Neoadjuvant ARX788 plus pyrotinib versus trastuzumab, pertuzumab, docetaxel and carboplatin for HER2-positive breast cancer: a randomised phase 2b trial.

Antibody-drug conjugates (ADCs) and tyrosine kinase inhibitors (TKIs) are widely used for HER2-positive metastatic breast cancer, but their efficacy in the neoadjuvant setting remains under investigation. The MUKDEN 06 trial (NCT05426486), a multicentre, randomised, phase 2b study, compared ARX788 (anti-HER2 ADC) plus pyrotinib (TKI) with the standard neoadjuvant regimen of docetaxel, carboplatin, trastuzumab, and pertuzumab (TCbHP) in female patients with early or locally advanced HER2-positive breast cancer. The primary endpoint was the pathological complete response (pCR, ypT0/is, ypN0) rate, analyzed in the intention-to-treat population. pCR was achieved in 70.6% (48/68) of patients receiving ARX788 plus pyrotinib, compared to 51.5% (35/68) in the TCbHP group, with a significant absolute difference of 19.1% (95% CI, 2.7-34.6; p = 0.023). No treatment-related deaths occurred. The most common grade 3-4 adverse events were diarrhea and hepatic dysfunction in the ARX788 plus pyrotinib group, and fatigue, nausea and anorexia in the TCbHP group. Interstitial lung disease (ILD)/pneumonitis and ocular events were observed with ARX788 plus pyrotinib, indicating a distinct safety profile. These findings offer clinical insights into the potential of dual HER2-targeted blockade with an ADC and TKI as an optional neoadjuvant strategy for patients with early or locally advanced HER2-positive breast cancer.