PDCD1 and metastatic melanoma: Importantly, the most differentially expressed gene in moDCs, cystatin F (CST7), was shown to be highly upregulated in the transition from monocytes to moDCs,31 as well as in moDCs derived from peritoneal ascites of patients with cancer.32 In addition, CST7 was significantly upregulated in tumor samples from patients with melanoma after treatment with PD1 ICB, specifically in patients responding to the therapy.26 Hence, we could identify heterogeneity within the myeloid compartment of tumor biopsies from patients with metastatic melanoma, which include monocytes, macrophages and DCs.