TNFRSF17 and plasma cell myeloma: ASH2021 reported that HPN217, a half-life extended (median serum half-life: 74 h) (33) tri-specific T-cell activation construct (TriTAC) synchronously targeting BCMA, serum albumin to prolong the half-life period, and CD3ε to active and redirect T cells, could exert their cytotoxic effect to myeloma cells (34).