The role of alpha therapy for local and systemic treatment of cancer

Full text: Major problems in the management of cancer relate to the inability to control critical primary lesions, eg glioblastoma multiforme (GBM), and the inability to deal with metastases arising from malignant cancers such as melanoma, breast and other cancers. Binary alpha therapy using neutron capture in boron-10 offers improved prognosis for high grade brain tumours such as GBM and melanoma metastases to the brain. The selective carrier of choice is BPA which gives a tumour to normal tissue ratio of 4 in melanoma. Clinical trials with an epithermal neutron beam are underway in the US and may soon commence in Europe. Metastatic cancer proceeds through a number of quite separate stages in the development of lethal disease, i e cells in transit, preangiogenic lesions, subclinical and clinical lesions. Early stages offer the potential for control if targeted cancer therapy is applied. Prophylactic therapy requires the localisation of dose to the cancer cell and rules out radioactive beta emitting radionuclides, which are more suited for clinical lesions. Alpha emitting radionuclides are the most appropriate toxins, as their efficacy depends on the energy and range of the alpha particles. After matching the cancer stage, radiolabel and carrier, we find that Tb-149 is the radionuclide of choice for systemic therapy in all aspects except production. The production of Tb-149 in μCi quantities has been achieved using the heavy ion reaction at the ANU tandem accelerator and in multi-mCi quantities using the spallation reaction in combination with on-line isotope separation at ISOLDE. Progress in this unique research and development project will be reviewed