Abstract 66P
Background
Leptin is one of the molecules released by adipocytes and displays an important role in BC tumorigenesis and progression. Leptin exerts its action through binding Ob-R. TILs represent an outstanding immune response in BC. The precise mechanism by which these T-cells are activated in and around the tumour remains partially unknown. Leptin could be one of the factors involved in activating TILs in BC. The primary aim of this study was to investigate the association between Ob-R and TILs and subsequent with pCR in early BC patients who have received neoadjuvant systemic treatment (NST).
Methods
A total of 87 women with BC receiving NST followed by surgery were retrospectively evaluated. Based on the IHC results, tumors were categorized using the St Gallen criteria, as luminal A and B, HER2+, or triple-negative subtypes. Ob-R expression was routinely measured in the diagnostic biopsy using the BOND RX Research Platform (Leica Biosystems). The Ob-R was classified as over-expressed if there were more than 50% positive cells with weak or strong staining. TILs were scored centrally in pre-treatment biopsy and considered as continuous variable. Associations with pCR (ypT0/isN0) were assessed using logistic regression.
Results
Over-expression of Ob-R was found in 52% of tumors and there was a significantly higher incidence in the HER2+ and TNBC than luminal subgroups. High TILs levels were significant associated with pCR (23.5% vs non responders 15.7%; p=0-034). The mean percentage of TILs were 21.1% in Ob-R positive tumors and 15% in Ob-R negative tumors (p=0.104); this association was significant in HER2+ subtype (21.5% vs. 9%; P=0.015). In patients with pCR, mean percentage of TILs were significantly higher with Ob-R over-expressed tumors compared with negative Ob-R tumors (26.6% vs 12.5%; p=0.005). This difference was not observed in non-responders where mean percentage of TILs was not statistically different between tumors with and without Ob-R over-expression.
Conclusions
High levels of TILs are associated with Ob-R overexpression particularly in HER2+. Leptin-Ob-R axis could be modifying the effect of TILs in those tumours achieving a pCR.
Clinical trial identification
Editorial acknowledgement
Legal entity responsible for the study
Foundation MD Anderson International, Madrid, Spain.
Funding
Foundation ACS Madrid, Spain.
Disclosure
All authors have declared no conflicts of interest.