Traditional cancer drug discovery has long grappled with the precarious balance between efficacy and safety. Approximately 85% to 97% of candidate therapeutics entering phase 1 clinical trials fail to secure FDA approval, a significant proportion of which is attributable to toxicity issues manifesting in normal tissues. This adversity is especially pronounced in pediatric oncology, where toxic side effects can precipitate severe long-term health complications that endure for decades beyond successful remission. Historically, the analysis of such toxicological risks has been relegated to the later stages of drug development, often manifesting as costly and time-consuming setbacks. The innovative strategy developed by the St. Jude team aims to overhaul this paradigm by integrating toxicity prediction into the earliest phases of drug target identification.

Dr. Samuel Brady, PhD, leading the Department of Pharmacy & Pharmaceutical Sciences at St. Jude and corresponding author of the study, highlights the novelty and significance of this work. He emphasizes that prior strategies prioritized target efficacy without adequate foresight into potential toxicity, which frequently led to failures during clinical evaluation. By proactively filtering for targets with favorable toxicity profiles, the research delineates a path toward developing safer, more effective cancer therapeutics. Central to this study is the identification of IRS4, a gene that emerges as a compelling cross-cancer dependency suitable for targeted intervention.

The investigational pipeline devised by the team began with an exhaustive interrogation of the Dependency Map portal, a comprehensive database cataloging genes crucial for cancer cell survival. From thousands of candidates, the researchers employed stringent criteria inspired by characteristics shared by currently FDA-approved targeted therapies, winnowing the list to 346 promising targets. The innovation continued as AI-driven literature mining was employed to identify individuals with naturally occurring deletions or mutations in these genes who exhibited minimal adverse health effects—a surrogate marker for potentially tolerable toxicity in therapeutic contexts.

This integrative AI-literature approach narrowed the field further to just 25 candidates, a cluster that included several already validated targets and an intriguing subset of previously unexplored genes. Among these, IRS4 stood out due to a unique combination of attributes: it exhibited cancer-specific dependency across multiple solid tumors, harbored a potential druggable binding pocket, and showed low expression in normal adult tissues. Notably, although the identified binding pocket on IRS4 was not essential for its role in cancer progression, this insight directs drug development efforts toward alternative strategies such as targeted protein degradation, widening the scope for molecular interventions.

Experimental validation underscored the therapeutic promise of IRS4. Cancer cells dependent on IRS4 abruptly lost proliferative capacity upon genetic ablation or chemical degradation of the IRS4 protein, confirming its status as a critical oncogenic driver. Importantly, the gene’s low expression in non-cancerous adult tissues and data from individuals lacking functional IRS4 suggest manageable side-effect profiles, principally thyroid-related anomalies, reassuring the pursuit of IRS4 as a viable drug target. This dual evidence underpins the therapeutic index advantage—an essential metric reflecting the balance between drug efficacy and safety—in favor of IRS4-targeted interventions.

Dr. Brady metaphorically describes IRS4 as an “on-off switch” within cancer cells: its presence is indispensable for tumor survival, rendering it a suitable biomarker for patient stratification and therapeutic targeting. This dual functionality enhances precision oncology by allowing clinicians to predict which tumors will respond to IRS4-centric therapies, thereby enhancing treatment personalization and efficacy. The mechanistic role of IRS4 centers on its ability to activate the PI3K pathway, a critical signaling axis mediating cellular growth and survival, often co-opted in cancerous transformation.

The research elucidates IRS4’s involvement in a broad array of malignancies, notably pediatric tumors including malignant rhabdoid tumors, osteosarcomas, and select brain cancers, as well as adult cancers such as breast, lung, uterine, and gastric carcinomas. This cross-cancer applicability amplifies the clinical impact of targeting IRS4, opening avenues for both pediatric and adult oncology. The study also signals a paradigm shift in drug discovery by spotlighting the utility of incorporating toxicity considerations from the initial conceptualization stages, potentially accelerating the clinical translation of safer drugs.

Beyond IRS4, the methodology itself represents an adaptable framework, combining robust genomic datasets, AI-powered analytics, and phenotypic validations to systematically weed out candidates with unacceptable toxicity profiles. This multidisciplinary fusion leverages computational power and biological insight, potentially revolutionizing target discovery across a spectrum of diseases beyond oncology. By predicting toxicity risks upfront, drug developers stand to save substantial time, costs, and patient exposure to harmful side effects.

The implications of this research resonate profoundly in pediatric oncology, where curative success rates have improved markedly but often at the cost of life-altering late effects. St. Jude’s approach aspires not only to enhance survival but to ensure survivors can lead healthier, fuller lives unburdened by the sequelae of harsh treatments. Dr. Brady stresses the holistic vision driving the work: an oncology future where therapeutic interventions are defined by precision, efficacy, and a gentle toxicity footprint.

The study owes its broad expertise and rigorous execution to the collaborative efforts of co-first authors Khadija Banu and Mohammad Aslam Khan, along with a multidisciplinary team spanning molecular biology, pharmacology, computational science, and clinical research. Funding support from the National Health and Medical Research Council of Australia, Western Australian Future Health Research and Innovation Fund, National Cancer Institute, and St. Jude’s associated charity ALSAC underscores the transnational and institutional commitment fueling this breakthrough.

By openly sharing their methodology and findings, the St. Jude team paves the way for adoption and iterative refinement by the wider scientific community. As precision medicine advances, the integration of AI with human genetic data to anticipate drug target safety signals a transformative era—one wherein cancer therapy becomes not only more effective but fundamentally safer from inception to clinical application.

Subject of Research:
Drug target discovery and toxicity prediction in cancer therapy using AI-assisted genetic dependency analysis.

