This narrative review aims to clarify the role of tertiary lymphoid structures in breast cancer. We examine their development, composition, and prognostic value, and current ways of recognizing them. A comprehensive literature review was performed using the PubMed/Medline, Scopus, and EMBASE databases. A significant area of interest in breast cancer research involves targeting immune checkpoint molecules, particularly in the triple-negative subtype, where treatment options remain limited. However, existing biomarkers have limitations in accurately predicting treatment response. In this context, tertiary lymphoid structures (TLSs) emerge as a prognostic biomarker and also as a promising predictive marker for response. TLSs are ectopic lymphoid formations or neo-organogenesis that can develop after prolonged exposure to inflammatory signals mediated by chemokines and cytokines. Their presence is inversely correlated with estrogen receptor (ER) and/or progesterone receptor (PR) expression, but positively associated with a higher pathologic complete response rate and improved overall survival. In certain scenarios, TLS-positive tumors were associated with improved outcomes regardless of the presence of PDL-1 (programmed cell death ligand 1) expression or TILs (tumor-infiltrating lymphocytes).

Currently, therapy for early-stage human epidermal growth factor receptor 2-positive (HER2+) breast cancer (BC) is based on the combination of trastuzumab and pertuzumab plus chemotherapy in a neoadjuvant regimen. The INMUNOHER study aimed to detect immunological markers in peripheral blood and their association with treatment response. Sixty-two HER2+ BC patients were recruited. Pre-treatment samples were obtained before the start of treatment, while post-treatment samples were obtained after completing therapy and before surgery and were analyzed by flow cytometry. The pathologic complete response (pCR) rate achieved was 82.3%. The expression of the NKp30, PD-1, and TIM-3 receptors was reduced in the Natural Killer (NK)-CD56dim subset of patients who did not achieve pCR. Following therapy, many changes were found in leukocytes, including alterations in T cell lymphocyte proportions. Also, the percentage of NK cells decreased, and several phenotypic changes were observed in this population. After treatment, IFN-γ production by NK cells against HER2+-cells with or without trastuzumab was significantly reduced. HER2-targeted therapy plus chemotherapy demonstrated high efficacy in most patients, reducing the statistical power for finding immunological markers. However, NK subset phenotypes correlated better with response groups, and numerous changes in the percentage of leukocytes and T and NK cells, as well as changes in the functionality of NK cells, were observed in most patients after treatment, encouraging further research into these immune populations.

This narrative review aims to clarify the role of tertiary lymphoid structures in breast cancer. We examine their development, composition, prognostic value and current ways of recognising them. A comprehensive literature review was performed using PubMed/Medline, Scopus and EMBASE databases. A significant area of interest in breast cancer research involves targeting immune checkpoint molecules, particularly in the triple-negative subtype, where treatment options remain limited. However, existing biomarkers have limitations in accurately predicting treatment response. In this context, tertiary lymphoid structures (TLS) emerge as a prognostic biomarker and also as a promising predictive marker for response. TLS are ectopic lymphoid formations or neo-organogenesis that can develop after prolonged exposure to inflammatory signals mediated by chemokines and cytokines. Their presence is inversely correlated with estrogen receptor (ER) and/or progesterone receptor (PR) expression, but positively associated with a higher pathologic complete response rate and improved overall survival. In certain scenarios, TLS-positive tumors were associated with improved outcomes regardless of the presence of PDL-1 (programmed cell death ligand 1) expression or and TILs (tumor-infiltrating lymphocytes).

El cáncer de mama es una de las enfermedades más frecuentes en todo el mundo. La amplificación del proto-oncogén HER2 se presenta en 20-25% de los tumores de mama. TDM-1 es un conjugado anticuerpo-quimioterápico. Se realizó en forma retrospectiva, observacional y descriptiva un análisis de los datos de pacientes con diagnóstico de cáncer de mama metastásico HER2 positivo, que realizaban y/o habían realizado tratamiento con dicho fármaco. Se evaluaron 27 mujeres. La indicación de TDM-1 fue en 7.4% (2) en primera línea, 37% (10) en segunda línea, y 55.5% (15) en líneas posteriores, con un tiempo a la progresión de 7.44 meses (IC: 4.33-NC) para el global de pacientes, tasa de respuesta objetiva de 44% y se constataron 7 (26%) toxicidades G3-4.