DUALITYBIO-B (09606.HK): DYNASTY-Breast02 meets primary endpoint, PFS gain modest, clinical benefit may be limited

NewTimeSpace News: DUALITYBIO-B (09606.HK) released inside information that its DYNASTY-Breast02 global Phase 3 clinical trial (NCT06018337) met its primary endpoint, demonstrating a statistically significant, yet modest improvement in progression-free survival (PFS) with trastuzumab pamirtecan compared to investigator's choice of chemotherapy in chemotherapy-naive patients with HR+/HER2-low metastatic breast cancer who have progressed on endocrine therapy. At this interim analysis, data for the secondary endpoint of overall survival (OS) were not mature.

According to the announcement, a higher rate of interstitial lung disease (ILD) was reported in this trial compared to prior trials with trastuzumab pamirtecan, with most cases being Grade 1 and 2; severe and fatal events were reported in a small proportion of patients (Grade 3 to 5). Otherwise, the overall safety profile was consistent with prior clinical trials and no new safety signals were observed.

The Company said the available efficacy and safety data as of this data cut-off date suggest that the potential benefit to patients would be limited in the context of the HR+/HER2-low metastatic breast cancer treatment landscape. The Company and its collaboration partner BioNTech SE will further discuss the data and determine next steps. The announcement carries the Rule 18A.05 warning that there is no assurance that trastuzumab pamirtecan will ultimately be successfully developed, marketed and commercialised.