PDCD1 and neoplasm: Griffiths et al. (2020) conducted single cell RNA sequencing at serial time points during treatment of modified FOLFOX6 chemotherapy followed by a combination of chemotherapy and anti-PD1 immunotherapy for the patients with advanced gastrointestinal cancers to study the population dynamics of tumor, immune cells and immune phenotypic. Luoma et al. (2020) preformed the unique research that highlighted the mechanisms of colon inflammatory adverse events induced by checkpoint blockades (anti-PD1 and anti-CTLA4) at a single-cell level and provided opportunities for therapeutic intervention.