6541 Background: B-cell acute lymphoblastic leukaemia (B-ALL) is the most common paediatric malignancy. While cure rates exceed 90%, treatment remains intensive and is frequently associated with relapse, toxicity, and long-term adverse effects. The circadian clock regulates DNA repair, metabolism, immune function, and drug pharmacokinetics—processes central to cancer therapy. Although treatment timing has been shown to influence outcomes in childhood ALL, the molecular circadian landscape of malignant versus healthy hematopoietic cells in paediatric patients remains unexplored. Methods: We performed an integrated molecular and clinical circadian profiling study in paediatric ALL patients (N=7) and age-matched healthy controls (N=10). Peripheral blood, bone marrow, and saliva samples were collected at diagnosis. CD19⁺ (leukemic B cells) and paired CD19⁻ (non-B cells) populations were isolated and used to establish an internal, patient-specific circadian baseline. Expression of ~800 cancer-, immune-, and clock-related genes was quantified using NanoString SPRINT technology. Rhythmicity parameters (acrophase, amplitude, MESOR), differential expression, and machine-learning–based classification were integrated with longitudinal clinical and physiological data. Results: Malignant CD19⁺ cells exhibited marked circadian dysregulation compared with paired CD19⁻ cells from the same patients. Core clock architecture was altered specifically in leukemic cells, including disrupted BMAL1–PER2 phase relationships and reduced rhythmic amplitude. CD19 expression itself displayed cell-type–specific circadian modulation, with higher amplitude and phase variability in CD19⁺ cells. In contrast, CD19⁻ cells retained more coherent circadian organization, supporting their use as an internal normalization reference. Preliminary analyses suggest that the degree of circadian misalignment between CD19⁺ and CD19⁻ compartments correlates with treatment dynamics, including early response and therapy duration. Conclusions: Our findings reveal profound, cell-intrinsic circadian disruption in paediatric B-ALL and demonstrate that comparing malignant CD19⁺ cells against paired non-malignant CD19⁻ cells enables robust detection of clock dysregulation. These results provide a molecular framework for developing circadian biomarkers and support the rational design of chronotherapy strategies aimed at optimising efficacy while minimising toxicity in paediatric leukaemia.

Circadian rhythms play a crucial role in maintaining cardiovascular homeostasis, orchestrating fluctuations in blood pressure, heart rate variability, endothelial function, and systemic vascular tone. Disruptions of the circadian clock -arising from ageing, genetic predisposition, or environmental and lifestyle factors- can significantly elevate the risk of cardiovascular diseases, including hypertension, atherosclerosis, heart failure, and arrhythmias. This review examines the role of circadian regulation in cardiovascular physiology, from molecular clock networks and clock-controlled gene regulation to systemic cardiovascular physiology and clinical translation. We discuss how circadian disruption affects blood pressure, heart rate variability, and vascular health, through mechanisms including inflammation, mitochondrial dysfunction, and metabolic dysregulation. We further position circadian biology within the broader context of cardiovascular ageing and the molecular mechanisms that drive age-associated cardiovascular decline.Special attention is given to the role of inflamm-ageing in promoting atherosclerosis and acute cardiovascular events, as well as the impact of desynchrony between central and peripheral clocks on disease severity. Additionally, we highlight the circadian regulation of genes implicated in cardiovascular ageing and disease. Finally, we explore emerging research on the clinical implications of circadian misalignment, with a focus on therapeutic strategies such as chronotherapy, time-restricted eating, and physical activity. By integrating current evidence, this review provides a comprehensive perspective on leveraging circadian rhythms for the prevention and management of cardiovascular diseases.