Article Title:
IRS4 is a PI3K-activating cancer dependency upregulated through DNA rearrangements or epigenetic mechanisms in multiple solid tumors

News Publication Date:
April 29, 2026

Web References:
DOI link

Image Credits:
St. Jude Children’s Research Hospital

Keywords:
Solid tumors, Artificial intelligence, Drug discovery, Drug targets, Cancer dependency, Therapeutic index, IRS4, PI3K pathway, Pediatric cancer, Toxicity prediction, Protein degradation, Precision oncology

The crux of this innovative therapy revolves around the selective depletion of the mutant HNRNPH2 protein, which has been implicated in the disease pathology. ASOs—short, synthetic strands of nucleic acids—are designed to bind specifically to the messenger RNA (mRNA) transcripts of HNRNPH2. By doing so, they mark these transcripts for degradation, thereby preventing the synthesis of the aberrant protein that is central to disease development. Importantly, this mechanism acts upstream at the RNA level, sparing the genome from alterations while directly modulating pathogenic protein production.

An extraordinary aspect of this therapeutic strategy lies in the compensatory dynamics between HNRNPH2 and its closely related paralog, HNRNPH1. Both proteins are multifunctional RNA-binding factors essential for proper RNA processing during neurodevelopment. Whereas HNRNPH1 expression diminishes as development progresses, and cells increasingly depend on HNRNPH2, the researchers found that knocking down the mutant HNRNPH2 with ASO treatment triggers a significant upregulation of HNRNPH1. This compensatory boost plays a key role in mitigating the disease phenotype, suggesting that enhancing HNRNPH1 can substitute for dysfunctional HNRNPH2 protein function.

Prior ambiguity existed concerning whether HNRNPH2 mutations led to a toxic gain of function or a loss of normal protein function. This study resolved that conundrum by demonstrating that HNRNPH2 regulates its homolog’s expression through alternative splicing mechanisms that selectively skip vital exons in HNRNPH1 mRNA, marking it for degradation. The ASO-mediated silencing of mutant HNRNPH2 reverses this exon skipping, rescuing HNRNPH1 mRNA stability and expression. Consequently, this dual effect—suppression of the harmful mutant protein and restoration of compensatory HNRNPH1 levels—underpins the therapeutic efficacy observed in preclinical models.

Strikingly, the research team demonstrated that neonatal administration of ASOs reversed multiple symptomatic hallmarks of the disorder in mouse models. Furthermore, effectiveness was also confirmed in juvenile animals, an encouraging sign for potential treatment windows extending beyond infancy. Given that genetic diagnoses for rare disorders often take years, this finding underscores the translational potential of ASO therapy for patients diagnosed later in development.

The ASO platform, increasingly recognized for its precision and adaptability, has transformed the therapeutic landscape for genetic diseases. Unlike gene-editing technologies, ASOs provide a reversible and tunable intervention, perfectly suited for diseases driven by toxic gain- or loss-of-function mutant proteins, such as HNRNPH2-related disorders. This study represents a critical milestone not only for this ultrarare disease but for the broader neurodevelopmental disorder community, where treatment options remain limited.

Noteworthy is the pace of progress: from the initial clinical description of HNRNPH2-associated neurodevelopmental disorder a decade ago, the St. Jude team has moved swiftly to elucidate its molecular underpinnings, culminating in a near-ready translational treatment. This rapid progression exemplifies the synergy between fundamental molecular biology and therapeutic innovation, enabled by cutting-edge technologies and collaborative research efforts.

Dr. J. Paul Taylor, the study’s corresponding author and a leading figure in cell and molecular biology, emphasized the unique suitability of ASO technology to the molecular pathology of this disorder. By targeting the disease’s root cause at the RNA transcript level, the therapy avoids the complexities and risks associated with direct gene editing, while modulating protein expression with remarkable specificity and potency.

First author Dr. Ané Korff noted that the mechanistic insights uncovered through this research shed light on an essential developmental regulatory circuit involving HNRNPH proteins. The ability to manipulate this circuit pharmacologically opens new avenues for addressing not only HNRNPH2-related disease but potentially other RNA splicing dysfunction disorders, broadening the impact of this discovery.

The investigation also involved partners from Ionis Pharmaceuticals, a pioneer in ASO development, reflecting an effective academic-industry collaboration critical for transitioning preclinical breakthroughs into clinical realities. The study was funded by the National Institutes of Health and the American Lebanese Syrian Associated Charities (ALSAC), underscoring the vital role of public and philanthropic support.

With this compelling preclinical evidence, the researchers are poised to advance ASO therapy into clinical trials. Success in human patients could revolutionize the management of HNRNPH2-related neurodevelopmental disorder, transforming a previously untreatable condition into a manageable disease with tangible symptom relief.

As rare genetic disorders wait desperately for effective therapies, this breakthrough offers a beacon of hope. The study not only highlights the potential of antisense oligonucleotide strategies but also exemplifies the power of precision medicine driven by deep mechanistic understanding. For the ultrarare disease community, these findings signal a historic shift toward feasible and effective treatments crafted from molecular insight.

Subject of Research:
The research focuses on developing and evaluating antisense oligonucleotide therapy targeting mutant HNRNPH2 mRNA to treat HNRNPH2-related neurodevelopmental disorder, an ultrarare X-linked condition.

