Tumor-Infiltrating Lymphocyte Dynamics Predict Neoadjuvant Response in Luminal Breast Cancer
Overview
This study evaluated stromal tumor-infiltrating lymphocytes (TILs) before and after neoadjuvant chemotherapy (NAC) in hormone receptor–positive/HER2-negative breast cancer. Dynamic changes in TILs (delta-TIL) were analyzed for associations with pathological complete response (pCR) and progression-free survival (PFS). Findings suggest that TIL dynamics may provide prognostic information beyond baseline TIL levels in this subtype.
Background
Tumor-infiltrating lymphocytes reflect the host immune response and have established predictive and prognostic roles in triple-negative and HER2-positive breast cancers. However, HR+/HER2− breast cancers are typically immunologically cold with lower TIL infiltration and reduced chemosensitivity. Neoadjuvant chemotherapy is used in high-risk luminal breast cancer to assess treatment response, but the prognostic value of TILs in this context remains unclear. Investigating TIL dynamics during therapy may clarify their role in predicting outcomes.
Data Highlights
Characteristic
Value
Number of patients
87
Median age (range)
48 years (29–86)
Menopausal status
71.3% pre/perimenopausal
Most common clinical stage
Stage 2B (40.7%)
Tumor size (cT2)
66.3%
Node status (cN1)
51.2%
Histology
85.1% invasive ductal carcinoma
Lymphovascular invasion (LVI)
25.2%
Perineural invasion (PNI)
13.7%
Tumor grade 2
57.3%
Key Findings
Baseline stromal TILs were quantified in pre-treatment biopsies and post-treatment surgical specimens.
Delta-TIL, defined as the change in TIL percentage from pre- to post-treatment, was calculated for each patient.
Higher baseline TIL levels correlated with improved pathological complete response rates to neoadjuvant chemotherapy.
Dynamic increases in TILs during treatment (positive delta-TIL) were associated with better pathological response and longer progression-free survival.
HR+/HER2− tumors generally exhibited lower TIL infiltration compared to more immunogenic subtypes, consistent with their immunologically cold microenvironment.
TIL dynamics provided additional prognostic information beyond classical pathological parameters in luminal breast cancer.
Clinical Implications
Assessment of TIL dynamics before and after neoadjuvant chemotherapy may help identify HR+/HER2− breast cancer patients more likely to achieve pathological complete response and improved progression-free survival. Incorporating TIL evaluation into routine pathological assessment could refine risk stratification and guide treatment decisions in luminal breast cancer. Further prospective studies are warranted to validate TIL dynamics as a biomarker in this setting.
Conclusion
Dynamic changes in tumor-infiltrating lymphocytes during neoadjuvant chemotherapy are associated with treatment response and progression-free survival in luminal breast cancer. Monitoring TIL dynamics may enhance prognostic accuracy beyond baseline measurements in HR+/HER2− tumors.
Related Resources & Content
International TILs Working Group -- Recommendations on TIL assessment
Studies on TILs in triple-negative and HER2-positive breast cancer
Research on immune microenvironment in HR+/HER2− breast cancer
Clinical studies on neoadjuvant chemotherapy in luminal breast cancer
Investigations of TIL dynamics and prognostic relevance
