Rontalizumab is a humanized monoclonal antibody being developed by Genentech. As of November 2009, it is being investigated in a clinical trial for the treatment of systemic lupus erythematosus. Rontalizumab is a humanized monoclonal antibody being developed by Genentech. As of November 2009, it is being investigated in a clinical trial for the treatment of systemic lupus erythematosus.