Article Title:
Preclinical evaluation of antisense oligonucleotide therapy in a mouse model of HNRNPH2-related neurodevelopmental disorder

News Publication Date:
22-Apr-2026

Web References:
https://www.stjude.org/
https://www.stjude.org/research/departments/cell-molecular-biology.html
https://www.stjude.org/research/initiatives/pediatric-translational-neuroscience-initiative.html
http://dx.doi.org/10.1126/scitranslmed.adx3491

References:
Taylor JP et al. Preclinical evaluation of antisense oligonucleotide therapy in a mouse model of HNRNPH2-related neurodevelopmental disorder. Science Translational Medicine. 2026 Apr 22; DOI: 10.1126/scitranslmed.adx3491.

Image Credits:
St. Jude Children’s Research Hospital

Keywords:
Antisense oligonucleotide, HNRNPH2, neurodevelopmental disorder, RNA processing, genetic therapy, RNA splicing, ultrarare disease, neurogenetics, preclinical model, pediatric neurology

The investigative team, spearheaded by Heather Conklin, PhD, from the Department of Psychology & Biobehavioral Sciences at St. Jude, embarked on a comprehensive study involving 145 pediatric patients undergoing radiation treatment for ependymoma. Strikingly, over a third of these children developed severe hearing impairment in at least one ear. Such a high incidence of ototoxicity underscores the vulnerability of the pediatric population, especially since the anatomical positioning of ependymoma tumors often exposes the cochlea to radiation. This exposure correlates directly with measurable decrements in intellectual ability and communication skills, with cognitive decline escalating over time for those affected by hearing loss.

In a technical context, the study’s findings illuminate the pathophysiological cascade initiated by radiation-induced damage to the delicate cochlear hair cells, essential for auditory transduction. Disruption within these sensory cells compromises auditory input, which is critical during early brain development stages. The lack of adequate auditory stimuli impairs neural circuits underlying language acquisition and cognitive processing, resulting in an observable reduction in cognitive function. Notably, the study reported stability in verbal learning and memory, indicating that hearing loss predominantly affects broader intellectual domains and communication rather than all cognitive faculties uniformly.

This research challenges previously held conceptions that hearing loss-related cognitive decline primarily afflicts children undergoing combination therapies involving both chemotherapy and radiation. In contrast, the findings present compelling evidence that radiation therapy alone can precipitate significant neurocognitive repercussions linked to auditory deficits. This nuance elevates the imperative for oncological protocols to meticulously weigh the necessity of radiation dosage and delivery methodologies to mitigate unintended but deleterious side effects.

The phenomenon of heightened hearing loss prevalence in ependymoma patients can be attributed to the cohort’s younger age at diagnosis and the anatomical tumor location proximal to the cochlea. Younger brains are inherently more susceptible to the adverse effects of sensory deprivation during critical periods of neurodevelopment. Moreover, tumor positioning within or adjacent to auditory pathways necessitates radiation fields that encompass cochlear structures, thereby amplifying ototoxic risk.

Beyond hearing loss, the investigation identified a constellation of co-factors exacerbating cognitive decline severity. Hydrocephalus, an abnormal cerebrospinal fluid build-up in the brain often necessitating shunting procedures, multiple surgical interventions, and antecedent chemotherapy before irradiation collectively compound neurological vulnerability. However, the study found no statistically significant associations between cognitive outcomes and patient sex, race, or socioeconomic indicators, suggesting that the observed effects transcend demographic variables.

From a translational medicine perspective, the findings advocate for the integration of emerging otoprotective strategies in pediatric neuro-oncology. Pharmacological agents targeting the preservation of cochlear hair cells during cytotoxic treatments represent a promising avenue for clinical intervention. Additionally, advancements in radiation delivery, such as the shift from traditional photon-based modalities to proton therapy, offer superior precision allowing for maximal tumor control while sparing surrounding healthy tissue including the cochlea.

Rehabilitative approaches following treatment are equally vital. Hearing aids, cochlear implants, and specialized educational programs provide crucial support for children who have incurred auditory damages. Yet, the successful adoption of these interventions faces practical challenges encompassing device discomfort, social stigma, and the complexity of long-term management. Increasing adherence to these supportive measures remains a primary objective to enhance quality of life and cognitive rehabilitation.

Parental perceptions significantly influence the engagement with hearing assistance technologies. The study highlights a direct correlation between caregiver belief in the positive impact of hearing aid use on brain development and their dedication to ensuring consistent device use. Dr. Conklin emphasizes the importance of educational outreach to empower families with comprehensive knowledge about the cognitive risks of untreated hearing loss and the benefits of intervention.

This research marks a pivotal step in redefining survivorship care for pediatric brain tumor patients, emphasizing a holistic approach that addresses both oncological and neurodevelopmental priorities. The intricate interplay between cancer treatment modalities and long-term neurocognitive outcomes necessitates a multidisciplinary framework integrating oncology, audiology, psychology, and rehabilitation sciences.

Moreover, the study’s rigorous longitudinal design offers invaluable data supporting the temporal dynamics of cognitive decline associated with hearing loss. By identifying early biomarkers of auditory impairment and cognitive vulnerability, clinicians can tailor intervention timelines to maximize therapeutic efficacy and prevent irreversible deficits.

The research team comprises not only Dr. Conklin but also first author Jeanelle Ali, now at the Children’s Hospital of Eastern Ontario, alongside a multidisciplinary group of scientists and clinicians at St. Jude including Johnnie Bass, Fang Wang, Xiaomeng Yuan, Haitao Pan, Jason Ashford, Niki Jurbergs, Nicole Salman, and Thomas Merchant. Their collective expertise in neuropsychology, oncology, audiology, and biostatistics underpins the robustness and clinical relevance of the study.

Supported by significant grants from the National Cancer Institute and the American Lebanese Syrian Associated Charities (ALSAC), the study embodies a successful model of collaborative funding which fuels innovation in pediatric cancer research. These investments are critical in advancing knowledge and developing safer, more effective treatment paradigms to improve long-term outcomes for childhood cancer survivors.

