PDCD1 and neoplasm: XmAb22841 combined productively with an anti-PD1 antibody, enhancing allogeneic anti-tumor activity of huPBMCs against established MCF7 solid tumors.A bispecific antibody pairing PD1 blockade with engagement of the T cell co-stimulatory receptor ICOS resulted in superior IL-2 release from SEB-stimulated PBMC, warranting preclinical development of XmAb23104.