A Study to Investigate the Safety, Tolerability, and Pharmacokinetics of VS 105

This is a first in human, 3 part, single and multiple ascending dose study in healthy subjects and subjects with end stage renal disease (ESRD) requiring hemodialysis (HD). A Safety Monitoring Committee (SMC) will evaluate safety data from each dose cohort before proceeding with the subsequent cohort. The SMC will also review data from each Part of the study before proceeding to the next scheduled Part. In Part 1, single ascending doses (SAD) of VS 105 will be administered to approximately 5 dose cohorts of 8 healthy subjects each. In Part 2, multiple ascending doses (MAD) of VS 105 will be administered to approximately 3 dose cohorts of 8 healthy subjects each. VS 105 doses for MAD cohorts in Part 2 will be determined by the SMC and based on results from Part 1. In Part 3, MAD of VS 105 will be administered to approximately 3 successive dose cohorts that will each include 4 subjects with ESRD requiring HD. VS 105 doses used in Part 3 will be selected by the SMC based on review of safety and/or pharmacokinetic (PK) results from Part 1 and Part 2. Parts 1 \& 2 of the study will assess the safety, tolerability, and PK of ascending doses of VS 105 to determine the dose range that is safe and well tolerated in healthy subjects. Part 3 of the study will assess the safety, tolerability, and PK of various doses of VS 105 in subjects with ESRD requiring HD (ie, HD subjects), who represent the target population with secondary hyperparathyroidism (SHPT).