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.