CTA018 Injection

CTA018 Injection is a novel dual-action Vitamin D hormone replacement therapy to treat secondary hyperparathyroidism (SHPT) in patients with Stage 5 CKD. CTA018 Injection is expected to provide nephrologists with a safer and more effective therapeutic option for managing SHPT as it elicits a therapeutic response via the Vitamin D signaling pathway while concurrently inhibiting CYP24 activity, a key resistance mechanism that reduces the efficacy of existing therapeutics. The product is formulated for intravenous delivery during the course of the hemodialysis session and is expected to better preserve Vitamin D, calcium and phosphorus homeostasis.

Mechanism of Action

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.

Exhibit 4. Dual mechanism of action: CTA018 activates VDR-mediated gene regulation and inhibits CYP24.

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