PALLIATION OF PAIN ASSOCIATED WITH METASTATIC BONE CANCER USING SM-153 LEXIDRONAM - A DOUBLE-BLIND PLACEBO-CONTROLLED CLINICAL-TRIAL

Purpose: To evaluate the effectiveness and safety of samarium-153 (Sm- 153) lexidronam (EDTMP) in a double-blind, placebo-controlled study. P atients and Method: Patients with painful bone metastases secondary to a variety of primary malignancies were randomized to receive Sm-153-E DTMP 0.5 or 1.0 mCi/kg, or placebo. Treatment was unblinded for patien ts who did not respond by week 4, with those who had received placebo eligible to receive 1.0 mCi/kg of active drug in an open-label manner. Patient and physician evaluations were used to assess pain relief, as was concurrent change in opioid analgesia. Results: One hundred eight een patients were enrolled onto the study. Patients who received 1.0 m Ci/kg of active drug had significant reductions in pain during each of the first 4 weeks in both patient-rated and physician-rated evaluatio ns. Pain relief was observed in 62% to 72% of those who received the 1 .0-mCi/kg dose during the first 4 weeks, with marked or complete relie f noted in 31% by week 4. Persistence of pain relief was seen through week 16 in 43% of patients who received 1.0 mCi/kg, of active drug. A significant correlation (P = .01) was observed between reductions in o pioid analgesic use and pain scores only for those patients who receiv ed 1.0 mCi/kg Sm-153-EDTMP. Bone marrow suppression was mild, reversib le, and not associated with grade 4 toxicity. Conclusion: A single dos e of 1.0 mCi/kg of Sm-153-EDTMP provided relief from pain associated w ith bone metastases. Pain relief was observed within 1 week of adminis tration and persisted until at least week 16 in the majority of patien ts who responded. (C) 1998 by American Society of Clinical Oncology.