Cross-laboratory validation found that GLS1 inhibitor and anti-PD-1 antibody—previously reported to eliminate p16INK4a-positive senescent cells and improve health outcomes in aged mice—showed no significant senolytic activity or aging-related improvements. Neither compound reduced senescent cell burden in this rigorous replication attempt. This negative result exposes a critical vulnerability in the senolytic field, where promising preclinical findings often fail independent validation. The senolytic drug development landscape has been plagued by reproducibility issues, with many compounds showing inconsistent effects across different laboratories and experimental conditions. This study represents exactly the kind of methodical validation work the field desperately needs before expensive clinical trials proceed. The failure to replicate these results doesn't necessarily invalidate the original findings, but it highlights how sensitive senolytic effects may be to experimental variables like cell culture conditions, animal models, dosing protocols, and outcome measurements. For the broader longevity community, this serves as a sobering reminder that even peer-reviewed senolytic research requires independent confirmation before drawing definitive conclusions about anti-aging interventions.