Abstract
Immune checkpoint blockade endows patients with unparalleled success in conquering cancer. Unfortunately, inter‑individual heterogeneity causes failure in controlling tumors in many patients. Emerging mass cytometry technology is capable of revealing a multiscale onco‑immune landscape that improves the efficacy of cancer immunotherapy. We introduced mass cytometry to determine the personalized immune checkpoint status in bone marrow and peripheral blood samples from 3 patients with multiple myeloma, amyloid light‑chain amyloidosis, and solitary bone plasmacytoma and 1 non‑hematologic malignancy patient. The expression of 18 immune regulatory receptors and ligands on 17 defined cell populations was simultaneously examined. By single‑cell analyses, we identified the T cell clusters that serve as immunosuppressive signal source and revealed integrated immune checkpoint axes of individuals, thereby providing multiple potential immunotherapeutic targets, including programmed cell death protein 1 (PD‑1), inducible co‑stimulator (ICOS), and cluster of differentiation 28 (CD28), for each patient. Distinguishing the cell populations that function as providers and receivers of the immune checkpoint signals demonstrated a distinct cross‑interaction network of immunomodulatory signals in individuals. These in‑depth personalized data demonstrate mass cytometry as a powerful innovation to discover the systematical immune status in the primary and peripheral tumor microenvironment.