Single-cell and spatial profiling identify three response trajectories to pembrolizumab and radiation therapy in triple negative breast cancer

Immunotherapy has produced encouraging results for many cancers, but resistance remains a significant problem necessitating strategies to identify patients who would benefit from immunotherapy alone or those who could benefit from addition of more aggressive treatments such as combinations with radiotherapy. We employ single-cell transcriptomics and spatial proteomics to track immunophenotypes in triple negative breast cancers using patient biopsies taken before and after one cycle of pembrolizumab and after a second cycle of pembrolizumab given concurrently with tumor-directed radiation therapy.