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 subjects voluntarily sign an informed consent form, voluntarily participate in the trial, and are willing and able to receive medication, examination, visits, and other related operations according to the trial protocol;
When signing the informed consent form, adult male or female subjects aged ≥ 18 years old；
Previous medical records confirm that the subject has cancer and is diagnosed with bone metastasis; During screening or within 120 days prior to screening visits, Confirming bone metastasis through imaging according to local medical standards, such as bone scans, magnetic resonance imaging (MRI), computed tomography (CT) scans, or positron emission computed tomography (PET-CT) Scanning, diagnosed as bone metastasis based on CT/MRI/PET-CT. If the above examination is not performed within 120 days, a bone scan confirmation is required. If imaging only involves bone scanning, additional CT, MRI, or PET is required to confirm bone metastasis；
Weight ≥ 40kg during screening；
During screening, there was hypercalcemia (blood calcium concentration ≥ 2.75mmol/L or 11.0mg/dL)；
The pain of the subjects is caused by reasons unrelated to cancer bone metastasis (such as intestinal obstruction/perforation, spinal cord compression, brain metastasis, pathological fractures or near fractures, etc.)；
The pain of the subjects is neuropathic pain, visceral pain, or unknown in nature, caused by previous anti-tumor treatment, infection, or other reasons mainly unrelated to bone metastasis；
Subjects with brain or meningeal metastases (patients with stable brain metastases can be included in this study)；