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Updated: Mar 6, 2026
Predictive Immune Modeling of Solid Tumors
Published on: February 25, 2020
Tumor-infiltrating lymphocytes and molecular response after neoadjuvant therapy for HR+/HER2- breast cancer: results
M V Dieci1,2, A Frassoldati3, D Generali4,5
1Department of Surgery, Oncology and Gastroenterology, University of Padova, via Giustiniani 2, 35128, Padua, Italy.
Purpose:
The aim was to evaluate the role of tumor-infiltrating lymphocytes (TIL) in predicting molecular response after preoperative endocrine or cytotoxic treatment for HR+/HER2- patients who do not achieve a pathological complete response.
Methods:
Stromal (Str) TIL were centrally evaluated on samples from diagnostic core-biopsies of HR+/HER2- patients included in two prospective randomized trials: the LETLOB trial (neoadjuvant endocrine-based treatment) and the GIOB trial (neoadjuvant chemotherapy-based treatment). Pre- and post-treatment Ki67 was centrally assessed.
Results:
StrTIL were evaluable in 111 cases (n = 73 from the LETLOB trial and n = 38 from the GIOB trial). Median StrTIL was 2%. Patients with high StrTIL (StrTIL ≥10%, n = 28) had more frequently breast cancer of ductal histology (p = 0.02), high grade (p = 0.049), and high Ki67 (p = 0.02). After neoadjuvant endocrine treatment (LETLOB cohort), a significant Ki67 suppression (p < 0.01) from pre- to post-treatment was observed in both the low and high StrTIL groups. High StrTIL patients achieve more frequently a relative Ki67 suppression ≥50% from baseline as compared to low StrTIL patients (55 vs. 35%, p non significant). After neoadjuvant chemotherapy (GIOB cohort), a significant Ki67 suppression was observed only for low StrTIL patients (Wilcoxon p = 0.001) and not in the high StrTIL group (p = 0.612). In this cohort, the rate of patients achieving a relative Ki67 suppression ≥50% from baseline was significantly higher in the low vs high StrTIL group (64% vs 10%, p = 0.003). Geometric mean Ki67 suppression was evaluated in each cohort according to StrTIL: the lowest value (-41%) was observed for high StrTIL cases treated with chemotherapy.
Conclusions:
This hypothesis-generating study suggests that in HR+/HER2- breast cancer StrTIL at baseline may influence the achievement of a molecular response after neoadjuvant treatment. Further evaluation in large studies is needed, and interaction with the type of treatment warrants to be explored.
