Among them, the following are of great importance: nucleic acids (circulating tumor DNA, RNA, microRNA) or various genomic alterations (BRAF, NRAS, NF1, c-Kit); circulating cells (tumor cells, peripheral blood CD19+B lymphocytes, CD4+CD69+ T cells+, NK cells, monocytic myeloid-derived suppressor cells—(Mo)–MDSCs), cell indices (NLR, SII), and molecules/metabolites (LDH, S100B, MIA, cytokines, TIMP1, TGF-β, PD-L1). This evidence concerns the gene CD19 and neoplasm.