In conclusion, this research underscores the imperative for oncologists and healthcare teams to balance aggressive tumor control with the preservation of cognitive and sensory health. Judicious adjustment of radiation protocols, incorporation of otoprotective measures, and diligent application of rehabilitative technologies constitute a multipronged strategy essential to safeguard the brain development trajectories of children overcoming ependymoma. As the scientific and medical communities continue to unravel the complexities of neurocognitive late effects, studies like this chart the course toward a future where cure no longer comes at the cost of diminished quality of life.

Subject of Research: Cognitive decline and hearing loss in children treated for ependymoma using radiation therapy.

Article Title: Hearing loss contributes to cognitive decline after childhood cancer treatment.

News Publication Date: February 20, 2026.

Web References:

• St. Jude Children’s Research Hospital: https://www.stjude.org/
• St. Jude Psychology & Biobehavioral Sciences: https://sjr-redesign.stjude.org/departments/psychology.html
• Neuro-Oncology Article DOI: http://dx.doi.org/10.1093/neuonc/noag029

References:

• Conklin, H., Ali, J., Bass, J., et al. (2026). Neuro-Oncology. DOI: 10.1093/neuonc/noag029

Image Credits: St. Jude Children’s Research Hospital

Keywords: Hearing loss, Brain cancer, Radiation therapy

The research centered on understanding whether repeated consumption of pasteurized milk containing inactivated H5N1 viral particles could impact the immune system’s response to subsequent influenza infections. Of particular concern was the phenomenon known as oral tolerance, where the immune system might become accustomed to viral proteins delivered via the digestive tract, potentially dampening immune vigilance against those viral components if encountered in a future infection. This could theoretically increase susceptibility to influenza, if the immune system learns to regard these viral elements as harmless.

To investigate, the team conducted a controlled experimental study involving murine models. Mice received either uncontaminated pasteurized milk or pasteurized milk spiked with inactivated H5N1 virus for a period of five days, simulating typical human milk consumption patterns over time. Several weeks following exposure, the mice were challenged with an active H5N1 infection. Remarkably, the outcomes demonstrated no significant difference between the two groups in terms of disease severity, viral load, or immune response, indicating that prior ingestion of inactivated viral proteins via milk did not compromise immunity or exacerbate infection.

Dr. Stacey Schultz-Cherry, senior author and leader of the St. Jude Department of Host-Microbe Interactions, emphasized the importance of these findings. She explained that the study delivered robust evidence that consuming pasteurized milk containing inactive viral particles had neither a detrimental nor beneficial impact on influenza infection outcomes. This conclusion provides reassurance for public health and consumer safety, reaffirming the efficacy of pasteurization and existing food safety protocols in mitigating risks related to viral contamination.

While the research consistently found no adverse immune consequences from pasteurized milk exposure, the scenario changed drastically when unpasteurized milk contaminated with the active H5N1 virus was used. In this cohort, mice rapidly succumbed to infection, underlining the critical role of pasteurization as a barrier against viral transmission through dairy products. This stark contrast further underscores the dangers associated with consuming raw milk, especially amid outbreaks of zoonotic pathogens such as avian influenza.

To extend the relevance of their findings to human populations, the researchers incorporated models that better represented pre-existing immunity to influenza. Mice were first infected with a non-lethal dose of H1N1 virus to mimic the immune memory generated by previous infections or vaccinations common in humans worldwide. Afterward, these mice were administered either uncontaminated or H5N1-contaminated milk, both pasteurized, before being challenged with lethal H5N1 infection. Notably, all mice possessing prior H1N1 immunity survived the lethal challenge, irrespective of milk exposure, while those lacking immunity succumbed to the disease. This reinforced the protective effect of vaccination and prior exposure despite receipt of inactivated viral components in milk.

The study also explored the biological mechanisms underpinning lack of oral tolerance induction through repeated consumption of inactivated viral protein-laden milk. The gut-associated lymphoid tissue likely treated these fragments as non-threatening antigens, failing to trigger systemic immune suppression. This finding is important for understanding host-pathogen interactions at mucosal surfaces and the broader implications for viral antigen exposure through diet and environment.

Moreover, the research highlights the necessity for continued surveillance of zoonotic viruses in the food supply, particularly in the context of emerging influenza strains capable of crossing species barriers. Despite reassuring safety profiles associated with pasteurization, vigilance remains essential given the mutagenic capacity of influenza viruses and the potential for novel transmissible variants to arise from livestock reservoirs.

This comprehensive analysis from the St. Jude team fills critical knowledge gaps about foodborne influenza exposure risks and mitigates unfounded public fears while reinforcing safe milk consumption practices. By bridging experimental immunology with real-world epidemiological concerns, the study offers a robust scientific foundation supporting current public health policies concerning pasteurization and milk safety standards.

The implications extend beyond influenza, suggesting frameworks for evaluating other viral contaminants in food and assessing immune outcomes following dietary exposure to noninfectious viral materials. Such insights will prove invaluable in shaping future guidelines as global health agencies grapple with food safety challenges in the face of increasingly complex zoonotic pathogen dynamics.

In conclusion, the study robustly establishes that pasteurized milk containing noninfectious H5N1 viral particles does not induce oral tolerance or compromise immune defenses against influenza. These findings reinforce the importance of pasteurization in protecting public health and demonstrate the power of pre-existing immunity in guarding against severe influenza disease caused by emerging viral strains. The ongoing commitment to vigilant monitoring and vaccination remains paramount in safeguarding against future outbreaks and mitigating risks from foodborne viral contamination.

