Radioimmunotherapy Allison Spencer July 27, 2006

Radioimmunotherapy Uses the body’s immune system to deliver toxic radiation to cancerous cells Special combination of factors: Tumor antigen targeting Monoclonal antibodies Radionuclides Localized treatment

Bio 101: Antigens Molecules that stimulate an immune response Proteins or polysaccharides on cell surfaces Many different types –Tumor Antigens Tumor Associated Tumor Specific

Bio 101: Antibodies Large, Y shaped proteins Identify and neutralize antigens –Induce apoptosis –Cell cycle redistribution Multiple antibodies for every antigen

Monoclonal Antibodies Highly specific Clones of single cell Fuse B cell and tumor cell Screen for antibody production

Radioimmunotherapy Adds a radioactive molecule to a monoclonal antibody (MoAb) Yttrium 90 labeled MoAb

Non-Hodgkin’s Lymphoma 58,870 cases will be diagnosed in th leading cause of cancer death Traditionally treated with: –Chemotherapy –External beam therapy –Immunotherapy

RIT and Non-Hodgkin’s Lymphoma Specific antigen targeted: CD20 –Tumor associated –Does not shed or internalize Isotopes used: –Yttrium-90:half life 64 hours, beta emitter –Iodine-131:half life 8 days, alpha and gamma –Vary in conjugation

Process of Attack 90 Y Cancerous B Cell

Advantages of RIT Precision of treatment –Less damage to healthy tissue Irradiation of nearby, unbound cells Patient comfort –1 hour intravenous procedure –Y-90 outpatient administration Unbound cells receive toxic radiation

RIT Success in NHL With traditional treatments: –Low grade kills ~95% of patients in first 5 years –Aggressive kills ~50% of patients in first 5 years Yttrium-90 labeled Zevalin: –80% overall response rate with Y-90 Zevalin –34% complete response –32% still in remission 3-4 years later

Radioimmunotherapy Allison Spencer