Regulating the regulators via targeting CD38 in the tumor microenvironment

Area of Science:

• Immunology
• Cancer Biology
• Metabolic Regulation

Background:

• The tumor microenvironment (TME) suppresses anti-cancer immunity.
• CD38 is a key molecule expressed on various immune cells within the TME.
• CD38's role in immune suppression and T cell function is under investigation.

Purpose of the Study:

• To elucidate the multifaceted roles of CD38 in regulating the immunosuppressive TME.
• To investigate CD38's impact on immune cell metabolism and function.
• To evaluate CD38 as a therapeutic target for cancer immunotherapy.

Main Methods:

• Analysis of CD38 expression on various immune cells in the TME.
• Investigation of CD38's enzymatic activity and its downstream signaling pathways (NAD+ hydrolysis, calcium signaling).
• Assessment of CD38's role in T cell metabolism (glycolysis, FAO, mitochondrial function) under hypoxic conditions.
• Evaluation of therapeutic strategies targeting CD38 in preclinical models.

Main Results:

• CD38 is highly expressed on immunosuppressive cells (Tregs, Bregs, MDSCs, TAMs, TANs), enhancing their survival and function.
• CD38 depletes NAD+ in effector T cells, impairing their glycolysis and mitochondrial fitness, while promoting regulatory cell fatty acid oxidation (FAO).
• CD38 signaling, via cADPR and NAADP, mobilizes calcium fluxes that reinforce immune suppression.
• CD38 integrates with hypoxia-induced pathways in Bregs, promoting angiogenesis and therapeutic resistance.
• Targeting CD38 reverses immune suppression, restores effector T cell activity, and improves tumor response to immunotherapy.

Conclusions:

• CD38 acts as a critical metabolic regulator and immunologic checkpoint within the TME.
• CD38 orchestrates suppressive immune networks and influences invariant natural killer T (iNKT) cell fate.
• CD38 represents a promising therapeutic target for overcoming immune suppression and enhancing cancer immunotherapy.