Real‐world treatment patterns and outcomes of pyrotinib‐based therapy in patients with HER2‐positive advanced breast cancer (PRETTY): A nationwide, prospective, observational study.

Pyrotinib, an irreversible pan‐ErbB inhibitor, has been approved for treating HER2‐positive advanced breast cancer in China. We conducted a nationwide, prospective observational study to examine the real‐world data of pyrotinib‐based therapy in this population. Patients from 61 sites across China were included. Pyrotinib‐based regimens were prescribed at local physician's discretion. Demographics, treatment patterns, prognosis and safety were evaluated. The primary outcome was real‐world progression‐free survival (rwPFS). Of 1129 patients, pyrotinib‐based therapy was prescribed as first‐, second‐ and third‐ or later‐line treatment in 437 (38.7%), 476 (42.2%) and 216 (19.1%) patients, respectively. Median rwPFS (mrwPFS) was 14.3 (95% CI, 13.3‐15.2) months in the total population, with the longest mrwPFS of 17.8 (95% CI, 15.2‐24.9) months in the first‐line setting, followed by 14.4 (95% CI, 12.9‐15.3) months in the second‐line setting. Patients with third‐ or later‐line treatment also achieved a mrwPFS of 9.3 (95% CI, 8.4‐11.8) months. Patients with trastuzumab‐ or trastuzumab‐pertuzumab‐treated disease achieved a mrwPFS of 14.3 and 13.6 months, respectively. Dual HER2 blockade with pyrotinib plus trastuzumab showed a mrwPFS of 16.2 months in the total population, with data not mature in the first‐line setting. For patients with baseline brain metastases, the mrwPFS was 11.7 months. The most common adverse event was diarrhea (any grade, 73.5%; grade ≥ 3, 15.3%). In real world, pyrotinib‐based therapy shows promising effectiveness in the first‐, as well as second‐ and later‐line treatment, with acceptable tolerability. Further investigations regarding front‐line use or novel combinations of pyrotinib might facilitate to maximize its anti‐tumor potential. [ABSTRACT FROM AUTHOR]