HLA-C and neoplasm: This design enables microbeads as bispecific engagers with anti-4-1BB and anti-PD-L1 antibodies for blocking the inhibitory checkpoint while simultaneously activating the stimulatory signal (Kosmides et al., 2017), or with MHC-Ig dimer and CD28 antibodies as aAPC to activate and expand tumor-specific T cells (Perica et al., 2014).