Allogeneic NK Cell Therapy Combined With Standard Maintenance Treatment in Advanced Solid Tumors

This is a prospective, open-label, exploratory clinical study to evaluate the safety and preliminary efficacy of allogeneic natural killer (NK) cell injection combined with standard maintenance therapy in patients with locally advanced or metastatic solid tumors. The study consists of 5 cohorts: Cohort 1 (advanced non-squamous NSCLC with NK cells + PD-(L)1 inhibitor + pemetrexed), Cohort 2 (advanced colorectal adenocarcinoma with NK cells + cetuximab/bevacizumab + capecitabine), Cohort 3 (lymphodepletion exploration cohort with fludarabine + cyclophosph preconditioning followed by NK cells + PD-(L)1 inhibitor + pemetrexed), Cohort 4 (advanced HCC with NK cells + VEGF + PD-(L)1), and Cohort 5 (advanced GC with NK cells + PD-(L)1 + S-1).

Inclusion Criteria: 1. Age 18-75 years, either gender 2. Subjects must meet one of the following conditions: Cohort 1, Cohort 3: * Histologically/cytologically confirmed locally advanced unresectable or metastatic non-squamous non-small cell lung cancer (Stage IIIB\~IV), without known drug-targetable driver mutations (including but not limited to: EGFR sensitive mutations, ALK gene rearrangements, ROS1 mutations, BRAF 600E mutations, KRAS mutations); * Previously received 4\~6 cycles of first-line induction therapy with PD-(L)1 combined with pemetrexed and platinum (cycles not combined with chemotherapy are not counted as combined treatment cycles), and imaging assessment shows non-progressive disease (i.e., CR, PR, or SD per RECIST 1.1). 3. Cohort 2: * Histologically/cytologically confirmed locally advanced unresectable or metastatic (unresectable Stage III or Stage IV per AJCC 8th Edition) colorectal adenocarcinoma; * Previously received 6\~9 cycles of first-line induction therapy with cetuximab/bevacizumab combined with FOLFOX/FOLFIRI (cycles not combined with chemotherapy are not counted as combined treatment cycles), and imaging assessment shows non-progressive disease (i.e., CR, PR, or SD per RECIST 1.1). 4. Cohort 4: * Histologically/cytologically or clinically diagnosed (by dynamic enhanced MRI/dynamic enhanced CT scan, etc.) locally advanced unresectable or metastatic hepatocellular carcinoma; * Barcelona Clinic Liver Cancer (BCLC) Stage C or Stage B (not suitable for surgery/locoregional therapy, including ablation, intervention, and radiotherapy); * Child-Pugh score ≤ 7 (Child-Pugh A/B), with no history of hepatic encephalopathy; * No prior systemic anti-tumor therapy for HCC; * According to RECIST 1.1, at least one measurable lesion exists: non-lymph node lesion long diameter ≥ 1.0 cm, or lymph node lesion short diameter ≥ 1.5 cm; lesions that have received locoregional therapy (e.g., radiotherapy or interventional therapy) cannot be considered target lesions unless there is imaging evidence confirming definite progression of the lesion. 5. Cohort 5: * Pathologically histologically or cytologically diagnosed locally advanced or metastatic gastric or gastroesophageal junction adenocarcinoma, with HER2 low or negative expression; * Previously received 6\~9 cycles of first-line induction therapy with PD-(L)1 combined with oxaliplatin and fluoropyrimidine-based chemotherapy (cycles not combined with chemotherapy are not counted as combined treatment cycles), and imaging assessment shows non-progressive disease (i.e., CR, PR, or SD per RECIST 1.1). 6. Prior neoadjuvant/adjuvant chemotherapy is permitted, provided that disease recurrence or metastasis occurs more than 6 months after the last dose of chemotherapy 7. Adequate bone marrow and organ function: 1. ANC ≥1.5×10⁹/L; Platelet \>90×10⁹/L; Hemoglobin \>9 g/dL 2. Liver function: Total bilirubin \