DOSE-RESPONSE RELATIONSHIP AND MULTIPLE-DOSE EFFICACY AND TOXICITY OFSAMARIUM-153-EDTMP IN METASTATIC CANCER TO BONE

Introduction: The optimal dose of samarium-153-EDTMF (Sm-153-EDTMP) fo r effective palliation of painful metastases to bone is under investig ation. It is not known whether increased doses of (SmEDTMP)-Sm-153 wil l lead to better and longer pain and tumour control and survival. Mult iple dose efficacy and toxicity is of importance as most Patients will require prolonged support for pain. Methods: Twenty-eight (28) patien ts were treated with 0.75 mCi/kg, 35 patients with 1.5 mCi/kg and 19 p atients with 3 mCi/kg in three sequential Phase I-II trials. Multiple doses were given to patients on the 0.75 mCi/kg and 1.5 mCi/kg dose le vels, Results: At all dose levels adequate pain control was achieved i n 78-95% of patients. The duration of pain control was 40-56 days with the best results in the 1.5 mCi/kg group (56 days). There is no evide nce that increasing dose leads to better and longer pain control, tumo ur response and survival, but toxicity is increased. Multiple doses ca n be given with acceptable toxicity and pain control, however, only 38 % of patients will qualify for multiple treatments. Conclusion: Sm-153 -EDTMP provides adequate and safe palliation but multiple doses can on ly be given in 38% of patients, There is not a clear dose-response rel ationship. The length of pain control is satisfactory but not ideal an d hospitalisation for 4 days every 6-8 weeks is a disadvantage, Furthe r research is required to combine Sm-153-EDTMP with cytostatics and to administer it on an out patient basis. (C) 1997 Elsevier Science Irel and Ltd.