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A Standardized Investigational Ki-67 Immunohistochemistry Assay Used to Assess High-Risk Early Breast Cancer Patients in the monarchE Phase 3 Clinical Study Identifies a Population With Greater Risk of Disease Recurrence When Treated With Endocrine Therapy Alone

The objectives were to develop a standardized Ki-67 immunohistochemistry (IHC) method for precise, robust, and reproducible assessment of patients with early breast cancer, and utilize this assay to evaluate patients participating in the monarchE study (NCT03155997). The Ki-67 assay was developed an...

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Detalles Bibliográficos
Autores principales: Polewski, Monika D., Nielsen, Gitte B., Gu, Ying, Weaver, Aaron T., Gegg, Gavin, Tabuena-Frolli, Siena, Cajaiba, Mariana, Hanks, Debra, Method, Michael, Press, Michael F., Gottstein, Claudia, Gruver, Aaron M.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Lippincott Williams & Wilkins 2022
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8989635/
https://www.ncbi.nlm.nih.gov/pubmed/35384873
http://dx.doi.org/10.1097/PAI.0000000000001009
Descripción
Sumario:The objectives were to develop a standardized Ki-67 immunohistochemistry (IHC) method for precise, robust, and reproducible assessment of patients with early breast cancer, and utilize this assay to evaluate patients participating in the monarchE study (NCT03155997). The Ki-67 assay was developed and validated for sensitivity, specificity, repeatability, precision, and robustness using a predefined ≥20% cutoff. Reproducibility studies (intersite and intrasite, interobserver and intraobserver) were conducted at 3 external laboratories using detailed scoring instructions designed for monarchE. Using the assay, patient tumors were classified as displaying high (≥20%) or low (<20%) Ki-67 expression; Kaplan-Meier methods evaluated 2-year invasive disease-free survival rates for these 2 groups among patients treated with endocrine therapy (ET) alone. All analytical validation and reproducibility studies achieved point estimates of >90% for negative, positive, and overall percent agreement. Intersite reproducibility produced point estimate values of 94.7%, 100.0%, and 97.3%. External interobserver reproducibility produced point estimate values of 98.9%, 97.8%, and 98.3%. Among 1954 patients receiving ET alone, 986 (50.5%) had high and 968 (49.5%) had low Ki-67 expression. Patients with high Ki-67 had a clinically meaningful increased risk of developing invasive disease within 2 years compared with those with low Ki-67 [2-y invasive disease-free survival rate: 86.1% (95% confidence interval: 83.1%-88.7%) vs. 92.0% (95% confidence interval: 89.7%-93.9%), respectively]. This standardized Ki-67 methodology resulted in high concordance across multiple laboratories, and its use in the monarchE study prospectively demonstrated the prognostic value of Ki-67 IHC in HR+, HER2− early breast cancer with high-risk clinicopathologic features.