Genetic characteristics involving the PD-1/PD-L1/L2 and CD73/A2aR axes and the immunosuppressive microenvironment in
Tingting Zhang1, Hengqi Liu1, Lei Jiao2
1Department of Lymphoma, Tianjin Medical University Cancer Institute and Hospital, National Clinical Research Center of Cancer, Key Laboratory of Cancer Prevention and Therapy, Tianjin's Clinical Research Center for Cancer, the Sino-US Center for Lymphoma and Leukemia Research, Tianjin, China.
Background:
Targeting the PD-1/PD-L1/L2 (programmed cell death protein 1/programmed cell death ligand 1/ligand 2) pathway combined with other immunosuppressive signalings, such as CD73/A2aR (A2a adenosine receptor) adenosine signaling, has emerged as a promising strategy for cancer treatment. The genetic characteristics of these immune checkpoints need to be further investigated in diffuse large B-cell lymphoma (DLBCL).
Methods:
We performed whole-exome sequencing/targeted deep sequencing to investigate the genetic characteristics of PD-1/PD-L1/L2 and CD73/A2aR. The immunosuppressive effect of these two pathways on the tumor microenvironment was evaluated via RNA sequencing. Single-cell RNA sequencing was further applied to investigate the dysfunctional CD8+ T cells. In addition, multiplex immunofluorescence staining was used to quantitatively assess the expression of dysfunctional CD8+ T cells in DLBCL.
Results:
SP140 was identified as a novel translocation partner for PD-L1, and a new inversion was detected between PD-L1 and PD-L2, both leading to the upregulation of PD-L1 expression. CD73 genetic mutations did not increase mRNA and protein expression. Patients with genetically altered CD73 tended to have a better overall survival than patients with wild-type CD73. Both PD-1/PD-L1 and CD73/A2aR signaling mediated the immunosuppressive microenvironment in DLBCL. The numbers of CD8+ T cells with PD-1 and A2aR expression were positively correlated with the number of dysfunctional CD8+ T cells (R2=0.974, p=0.013). According to the grades of dysfunctional CD8+ T cells we defined, grade 1 dysfunctional CD8+ T cells, with either PD-1+ or A2aR+, were significantly associated with poorer survival than grade 0 dysfunctional CD8+ T cells, with both PD-1- and A2aR-; and patients with grade 2 dysfunctional CD8+ T cells showed the worst clinical outcomes.
Conclusions:
This study describes the additional genetic basis of PD-L1 overexpression and characterizes certain genetic alterations of CD73/A2aR in DLBCL. The degree of T-cell dysfunction is correlated with clinical outcomes. Strategies that reverse T-cell dysfunction by inhibiting PD-1/PD-L1/L2, particularly in combination with CD73/A2aR, may show potential as effective therapeutic options for DLBCL.
Insights
This study reveals genetic alterations in PD-L1 and CD73/A2aR pathways in diffuse large B-cell lymphoma (DLBCL). T-cell dysfunction correlates with survival, suggesting combined inhibition strategies for DLBCL treatment.
Area of Science:
- Immunology
- Oncology
- Genetics
Background:
- The PD-1/PD-L1/L2 pathway and CD73/A2aR adenosine signaling are crucial immune checkpoints in cancer.
- Investigating these pathways' genetic characteristics in diffuse large B-cell lymphoma (DLBCL) is essential for therapeutic development.
Purpose of the Study:
- To explore the genetic landscape of PD-1/PD-L1/L2 and CD73/A2aR in DLBCL.
- To evaluate the impact of these genetic alterations on the tumor microenvironment and T-cell dysfunction.
- To correlate T-cell dysfunction with clinical outcomes in DLBCL patients.
Main Methods:
- Whole-exome and targeted deep sequencing were employed to analyze PD-1/PD-L1/L2 and CD73/A2aR.
- RNA sequencing assessed the immunosuppressive effects of these pathways.
- Single-cell RNA sequencing and multiplex immunofluorescence identified and quantified dysfunctional CD8+ T cells.
Main Results:
- SP140 translocation and PD-L1/PD-L2 inversion were identified, leading to PD-L1 upregulation.
- CD73 genetic mutations did not affect its expression but were associated with better overall survival.
- PD-1/PD-L1 and CD73/A2aR signaling contribute to an immunosuppressive tumor microenvironment, with T-cell dysfunction grades correlating with survival outcomes.
Conclusions:
- This study elucidates the genetic basis for PD-L1 overexpression and CD73/A2aR alterations in DLBCL.
- T-cell dysfunction is a significant prognostic factor in DLBCL.
- Combined inhibition of PD-1/PD-L1/L2 and CD73/A2aR pathways presents a promising therapeutic strategy for DLBCL.
