Primary Objective: To evaluate the effect of nanocrystalline megestrol acetate versus placebo on body weight and appetite in patients with unresectable hepatocellular carcinoma receiving TACE combined with targeted and immunotherapy.Secondary Objectives: To evaluate the effect of nanocrystalline megestrol acetate versus placebo on quality of life, inflammatory markers, nutritional indicators, and psychological stress in patients with unresectable hepatocellular carcinoma receiving TACE combined with targeted and immunotherapy.Exploratory Objective: To explore the impact of nanocrystalline megestrol acetate versus placebo on survival benefit in patients with unresectable hepatocellular carcinoma receiving TACE combined with targeted and immunotherapy.

Inclusion Criteria:

• Patients with unresectable primary hepatocellular carcinoma (HCC) confirmed by imaging or histopathology
• No previous receipt of immunotherapy and/or targeted drug therapy
• Child-Pugh score ≤ 7
• At least one measurable lesion per RECIST 1.1 criteria; lesions without prior radiotherapy, cryotherapy or other local treatment
• Single intrahepatic lesion < 10 cm, or fewer than 10 intrahepatic lesions with tumor burden < 50%
• Meet precachexia criteria: non-volitional weight loss ≤ 5% in 6 months, plus systemic inflammation (CRP > 5 mg/L) or decreased appetite (FAACT-A/CS-12 score ≤ 37 points)
• Meet cachexia criteria: accompanied by decreased appetite or systemic inflammation, with either non-volitional weight loss > 5% in 6 months or BMI < 18.5 kg/m² plus weight loss > 2%
• Voluntarily participate and sign informed consent
• Age ≥ 18 years, male or female
• Able to swallow tablets normally
• ECOG performance status 0 or 1
• Life expectancy ≥ 12 weeks
• Adequate major organ function without blood products or colony-stimulating factors within 14 days
• Hematology: ANC ≥ 1.5×10⁹/L, Hb ≥ 80 g/L, PLT ≥ 50×10⁹/L
• Liver function: TBIL ≤ 1.5×ULN, AST/ALT ≤ 5.0×ULN, ALB ≥ 28 g/L
• Coagulation function: INR, PT or aPTT ≤ 1.5×ULN
• Renal function: SCr ≤ 1.5×ULN or creatinine clearance ≥ 60 mL/min
• Urine protein ≤ 1+ or 24-hour urine protein < 1.0 g
• Cardiac function: LVEF ≥ 50%
• Females of childbearing potential with negative pregnancy test within 3 days before first dosing
• Fertile male and female patients agree to effective contraception from screening to 120 days after last study drug
• HBV/HCV infected patients receive stable antiviral therapy without drug interaction

Exclusion Criteria:

• Active or untreated CNS metastases; inadequately controlled metastatic brain or leptomeningeal disease
• Uncontrolled tumor-related pain
• Thromboembolic disease, ascites or lower limb edema within 6 months
• History of other malignancies within 5 years before randomization, except curable low-risk tumors
• Unresolved adverse toxicities from prior antitumor therapy not recovered to ≤ Grade 1 (CTCAE v5.0), excluding alopecia
• Pregnant, breastfeeding females or those planning pregnancy during the study
• Any unstable medical, psychiatric or social condition that may interfere with study participation
• Positive HIV infection
• Major surgery within 28 days prior to randomization
• Severe cardiovascular disease, myocardial infarction, unstable arrhythmia, angina or cerebrovascular events
• Severe systemic infection within 4 weeks before dosing or active infection requiring systemic anti-infective treatment
• Impaired gastrointestinal absorption, long-term tube feeding, parenteral nutrition or eating disorders
• Concomitant use of other appetite-enhancing or weight-stimulating agents
• Cushing's syndrome, adrenal or pituitary insufficiency, poorly controlled diabetes
• Uncontrolled hypertension despite oral antihypertensive treatment
• Esophagogastric varices, severe ulcers, gastrointestinal bleeding, obstruction, perforation or fistula within 6 months
• Known hypersensitivity to any component of the investigational product
• Any other condition considered inappropriate for enrollment by the investigator.