Previously defined criteria relating to serum levels of iPTH, Ca, and P will be reviewed by the Medical Monitor to determine subject safety. If any of the criteria are observed, subjects will be discontinued from the study, receiving no further administration of the study drug and will be followed for safety. Safety data will be reviewed by the Medical Monitor for the first 2 subjects in the 270 µg group. If the first 2 subjects meet dose group discontinuation criteria, including treatment emergent calciphylaxis, treatment-emergent adverse events (TEAEs) related to elevated serum Ca levels, or a reported death associated with elevated serum Ca levels or related to study drug, subjects beyond the first 2 will not be dosed.