MONOCLONAL ANTIBODIES

As therapeuticsAs diagnosticsAs 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.

ELISAEnzyme

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.

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.

SUPPRESSING THE IMMUNE SYSTEM

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

Blue: Mouse sequencesRed: Human sequences

Humanized Human

MOUSE Fv region

MOUSE CDR

Regions “A”

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 Results showed a significant clinical improvement in all Infliximab doses.in all Infliximab doses.Treatment is usually given together with Treatment is usually given together with methotrexate.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

XX

Toxin

Cancer cellexpressing tumor antigen

CONCLUSION

Monoclonal Antibodies used as in vitro Diagnostic Agent In vivo imaging agents Therapeutics agents

Supressing immune systemKilling Malignant cells

Targeting Agents (MAb linked to toxin)