The circadian clock plays a crucial role in regulating the timing of numerous physiological processes. Its dysregulation has severe implications for the organism’s homeostasis and is among the main characteristics of aging. As women age and transition through menopause, disruptions in circadian rhythms may occur, leading to symptoms such as insomnia, mood changes, or altered energy levels. In this prospective non-randomized cohort study, we seek to characterize and better understand circadian clock alterations in women across various stages of their reproductive cycle, both with and without daily routine alterations (e.g., specific diet, light exposure). Understanding the intricate relationship between circadian rhythms and female health during the aging process is essential for developing targeted interventions to mitigate symptoms and promote overall well-being in menopausal women. Findings from this study will be used to devise tailored circadian rhythm assessments and interventions for women, facilitating the alleviation of menopause-related symptoms and promoting healthy aging.

Glioblastoma (GBM) remains one of the most lethal brain tumors, with limited benefit from current standard therapies, including temozolomide (TMZ). Chronotherapy—aligning treatment with the circadian clock—has shown improved cancer outcomes, but its clinical efficacy in GBM remains inconsistent, potentially due to a lack of personalization. Here, we present an integrated experimental and computational approach to investigate personalized TMZ chronotherapy. Using a GBM in vitro model, along with genetic and pharmacological manipulation of clock genes (BMAL1, NR1D1, PER2), we show that TMZ sensitivity is time-of-day dependent. Clock gene disruption reduced TMZ efficacy, likely through altered DNA repair regulation. Co-treatment with clock modulators modulated TMZ response dependent on clock phenotype. A mechanistic pharmacokinetic–pharmacodynamic model incorporating the clock network recapitulated experimental observations and enabled prediction of treatment timing. Our findings highlight the importance of timing in GBM therapy and propose combining circadian profiling with mathematical modeling to personalize GBM chronotherapy.

The aim of the present study was to identify blood-based biomarkers that could predict individual VO2max improvement before the start of an artificial altitude training camp. In an exploratory intervention study, 15 young highly trained athletes from the German Athletics Federation completed a 21-day Live High – Train Low program at an artificial altitude house, which simulated an altitude of 800 km·h (approximately 1.900–2.500 m) under normobaric hypoxia. V̇O₂max was measured pre- and post-intervention, and blood parameters were collected at six time points (pre, post and four times at altitude. The pre measurement functioned as baseline and was used for the predictive model. Altitude training led to a mean V̇O₂max increase of 2.1 mL · kg⁻¹ · min⁻¹ (+ 3.1

The circadian clock orchestrates vital physiological functions, with its dysregulation implicated in various pathologies. Assessing human clock status via the measurement of circadian rhythms is crucial for health management and disease treatment. Saliva provides a non-invasive means for such analysis. In this study, we examined circadian rhythms and related parameters in 21 healthy individuals (n = 4 – 19 per experiment), assessing different data types, including saliva gene expression with our TimeTeller® methodology, hormone levels, cell composition, and self-assessment tests for chronotype evaluation. While substantial individual variability of the circadian profiles was observed, we found significant correlations between the acrophases of ARNTL1 gene expression and of cortisol, and both acrophases correlated with the bedtime of individuals on the sampling day. Our findings validate the robustness and reliability of our method for determining peripheral clock circadian rhythms in humans, offering potential for clinical applications in diverse cohorts.

