Exploratory Study With Parallel Controls on the Safety and Efficacy of Neoadjuvant Low Branched-Chain Amino Acid Diet in Combination With Anti-PD-1 Monoclonal Antibody for Stage III Melanoma

1. Primary Objective: To evaluate the safety of a low branched-chain amino acid diet (60% of the normal dietary BCAA content) combined with anti-PD-1 monoclonal antibody as neoadjuvant therapy in patients with stage III melanoma, by documenting the incidence of all adverse events (AEs) and serious adverse events (SAEs), and analyzing changes from baseline in physical examinations, vital signs, and laboratory test results. 2. Secondary Objectives: To assess the pathological response rates (including pCR, near-pCR, pPR, and pNR) of the combination therapy in stage III melanoma; to evaluate the objective response rate (ORR) according to the Response Evaluation Criteria in Solid Tumors (RECIST v1.1) and the immune-related RECIST (irRECIST) criteria; and to estimate event-free survival (EFS) and overall survival (OS) through long-term follow-up. 3. Exploratory Objectives: To investigate the quality of life (QoL) in patients receiving the low BCAA diet combined with anti-PD-1 therapy; and to identify predictive biomarkers for treatment outcome differences, such as immune-related gene signatures (e.g., PD-L1 expression) and driver gene mutations in somatic variants.