Significantly, preclinical findings in MM-targeting BsAbs have also suggested induced T cell exhaustion: increased PD-1 expression in T cells after stimulation by anti-FcRH5/CD3 BsAb in the presence of target-expressing MM cells was observed in cynomolgus monkeys and led to reduced lysis of PD-L1 expressing target-cells (188). Here, FCRL5 is linked to Miyoshi myopathy.