This is a Phase I/II, multi-site, open-label, two-part study designed to evaluate the efficacy, safety, optimized dose and contribution of components of BNT323 (also known as trastuzumab pamirtecan and DB-1303) in combination with BNT327 (also known as pumitamig and PM8002) in participants with hormone receptor-positive (HR+) or hormone receptor-negative (HR-), Human epidermal growth factor receptor (HER)2-positive, HER2-low (immunohistochemistry \[IHC\] 1+ or IHC 2+/in situ hybridization -), HER2-ultralow (IHC 0, with membrane staining) or HER2-null breast cancer (BC), or triple-negative breast cancer (TNBC).
Is locally advanced, unresectable or metastatic.
Has a confirmed HER2 status as determined by the local laboratory as standard of care testing prior to study screening (Part 1, Part 2 Cohorts 2 and 4) or the central laboratory (Part 2, Cohorts 1 and 3) from the most recently collected pre-randomization tumor sample.
Has a documented history of HER2 expression consistent with the subgroup definitions (i.e., HER2-low, HER2-ultralow, HER2-null, HER2-positive, or TNBC) as per current American Society of Clinical Oncology/College of American Pathologists guidelines.
Have measurable disease defined by RECIST v1.1.
Have history of small bowel obstruction requiring hospitalization within the past 3 months prior to the first dose of IMP.
Have an uncontrolled intercurrent illness that would limit compliance with study requirement or substantially increase risk of incurring adverse events.
Have clinically uncontrolled pleural effusion, ascites or pericardial effusion requiring drainage, peritoneal shunt, or cell-free concentrated ascites reinfusion therapy within 2 weeks prior to randomization/enrollment.
Have a history of (non-infectious) interstitial lung disease (ILD)/pneumonitis that required steroids, have current ILD/pneumonitis, or where suspected ILD/pneumonitis cannot be ruled out by imaging at screening.
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Treatment groupsSee each treatment group below.
BioNTech SE
Lead sponsor
DualityBio Inc.
Collaborator
BioNTech (Shanghai) Pharmaceuticals Co., Ltd.
Collaborator