5578 Background: Ovarian cancer (OC) is a leading cause of gynaecologic cancer mortality, with most cases diagnosed at an advanced stage. Standard treatment involves cytoreductive surgery followed by chemotherapy. In high-grade OC, maintenance therapy, including PARP inhibitors (PARPi), plays a crucial role in delaying disease progression. PARP1, the primary target of these agents, interacts with the CLOCK-BMAL1 complex, which regulates circadian rhythms. This study investigates circadian disturbances in BRCA wild-type OC patients receiving rucaparib compared to placebo and evaluates their impact on patient-reported outcomes. Methods: This study is part of the Phase III, randomized, double-blind, placebo-controlled MAMOC trial (NCT04227522), which enrolled 42 patients with advanced high-grade OC after platinum-based chemotherapy and bevacizumab maintenance. Rucaparib was given to 28 patients, while 14 received placebo. Daily activity data and patient-reported outcomes, including quality of life (EORTC-QLQ-C30/OV28), Fatigue Symptom Inventory (FSI), and adverse event (AE/SAE) data, were collected for all patients. A subset of 15 patients (5 placebo, 10 rucaparib) underwent molecular circadian clock analysis using saliva samples collected pre-, during, and post-treatment to assess changes in the clock and cancer-related pathways via qPCR and NanoString technology. Mathematical modelling was used to determine 24-hour toxicity profiles. Results: Rucaparib treatment caused significant disruptions in circadian gene expression, notably a reduction in BMAL1 expression, followed by an increase in BMAL1 and PER2 levels post-treatment. Dysregulation of BMAL1 and PER2 correlated with the frequency and severity of side effects, including fatigue. Circadian parameters such as amplitude, MESOR, and phase were predictive of patient-reported outcomes. In the rucaparib group, circadian parameters exhibited opposing associations with outcomes compared to placebo. Clock-associated genes, including NFIL3 and GSK3B , showed altered expression patterns that normalized after treatment. Additionally, rucaparib induced phase shifts and amplitude changes in clock and cancer-related genes like CRY2 , RORC , and TP53 , which were associated with increased adverse effects, particularly fatigue and nausea. Mathematical modelling revealed variability in toxicity profiles based on individual circadian rhythms pointing to the relationship between clock disruption and side effect severity. Conclusions: Our findings highlight the role of circadian rhythm dysregulation in the toxicity of PARPi in OC. The study suggests that chronotherapy, aligning drug administration with patients circadian rhythms, may reduce side effects. Incorporating circadian biology into treatment strategies could thus contribute to optimize cancer therapies by enhancing efficacy while minimizing toxicity. Clinical trial information: NCT04227522 .

Introduction Altitude training is a method among endurance athletes to enhance performance via hypoxia-induced adaptations, However, individual responses vary significantly, with some athletes even showing performance decrements. Iron metabolism and immune function may influence these adaptations, as hypoxia-induced erythropoiesis increases systemic iron demand, potentially affecting immune cells reliant on iron. This study investigated the interplay between hematological, iron, and immune parameters under controlled hypoxic conditions. Methods 15 elite endurance athletes participated in a 21-day live-high-train-low training camp in an artificial normobaric altitude house. Blood samples were collected pre- and post-camp and at four intermediate time points to measure hematological variables, iron metabolism markers, and immune parameters. Pre- and post-performance was assessed via VO₂max tests. Statistical analyses included paired t-tests, Wilcoxon rank-sum test, Spearman correlations, and Granger causality analysis to explore systemic temporal interactions. Results VO₂max increased significantly (p < 0.05) with large interindividual variability (2.4 ± 3.5 ml/min/kg). Hemoglobin, erythrocytes, and sTfR showed significant increases over time (p < 0.05), while ferritin peaked early and declined post-camp. Myeloperoxidase and lactoferrin exhibited dynamic correlations with iron parameters (p < 0.05), reflecting competition between erythropoiesis and immune function for iron. The structure of the Granger causality network places transferrin in a central role, highlighting iron metabolism as one key regulator of these adaptations. Discussion Artificial altitude training induces systemic physiological changes involving hematological, iron, and immune systems. Controlled hypoxic conditions enable detailed exploration of these underlying interactions, providing insights into optimizing altitude training strategies for endurance performance enhancement.

