2MO - Expression levels of immune checkpoint markers (IC) in hormone receptor-positive/HER2-negative (HR+/HER2-) metastatic breast cancer (BC)

Background

IC markers against which inhibitors are currently used/evaluated clinically, have not yet been studied in detail in metastases (M) from patients with primary HR+/HER2- BC. In this study, we examined expression levels of these IC markers in multiple M and primary tumors (P) from primary HR+/HER2- BC patients who enrolled in our postmortem tissue donation program UPTIDER (NCT04531696).

Methods

326 samples (23 untreated P and 290 postmortem M samples) from 10 UPTIDER patients with primary HR+/HER2- BC underwent bulk RNA sequencing (Lexogen). Quality control (QC) was set for 500000 assigned reads and gene counts were normalized using variance stabilizing transformation. We selected IC markers being clinically investigated in BC (BTLA, CD40, CD47, CD86, CD137, CD137L, CD158A, CD226, CTLA4, ICOS, LAG3, OX40, PD-1, PD-L1, TIM3, TIGIT) from literature and clinicaltrials.gov. Available matched FFPE samples were evaluated for histology (invasive lobular, ILC, and BC of no special type, NST) and ER-status. Associations between sample status (outcome: M vs P/ ER+ vs ER- for M) and individual gene expression were assessed by logistic linear regressions with data clustering by patient using the generalized estimating equation method. We studied the association between sample specific postmortem interval (ssPMI) and gene expression by repeated sampling (at 1.5h intervals) of the same M in 7 patients.

Results

324/326 samples passed QC (289 M and 22 P) and the IC expression was stable with increasing ssPMI. TIM3was highly expressed, and PD-1 was among the least expressed in M. Intra-patient inter-M heterogeneity was observed for all markers. M showed lower expression of PD-1, PD-L1, CTLA4, LAG3, OX40 and TIGIT (Odds ratio (OR) range: 0.27-0.53, p<0.05) and higher expression of TIM3 and BTLA (OR range:1.37-6.19, p<0.05) compared to P. BTLA, CD86, CTLA4, OX40 and TIM3 were more expressed in NST M compared to ILC M (OR range: 1-1.43). PD-L1, CD47, LAG3, CD40 and TIGIT were found more expressed in ER+ vs ER- M in both NST and ILC (OR NST: 1.02-1.37, OR ILC: 1.12-5.52).

Conclusions

This study sheds light on the expression of IC markers in M from patients with HR+/HER2- primary BC as well as on the impact of histology and ER-expression.

Clinical trial identification

NCT04531696.

Legal entity responsible for the study

Laboratory for Translational Breast Cancer Research.

Funding

KU Leuven, Leuven, Belgium.

Disclosure

K. Punie: Financial Interests, Institutional, Advisory Board: AstraZeneca, Novartis, Roche, Vifor Pharma, Eli Lilly, Pierre Fabre, McCann Health, Roularta, Teva, Gilead Sciences, Pfizer, Gilead, MSD; Financial Interests, Institutional, Invited Speaker: Pfizer, Roche, Novartis, Eli Lilly, Mundi Pharma, MSD, Medscape, MSD; Financial Interests, Institutional, Other, Consultancy: Roche; Financial Interests, Personal, Other, Consultancy: Gilead, Novartis, MSD, Roche; Financial Interests, Personal, Invited Speaker: AstraZeneca, Sanofi; Financial Interests, Personal, Advisory Board: Seagen; Financial Interests, Institutional, Funding: Sanofi; Non-Financial Interests, Principal Investigator: EORTC 1745-ETF-BCG trial; Non-Financial Interests, Other, Committee member: ESMO Young Oncologists Committee; Non-Financial Interests, Invited Speaker: BSMO; Non-Financial Interests, Other, Committee Member: ESMO Resilience Task Force; Non-Financial Interests, Advisory Role: Commission Personalized Medecine Federal Government Belgium; Non-Financial Interests, Advisory Role, External Scientific Advisor: European Medicine Agency. H. Wildiers: Financial Interests, Institutional, Advisory Board: Roche, Lilly, AstraZeneca, Daiichi Sankyo, PSI Cro AG, KCE, MSD, MSD, E Squared Communications LLC; Financial Interests, Institutional, Invited Speaker: Eisai, AstraZeneca; Financial Interests, Institutional, Other, Consultancy fee: AbbVie, Immutep Pty; Financial Interests, Institutional, Expert Testimony: Daiichi Sankyo; Financial Interests, Institutional, Other, Consultancy: Daiichi Sankyo; Financial Interests, Institutional, Research Grant, Grant to the Leuven Breast Center to support the research database: Roche; Financial Interests, Institutional, Research Grant, Grant to institute to perform a multicentric national academic trial: Novartis; Other, Travel & accomodations: Pfizer; Other, Travel & accomodation: Roche; Other, Subscription fee: Gilead. G. Floris: Financial Interests, Institutional, Advisory Board: AstraZeneca. All other authors have declared no conflicts of interest.