KJ-015

Primary objective: The dose escalation phase evaluates the safety and tolerability of KJ015 in subjects with locally advanced or metastatic solid tumors expressing HER2; determines the dose-limiting toxicity (DLT), maximum tolerated dose (MTD), and backfill recommended dose (RED) of KJ015 in subjects with locally advanced or metastatic solid tumors expressing HER2. The backfill phase further evaluates the safety and tolerability of KJ015 in subjects with HER2-expressing solid tumors (including but not limited to gastric/gastroesophageal junction adenocarcinoma [G/GEJ], breast cancer [BC], colorectal cancer [CRC], bile duct cancer [BTC], head and neck squamous cell carcinoma [SCCHN], non-small cell lung cancer [NSCLC], etc.). Secondary objective: The dose escalation phase evaluates the pharmacokinetic (PK) characteristics and immunogenicity of KJ015; preliminarily evaluates the efficacy of KJ015 in subjects with HER2-expressing solid tumors. The backfill phase will preliminarily evaluate the effectiveness of KJ015 in treating subjects with HER2-expressing solid tumors (including but not limited to gastric/gastroesophageal junction adenocarcinoma [G/GEJ], breast cancer [BC], colorectal cancer [CRC], bile duct carcinoma [BTC], head and neck squamous cell carcinoma [SCCHN], non-small cell lung cancer [NSCLC], etc.); and assess the PK characteristics and immunogenicity of KJ015.