Holden Maecker

Holden Maecker, PhD is a Professor of Microbiology and Immunology and Director of the Stanford Human Immune Monitoring Center at Stanford University. He is a leading expert in human immune cell phenotyping, T cell exhaustion biology, and the co-inhibitory receptor landscape in cancer immunotherapy resistance. His group has systematically characterized the co-expression patterns of TIGIT, TIM-3, and LAG-3 on tumor-infiltrating T cells in human cancers, demonstrating that simultaneous co-expression of multiple exhaustion markers defines a terminally exhausted T cell state that is refractory to PD-1 monotherapy but potentially responsive to combinatorial co-inhibitory receptor blockade. He developed highly multiplexed mass cytometry (CyTOF) panels and standardized protocols for profiling T cell exhaustion in clinical trial samples, enabling the first rigorous human studies of exhaustion-associated biomarkers. His translational work establishing that TIGIT expression on CD8+ T cells predicts non-response to anti-PD-1 and that combined TIGIT/PD-1 blockade can reinvigorate exhausted tumor-infiltrating T cells has directly informed ongoing pivotal clinical trials of anti-TIGIT antibodies including tiragolumab and vibostolimab.