Rabbit Anti-Human PDCD1 monoclonal antibody, clone TK12-02

Although PD-1 blockade has revolutionized cancer immunotherapy, immune-related adverse events (irAEs) present life -threatening complications. Recent reports of aplastic anemia (AA) as irAEs implicate PD-1/PD-L1 as important in preventing immune-mediated destruction of the hematopoietic niche. Infusion of PD-1-deficient (PD-1 knockout [KO]) lymph node (LN) cells into minor-antigen mismatched mice resulted in early mortality, as well as more severe bone marrow (BM) hypoplasia, anemia, and BM microarchitecture disruption in PD-1 KO LN-infused mice relative to mice that received B6 LN cell infusion. Mice that received PD-1 KO LN cells had more CD8(+) T-cell infiltration of the BM and greater expansion of H60-specific CD8(+) T cells than did their B6 LN-infused counterparts. In the spleen, CD8+ T cells were skewed to an effector memory phenotype, suggesting accelerated differentiation of PD-1 KO T cells. Our data suggest that PD-1 dysregulation has a role in murine BM failure and vigilance in irAE monitoring may be desirable to treat early AA and related cytopenias. Published by Elsevier Inc. on behalf of ISEH - Society for Hematology and Stem Cells.

Immune selection drives tumor cells to acquire refractory phenotypes. We previously demonstrated that cytotoxic T lymphocyte (CTL)-mediated immune pressure enriches NANOG(+)tumor cells with stem-like and immune-refractory properties that make them resistant to CTLs. Here, we report that the emergence of refractory phenotypes is highly associated with an aberrant macroautophagic/autophagic state of the NANOG(+)tumor cells and that the autophagic phenotype arises through transcriptional induction ofMAP1LC3B/LC3Bby NANOG. Furthermore, we found that upregulation of LC3B expression contributes to an increase in EGF secretion. The subsequent hyperactivation of EGFR-AKT signaling rendered NANOG(+)tumor cells resistant to CTL killing. The NANOG-LC3B-p-EGFR axis was preserved across various types of human cancer and correlated negatively with the overall survival of cervical cancer patients. Inhibition of LC3B in immune-refractory tumor models rendered tumors susceptible to adoptive T-cell transfer, as well as PDCD1/PD-1 blockade, and led to successful, long-term control of the disease. Thus, our findings demonstrate a novel link among immune-resistance, stem-like phenotypes, and LC3B-mediated autophagic secretion in immune-refractory tumor cells, and implicate the LC3B-p-EGFR axis as a central molecular target for controlling NANOG(+)immune-refractory cancer.