Both the size of the target antigen and the distance of the target epitope to the T-cell membrane have been identified as important factors contributing to the anti-tumour activity of CD3+ T-cell engagers.78,79 Interestingly, anti-CD3 × anti-chondroitin sulphate proteoglycan 4 (CSPG4) bispecific antibodies demonstrated greater potency, in terms of T-cell-mediated tumour lysis, when the size of the target antigen was smaller. The gene discussed is CSPG4; the disease is neoplasm.