HER2 gene is one of the four members of the EGFR family, which is an important regulator of cell proliferation, differentiation and survival. The most commonly used targeted drug approved by FDA is trastuzumab (Herceptin), which can selectively act on the extracellular region of HER2 and is suitable for the treatment of HER2 overexpressed breast cancer, and can also be used alone for the treatment of metastatic breast cancer that has received chemotherapy or combined with paclitaxel for the first-line treatment of metastatic breast cancer. higher. Clinical applications have found that Herceptin does not apply to all patients, and NCCN guidelines emphasize that only patients with HER2 overexpression (or gene amplification) will benefit from Herceptin treatment. The phase III clinical study of trastuzumab (Herceptin) in combination with paclitaxel showed that trastuzumab (Herceptin) in combination with paclitaxel had significantly better efficiency, time to disease progression (TTP) and maintenance of efficacy compared with paclitaxel alone, with overall survival (OS) extending from 17.9 months to 24.8 months. Results from the phase III clinical study of trastuzumab (Herceptin) in combination with docetaxel in the first-line treatment of metastatic breast cancer also showed that the combination group had significantly better efficacy (61.0% vs. 34.0%), TTP (10.6 vs. 5.7 months), maintenance of efficacy (11.4 vs. 5.1 months), and OS (30.5 vs. 22.1 months) than the docetaxel monotherapy group (all statistically significant differences ). HER2 gene amplification test Clinical significance Related drugs HER2 gene amplification Clinical applications have found that Herceptin is not indicated for all patients, and NCCN guidelines emphasize that only patients with HER2 gene amplification will benefit from Herceptin therapy.