BioNTech and DualityBio said their experimental breast cancer treatment trastuzumab pamirtecan met the primary goal of a global Phase 3 trial, but its potential benefit appeared limited amid increased reports of lung disease.
The companies reported October 26 that DYNASTY-Breast02 showed a statistically significant but modest improvement in progression-free survival compared with chemotherapy. Overall survival data were not mature at the interim analysis.
The trial enrolled 541 patients with hormone receptor-positive, HER2-low metastatic breast cancer who had not received chemotherapy and whose disease had progressed after endocrine therapy. Participants were randomly assigned equally to trastuzumab pamirtecan or physician-selected chemotherapy: capecitabine, paclitaxel or nab-paclitaxel.
Patients had experienced progression after at least two hormone therapy regimens, or within six months of first-line hormone therapy combined with a CDK4/6 inhibitor in the metastatic setting.
The companies reported a higher rate of interstitial lung disease than in earlier trials of trastuzumab pamirtecan. Most cases were Grade 1 or 2, but severe and fatal events occurred in a small proportion of patients. Otherwise, safety findings were consistent with previous studies, with no new safety signals reported.
The release did not disclose numerical progression-free survival results, a hazard ratio or specific rates of lung disease.
BioNTech and DualityBio said the available efficacy and safety findings suggested limited potential benefit within the current treatment landscape. They will discuss the data and determine next steps.
Trastuzumab pamirtecan, also called BNT323/DB-1303, is a HER2-targeting antibody-drug conjugate. It remains under study in endometrial cancer and advanced solid tumors, alongside the breast cancer trial.
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