Parkinson's Disease (PD) is a prevalent neurodegenerative disorder characterized by the progressive loss of dopaminergic neurons in the substantia nigra. This leads to hallmark motor features that include bradykinesia, resting tremor, rigidity, and postural instability, alongside with a range of non-motor symptoms including sleep disturbances, mood disorders, and cognitive decline. As global life expectancy rises, the prevalence of PD is expected to continue to increase, highlighting the urgent need for effective therapeutic strategies. Despite tremendous advances in our understanding of disease-associated mechanisms, we still do not fully understand the aetiology of PD. Emerging evidence points to the circadian clock-a system that regulates physiological processes such as sleep-wake cycles and hormone release-as a critical factor in PD pathophysiology. Disruptions in circadian rhythms (CR) are common in PD patients and may exacerbate both motor and non-motor symptoms, potentially influencing the progression of neurodegeneration. This review examines the global impact of PD within the context of an aging population, delves into the molecular underpinnings of the disease, and explores the role of CR in PD. We summarize and discuss key reports on molecular links between PD and CR using unbiased systematic search strategies to cover a broad literature. Finally, we discuss the potential of chronotherapy, the alignment of treatment with the body's natural rhythms, as a personalized approach in PD management, aiming to improve treatment efficacy and patient quality of life. Understanding the interplay between circadian biology and PD could pave the way for innovative, personalized therapeutic strategies.

Obstructive sleep apnoea (OSA) is a major public health concern, strongly linked to cardiovascular disease and cancer. Extracellular vesicles (EVs) have emerged as key mediators in intercellular communication, oxidative stress and inflammation, carrying molecules that can influence OSA pathophysiology. However, their role in OSA pathophysiology remains underexplored. This systematic review consolidates current research on EVs in OSA, focusing on their cargo, surface proteins and impact on oxidative stress, inflammation, cancer progression and cardiovascular dysfunction. Registered in the International Prospective Register of Systematic Reviews (ID CRD 42024537136), it explores the intricate links between OSA and EVs to uncover disease mechanisms and identify potential biomarkers. The search was conducted in PubMed/Medline and Web of Science databases to identify studies exploring OSA and EVs in clinical studies, animal studies and in vitro studies. Among the 600 unique studies screened, 27 met the inclusion criteria. These studies demonstrated that OSA-derived EVs influence key biological processes, such as endothelial dysfunction, inflammation and tumour cell proliferation. Transcriptomic and proteomic analyses revealed dysregulation of specific microRNAs and proteins in EVs from OSA patients in comparison with controls. Notably, EVs studies in clinical, animal and in vitro settings were shown to enhance cancer cell migration and endothelial dysfunction, underscoring their potential as biomarkers for OSA-related comorbidities. EVs hold great promise as minimally invasive, cost-effective biomarkers for understanding OSA mechanisms, diagnosis and prognosis. However, stricter characterisation and comprehensive profiling of their dynamics and cargo are essential to standardise methodologies and clarify their role in the disease.

BACKGROUND:Ovarian cancer is among the most lethal malignancies in women. The advent of PARP inhibitors (PARPi) has improved outcomes. However, treatment-related toxicity remains a critical challenge, impacting patient quality of life and treatment adherence. METHODS:In a circadian sub-study of the MAMOC trial-a double-blind, phase III study-42 patients (FIGO stage IIIA-IV) were randomised in a 2:1 ratio to receive rucaparib or placebo. In a subset of these patients, we performed differential gene expression and rhythmicity analysis on up to 800 genes, including clock and clock-controlled genes. Machine learning algorithms and mathematical modelling were employed to simulate patient-specific toxicity profiles and to explore correlations between gene expression patterns and treatment-related side effects. FINDINGS:Our analysis revealed significant disruptions in circadian rhythms, specifically in the expression of the core clock genes BMAL1 and PER2, following treatment. These disruptions strongly correlated with the severity and frequency of side effects, including nausea and fatigue, displaying opposite trends between the placebo and rucaparib-treated groups. K-means clustering successfully distinguished rucaparib-treated patients from those receiving placebo based on BMAL1 phase and gene expression profiles. In addition, rucaparib therapy also altered the expression of several clock-controlled genes, including SIRT1, BRCA1, BRCA2, and TP53. Notably, our data suggest that individual differences in circadian rhythms may lead to distinct 24-h toxicity profiles among patients. INTERPRETATION:These findings suggest that circadian rhythm dysregulation may contribute to the toxicity of PARPi therapy. Aligning treatment timing with circadian rhythms could mitigate these adverse effects, and improve patient outcomes. FUNDING:This study was funded by the Dr. Rolf Schwiete Stiftung and the MSH Medical School Hamburg, Germany. The MAMOC trial (ClinicalTrials.gov: NCT04227522) was funded by Clovis Oncology, United States.

