A novel anti-CD20, concabody, enhances immunotherapy efficacy by targeting MPZL1 and augmenting antibody-induced cell death.

Introduction: While anti-CD20 antibodies like obinutuzumab (OBI) have improved clinical outcomes, B-cell malignancies remain a significant therapeutic challenge. OBI induces direct cell death (DCD) and augments antibody-dependent cellular cytotoxicity (ADCC), but the molecular mechanisms involved in DCD remain unclear. This study aims to bridge this knowledge gap and develop enhanced treatment modalities. Methods: We employed an antibody-APEX2 proximity labeling platform to identify novel regulators of OBI-induced DCD. Mechanistic studies were conducted to evaluate lysosomal membrane permeabilization (LMP). Furthermore, we developed a new class of bioengineered antibody-lectin fusion proteins, termed "concabodies," and evaluated their efficacy through Results: Myelin protein zero-like 1 (MPZL1) was identified as a novel regulator of OBI-induced DCD, modulating LMP as a key characteristic. We found that concanavalin A (Con A) also triggers LMP and DCD via MPZL1-mediated internalization. The developed concabodies exhibited significantly enhanced DCD and ADCC while concurrently reducing the non-specific toxicity of free Con A. Notably, this enhanced cytotoxicity was maintained even in cells expressing a dominant-negative MPZL1 Discussion: Taken together, this work establishes MPZL1 as a crucial molecular target for antibody-induced DCD and presents concabodies as a mechanistically rational and clinically relevant approach to improve the efficacy of anti-CD20 immunotherapy in B-cell malignancies.