"This project aims at improving drug delivery to cancer cells by developing targeted radiotherapy with alpha-emitting radionuclides. Alpha particles emitted by radionuclides have short tracks (about 100 microns) in body tissues. As a result, they should be most appropriate to treat small-size tumours and isolated cancer cells. This project proposes the development of improved vectors and targeting technology based on specific targeting agents (recombinant antibody fragments and synthetic peptides), pretargeting approaches and nano-colloids especially designed to deliver alpha-emitting radionuclides to cancer cells after local or systemic administration. The concept of in situ generator, that allows the use of longer half-life parents of alpha-emitting radionuclides will be developed. Several approaches to prevent the release of radionuclides after parent isotope disintegration, including encapsulation in nano-colloids, are proposed. Improved targeting methods will be tested in animal models of small-size tumours and associated dosimetry (including micro-dosimetry) and toxicity studies will be performed. The final goal of the project will be to propose one or several new products for targeted delivery of alpha-emitting radionuclides for clinical development."