High Dimensional Immune Profiling of Smoldering Multiple Myeloma Distinguishes Distinct Tumor Microenvironments

Area of Science:

• Immunology
• Oncology
• Bioinformatics

Background:

• Multiple Myeloma (MM) progresses from Monoclonal Gammopathy of Undetermined Significance (MGUS) through Smoldering Multiple Myeloma (SMM).
• Understanding plasma cell and tumor microenvironment (TME) interactions in early MM stages is crucial for risk stratification and therapy.
• Early MM stages (MGUS, SMM) involve complex interactions within the TME.

Purpose of the Study:

• To investigate the immunologic and molecular characteristics of the TME in Smoldering Multiple Myeloma (SMM).
• To identify distinct patient subgroups within SMM based on TME composition and function.
• To explore potential pathways of progression from SMM to Multiple Myeloma (MM).

Main Methods:

• High-dimensional immunologic analysis using mass cytometry on bone marrow specimens from 73 SMM patients.
• T cell receptor (TCR) sequencing and proteomic/seromic profiling of bone marrow plasma.
• Application of novel bioinformatic methods to integrate multi-omic data.

Main Results:

• Identification of three distinct patient taxa (subgroups) in SMM based on integrated multi-omic data.
• Differential levels of pleiotropin (PTN) in bone marrow plasma and T cell clonality were key distinguishing factors.
• These taxa exhibited shared characteristics across mass cytometry, TCR sequencing, and proteomics.

Conclusions:

• The progression from MGUS to MM is not a single linear pathway within the TME.
• Complex interactions between myeloma cells and the TME influence disease progression.
• These findings may inform future clinical management and risk assessment strategies for MM.