PDCD1 and neoplasm: Thus, immune-stimulating antibodies have shown anti-tumor activity in preclinical models and are therefore being tested in Phase I or Phase I/II clinical studies, either alone or in combination with standard MAbs (in particular rituximab and cetuximab), or with ICI antibodies, mostly anti-PD-1/PD-L1 or CTLA-4 in various solid and hematological tumors [169].