Subject of Research: Cells

Article Title: Repeated Oral Exposure to H5N1 Influenza Virus in Pasteurized Milk Does Not Cause Adverse Responses to Subsequent Influenza Infection

News Publication Date: 26-Sep-2025

Image Credits: Courtesy of St. Jude Children’s Research Hospital

Keywords: Avian influenza

Mitochondria, known primarily for their essential role as the powerhouses of the cell, possess their own DNA distinct from the nuclear genome. Unlike nuclear DNA, each cell contains hundreds to thousands of mitochondrial DNA copies, a feature which has complicated the study of mtDNA mutations. These mutations often occur heteroplasmically, meaning mutated and wild-type mtDNA coexist within the same cell, creating a complex mosaicism. Historically, determining the functional consequences of such heteroplasmic mtDNA mutations in cancer cells has been a daunting task for researchers given their subtle and variable distribution across cell populations.

The team, led by corresponding author Dr. Mondira Kundu and first author Dr. Kelly McCastlain at St. Jude’s Department of Cell & Molecular Biology, employed a suite of cutting-edge technologies to dissect mtDNA mutations at unprecedented resolution. This included bulk whole-genome sequencing, single-cell genomic assays, and the deployment of powerful computational tools capable of interpreting complex multi-omics datasets. Their meticulous analysis revealed that some somatic mtDNA mutations arise early in the oncogenic process, preceding the full transformation of normal cells into malignant leukemic cells. This early occurrence suggests that mtDNA mutations might play an active role in initiating or promoting tumorigenesis, rather than being mere incidental passengers.

One of the most enlightening findings from this study is the non-random selection of mtDNA mutations within cancer cells. Contrary to the traditional view that mitochondrial mutations accumulate passively during tumor evolution, the data indicate that cancer cells can selectively maintain a mixture of wild-type and mutated mtDNA. This heteroplasmic balance appears to generate functional heterogeneity among leukemic cells, potentially equipping them with diverse metabolic profiles and survival advantages that impact disease progression and therapeutic responsiveness.

To further decipher the biological implications of these mitochondrial alterations, the research group utilized the NetBID2 computational platform, a next-generation systems biology tool developed by co-author Dr. Jiyang Yu from the Department of Computational Biology at St. Jude. NetBID2 can extract regulatory network signals from multi-omics data, allowing researchers to associate specific mtDNA mutations with changes in cellular pathways. Their analyses uncovered that certain mitochondrial mutations correlate with dysregulation in pathways mediating resistance to glucocorticoids, a cornerstone therapy in acute lymphoblastic leukemia (ALL). This finding highlights mtDNA mutations as potential contributors to drug resistance, complicating treatment outcomes.

The revelation that mitochondrial genome alterations can influence therapeutic responses marks a paradigm shift in cancer biology, emphasizing mtDNA as a critical layer of genomic complexity in malignancies. The presence of resistant subpopulations with distinct mitochondrial genotypes may underlie relapses in leukemia patients who initially respond to conventional treatments but later experience disease recurrence. Understanding these mechanisms opens avenues for novel interventions aimed at targeting mitochondrial function and heterogeneity.

Dr. Kundu and colleagues’ work also underscores the value of integrating multi-modal data to parse the intricate genotype-phenotype relationships within tumors. The heteroplasmy levels of mtDNA mutations were quantified at the single-cell level, enabling the dissection of clonal architectures and the temporal sequence of mutations during leukemia evolution. This granular approach provides insights into how mitochondrial genetics intertwines with nuclear oncogenic events, shaping the trajectory of cancer progression in a dynamic and heterogeneous manner.

While the current study focuses predominantly on leukemia, the methodologies developed are broadly applicable across diverse cancer types, offering a framework to systematically investigate mitochondrial contributions to tumor biology. The authors advocate for expanding their analyses to include larger patient cohorts with various malignancies to fully delineate the impact of mtDNA mutations across cancer subtypes and stages.

The implications of this research extend beyond cancer, shedding light on mitochondrial dysfunction in human diseases more generally. Given mitochondria’s pivotal roles in energy metabolism, apoptosis, and cellular signaling, the ability to resolve mutation dynamics within these organelles could catalyze advances in understanding metabolic disorders, neurodegeneration, and aging.

In conclusion, the study spearheaded by the team at St. Jude Children’s Research Hospital represents a significant leap forward in mitochondrial oncology. By revealing that somatic mitochondrial DNA mutations, especially those at intermediate heteroplasmy levels, serve as a source of functional diversity among leukemia cells, the research redefines the mitochondrial genome from a static bystander to an active player in cancer biology. The novel integrative approach combining computational and experimental prowess sets a new standard for future investigations into the mitochondrial genome’s role in disease progression and treatment resistance.

The next frontier, as outlined by Dr. Kundu, involves leveraging these insights to develop mitochondrial-targeted therapeutics and incorporating mitochondrial genotyping into precision oncology paradigms. Such strategies could ultimately improve outcomes by overcoming therapy resistance and preventing disease relapse.

Subject of Research: The role and impact of mitochondrial DNA mutations in cancer progression, specifically in leukemia.

