Samarium Optimized for Long-lasting Analgesia in Cancerous End-stage Bone Pain

Inclusion Criteria: * Participants have had disease progression while on anti-cancer treatment, and are not eligible for the treatments, or their lesions are not amenable to palliative EBRT. * Participants must have a histologically confirmed diagnosis of malignancy at any time prior to their participation in this clinical trial with multiple metastatic bone lesions with at least 1 metastatic painful osteoblastic tumor that causes a minimum pain score of 4 on the NRS11. * Participants must have bone cancer in one or more skeletal locations as identified by a 99mTc-diphosphonate bone scan within 60 days of dosing. At least one lesion must be osteoblastic. If described as osteosclerotic, radiology confirmation that the lesion is osteoblastic is required. Adequate organ function, including: * Renal function, defined as a measured creatinine clearance (CrCl) ≥30 mL/min as per Cockroft Gault or based on radioisotope glomerular filtration rate (GFR). * Hematologic function, defined as a platelet count of \>100,000 cells/mm3 and an Absolute neutrophil count (ANC) of \>1000 cells/mm3. * Hemoglobin ≥8 g/dL. * Liver function: * Total bilirubin ≤1.5 × the upper limit of normal (ULN). * Alanine aminotransferase (ALT) or aspartate aminotransferase (AST) ≤5 × ULN with participants with known liver metastases. * Alanine aminotransferase (ALT) or aspartate aminotransferase (AST) ≤3 × ULN with participants with Gilbert's Syndrome. * Life expectancy of at least 16 weeks from the date of study…