MONOCLONAL ANTIBODIES As therapeutics As diagnostics As targeting agents

INTRODUCTION Have remarkable specificity Single specificity -> promising in human therapy Widely used as diagnostic & research reagents

MANUFACTURING OF MONOCLONAL ANTIBODIES Monoclonal antibodies are traditionally made from mice or rats that have been immunized with the desired antigen

CONVENTIONAL METHOD FOR MAKING mAbs

Clinical Uses for Monoclonal Antibodies In vitro diagnostic agents In vivo imaging agents Therapeutic agents (MAb works like a drug) Targeting agents (MAb linked to toxin)

Monoclonal Antibodies as in vitro Diagnostic Agents Detects the presence, absence or relative amount of protein. MAbs work nicely because they bind very specifically to the protein. Example: Pregnancy tests. MoAb detects elevated levels of HCG in the urine. High level of HCG is produced by placenta in the early stages of pregnancy.

ELISA Enzyme produces Color Enz

Monoclonal Abs on Therapeutics Suppressing The immune system Killing Malignant cells 59 MAbs currently in clinical trials 31 for cancer therapy

SUPPRESSING THE IMMUNE SYSTEM Monoclonal antibodies specific to the different receptors of various cells are used to prevent the normal usage of these receptors.

SUPPRESSING THE IMMUNE SYSTEM First MAb on market was OKT3, a murine MAb used to prevent renal transplant rejection Orthoclone OKT3  targets T-lymphocytes surface antigen CD3  reversal of acute kidney transplant rejection.

Problems with Mouse Ab in Humans Human immune response to mouse antibodies (HAMA-Human Anti-Mouse Antibodies) Endanger the patient and enhance the clearance of the Ab and reduce its therapeutic effect. Mouse antibodies do not activate human complement system or Ab-mediated cytotoxicity

To Overcome this Problem Hybrid monoclonal antibodies have been made by recombinant DNA technology

Types of MAbs Mouse Chimeric Humanized Human Blue: Mouse sequences Red: Human sequences

MOUSE CDR Regions “A” MOUSE Fv region Mutagenesis “ B”

SUPPRESSING THE IMMUNE SYSTEM Zenapax (Daclizumab)  targets Alpha-chain of IL-2 receptor (CD25) of T- lymphocytes.  prevention of acute kidney transplant rejection. Remicade (Infliximab)  targets tumor necrosis factor-alpha (TNF-α)  treatment of Crohn’s disease & rheumatoid arthritis. Xolair (Omalizumab)  targets IgE preventing the binding of IgE to mast cells against allergic asthma.

Zenapax: Humanized Monoclonal Antibody Mouse amino acids - Red Human amino acids - White Prevents rejection in kidney transplantations

Clinical trials with Infliximab… A chimeric Mab against TNF: Results showed a significant clinical improvement in all Infliximab doses. Treatment is usually given together with methotrexate.

TO KILL MAGLIGNANT CELLS Tumors have antigen on the surface that are specific to themselves. They are also more highly expressed than normal. Monoclonal antibodies used to target these tumors specific antigen (TSA)

TO KILL MAGLIGNANT CELLS

TO KILL MAGLIGNANT CELLS Mabthera/Rituxan (Rituximab)  targets CD20 surface antigen of B-lymphocytes  treatment of non-Hodgkin’s lymphoma. Herceptin (Trastuzumab)  targets Human epidermal growth factor-like receptor 2 (HER-2)  treatment of metastatic breast cancer over expressing HER-2 protein. The only monoclonal so far that is effective against solid tumors. MabCampath (Alemtuzumab)  targets B-lymphocytes CD52  treatment of B-cell chronic lymphocytic leukemia. Complete remission up till now.

MAbs: Site-directed Targeting Agents Link a toxic drug, protein or radioisotope to an MAb with a high specific affinity for a tumor-associated antigen.

Toxin X X Toxin Cancer cell expressing tumor antigen

CONCLUSION Monoclonal Antibodies used as in vitro Diagnostic Agent In vivo imaging agents Therapeutics agents Supressing immune system Killing Malignant cells Targeting Agents (MAb linked to toxin)