Article Title: Somatic mtDNA mutations at intermediate levels of heteroplasmy are a source of functional heterogeneity among primary leukemic cells

News Publication Date: 10-Sep-2025

Web References:

• Article DOI link: http://dx.doi.org/10.1126/sciadv.adt3873
• Kundu Lab: https://www.stjude.org/research/labs/kundu-lab.html
• Yu Lab & NetBID2 tool: https://www.stjude.org/media-resources/news-releases/2023-medicine-science-news/st-jude-tool-gets-more-out-of-multi-omics-data.html

Image Credits: St. Jude Children’s Research Hospital

Keywords: Mitochondrial DNA, somatic mutations, heteroplasmy, leukemia, cancer heterogeneity, therapy resistance, glucocorticoid resistance, single-cell sequencing, computational biology, NetBID2, mitochondrial genomics, acute lymphoblastic leukemia

While conventional therapeutic strategies for ependymoma have remained relatively stagnant for the past three decades, this research offers a transformative perspective by characterizing the ZFTA–RELA fusion protein’s unique molecular properties. The team, co-led by Dr. Stephen Mack and Dr. Richard Kriwacki at St. Jude, demonstrated that the intrinsically disordered regions within the RELA component of the fusion protein mediate the condensation into droplets within the nucleus of cells. These condensates serve as critical assemblies that not only concentrate proteins and nucleic acids but also modulate gene expression programs central to oncogenesis. This discovery provides a fresh conceptual framework for how fusion oncoproteins leverage phase separation and condensate formation to drive malignancy.

The fusion protein ZFTA–RELA is composed of two distinct domains with complementary functional contributions. The ZFTA portion directly binds to DNA, anchoring the condensates to chromatin and targeting specific gene loci, while the RELA region, characterized by a lack of defined tertiary structure, facilitates the dynamic assembly of condensates through multivalent weak interactions. This property, known as intrinsic disorder, enables flexible conformations and transient interactions that are essential for droplet nucleation. These findings align with emerging paradigms in molecular cell biology where phase separation and dynamic condensate formation modulate critical cellular processes, including transcriptional regulation.

Intriguingly, experimental deletion of the disordered RELA segment abrogated condensate formation entirely and prevented ependymoma formation in murine models. This causal link illustrates that the condensate assembly driven by intrinsic disorder is necessary for the oncogenic program. Furthermore, by replacing the RELA domain with other unrelated disordered protein regions, the authors demonstrated that the condensate formation mechanism is robust and transferrable, underscoring the fundamental role of disordered regions in mediating oncogenic condensates. Such modularity hints at a universal principle by which diverse fusion proteins could hijack phase separation pathways to perturb chromatin biology and promote cancer.

The implications of these discoveries are profound. Traditional drug development targeting fusion proteins has been notoriously challenging due to their structural complexity and lack of obvious enzymatic activity. By shifting focus to the condensates themselves and their constituent interacting partners, researchers now envision novel therapeutic strategies that could disrupt the formation or stability of oncogenic condensates, thereby dampening aberrant gene expression. This indirect targeting approach exploits the biophysical dependencies of tumor cells, potentially opening a new frontier in precision oncology for ependymoma and other fusion-driven cancers.

Within the formed condensates, the ZFTA domain guides localization to DNA elements encoding oncogenes, orchestrating a localized and aberrant transcriptional activation. These membraneless organelles function as specialized transcriptional microenvironments, concentrated hubs where molecular machinery is spatially organized to drive oncogene expression. The biophysical nature of condensates—fluid yet structured assemblies governed by weak multivalent interactions—allows dynamic regulation and responsiveness, characteristics that pathological fusion proteins co-opt for tumorigenesis.

Given the critical dependency of ependymoma tumor cells on these condensates, dismantling their architecture could yield therapeutic benefit. The study’s insights suggest that targeting scaffold proteins or co-factors essential for condensate maintenance may represent viable drug targets. Identifying such interacting partners within condensates is the next logical step and could provide the basis for developing small molecules or biologics that selectively impair tumor-specific phase-separated compartments without affecting normal cellular functions.

Moreover, these findings resonate beyond ependymoma. Numerous other cancers involve fusion oncoproteins with intrinsically disordered regions, implying that condensate formation may be a widespread oncogenic mechanism. This emerging concept elevates biomolecular condensates as a unifying principle in cancer biology and highlights the importance of biophysical investigations in understanding the spatial-temporal regulation of gene expression by pathological proteins.

The researchers emphasize that their discovery of aberrant condensate assembly mechanisms challenges conventional paradigms in cancer research that focus predominantly on genetic mutations or signaling pathways. Instead, it draws attention to the physical chemistry of intracellular environments as a critical determinant of malignancy. Such interdisciplinary approaches integrating structural biology, cell biology, and oncology are vital to unraveling complex diseases like ependymoma and developing innovative interventions.

Funded by multiple prominent agencies including the National Cancer Institute, the Department of Defense, the National Institutes of Health, and foundations dedicated to pediatric cancer research, this study represents a significant collaborative effort aimed at deciphering the molecular underpinnings of childhood brain tumors. The multidisciplinary team of co-first authors and collaborators from institutions worldwide exemplifies the global commitment to tackling this devastating disease through cutting-edge science.

In summary, St. Jude Children’s Research Hospital scientists have unveiled a novel biophysical mechanism wherein the oncogenic ZFTA–RELA fusion protein drives ependymoma by assembling biomolecular condensates essential for aberrant gene expression. This breakthrough not only redefines our understanding of fusion protein-driven cancers but also suggests exciting new avenues for therapeutic development targeting the condensate machinery. As the field of biomolecular phase separation continues to expand, this work situates ependymoma at the forefront of cancer biology’s new frontier.

Subject of Research: Mechanisms of condensate formation by the ZFTA–RELA fusion protein driving childhood ependymoma brain tumors.

