Personalized chronotherapy in glioblastoma: integrating circadian profiling and PK-PD modelling to optimize temozolomide timing.

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.