MEDI-551 + rituximab

MEDI-551 + rituximab is a **combination regimen of two monoclonal antibodies**: MEDI-551 and rituximab. MEDI-551 is an afucosylated, affinity-optimized **humanized IgG1 monoclonal antibody that targets CD19** on B cells, leading to B cell depletion primarily by antibody-dependent cellular cytotoxicity (ADCC). Rituximab is a **chimeric anti-CD20 monoclonal antibody** which also depletes B cells, widely used in the treatment of B cell malignancies. This combination has been studied for **relapsed or refractory chronic lymphocytic leukemia (CLL)** and other advanced B cell malignancies to leverage dual targeting and potentially overcome resistance to anti-CD20 therapy. Clinical trials have explored MEDI-551, sometimes in combination with other agents, and often compared its efficacy and safety to rituximab-based regimens[1][2][3][4][5].