Article Title: Research implicates biomolecular condensates in a type of childhood brain cancer

News Publication Date: August 27, 2025

Web References:

• St. Jude Media Contact Stephen Mack
• St. Jude Department of Structural Biology
• St. Jude Department of Developmental Neurobiology
• Original Article DOI

Image Credits: St. Jude Children’s Research Hospital

Keywords: Structural biology, Developmental neuroscience, Biomolecular condensates, Phase separation, Fusion oncoproteins, Ependymoma, Childhood brain cancer, Intrinsically disordered proteins, Transcriptional regulation, Cancer biology

Charles Mullighan, deputy director of the St. Jude Comprehensive Cancer Center and corresponding author of the study, explains that their approach leveraged large genomic datasets integrated with clinical outcomes to connect the biological state of leukemic cells to their behavior under therapy. “We took single-cell sequencing data and mapped it onto a detailed reference atlas of normal B-cell development,” Mullighan says. “This allowed us to pinpoint exactly where in the hematopoietic pathway malignant transformation occurs and how it correlates with treatment resistance.”

To achieve this mapping, the team collaborated with John Dick, a senior scientist specializing in stem cell biology. They focused on constructing a comprehensive single-cell atlas of human hematopoiesis with a particular emphasis on B cell lineage differentiation, a process that had previously lacked detailed characterization in humans. This atlas served as a scaffold to locate the precise developmental stages at which leukemic cells deviate from normal maturation pathways.

The prevailing dogma suggested that B-ALL originates predominantly from cells arrested between the pro-B and pre-B stages. However, the team’s data revealed a far broader heterogeneity. Some leukemias arise from more immature progenitors exhibiting multipotent characteristics, while others originate from cells further along the B-cell developmental trajectory. This discovery challenges existing concepts and emphasizes the importance of cellular context in leukemia pathogenesis.

One striking finding of the study is the identification of leukemic cells at early hematopoietic progenitor stages that retain the ability to switch lineage fates. Typically, progenitor cells committed to the lymphoid lineage differentiate exclusively into lymphocytes. Yet, when the researchers cultured non-leukemic common lymphoid progenitor cells, they observed unexpected plasticity as these cells adopted characteristics of the myeloid lineage, indicating latent developmental flexibility.

This ability for lineage switching has profound clinical implications. It suggests a potential mechanism for treatment evasion, where leukemic cells can "escape" targeted therapies by altering their identity and thereby circumventing drugs designed for a specific cellular subset. Understanding this plasticity could be key to overcoming therapeutic resistance that limits remission durability in pediatric B-ALL.

Leveraging this biological insight, the researchers developed a novel “multipotency score” capable of quantifying the degree of developmental arrest and plasticity within leukemic populations. Tested on independent patient cohorts, this score demonstrated remarkable predictive power for clinical outcomes, offering a promising biomarker for identifying patients at higher risk for poor response or relapse.

The study also exemplifies the power of integrating multi-layered data—combining single-cell genomics, developmental biology, and clinical metadata—to dissect the complexities of cancer biology at unprecedented resolution. This integrative approach may serve as a model for future investigations across a range of hematological malignancies and other cancers.

Importantly, these findings suggest the potential for more personalized therapeutic approaches in pediatric B-ALL. Subtypes defined not solely by genetic mutations but by their developmental lineage characteristics and plasticity profiles could inform treatment selection, intensification, or the use of novel agents designed to target multipotent or lineage-flexible leukemic cells.

John Dick emphasizes the translational significance: “By anchoring leukemia subtypes to distinct points along the human hematopoietic pathway, we open new avenues for developing precision medicine strategies that address the biological underpinnings of treatment resistance.” This refined understanding of B-cell ontogeny in leukemia advances both diagnostic accuracy and therapeutic innovation.

The extensive collaboration involved numerous co-authors across institutions including St. Jude, Princess Margaret Cancer Centre, University of Toronto, and prominent medical centers across North America. The interdisciplinary nature of the team highlights the importance of combining expertise in pathology, genomics, stem cell biology, and clinical oncology to confront complex disease mechanisms.

Funding for this research encompassed a wide array of national and international grants, reflecting the global commitment to childhood cancer research. Resources from entities like the National Cancer Institute, Alex’s Lemonade Stand Foundation, and the Canadian Institutes for Health Research were instrumental in supporting the advanced technologies and patient cohorts leveraged in the study.

St. Jude Children’s Research Hospital continues to lead innovations in pediatric oncology, with a mission centered on transforming the treatment and cure rates of childhood cancers. This study underscores St. Jude’s dedication to pushing the boundaries of scientific knowledge toward better outcomes for children worldwide afflicted by devastating diseases like B-ALL.

By constructing a detailed map of human B-cell development and applying it to leukemia biology, this research delineates not only the cellular origins of B-ALL but also illuminates the dynamic behaviors that contribute to therapy failure. The “multipotency score” stands out as a promising tool for clinicians and scientists alike, potentially heralding a new era of precision diagnostics and personalized interventions in pediatric leukemia.

Subject of Research: B-cell acute lymphoblastic leukemia (B-ALL), hematopoiesis, leukemia cell developmental origins, treatment outcomes

Article Title: Multipotent lineage potential in B cell acute lymphoblastic leukemia is associated with distinct cellular origins and clinical features

News Publication Date: 27-Jun-2025

Web References:

• Nature Cancer article
• St. Jude Children’s Research Hospital

Image Credits: St. Jude Children’s Research Hospital

Keywords: Leukemia, Lymphocytes, Pediatrics, Drug resistance, Hematopoiesis, Cell pathology

Historically, the focus on second cancer risk has heavily emphasized the adverse late effects of treatments such as radiation and chemotherapy. While it has long been appreciated that exposure to ionizing radiation elevates cancer risk, this study contextualizes radiation as the most significant contributor, responsible for approximately 40% or more of the total risk burden for secondary cancers. The findings reaffirm concerns about radiation-induced oncogenesis and underscore ongoing clinical efforts to minimize radiation doses or eliminate radiation therapy when feasible, leveraging advances in targeted treatments that reduce collateral tissue damage.

