Rhenium-188-HEDP in the palliative treatment of bone metastases

Introduction: Rhenium-188-HEDP (Re-188-HEDP) is a new and attractive radiop harmaceutical for the treatment of bone pain due to metastases. As a produc t of a W-188/Re-188 generator it is convenient for clinical use. With a sho rt physical half life of 16.9 hours and a maximal beta-energy of 2.1 MeV, i t is suitable for therapy. Methods: We investigated the influence of Re-188 HEDP on pain relief analge sic intake and impairment of bone marrow function in 15 patients. All patie nts were interviewed using standardized questions before, and 1, 2, 3, 4 8 and 12 weeks after therapy. Blood samples were drawn weekly for 12 weeks, a nd a blood count was performed Patients underwent gamma camera imaging to d etermine the radionuclide accumulation 4, 20 and 28 hours after therapy. Th e patients were treated with 1600 to 3459 MBq of Re-188-HEDP. Results: Patients showed an improvement of the Karnofsky performance index from 74 +/- 8% to 84 +/- 11% 12 weeks after therapy. This improvement was s tatistically significant (p = 0.001). Eighty percent of the patients descri bed pain relief and reduction of analgesics. Twenty percent of the patients could discontinue their analgesics. Mean platelet count decreased from (28 4 +/- 84)*10(3)/mu l to (205 +/- 62)*10(3)/mu l, and mean leukocyte count f rom (7.5 +/- 1.5)*10(3)/mu l to (5.9 +/- 2.1)*10(3)/mu l after therapy. The maximal differences between the values of platelets and leukocytes before and after therapy were not statistically significant (p = 0.021 and p = 009 4). Prostate specific antigen decreased from 95 +/- 83 ng/ml to 41 +/- 21 n g/ml, the difference was not statistically significant (p = 0.443). The bon e accumulation 4, 20 and 28 hours after therapy was 1.3 +/- 0.5%, 0.6 +/- 0 .3%, and 0.45 +/- 0.2% of the injected dose of a single metastasis, and 57 +/- 17%, 15.5 +/- 2% and II +/- 3% in the whole body, respectively. The eff ective half-life of Re-188-HEDP was 15.3 +/- 3.0 hours in the bone metastas es, and 11.4 +/- 2.8 hours in the whole body. This corresponds to a residen ce time of 0.22 +/- 0.25 hours in the bone metastases, and of 10.54 +/- 2.5 9 hours in the whole body. Conclusion: In a small patient population, Re-188-HEDP therapy for bone pai n palliation was effective and was associated with minimal toxicity.