One group of target proteins for MABs are CD (‘cluster of differentiation’) receptors which are often present in significantly higher concentrations on cancerous or other disease state cells.

CD receptor types are numbered and include CD22, the target for inotuzumab ozogamicin for use in acute lymphoblastic leukaemia (ALL), and CD30 for brentuximab vedotin for various lymphomas. CD38 is the target for daratumumab for multiple myeloma, and CD79b for polatuzumab vedotin for diffuse large B-cell lymphoma.⁴

CD38 protein has multiple functions such as receptor mediated adhesion, signalling and enzymatic activity. Daratumumab binds to the CD38 protein expressed on the surface of cells in a variety of haematological malignancies, including clonal plasma cells in multiple myeloma and AL amyloidosis, as well as other cell types and tissues.

Rituximab targets CD20 receptors found on both normal and malignant B cells, giving it applications in non-Hodgkin’s lymphoma and chronic lymphocytic leukaemia (CLL) as well as rheumatoid arthritis and pemphigus vulgaris.

MABs for multiple sclerosis, such as ofatumumab or ocrelizumab, target the CD20 cell surface antigen on pre-B cells. These are mature and memory B cells which are involved in attacking myelin around nerve cells. While the precise mechanism in MS is not understood, the MABs binding to CD20 cause problem B cells to be inactivated and undergo phagocytosis.

Meanwhile, alemtuzumab targets the CD52 receptor which is found in high levels on some T and B lymphocytes which attack myelin. It may also promote an increase in ‘healthy’ T and B cells which will not damage nerves.