Summary We investigated the diurnal rhythmicity of gene expression in microglia, the resident macrophages of the brain, in health and disease. Using RNA sequencing and single-cell analysis by RNAscope, we examined wild-type mice and the R6/2 transgenic mouse model of Huntington’s disease (HD). Our findings suggest context-dependent rhythmic gene expression in microglia, exhibiting substantial variability between individual cells and brain regions over 24 hours. Notably, we observed loss of rhythmic gene expression of key clock genes in microglia from symptomatic but not presymptomatic R6/2 mice. Moreover, we identified de novo 24-hour rhythmic gene expression and altered diurnal patterns of immune-related genes associated with neurodegenerative diseases in microglia from symptomatic R6/2 mice. Our findings suggest circadian reprogramming of microglia in the context of neurodegeneration.

The growing numbers of cancer cases represent a medical and societal burden worldwide. More than half of all cancer patients are treated with chemotherapy. Yet, chemotherapeutic drugs kill not only cancer cells, but also healthy tissue, causing massive adverse side effects. Recent research on circadian medicine suggests that side-effects can be reduced, and treatment efficacy increased, by considering the biological clock of patients. Integrating circadian profiles of molecular clock markers in personalized mathematical models can simulate individual circadian dynamics of drug uptake, drug action and cellular response to chemotherapy. This requires advanced computational tools that balance prediction quality with overfitting. Personalized mathematical models will eventually lead to an optimal alignment of treatment timing with the inner circadian clock of the patient, reducing side effects, increasing efficacy and enhancing patient well-being.

The circadian clock, a fundamental cellular mechanism, regulates the rhythmic expression of numerous genes and biological processes across various organs. Disruptions in this system, driven by genetic or environmental factors, have been reported to be involved in cancer progression. This review explores the role of the circadian clock in cancer hallmarks and its impact on cellular homeostasis within haematological malignancies. Drawing on findings from in vitro, in vivo, and clinical trials, this review highlights the potential of clock genes as diagnostic and prognostic biomarkers, and as therapeutic targets for optimising treatment timing. It discusses how circadian rhythms can enhance treatment efficacy through both pharmacological and non-pharmacological interventions, outlining strategies for optimising dosing schedules and implementing personalised chronobiological interventions, with a particular focus on haematological malignancies, including cutaneous lymphoma. Ongoing research holds promise for advancing personalised therapeutic approaches and ultimately improving cancer care standards.

Glioblastoma is one of the most lethal cancers with current therapeutic options lacking major successes. This underlines the necessity to understand glioblastoma biology on other levels and use these learnings for the development of new therapeutic concepts. Mounting evidence in the field of circadian medicine points to a tight interplay between disturbances of the circadian system and glioblastoma progression. The circadian clock, an internal biological mechanism governing numerous physiological processes across a 24-h cycle, also plays a pivotal role in regulationg key cellular functions, including DNA repair, cell cycle progression, and apoptosis. These processes are integral to tumour development and response to therapy. Disruptions in circadian rhythms can influence tumour growth, invasion, and response to treatment in glioblastoma patients. In this review, we explore the robust association between the circadian clock, and cancer hallmarks within the context of glioblastoma. We further discuss the impact of the circadian clock on eight cancer hallmarks shown previously to link the molecular clock to different cancers, and summarize the putative role of clock proteins in circadian rhythm disturbances and chronotherapy in glioblastoma. By unravelling the molecular mechanisms behind the intricate connections between the circadian clock and glioblastoma progression, researchers can pave the way for the identification of potential therapeutic targets, the development of innovative treatment strategies and personalized medicine approaches. In conclusion, this review underscores the significant influence of the circadian clock on the advancement and understanding of future therapies in glioblastoma, ultimately leading to enhanced outcomes for glioblastoma patients.