Two-year clinical follow-up results of intracoronary radiation therapy with rhenium-188-diethylene triamine penta-acetic acid-filled balloon

Dosimetry of bone seeking beta emitters for bone pain palliation metastases

Amongst cancer patients, bone pain due to skeletal metastases is a major cause of morbidity. A number of beta-emitting radiopharmaceuticals have been used to provide internal radiotherapy of bone metastases and provide palliative pain relief. In this article we describe the different physical characteristics of the various beta emitting radionuclides which have been used in this clinical setting and the potential impact of differences in dose-rate on radiobiological outcomes. A detailed review of the biodistribution of these treatments, based on both in-vivo clinical investigations and post mortem autoradiography assessments is provided. These treatments result in physiological delivery of radiation doses to the target disease as well as to critical healthy organs. Particular attention is paid to the radiation doses received by normal bone tissue, bone marrow as well as metastatic bone disease. The underlying models of radiation transport within bone and bone marrow are reviewed alongside the practical steps that must be taken to acquire and analyse the information require for clinical dosimetry assessments. The role of whole body measurements, blood and faecal assays as well as both planar and tomographic gamma camera imaging are considered. In addition we review the rationale for allocating measured bone uptake between trabecular and cortical bone tissue. The difference between bone volume and bone surface seeking radiopharmaceuticals are also discussed. This review also extends to the development of preclinical models of bone metastases which may inform future dosimetric calculations. Finally, we also present a comprehensive review of the dosimetry of the established treatments ⁸⁹Strontium-chloride; ³²Phosphorus; ¹⁸⁸Rhenium-hydroxyethylidine disphosphonate; ¹⁸⁶Rhenium-1,1-hydroxyethylidene disphosphonate (¹⁸⁶Re-HEDP); ¹⁵³Samarium-ethylenediaminetetramethylene phosphonate; as well as the emerging treatments ¹⁸⁸Rhenium-zoledronic acid; ¹⁸⁸Rhenium-ibedronat; ¹⁷⁷Lutetium-zoledronic acid; and ¹⁷⁷Lutetium ethylenediaminetetramethylene phosphonate. This review highlights not only the inter treatment differences in the radiation absorbed doses delivered to metastatic disease by different radiopharmaceuticals but also the intra treatment differences which result in a large range of observed doses between patients.

188Re-HEDP therapy in the therapy of painful bone metastases

For bone-targeted radionuclide therapy (BTRT), different commercial radiopharmaceuticals are available such as strontium-89, 186Rhenium-hydroxyethylidene diphosphonate (186Re-HEDP), Samarium-153-ethylenediamine tetramethylene phosphonic acid, and radium-223. Unfortunately, the commercial available radiopharmaceuticals are very expensive (from 1,200 to 36,000€ per patient in Europe). The 188W/188Re generator is an ideal source for the long-term (4-6 months) continuous availability of 188Re suitable for the preparation of radiopharmaceuticals for different radionuclide therapies. Labeling at HEDP, it can use cost-effective for BTRT, if enough patients are available for therapy. And so, 188Re-HEDP is the ideal candidate in developing countries which high population to replace the other agents. Two German groups documented a response rate of 80% without any severe side effects and similar bone marrow toxicity compared to the other compounds for 188Re-HEDP. Using 188Re-HEDP in repeated treatments, a prolonged overall survival of repeated to single application was observed (from 4.5 months for single to 15.7 months using ≥≥3 applications).