Real-world Study of Pyrotinib in Neoadjuvant Therapy for HER2-positive Breast Cancer

Pyrotinib is a small molecule, irreversible, pan-ErbB receptor tyrosine kinase inhibitor that simultaneously acts on three targets, HER1, HER2, and HER4, and is stable, well tolerated, and easily penetrates the blood-brain barrier compared with macromolecular targeted drugs. In the phase II study of pyrotinib combined with capecitabine in HER2-positive breast cancer, the primary study endpoint ORR was 78.5%, and the investigator-assessed PFS reached 18.1 months with good safety; it was precisely by virtue of the phase II clinical study that the drug was preferentially approved by the State Drug Administration for marketing. During the four years of marketing, significant therapeutic effects have also been achieved in phase III clinical studies, such as the PHOEBE study and the PHENIX study; neoadjuvant treatment of patients with early and locally advanced HER2-positive breast cancer was approved for the PHEDRA study in 2022. Pyrotinib is currently being investigated in both registration studies and investigator-initiated studies in the neoadjuvant and adjuvant setting for HER2-positive breast cancer, all of which are RCTs, but randomized clinical studies have selected specific populations in defined settings, which may differ from the actual clinical setting. Given the limited real-world data on pyrotinib, real-world studies focusing on neoadjuvant therapy have not been reported. At present, we hope to collect the data of neoadjuvant therapy for HER2-positive breast cancer patients who have been prescribed pyrotinib, and explore the efficacy and safety of pyrotinib-based neoadjuvant therapy for HER2-positive early or locally advanced breast cancer patients; exploratory analysis to explore the correlation between TMB levels and pCR rate of neoadjuvant therapy in HER2-positive breast cancer patients, and the effect of pyrotinib-based neoadjuvant therapy on intestinal flora.