We aimed to evaluate the antitumor efficacy of NK cells across various stages: resting NK cells on Day 0, semifinished NK cells on Day 6, and expanded NK cells on Day 13 against the HER2+ SK‐BR‐3 breast cancer cell line using the LDH assay to gauge the potency of TSBio autologous cell therapy. This evidence concerns the gene ERBB2 and breast carcinoma.