15. Subjects who are expected to receive bisphosphonate at the time of study entry under the investigator's discretion or who are expected to be given during the course of the trial, such as prophylactic use in the absence of any bone disease (However, subjects who are receiving bisphosphonate prior to administration of study drug for the treatment of bone metastases or osteoporosis are eligible for the study and the concomitant use of bisphosphonates is allowed during the study period.