Abstract 182P
Background
Cancer stem cells (CSC) have been suggested as a mechanism of resistance and relapse in BC. TN and HER2+ BC have been associated with a more immunogenic tumor microenvironment, with higher presence of tumor-infiltrating lymphocytes (TILs) and activation of pathways as PD-L1. ALDH1 is a CSC marker that appears to be predictive of clinical outcomes. The study aims to analyze ALDH1 and PD-L1 expression, and the presence of TILs in TN and HER2+ BC tumors, and its association with clinical-pathological characteristics and clinical outcomes.
Methods
Retrospective study of 75 TN and HER2+ BC patients treated with neoadjuvant chemotherapy between 2008 and 2018. Minimum follow-up was 24 months or until death. ALDH1, PD-L1 expression and TILs subtypes were assessed by immunohistochemistry. ALDH1 and PD-L1 were positive if expression ≥1%. TILs were evaluated following International Expert Consensus recommendations with 15 as cut off for high (HTILs) or low (LTILs).
Results
ALDH1 expression was related with HTILs (p=0.005) and PD-L1+ tumors (p=0.004). ALDH1+ tumors present higher CD3+ (p=0.008), CD4+ (p=0.005), CD8+ (p=0.003), CD20+ (p=0.006) TILs. PD-L1+ was related to TILs (p=0.0001). TN/ALDH1+ tumors were related to PD-L1+ (p=0.026), CD20+ (p=0.006) and HTILs (p=0.01). No associations were found in HER2+/ALDH1+ tumors. HER2+/PD-L1+ were related to positive androgen receptor (AR) (p=0.029), HTILs (p < 0.001) and CD20+ (p=0.001). ALDH1+ (p=0.018), PD-L1+ (p=0.004) and HTILs (p < 0.001) were related to smaller tumors. ALDH1+ was related to pathologic complete response (PCR) (p=0.048). HTILs were related to postmenopausal status (p=0.035). Median disease-free survival (DFS) and overall survival had not been reached. HTILs were related with improved DFS (p=0,027). Table: 182P
Clinical-pathological characteristics
| Total cases (%) | |
| Age | 53 (27-79) years |
| Premenopausal | 45.3 |
| TN / HER2+ | 42.6 / 57.1 |
| AR + | 57.33 |
| Tumor sized (< 5cm) | 57.33 |
| Nodes + | 69.33 |
| PCR | 49.33 |
| Relapse | 38.7 |
| Exitus | 26.7 |
Conclusions
ALDH1+ relates to PD-L1+, HITLs, CD3+, CD4+, CD8+, CD20+ and PCR. This could mean that ALDH1+ tumors are more immunogenic. Further investigations are needed to reveal possible therapies in this setting.
Clinical trial identification
Editorial acknowledgement
Legal entity responsible for the study
The authors.
Funding
Has not received any funding.
Disclosure
All authors have declared no conflicts of interest.