Monoclonal Antibodies: Lesson 4 PDF

Lesson-4: Monoclonal antibodies and their use in diagnosis and therapy Polyclonal antibodies: mix of Abs of different specificity and affinity. Produced by distinct cellular clones. Until the arrival of MoAbs they were obtained by injecting antigens to animals and recovering their serum...

Lesson-4: Monoclonal antibodies and their use in diagnosis and therapy Polyclonal antibodies: mix of Abs of different specificity and affinity. Produced by distinct cellular clones. Until the arrival of MoAbs they were obtained by injecting antigens to animals and recovering their serum (immunization) Monoclonal Ab: are directed against only one epitope, produced by an only B lymphocyte and their clonal cells.  Monoclonal antibodies synthesis Kohler G. and Milstein C. (Nature, 1975). Hybridoma: fusion of a murine tumoral cell (myeloma) and an antibody-producing cell. This generates “hybrid” cells that divide very actively (as tumor) while secreting big amounts of antibodies. MoAbs have revolutionized therapy, diagnosis and the knowledge of life molecules.  Diagnostic applications of Abs and MoAbs Abs can identify any human substance (hormone, cytokine, enzyme, other antibody, etc) in biological fluids, cells or tissues, by different techniques: – Enzyme-linked-immune-sorbent-assay (ELISA) and Radio-immune-analysis (RIA) – Immune transference (Western-blot) – Immunofluorescence / Immunohistochemistry – Flow Cytometry and sorting (CD system)  APPLICATIONS OF MoAbs in THERAPY ANTITUMORAL: – Antigens limited to a cellular group – Tumoral antigens IMMUNOMODULATORS: – Transplants – Autoimmune diseases – Allergy INFECTIONS: – Antigens from microorganisms.  Therapeutic use of murine MoAbs Problems: Derive from the fact of not being of human origin: Short half life in blood Poor effector responses Immunogenicity: generation of an immune response (human) against the MoAbs (murine, HAMA –Human anti murine antibodies-) that impairs its function. Solutions: building chimeric and humanized antibodies 1. Xenogeneic MoAbs – Stimulate formation of anti-antibodies 2. Chimeric antibodies – Murine variable regions – Human constant regions (improve effector functions) 3. Humanized antibodies – Substitution of the original variable domain framework regions by human ones to reduce immunogenicity even more. Solutions: building chimeric and humanized antibodies 1. Xenogeneic (murine) MoAbs – Stimulate formation of anti-antibodies 2. Chimeric antibodies Chimera – Murine variable regions (Greek mythology) – Human constant regions (improve effector functions) 3. Humanized antibodies – Substitution of the original variable domain framework regions by human ones to reduce immunogenicity even more.  Technologies to improve therapy based on MoAbs 1. Combination with toxins 2. Combination with enzymes Pretoxin or inactive drug Enzymes Combined Pre- toxin Alkaline phosphatase Etoposide, doxorubicin E Carboxypeptidase G2 Hodgkin lymphoma Nitrogen mustard No-Hodgkin B lymphoma Beta-lactamase Paclitaxel, mitomycin Chronic lymphoid leukemia No-Hodgkin T lymphoma Acute myeloid leukemia Active drug Brain-spine metastatic tumor Lung cancer Acute lymhoid leukemia Breast cancer Mesothelioma Toxins: Ricin, Pseudomonas exotoxin, saporin.. 3. Conjugation with Radioisotopes 4. Bispecific antibodies 5. Immunocytokines TNFα IFNγ IL2 Isotopes Therapeutic aplications GM CSF Itrium 90 Acute myeloid leukemia Iodine 131 No-Hodgkin B ymphoma MoAbs therapeutical mechanisms: Effector elements of immune response (cell activation….) Blocking: cytokines , receptors, grow factors …. Transportation of other therapeutical agents (drugs, toxins…)  Nomenclature (I) … mumab … zumab … ximab Recombinant human MoAb Humanized MoAb 5 % murine 95 % human Chimeric MoAb … momab 30 % murine 70 % human 100% murine MoAb Estructure similar to a human IgG1 Murin Human Momab (Mouse monoclonal) Ximab Chimeric (XImeric), mouse and human. Zumab Monoclonal hUmaniZed Mumab Monoclonal hUman Nomenclature (II): Codification of generic name of MoAbs Therapeutical class: – Antibacterian : -ba- – Cardio-vascular system : -ci- – Infectious lesions: -le- – Immunomodulator : -li(m)- – Antiviral: -vi ®- Antibodies used for cancer treatment: letters according to the implied organ: – Colon : - co- – Mama : -ma- – Melanoma : -me- – Prostate : -pr- – Other tumors: -tu-  Nomenclature example: RITUXIMAB MAB: monoclonal antibody XI: Chimeric TU : Other tumors RI : Original name The variable domains come from an anti- human CD20 made in mouse. Constant domains of Rituximab are from human IgG → Chimeric antibody used in « other » tumors → anti-CD20:follicular lymphoma: first indication  Anti-TNF monoclonal antibodies Momab Ximab Zumab Mumab Fully-Human 3rd Humanized 2nd Chimeric 1st Murine Human (No Mouse Protein) 10% Mouse Protein Adalimumab (D2E7) Certolizumab 25% Mouse Protein 100% Mouse Protein Infliximab  Monoclonal Antibodies in Cancer Anti-HER2 MoAb (human epidermal grow factor receptor 2). Use in metastatic breast cancer in patients with tumours expressing HER2 (30%): trastuzumab MoAb anti-EGFR: Colon cancer unresponsive to chemotherapy: cetuximab Monoclonal antibodies in allergy Anti-IgE MoAb: Omalizumab Use in moderate-severe asthma without control by corticoids in individuals older than 12 http://cancerimmunity.org/v12p14/ The end