The alpha immunoterapy-a successful solution in cancer treatment

Daniela Ciorba . C. Cosma

Facultatea de Ştiinţa Mediului- Universitatea Babeş-Bolyai, Cluj-Napoca

	Radiation has been used in cancer therapy for many years. If, in the past treatment mainly involved use of relatively low energy beta-emitters, more recently, isotopes emitting alpha particles have been more effective and selective against blood-borne cancers, widespread tumors and residual cells remaining after surgical intervention. 
	This study show that radio immuno therapy (RIT) with emitters may be therapeutically more effective than RIT with conventional ß emitters. 
	In developing and designing radioimmunotherapy, the selection of the isotope is a major factor. This selection depends on a number of criteria and parameters, affecting usefulness and feasibility. Usefulness is directly related to the radiological performance of the ionising radiation in relation to tissue and its morphology, with a major distinction between the effects of alpha and beta-particles (or rays). Usefulness is also directly related to the pharmacodynamic performance of the isotope-carrier (e.g. antibody) complex, where the proper choice of isotope radiodecay halflife is of major importance. Feasibility depends on availability of the components in the isotope-ligand-carrier complex, and also on convenience and safety aspects in the preparation and the handling of the materials as well as in their application in patients.
	Alpha immunotherapy is based on emission of alpha particles by radionuclides. Due to its short physical t1/2, 213Bi appears to be especially suitable for use in conjunction with fast-clearing fragments; its 440-keV Error! Unknown switch argument.emission also can be used for quantitation by external scintigraphy. Bisumth-213, a short-lived alpha particle emitting radionuclide, is generated from the decay of 225Ac, which has a half-life of 10 days. The development of a clinical 225Ac/213Bi generator and the preparation of a 213Bi radiolabeled antibody for radioimmunotherapy of leukemia have been reported. 
	Alpha emitting radionuclides are amongst the most promising radionuclides for treatment of blood borne cancers and micrometastatic cancer cells. Because of their short range (60-100 micrometer) and high linear energy transfer values, alpha –emitters can deliver such a high radiation dose over the distance of a few cell diameters. When alpha emitters is coupled to a monoclonal antibody, which brings the alpha-emitting radionuclide close enough to the cancerous cell to destroy it without damaging surrounding tissue.