Abstract 94P
Background
LAG3 is an inhibitory receptor expressed by T cells related to inhibition of IFNg production and mitochondrial biogenesis in naive CD4 T cells. Combined expression with other immune checkpoints (ICs) like TIM3 and PD1 is associated with exhausted T cells. It is unknown if tumor-infiltrating lymphocytes (TIL) metabolism reprogramming is related to the presence of ICs impacting their anti-tumoral ability.
Methods
TIL expansion was performed using the TIL 3.0 methodology from 62 surgically resected liposarcoma (LPS) tumors. Flow cytometry phenotypic analysis included CD73, PD1, Tim3, CTLA4, LAG3, OX40, ICOS and 41BB. Cytotoxicity by IFNγ secretion and CD107a degranulation, reactive oxygen species (ROS) and mitochondrial membrane potential (ΔΨm) was measured on the expanded TIL.
Results
TIL expansion success was 54.8% (n=34/62 expanded). The median proportion of T cell populations post expansion was 2.68% CD4+, 80.7% CD8+ and 11.45% CD4-CD8- (DN) comprised mainly of γδ T cells. LAG3 was the highest expressed checkpoint receptor across the TIL subtypes (median 5.28% of CD4+, 3.37% of CD8+ and 15.7% of DN). Likewise, TIM3, OX40, and PD-1 were differentially expressed (median TIM3 1.23% CD4+, 2.73% CD8+, 7.3% DN; OX40 9.4% CD4+, 0.43% CD8+, 0.3% DN; PD-1 9.2% CD4+, 2.8% CD8+, 2.28% DN). Higher metabolic fitness by ROS and ΔΨm correlated with increased IFNγ and CD107a degranulation. We identified three distinctive clusters driven by LAG3 expression and metabolic signature. 1) High LAG3, cytotoxicity, and metabolic fitness, 2) Low cytotoxic-metabolic fitness and low LAG3 and 3) absence of LAG3 and high cytotoxic-metabolic fitness. The data suggest clusters 1 and 2 describe two different patterns; one more activated that might be associated with the presence of LAG3, and the other is dysfunctional by the lack of cytotoxic and metabolic response. Meanwhile, the third cluster suggests a naive bystander T-cell population with a high degranulation and metabolic profile.
Conclusions
We describe a potential relationship between metabolic profiles and LAG3 expression. This data underscores the importance of metabolic fitness driving cytotoxic function and deepens our understanding of potentially important biomarkers in adoptive T cell therapy.
Clinical trial identification
Research samples were collected using the IRB-approved protocol LAB08-0151.
Editorial acknowledgement
Legal entity responsible for the study
University of Texas MD Anderson Cancer Center.
Funding
Sarcoma-Oma Foundation.
Disclosure
C. Haymaker: Financial Interests, Personal, Advisory Board: Regeneron; Financial Interests, Personal, Other, Consulting: Avenge; Financial Interests, Personal, Other, Stock options as a member of the Scientific Advisory Board: Briacell; Financial Interests, Institutional, Research Grant: Iovance, Dragonfly, BTG, Sanofi, Avenge, KSQ; Non-Financial Interests, Personal, Advisory Role, Co-Chair of SAB: Mesothelioma Applied Research Foundation. All other authors have declared no conflicts of interest.