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Published on: May 6, 2019
Dual PD-1/IL-2Rα targeting restores CD8+ T cell fitness via STAT5/CD47 axis in SMARCA4-deficient NSCLC
Xiaoling Shang1, Bo Cheng2, Zhenxiang Li3
1Department of Internal Medicine-Oncology, Shandong Cancer Hospital and Institute, Shandong First Medical University and Shandong Academy of Medical Sciences, Jinan 250117, China.
Abstract:
SMARCA4-deficient non-small cell lung cancer (NSCLC) is a genomically distinct and clinically aggressive subtype characterized by primary resistance to immune checkpoint inhibitors. This study identifies that SMARCA4 deficiency profoundly disrupts the interleukin (IL)-2-STAT5 signaling pathway in tumor-infiltrating CD8+ T cells by suppressing IL-2 receptor alpha (IL-2Rα) (CD25) expression, leading to severe T cell exhaustion and resistance to PD-1 inhibition. An engineered PD-1/IL-2 bispecific antibody (bsAb) with α-receptor-targeting activity reverses this defect across multiple preclinical models by co-engaging PD-1 and delivering a CD25-targeted IL-2 signal, thereby restoring STAT5 activation and effector function in exhausted CD8+ T cells. Mechanistically, PD-1/IL-2 bsAb-driven STAT5 activation transcriptionally upregulates CD47 on CD8+ T cells, which shields them from macrophage-mediated phagocytosis and enhances T cell survival in the tumor microenvironment. These findings delineate a role for the IL-2-STAT5-CD47 axis in immune evasion and suggest reactivating this pathway with PD-1/IL-2 bsAb may represent a therapeutic strategy to overcome resistance in this subtype.
Insights
SMARCA4-deficient non-small cell lung cancer (NSCLC) resists immunotherapy due to disrupted IL-2 signaling in T cells. A novel bispecific antibody targeting PD-1 and IL-2 restores T cell function and overcomes resistance.
Area of Science:
- Oncology
- Immunology
- Molecular Biology
Background:
- SMARCA4-deficient non-small cell lung cancer (NSCLC) is aggressive and resistant to immune checkpoint inhibitors.
- This resistance is linked to impaired interleukin (IL)-2-STAT5 signaling in tumor-infiltrating CD8+ T cells.
- Specifically, SMARCA4 deficiency suppresses IL-2 receptor alpha (CD25) expression, causing T cell exhaustion.
Purpose of the Study:
- To investigate the mechanism of immune evasion in SMARCA4-deficient NSCLC.
- To identify a therapeutic strategy to overcome resistance to PD-1 inhibition in this subtype.
- To evaluate the efficacy of a novel PD-1/IL-2 bispecific antibody (bsAb).
Main Methods:
- Analysis of IL-2-STAT5 signaling pathway in tumor-infiltrating CD8+ T cells from SMARCA4-deficient NSCLC models.
- Development and testing of an engineered PD-1/IL-2 bsAb with CD25-targeting activity.
- Assessment of T cell exhaustion, STAT5 activation, CD47 expression, and anti-tumor effects in preclinical models.
Main Results:
- SMARCA4 deficiency suppresses CD25 expression, impairs IL-2-STAT5 signaling, and leads to exhausted CD8+ T cells resistant to PD-1 blockade.
- The PD-1/IL-2 bsAb restored STAT5 activation and effector function in exhausted CD8+ T cells.
- bsAb-induced STAT5 activation upregulated CD47 on CD8+ T cells, enhancing their survival by inhibiting phagocytosis.
Conclusions:
- The IL-2-STAT5-CD47 axis plays a critical role in immune evasion in SMARCA4-deficient NSCLC.
- Reactivating this pathway with a PD-1/IL-2 bsAb is a promising therapeutic strategy.
- This approach may overcome primary resistance to PD-1 inhibitors in this aggressive NSCLC subtype.
