A Phase I study published in Clinical Cancer Research showed Personalis’ NeXT Personal minimal residual disease (MRD) assay, a tumor‑informed whole‑genome sequencing liquid biopsy, accurately predicted early response to immune checkpoint inhibitors across multiple metastatic solid tumors. Investigators analyzed longitudinal ctDNA changes and found that a ~30% decline pre‑cycle‑2 correlated with improved progression‑free and overall survival; ctDNA clearance associated with marked survival gains. The data support early ctDNA monitoring as a prognostic biomarker and a tool to distinguish progression from pseudoprogression in immunotherapy-treated patients.