HER2-ultralow (pecho, IHC > 0 < 1+; mancha de membrana débil/incompleta ≤10%)
Vista determinista de la entidad fuente YAML. La autoridad clínica sigue con los ID de fuente citados y estado de firma del revisor.
| ID | BIO-HER2-ULTRALOW |
|---|---|
| Tipo | Biomarcador |
| Aliaces | ERBB2-ultralowHER2 0 con coloración de membranaHER2 IHC >0 <1+HER2-ultralow (РМЗ — ІГХ > 0 < 1+; слабке/неповне мембранне забарвлення ≤10%)HER2-ultralow pecho |
| Situación | reviewed 2026-04-29 | pending_clinical_signoff |
| Enfermedades | DIS-BREAST |
| Fuentes | SRC-CIVIC SRC-ESMO-BREAST-METASTATIC-2024 SRC-NCCN-BREAST-2025 |
Datos sobre biomarcadores
| Tipo de biomarcador | protein_expression_ihc |
|---|---|
| Medición | MétodoIHC (4B5 / HercepTest) — HER2-ultralow definido operacionalmente como IHC > 0 pero < 1+: mancha incompleta de membrana débil / poco perceptible en ≤10% de las células tumorales (criterio de inscripción DESTINY-Breast06). Esta subcategoría se encuentra entre IHC 0 (ausente) e IHC 1+ (colocación completa de membranas defectuosa > 10%). La reproducibilidad patológica es pobre — variabilidad central de revisión documentada en DESTINy-Bresast06. UnidadesIHC ultralow | 0 | 1+ | 2+ | 3+ (HER2-ultralow excludes 0, 1+, 2+, 3+) |
| Productos químicos y químicos | BIO-HER2-LOW BIO-HER2-SOLID BIO-ESTROGEN-RECEPTOR |
Notas
HER2-ultralow extends the HER2 expression spectrum below IHC 1+. DESTINY- Breast06 (ASCO 2024 plenary; Bardia et al.) randomized HR+ HER2-low or HER2-ultralow metastatic breast post-endocrine + CDK4/6i (chemo-naive in metastatic setting) to T-DXd vs investigator-choice chemotherapy. Primary PFS endpoint met in HER2-low cohort (mPFS 13.2 vs 8.1 mo, HR 0.62, p<0.0001); HER2-ultralow exploratory cohort (n=153) showed consistent benefit (mPFS 13.2 vs 8.3 mo, HR 0.78). FDA approval anticipated 2026 expanding T-DXd label below HER2-low. Pathology challenge dominant: IHC 0 vs ultralow is not part of standard ASCO/CAP scoring guideline (2018 / 2023 update); DESTINY-Breast06 used central pathology review and reported inter-observer kappa lower for ultralow than for HER2-low. Practical consequence: routine pathology reports today rarely distinguish ultralow from 0 — re-review of biopsy with ultralow scoring criteria required before T-DXd consideration. ILD class warning unchanged from HER2-low / HER2-positive T-DXd indications. Bibliographic record SRC-DESTINY-BREAST06-BARDIA-2024 is available; clinical claim mapping requires qualified clinical review.
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