PD-1 blockade elicits a systemic immune response but not in the tumor of TNBC mice
Xiaodan Hong1, Mei Ma1,2, Hongmei Cui2
1Longhua Hospital Affiliated to Shanghai University of Traditional Chinese Medicine, Shanghai 200032, China.
Abstract:
Triple-negative breast cancer (TNBC) is an aggressive subtype of breast cancer with limited treatment options due to the absence of hormone receptors and HER2 amplification. Immune checkpoint blockade, particularly targeting PD-1/PD-L1, has emerged as a promising therapeutic strategy. However, the response rate of TNBC patients to this monotherapy remains low. This study explores the systemic effect of PD-1 blockade on the immune and hematopoietic systems in 4T1 TNBC mice and demonstrates its limited efficacy in reducing the tumor burden and changing the number of tumor-infiltrating immune cells. However, PD-1 blockade increases systemic immune activity, as demonstrated by increased T cells and DCs in the peripheral blood, which may be associated with inflammatory side effects of this treatment. In addition, PD-1 blockade does not rescue the hematopoietic damage caused by TNBC, highlighting a limitation in long-term response. Furthermore, PD-1 blockade in tumor-free mice leads to an increase in hematopoietic stem/progenitor cells, suggesting that PD-1 blockade may yield better benefits post-tumor resection.
Insights
Immune checkpoint blockade shows limited efficacy in triple-negative breast cancer (TNBC) by not reducing tumor burden. However, it boosts systemic immunity and may benefit patients after tumor removal.
Area of Science:
- Oncology
- Immunology
- Hematology
Background:
- Triple-negative breast cancer (TNBC) is aggressive with few treatment options.
- Immune checkpoint inhibitors (PD-1/PD-L1 blockade) show promise but have low response rates in TNBC.
- Understanding systemic effects is crucial for improving TNBC therapy.
Purpose of the Study:
- To investigate the systemic effects of PD-1 blockade on the immune and hematopoietic systems in a 4T1 TNBC mouse model.
- To evaluate the efficacy of PD-1 blockade in reducing tumor burden and altering tumor-infiltrating immune cells.
- To assess the impact of PD-1 blockade on hematopoietic damage and stem/progenitor cells.
Main Methods:
- Utilized a 4T1 TNBC mouse model.
- Administered PD-1 blockade therapy.
- Analyzed peripheral blood for immune cell populations (T cells, DCs).
- Assessed tumor burden and tumor-infiltrating immune cells.
- Evaluated hematopoietic stem/progenitor cell populations.
Main Results:
- PD-1 blockade had limited efficacy in reducing tumor burden and altering tumor-infiltrating immune cells.
- Increased systemic immune activity was observed, with elevated T cells and dendritic cells (DCs) in peripheral blood.
- PD-1 blockade did not reverse TNBC-induced hematopoietic damage.
- In tumor-free mice, PD-1 blockade increased hematopoietic stem/progenitor cells.
Conclusions:
- PD-1 blockade shows limited direct anti-tumor efficacy in this TNBC model.
- Increased systemic immune activity suggests potential inflammatory side effects.
- PD-1 blockade does not mitigate long-term hematopoietic damage from TNBC.
- PD-1 blockade may offer benefits in the post-resection setting for TNBC patients.
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