Phase I Study of sss40 Injection for Moderate-to-Severe Bone Metastatic Cancer Pain

This is a Phase Ib/IIa, multicenter, sequential clinical trial evaluating the safety, tolerability, pharmacokinetics (PK), and preliminary efficacy of SSS40 injection in patients with moderate-to-severe bone metastatic cancer pain. The study includes two stages: a single-arm, open-label, dose-escalation and dose-expansion Phase Ib followed by a randomized, double-blind, placebo-controlled Phase IIa.

The study consists of two sequential phases: Phase Ib - Dose-Escalation and Dose-Expansion: This phase is a single-arm, multicenter, open-label clinical trial involving single-dose administration of SSS40 injection. Patients will be enrolled into sequential dose cohorts to evaluate the safety, tolerability, and PK profile of escalating doses of SSS40. Based on observed adverse events, particularly dose-limiting toxicities (DLTs), and PK data, the sponsor and investigators will determine whether adjustments to the dose escalation scheme (e.g., dosing interval, cohort size) are needed or if additional unplanned dose levels should be added. Following initial dose-escalation, a dose-expansion cohort will be conducted at the selected dose level to further characterize safety and gather additional preliminary efficacy data. Phase IIa - Randomized, Double-Blind, Placebo-Controlled Trial: After sufficient safety and efficacy data are obtained from Phase Ib, the sponsor and investigators may proceed to Phase IIa. This phase will be a randomized, double-blind, placebo-controlled study designed to further assess the efficacy, safety, tolerability, immunogenicity, and PK of SSS40 injection in patients with moderate-to-severe bone metastatic cancer pain. Patients will be randomly assigned to receive either SSS40 injection or placebo, and outcomes including pain intensity, analgesic use, and quality of life measures will be evaluated.