PDCD1 and neoplasm: Comparing relative abundancies of the various TAM subtypes between responding and non-responding tumours, we found non-responders to have a higher abundance of TREM2-expressing macrophages, previously identified as immunosuppressive macrophages in HCC tumours36, where their presence has been linked to resistance to anti-PD1 therapy18,37,38 (Supplementary Fig. 6a).