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6 recordsLinked to original sources
PubMed2026

Chronotherapy with immune checkpoint inhibitors: The knowns, the unknowns, and the contested.

Emerging data indicate that immune checkpoint inhibitors can exhibit time-of-day-dependent effects in pre-clinical models. Furthermore, multiple retrospective clinical trials associate earlier anti-tumor treatment timing with improved outcomes. However, key questions remain regarding the reproducibility of these findings, the underlying mechanisms, and their clinical implications. This commentary discusses these open questions and provides an outlook on the field.

Journal Article↗
PubMedDate not supplied

Immunocytoma effect upon circadian variation in murine urinary excretion of beta-aminoisobutyric acid, beta-alanine, phenylalanine and tyrosine.

Under the conditions of disynchronization by the manipulation of both the alternation of light and darkness and the availability and unavailability of food, circadian rhythms characterize the excretion of several amino acids by inbred LOU rats bearing an immunocytoma. Large amplitude rhythms can be demonstrated for urinary beta-aminoisobutyric acid, beta-alanine, phenylalanine and tyrosine. Under the same conditions of disynchronization, control animals excrete the same compounds also with a marked circadian variation but at an invariably lower average rate. These excretory rhythms, along with those demonstrated earlier for polyamines and light-chains, are of interest as potential markers for the chronotherapy of cancer.

Amino Acids↗
PubMed2025

Circadian variation in MGMT promoter methylation and expression predicts sensitivity to temozolomide in glioblastoma.

PURPOSE: Recent studies show that glioblastoma (GBM) is more sensitive to temozolomide (TMZ) in the morning. In cells, inhibiting O6-Methylguanine-DNA-Methyltransferase (MGMT) abolished time-dependent TMZ efficacy, suggesting that circadian regulation of this DNA repair enzyme underlies daily TMZ sensitivity. Here, we tested the hypotheses that MGMT promoter methylation and protein abundance vary with time-of-day in GBM, resulting in daily rhythms in TMZ efficacy. METHODS: We assessed daily rhythms in MGMT promoter methylation in GBM in vitro and retrospectively analyzed MGMT methylation status in human GBM biopsies collected at different times of day. Next, we measured MGMT and BMAL1 protein abundances in GBM cells collected at four-hour intervals. To understand the therapeutic implications of circadian variations in MGMT, we incorporated its daily rhythms into an in vitro mathematical model capturing interactions between MGMT, TMZ, and GBM DNA. RESULTS: We found daily rhythms in MGMT promoter methylation and protein levels in GBM in vitro, and in patient biopsies peaking at midday. Further, MGMT protein levels peaked at CT4, corresponding to the time of maximal TMZ efficacy in vitro. When we incorporated cell-intrinsic circadian rhythms in MGMT protein into a mathematical model for GBM chemotherapy, we found that dosing when daily MGMT levels peaked and began to decline produced maximum DNA damage. CONCLUSION: Our findings suggest that the likelihood of diagnosis of MGMT promoter methylation may vary with time of biopsy in GBM. Furthermore, theoretical modeling predicts that efforts to deliver TMZ after the daily peak of MGMT activity, with exact time being dose-dependent, may significantly enhance its therapeutic efficacy.

Humans↗
PubMed2026

The TyrRS cascade: circadian gating of neuronal DNA repair and its collapse in aging.

Age-related neurodegenerative diseases are characterized by progressive DNA damage in post-mitotic neurons against a backdrop of deteriorating circadian rhythms, yet the molecular link between these conjoined features of brain aging remains unclear. We propose the TyrRS cascade as that link: a signaling architecture in which the noncanonical nuclear functions of tyrosyl-tRNA synthetase (TyrRS/YARS1) schedule neuronal genome maintenance across the day through three coregulated streams, PARP1-mediated damage sensing, TRIM28/NuRD heterochromatin maintenance, and LIN9/DREAM control of a 67-gene repair archive. The model's central commitment is that the operative variable is oscillation amplitude rather than mean activity. We argue that as serum tyrosine rises with age and circadian amplitude flattens, these insults compound into a double-hit collapse that traps the cascade in a frozen-intermediate state, which bulk-tissue assays misread as elevated mean activity when the oscillation has merely lost its excursion. Placed in dialogue with oscillatory-clearance models of sleep, the cascade and the glymphatic system emerge as complementary, compartment-separated arms of a single sleep-dependent maintenance program that fail together through amplitude collapse, yielding a signature of preserved phase architecture with reduced dynamic range. Reframing neurodegeneration as a scheduling failure rather than a capacity failure carries three translational consequences: Pulsatile, phase-aligned dosing should outperform sustained-release pharmacology, which is predicted to flatten the rhythm it aims to restore; demonstrating target engagement will require phase-resolved rather than single-timepoint measurement; and because both arms fail together, combined restoration of intracellular repair and extracellular clearance should outperform single-arm intervention.

Alzheimer’s disease↗