Aptamer-based radiopharmaceuticals for diagnostic imaging and targeted radiotherapy of epithelial tumors

In the continuous search for earlier diagnosis and improved therapeutic modalities against cancer, based on our constantly increasing knowledge of cancer biology, aptamers hold the promise to expand on current antibody success, but overcoming some of the problems faced with antibodies as therapeutic or delivery agents in cancer. However, as the first aptamer reached the market as an inhibitor against angiogenesis for the treatment of macular degeneration, aptamers have found only limited applications or interest in oncology, and even less as radiopharmaceuticals for diagnostic imaging and targeted radiotherapy of tumours. Yet, the chemistry for the labelling of aptamers and the options to alter their pharmacokinetic properties, to make them suitable for use as radiopharmaceuticals is now available and recent advances in their development can demonstrate that these molecules would make them ideal delivery vehicles for the development of targeted radiopharmaceuticals that could deliver their radiation load with accuracy to the tumour site, offering improved therapeutic properties and reduced side effects.

Na contínua busca do diagnóstico precoce e melhores modalidades terapêuticas contra o câncer, com base no constante aumento do conhecimento da biologia do câncer, aptâmeros têm a promessa de expandir o atual sucesso dos anticorpos, e superar alguns dos problemas enfrentados com os anticorpos, como agentes terapêuticos ou como agentes que chegam ao processo neoplásico. Entretanto, como o primeiro aptâmero chegou ao mercado como um inibidor da angiogênese para o tratamento da degeneração macular, aptâmeros tem encontrado apenas aplicações ou interesse limitados em oncologia, e ainda menos como radiofármacos para o diagnóstico por imagem e radioterapia direcionada para tumores. A química para a marcação de aptâmeros e as opções para alterar suas propriedades radiofarmacocinéticas, para torná-los mais adequados para uso como radiofármacos, é agora disponível e os avanços recentes no seu desenvolvimento podem demonstrar que essas moléculas poderiam ser ideais como veículos para o desenvolvimento de radiofármacos sítio-dirigidos que poderiam levar radiação com precisão para o tumor, oferecendo melhores propriedades terapêuticas e reduzidos efeitos indesejados.

Antibody conjugate radioimmunotherapy of superficial bladder cancer

The administration of antibody conjugates for cancer therapy is now proving to be of clinical value. We are currently undertaking a programme of clinical studies using the monoclonal antibody C595 (IgG3) which reacts with the MUC1 glycoprotein antigen that is aberrantly expressed in a high proportion of bladder tumours. Radioimmunoconjugates of the C595 antibody have been produced with high radiolabelling efficiency and immunoreactivity using Tc-99m and In-111 for diagnostic imaging, and disease staging and the cytotoxic radionuclides Cu-67 and Re-188 for therapy of superficial bladder cancer. A Phase I/II therapeutic trail involving the intravesical administration of antibody directly into the bladder has now begun