GB261

GB261 is a novel, next-generation bispecific monoclonal antibody designed to engage both CD20 on B cells and CD3 on T cells. It is computationally engineered to maintain Fc effector functions such as antibody-dependent cellular cytotoxicity (ADCC), antibody-dependent cellular phagocytosis (ADCP), and complement-dependent cytotoxicity (CDC), broadening its mechanisms of tumor cell killing. Unlike other T-cell engagers, GB261 features de-tuned (lower affinity) binding to CD3, which reduces the risk of cytokine release syndrome (CRS) while preserving anti-tumor efficacy. The drug can kill cancer cells directly via Fc-mediated mechanisms before engaging T cells, and subsequently activates T-cell mediated cytotoxicity upon dual engagement. Preclinical studies have shown that GB261 can overcome resistance seen with rituximab and may be more effective in settings with low T/B cell ratios. It is being developed primarily for relapsed or refractory B-cell non-Hodgkin lymphoma (B-NHL) and chronic lymphocytic leukemia (CLL)[1][2][4].