspective

The scarcity of adequate pediatric drug labeling information has long been problematic in the pediatric population, which may place children at risk for adverse drug effects. The ontogeny of infants, children, and adolescents over the course of the first two decades of life pose complex pharmacokinetic, dosing, administration, effectiveness, and toxicity-related questions that require specific investigation. Here, we review the history that led to the passage of the Best Pharmaceuticals for Children Act (BPCA) and Pediatric Research Equity Act (PREA), and provide commentary on issues relevant to pediatric oncology now and in the future.

Gap between pediatric and adult approvals of molecular targeted drugs

To clarify the approval status of molecular targeted antineoplastic drugs in the United States (U.S.), the European Union (E.U.), and Japan (JP), we checked the status of pediatric indications according to the package insert of each drug. A total of 103 drugs were approved for adult patients in at least one of the three regions whereas only 19 drugs were approved for pediatric patients. Sixty-six of 103 drugs (64.1%) had adult indications in the U.S., the E.U., and JP, whereas only three drugs had pediatric indications in all three regions. Abnormalities in six genes (NRAS, ABL1, JAK2, KIT, ALK and BRAF) were common in childhood cancers as well as adult cancers, for which at least one approved drug could be a potentially actionable drug. Although there were 16 candidate drugs that had adult indications for these abnormalities, only three drugs (18.8%) had pediatric indications. We confirmed that there were few molecular targeted antineoplastic drugs with pediatric indications in the U.S., the E.U., and JP compared with the number of approved drugs for adults. Drugs targeting genomic abnormalities which were common in both adult and pediatric cancers were considered to be good candidates for expansion of their indication for pediatric patients.

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.