Lunacalcipol

CTA018 is a rationally designed Vitamin D hormone analog that acts as both a potent VDR agonist and CYP24 inhibitor. The Company believes this dual mechanism of action will provide efficacy and safety advantages over existing Vitamin D hormone replacement therapies for SHPT. CTA018 binds to the VDR located in parathyroid cells and triggers a genomic cascade of events resulting in suppression of PTH secretion. It also binds to the substrate binding pocket of CYP24, a cytochrome P450 enzyme that specifically and efficiently catabolizes Vitamin D hormones. By binding to CYP24 and blocking its activity, CTA018 levels in cells are more readily raised to therapeutic levels. Unlike common cytochrome P450 inhibitors (such as ketoconazole) which act non-specifically on all cytochromes, CTA018 specifically targets CYP24, making drug-drug interactions far less likely. The Company believes the novel dual activity of CTA018 will reduce the incidence of clinically-acquired resistance to Vitamin D hormone replacement therapy, allowing greatly improved efficacy at well tolerated dosages.