A single-arm, Phase 1 study evaluating safety, tolerability, and preliminary efficacy of IL-15 enhanced engineered NK cells in patients with refractory relapsed or metastatic solid tumors.

Inclusion Criteria:

1. Age 18-70 years;
2. ECOG 0-1;
3. histopathologically confirmed metastatic or recurrent solid tumors (breast, liver, lung, etc.);
4. failed prior standard therapy;
5. >=1 measurable lesion per RECIST 1.1;
6. adequate bone marrow, liver, kidney, and coagulation function;
7. recovered from prior treatment toxicities;
8. signed informed consent.

Exclusion Criteria:

1. Pregnancy/lactation;
2. other malignancy within 5 years (except cured localized tumors);
3. active autoimmune disease or immunodeficiency;
4. uncontrolled cardiovascular disease or infection;
5. active TB;
6. positive HBsAg/HBcAb or HCV antibody (unless viral load undetectable);
7. positive syphilis antibody;
8. major surgery or vaccination within 28 days;
9. prior cell therapy;
10. severe allergy to study drugs;
11. investigator judged unsuitable.