Abstract 206P
Background
In HER2+ early BC, several studies examined TILs as prognostic indicators and predictors of response, consistently revealing a positive correlation. Data on the role of TILs in advanced disease are limited.
Methods
We conducted a retrospective study on patients (pts) with stage IV HER2+ BC treated at the European Institute of Oncology between June 2013 and January 2024, using pertuzumab, trastuzumab, and taxane-based chemotherapy as first-line therapy. We collected 1 archival sample for each patient (46 from the metastatic site and 34 from the primary tumor), obtained before the start of treatment. TILs were evaluated on Haematoxylin and Eosin (H&E)-stained slides, according to the International TILs Working Group criteria. TILs were analyzed both as continuous variables and dichotomized into low vs high, with the median TILs value in the study population as cutoff. Correlative analyses were conducted, with significance set at p-value<0.05.
Results
80 consecutive pts were enrolled in the study, of whom 42 and 38 had hormone receptor-positive (HR+) and HR-negative (HR-) BC respectively. At the time of diagnosis, 57 pts (71.25%) had visceral disease, 30 pts (37.5%) had de novo metastatic disease, and 6 (7.5%) pts exhibited brain metastases (BMs). The median expression of TILs resulted to be 10% with 72.5% (58 pts) showing TILs expression of ≥10% (high-TILs). No statistically significant correlation was observed between TILs and ER expression, whether evaluated continuously or dichotomously (cut-off of 10%). Similarly, no correlation was found between TILs and HER2 expression, which was assessed dichotomously as 2+ ISH+ vs 3+. Furthermore, there was no correlation between the percentage of TILs and clinical outcomes, including progression-free survival (PFS) and overall survival (OS), even at multivariate analysis. Interestingly, TILs expression of ≥10% was associated with the presence of BMs at the time of diagnosis (p=0.035).
Conclusions
Based on our analysis, it seems that TILs expression does not play a prognostic role in first-line treated HER2+ BC. However, confirming the correlation with BMs at diagnosis would necessitate a larger case study.
Legal entity responsible for the study
The authors.
Funding
Has not received any funding.
Disclosure
A. Marra: Financial Interests, Personal, Advisory Board: Menarini/Stemline; Financial Interests, Personal, Invited Speaker: Roche; Financial Interests, Personal, Other, Travel Support: AstraZeneca. D. Trapani: Other, EMA Healthcare Professional Working Party (HCPWP), member: European Medicines Agency (EMA); Other, EML Cancer Medicines Working Group (CMWG), member: World Health Organization (WHO); Other, Strategic Advisory Group of Experts on In Vitro Diagnostics (SAGE IVD), chair: World Health Organization (WHO). A. Esposito: Financial Interests, Speaker’s Bureau: Novartis, AstraZeneca. E. Munzone: Financial Interests, Personal, Advisory Board: Daiichi Sankyo/AstraZeneca, Eisai, Exact Science, MSD Oncology, Pfizer, Seagen. N. Fusco: Financial Interests, Personal, Invited Speaker: Merck Sharp & Dohme (MSD), AstraZeneca, Daiichi Sankyo, GSK, Gilead, Novartis, Roche, Menarini, Lilly, Sysmex; Financial Interests, Personal, Advisory Board: Merck Sharp & Dohme (MSD), AstraZeneca, Menarini; Financial Interests, Personal and Institutional, Research Grant: Novartis, Sysmex, Veracyte. C. Criscitiello: Financial Interests, Personal, Invited Speaker: Pfizer, Novartis, Eli Lilly, Roche, Gilead; Financial Interests, Personal, Advisory Board: MSD, Seagen, AstraZeneca, Daiichi Sankyo. G. Curigliano: Financial Interests, Personal, Invited Speaker: Roche, AstraZeneca, Daiichi Sankyo, Novartis, Pfizer, Pfizer; Financial Interests, Personal, Advisory Board: Roche, AstraZeneca, Daiichi Sankyo, Lilly, Pfizer, Veracyte, BMS, Merck, Exact Sciences, Celcuity; Financial Interests, Personal, Advisory Board, Advisory Board: Menarini, Gilead; Financial Interests, Personal, Other, Advisory Board: Ellipsis; Financial Interests, Institutional, Research Grant, Investigator Initiated Trial: Merck; Financial Interests, Institutional, Funding, Phase I studies: BMS, Novartis, AstraZeneca, Daiichi Sankyo, Roche, Blueprint Medicine, Kymab, Astellas, Sanofi, Philogen; Financial Interests, Institutional, Invited Speaker, Phase I clinical basket trial: Relay Therapeutics; Non-Financial Interests, Officer, Italian National Health Council as Advisor for Ministry of Health: Consiglio Superiore di Sanità; Non-Financial Interests, Advisory Role, Member of the Scientific Council. Patient advocacy association: Europa Donna; Non-Financial Interests, Advisory Role, Cancer Research Foundation: Fondazione Beretta; Non-Financial Interests, Member of Board of Directors, No compensation for this role. This a public national company for cancer prevention: Lega Italiana Lotta ai Tumori; Non-Financial Interests, Officer, Member of the Advisory Council: EUSOMA; Non-Financial Interests, Officer, ESMO Clinical Practice Guidelines Chair: ESMO; Non-Financial Interests, Member of Board of Directors, Chair of Clinical Practice Guidelines Committee: ESMO. All other authors have declared no conflicts of interest.