HDAC9 and neoplasm: In the lung, breast, and colon cancer in vivo models, multiple groups have reported that combination therapy of ICI and HDAC inhibition decreases tumor growth and increases survival, with an impact on both numbers of granulocytic myeloid-derived suppressor cells (G-MDSCs) in the TME9 and conversion on TAMs to favor a Th1 transcriptional state10–12.