Add-on pyrotinib in neoadjuvant setting safe, effective for HER2-positive advanced breast cancer

In the treatment of patients with HER2-positive locally advanced breast cancer, adding pyrotinib to trastuzumab plus chemotherapy in the neoadjuvant setting yields high response rates while being safe, according to the results of NeoATP trial.

The phase II NeoATP trial enrolled 53 female patients with histologically confirmed stage IIA to IIIC and HER2-positive primary invasive breast cancer. These patients were given pyrotinib and trastuzumab with weekly paclitaxel–cisplatin neoadjuvant chemotherapy for four cycles.

Researchers assessed pathologic complete response (pCR; ypT0 ypN0) rate as the primary endpoint. They also evaluated locoregional pCR (ypT0/is ypN0) rate, biomarker changes, and safety as key secondary endpoints.

Of the enrolled patients (median age 47 years, 73.58 percent stage III), 52 completed the study treatment and surgery. The primary endpoint of pCR was documented in 37 patients (69.81 percent).

Among patients who harboured hormone receptor–negative and –positive tumours, the pCR rates were 85.71 percent and 59.38 percent, respectively, with the difference being statistically significant (p=0.041). On the other hand, the corresponding pCR rates were 69.23 percent and 70.00 percent among patients with and without PIK3CA mutation (p=0.958).

The most common grade 3 to 4 adverse events were diarrhoea (45.28 percent), leukopenia (39.62 percent), and neutropenia (32.08 percent). There were no deaths recorded, and none of the patients experienced left ventricular ejection fraction <50 percent or a >10-point drop from baseline to before surgery.

The findings warrant a controlled clinical trial.