ABS-011 HER2 PET Tracer: Phase 2b Feasibility Data Cannot Close a Clinical Utility Chasm

Curium Acquires Abscint, Expands Oncology PET Radiodiagnostic Pipeline

Curium, a global radiopharmaceutical company, has completed the acquisition of Abscint SA, a Belgian clinical-stage radiopharmaceutical company. This transaction grants Curium global rights to ABS-011, an investigational gallium-68-labeled PET radiodiagnostic tracer designed to target human epidermal growth factor receptor 2 (HER2). The acquisition strengthens Curium's oncology footprint, particularly in breast and gastric cancers, by enabling whole-body, quantitative imaging of HER2 expression. ABS-011 is currently being evaluated in the multicentered Phase 2b HERMIA trial (NCT 06369831) in Belgium, aiming to provide a more complete view of HER2 status for informed patient characterization and clinical assessment.

• Curium's acquisition of Abscint SA secures global rights to ABS-011, a gallium-68-labeled PET radiodiagnostic tracer. This strategic move enhances Curium's oncology portfolio, specifically targeting HER2 expression in cancers like breast and gastric, and leverages Abscint's expertise in radiolabeled single-domain antibodies for advanced diagnostic imaging.
• ABS-011 is designed to bind HER2 rapidly, allowing for same-day, whole-body PET imaging. This approach aims to reveal spatial heterogeneity of HER2 expression across multiple lesions, potentially improving patient characterization and guiding more informative biopsy selections compared to single-lesion biopsies.
• ABS-011 is currently undergoing evaluation in the multicentered Phase 2b HERMIA trial in Belgium (NCT 06369831). Curium plans to apply its extensive experience in radiopharmaceutical development, manufacturing, and commercialization to accelerate the program towards regulatory approval and broader patient access.

The Evolving Landscape of HER2 Diagnostics in Breast Cancer

In clinical practice, the identification and characterization of breast cancer relies on a core panel of immunohistochemical (IHC) biomarkers assessed in all invasive breast carcinomas. Estrogen receptor (ER) and progesterone receptor (PR) status are evaluated across both invasive carcinomas and ductal carcinoma in situ (DCIS), while HER2 receptor expression is determined through a dual-modality approach combining IHC and in situ hybridization (ISH). Together, these markers remain foundational in determining the need for and type of adjuvant therapy, forming the cornerstone of treatment stratification across breast cancer subtypes.

Molecular classification is further refined through a surrogate IHC panel that includes EGFR, CK5/6, Ki-67 (as a proliferation index), p53 mutation status, and androgen receptor (AR) expression. This panel enables classification into established molecular subtypes: Luminal A (strong ER-positive, PR-positive or -negative), Luminal B (weak to moderate ER-positive and/or PR-positive), HER2-enriched (moderate to strong HER2 positivity confirmed by silver-enhanced in situ hybridization), Basal (CK5/6- or EGFR-positive), and a penta-negative unclassified group. Each subtype carries distinct prognostic and therapeutic implications, underscoring the clinical utility of comprehensive biomarker profiling.

Imaging-based diagnostic criteria serve as a critical complement to tissue biomarkers. Dynamic contrast-enhanced MRI (DCE-MRI) applies morphologic and kinetic analyses within the Breast Imaging-Reporting and Data System (BI-RADS) framework, while diffusion-weighted imaging (DWI) with apparent diffusion coefficient (ADC) mapping provides quantitative differentiation between malignant and benign lesions — invasive ductal carcinoma yields a mean ADC of 0.92 ± 0.19 × 10 mm²/s, DCIS 1.11 ± 0.13 × 10 mm²/s, compared to 1.36 ± 0.22 × 10 mm²/s for benign lesions. Additionally, microcalcifications remain the most prevalent radiological feature driving DCIS detection through screening mammography, highlighting the indispensable role of multimodal imaging in early breast cancer identification.

Curium's HER2 Imaging Play: Reshaping Precision Oncology

Curium's strategic acquisition of Abscint SA and its lead asset, ABS-011, signals a significant commitment to advancing precision oncology through innovative radiopharmaceutical diagnostics. This move is particularly timely given the evolving understanding of human epidermal growth factor receptor 2 (HER2) expression in various cancers, notably breast and gastric. While HER2 status has long been a cornerstone for guiding targeted therapies, the limitations of current assessment methods are becoming increasingly apparent.

Traditional immunohistochemistry (IHC) and in situ hybridization (ISH) often struggle with the spatial and temporal heterogeneity of HER2 expression, meaning a single biopsy may not reflect the full disease burden or changes over time. This challenge is compounded by the emergence of HER2-low metastatic breast cancer, where identifying suitable candidates for novel antibody-drug conjugates (ADCs) is a critical clinical need. ABS-011, an investigational gallium-68-labeled PET radiodiagnostic tracer, offers a potential solution by enabling non-invasive, whole-body, quantitative imaging of HER2 expression. Preclinical and early clinical studies of similar nanobody-based HER2 tracers have demonstrated high specificity, fast blood clearance, favorable biodistribution, and low toxicity, making them ideal candidates for PET imaging.

For Curium, this acquisition strengthens its oncology footprint and positions it to potentially offer a critical tool for patient characterization and treatment selection. The ability to accurately assess HER2 status across all lesions could lead to more informed clinical decisions, potentially optimizing the use of HER2-targeted therapies and improving patient outcomes. However, the path forward is not without its considerations. ABS-011 is currently in a Phase 2b trial, and its ultimate clinical utility in predicting therapeutic response or guiding treatment decisions remains to be fully established. Furthermore, the competitive landscape for HER2 PET tracers is growing, with other gallium-68 and fluorine-18 labeled agents in development. Navigating regulatory approval and securing favorable reimbursement for a novel diagnostic imaging agent will also be crucial for its successful integration into clinical practice. Despite these challenges, the potential for ABS-011 to transform how HER2-expressing cancers are diagnosed and managed is substantial, offering a glimpse into a future where imaging plays an even more central role in personalized medicine.