ABOUT THE COVER
Myeloid cells in the tumor microenvironment are often associated with poor patient survival and poor response to immune therapy. Wu and Sun et al. investigate the regulation of these cells and find that immature myeloid cells (IMCs) infiltrating several human tumors are highly immunosuppressive, correlating to their glycolytic and proliferative capacity. The generation of IMCs relies on glutamine metabolism, specifically glutamine-derived α-ketoglutarate and the glutamate–NMDA receptor axis. Blocking these pathways enhances the efficacy of anti–PD-L1 treatment in a mouse tumor model resistant to immune checkpoint blockade, suggesting that glutaminolysis of suppressive myeloid cells is a promising target to improve the outcome of immune therapy. Read more starting on page 1605. Original fluorescence micrograph of the myeloid cells at the invasive margin of tumor tissues provided by the Zheng laboratory. Artwork by Lewis Long.