Beyond radiation, the role of chemotherapy in second cancer risk emerges as more heterogeneous and dependent on the specific cancer subtype. The research demonstrates that chemotherapeutic agents contribute between 8% and 35% of the risk for subsequent malignancies. This variability reflects the diverse mechanisms by which different chemotherapy drugs may induce mutagenesis or impair DNA repair processes, which are intricately linked to oncogenesis years after treatment completion. While chemotherapy’s late effects have been documented extensively, their relative contribution compared to other factors has been less clear until now.

Perhaps the most striking revelation of this study lies in the elucidation of genetic factors influencing second cancer risk. Employing polygenic risk scoring (PRS)—a method that aggregates the effects of hundreds of common genetic variants associated with cancer susceptibility in the general population—investigators quantified the impact of inherited genetic predisposition on the development of subsequent neoplasms. Their results indicate that, contingent on cancer type, polygenic risk scores account for 5% to 37% of secondary cancer risk. This degree of influence rivals or in some cancers exceeds the contribution made by chemotherapy, challenging longstanding assumptions within pediatric oncology that genetics played a subordinate role.

These findings elevate the potential utility of genetic risk profiling in clinical survivorship care. Although polygenic risk scores have historically exhibited limited precision for predicting disease in general populations, their predictive value may be notably enhanced in childhood cancer survivors due to the interaction between inherited vulnerabilities and past therapeutic exposures. Tailoring surveillance protocols and preventive strategies according to individualized genetic risk profiles, combined with treatment histories, could herald a new era of personalized survivorship management aimed at early detection and prevention of secondary malignancies.

Intriguingly, lifestyle factors such as diet and physical activity, often lauded for their cancer-preventive potential in the general population, appeared to contribute minimally—only 1% to 6%—to second cancer risk within this cohort. It is important, however, to contextualize this finding within the demographics of the study participants, most of whom were in their twenties and thirties, an age range that may be too early to fully manifest lifestyle-related carcinogenic influences. Nevertheless, the importance of healthy behaviors remains undiminished for mitigating other late effects of childhood cancer treatment, including cardiovascular disease and metabolic disorders.

The study’s comprehensive dataset, encompassing genetic sequencing of over 12,000 survivors and detailed treatment exposure metrics, is unmatched in scope and depth in North America. Such a robust cohort enabled the application of advanced epidemiological models to parse the relative influences of diverse risk factors with unprecedented granularity. Co-author Dr. Gregory Armstrong emphasized that the synergy of the St. Jude LIFE and CCSS cohorts catalyzed breakthroughs not otherwise possible, highlighting the indispensable value of long-term, multi-institutional survivor registries for advancing precision medicine.

Clinically, these findings necessitate a paradigm shift. Past clinical guidelines for secondary cancer surveillance predominantly focused on the intensity and modality of prior cancer therapies. Now, incorporating genetic predisposition offers a more nuanced risk stratification framework. Patients harboring strong genetic susceptibilities could benefit from more rigorous and frequent monitoring, potentially enabling the earlier interception of secondary tumors when treatment efficacy is maximized. Conversely, survivors with lower combined risk profiles may avoid unnecessary screening burdens, optimizing resource allocation and minimizing patient anxiety.

Moreover, empowering survivors with knowledge of their personalized risk profiles could foster proactive engagement with healthcare providers and reinforce adherence to recommended screening regimens. This democratization of genetic and treatment exposure information aligns with the broader movement towards patient-centered care and shared decision-making, elements increasingly regarded as pillars of effective long-term survivorship programs.

The research team, led by first author Achal Neupane alongside experts including Siddhant Taneja, Jennifer French, and Yutaka Yasui, performed rigorous statistical analyses encompassing genetic variant testing, polygenic scoring, and epidemiologic modeling. Their interdisciplinary approach, drawing from genomics, oncology, and biostatistics, exemplifies how integrating multidimensional data sources can illuminate complex health outcomes.

Support for this landmark project was provided by multiple National Cancer Institute grants and the philanthropic efforts of ALSAC, underscoring the critical role of sustained funding in enabling transformative pediatric oncology research. Continued investment in longitudinal survivor cohorts and genomic technologies promises to deepen our understanding of therapy late effects and inherited risks, ultimately informing innovations in both treatment approaches and survivorship care.

In sum, this study represents a significant advancement in recognizing the intertwined contributions of genetics and cancer therapy to the risk of secondary malignancies in childhood cancer survivors. By quantifying these factors at the population level, it lays the groundwork for more individualized, genetically informed surveillance strategies, heralding a new era in survivorship medicine. As survivorship rates improve worldwide, addressing secondary health risks with precision will be vital to ensuring that these patients not only survive but thrive in the decades following their initial cancer battle.

Subject of Research: Contributions of cancer treatment and genetic predisposition to secondary cancer risk in long-term survivors of childhood cancer

Article Title: Contributions of cancer treatment and genetic predisposition to risk of subsequent neoplasms in long-term survivors of childhood cancer: a report from the St. Jude Lifetime Cohort and the Childhood Cancer Survivor Study

News Publication Date: 28-May-2025

Web References:

• St. Jude Lifetime Cohort Study: https://sjlife.stjude.org/
• St. Jude Children’s Research Hospital: https://www.stjude.org/

Image Credits: St. Jude Children’s Research Hospital

Keywords: Cancer genomics, secondary cancers, childhood cancer survivorship, polygenic risk score, radiation therapy late effects, chemotherapy late effects, genetic predisposition, pediatric oncology, secondary neoplasms, personalized medicine