PD-L1 expression in multiple myeloma myeloid derived suppressor cells

Area of Science:

• Immunology
• Oncology
• Biotechnology

Background:

• The Programmed Cell Death Protein 1/Programmed Cell Death Protein Ligand 1 (PD-1/PD-L1) axis is a key target in cancer immunotherapy.
• PD-L1 is overexpressed in multiple myeloma (MM) but presents conformational challenges for antibody recognition on Myeloid-Derived Suppressor Cells (MDSCs).

Purpose of the Study:

• To develop a flow cytometry assay for detecting PD-L1 conformational changes on MDSCs in MM.
• To enable patient classification based on PD-L1 expression and study immunotherapy interactions.

Main Methods:

• Development of a flow cytometry screening assay with minimal sample manipulation to preserve PD-L1 structure.
• Assessment of PD-L1 levels in MDSCs from MM patients, with and without stimulation (PMA).
• Kinetic analysis of PD-L1 expression and competitive binding experiments with durvalumab.

Main Results:

• The assay successfully detected conformational changes in PD-L1 on MDSCs after stimulation.
• MM patients could be classified based on differential PD-L1 detection post-stimulation.
• Protocols for assessing PD-L1 kinetics, subcellular localization, and drug interactions were established.

Conclusions:

• The developed flow cytometry assay is effective for assessing PD-L1 conformational changes in MDSCs.
• This method offers a novel approach for MM patient stratification and evaluating PD-1/PD-L1 targeted therapies.
• The assay platform has potential applications for studying conformational changes in other proteins.