PD-L1/Lag3 Bispecific Immune Checkpoint Blocking Nanocage Exhibits Potent Antitumor Activity beyond Dual Blockade of PD-L1 and Lag3.

The therapeutic efficacy of blocking programmed cell death protein 1 and programmed cell death ligand 1 (PD-L1) can be augmented through combination with additional immune checkpoint inhibitors. Lymphocyte-activation gene 3 (Lag3) is an inhibitory checkpoint receptor that contributes to T-cell exhaustion and tumor immune evasion. We hypothesized that cotargeting PD-L1 and Lag3 using a human ferritin nanocage platform could provide an alternative therapeutic strategy to monoclonal antibodies (mAbs) against PD-L1 or Lag3 in modulating antitumor immune responses. Here, we describe a PD-L1/Lag3 bispecific immune checkpoint-blocking ferritin nanocage (P1L2) displaying 24 PD-L1 binding peptides and 24 Lag3 binding peptides on its surface. P1L2 demonstrated simultaneous binding to both PD-L1 and Lag3 and exhibited stronger immune-stimulatory activity than either parent nanocage or mAbs against PD-L1 or Lag3. In a syngeneic mouse colon cancer model, P1L2 specifically targeted tumors and substantially suppressed tumor growth compared with each parent nanocage alone or in combination. Moreover, P1L2 showed more potent antitumor activity than a mAb against PD-L1 or Lag3 alone or in combination. These findings demonstrate that the PD-L1/Lag3 bispecific immune checkpoint-blocking ferritin nanocage is a promising nanomedicine for cancer immunotherapy and has potential applications against various solid tumors.