Abstract 908
Background
Romidepsin (FK228), a histone deacetylase inhibitor (HDACi), has anti-tumor effects against several types of solid tumors. Studies have suggested that HDACi could upregulate PD-L1 expression in tumor cells, changing the state of anti-tumor immune responses. However, the influence of enhanced PD-L1 expression in tumor cells induced by romidepsin on anti-tumor immune responses are still under debate. So, the purpose of this study was to explore the anti-tumor effects and influence on immune responses of romidepsin in colon cancer.
Methods
The effects of romidepsin on proliferation, cell cycle and apoptosis in the murine colon cancer cell lines CT26 and MC38 were evaluated. PD-L1 expression levels were examined before and after treatment with romidepsin. To analyze the mechanisms through which romidepsin regulates PD-L1 expression, the acetylation of histones H3 and H4 and transcription factor BRD4 was measured. The influence of romidepsin on FOXP3+ regulatory T cells (Tregs), Th1/Th2 balance and IFN-γ+CD8+ T cells was evaluated in a subcutaneous transplanted tumor model and a colitis-associated cancer (CAC) model.
Results
The results indicated that romidepsin inhibited proliferation, induced G0/G1 cell cycle arrest and increased apoptosis in CT26 and MC38 cells. Romidepsin treatment increased PD-L1 expression in CT26 and MC38 cells via increasing the acetylation levels of histones H3 and H4 and regulating the transcription factor BRD4. In subcutaneous transplant tumor mice and CAC mice, romidepsin increased the percentage of FOXP3+ Tregs, decreased the ratio of Th1/Th2 cells and decreased the percentage of IFN-γ+CD8+ T cells in the peripheral blood and the tumor microenvironment. Upon combination with an anti-PD-1 antibody, the anti-tumor effects were enhanced, and the influence on CD4+ and CD8+ T cells was partially reversed.
Conclusions
Although romidepsin had direct anti-tumor effects in murine colon cancer, it increased PD-L1 expression in tumor cells and the percentage of immune-suppressive cells. Combination with anti-PD-1 antibody augmented the anti-tumor effects by reversing the influence of romidepsin on immune cells.
Clinical trial identification
Editorial acknowledgement
Legal entity responsible for the study
The author.
Funding
National Natural Science Foundation of China.
Disclosure
The author has declared no conflicts of interest.
Resources from the same session
5629 - Outcome of triple negative inflammatory breast cancers (TNIBC) treated with dose dense neoadjuvant epirubicin cyclophosphmide, prognostic impact of pre and post neoadjuvant chemotherapy (NAC) tumor infiltrating lymphocytes (TIL) and post NAC lymphovascular invasion
Presenter: Luca Campedel
Session: Poster Display session 2
Resources:
Abstract
5792 - A novel PET parameter for cancer stem cell metabolism: early prediction of chemosensitivity to neoadjuvant chemotherapy in locally advanced breast cancer
Presenter: Chanwoo Kim
Session: Poster Display session 2
Resources:
Abstract
3728 - Using nodal ratio to predict recurrence in patients with 4 or more positive lymph nodes early stage breast cancer
Presenter: Besma Graja
Session: Poster Display session 2
Resources:
Abstract
3395 - Re-sentinel node biopsy for local recurrence after breast-conserving surgery
Presenter: Yuka Matsubara
Session: Poster Display session 2
Resources:
Abstract
4302 - Assessment of prognostic and therapeutic factors in men with breast cancer
Presenter: Daniel Herrero Rivera
Session: Poster Display session 2
Resources:
Abstract
4263 - Genomic Profiling of Chinese Breast Cancer Patients
Presenter: Zhonghua Tao
Session: Poster Display session 2
Resources:
Abstract
2406 - Genome copy number alteration burden represents predictor of response in long-term, never relapse exceptional responders of trastuzumab-treated HER2+ metastatic breast cancer
Presenter: Naomi Walsh
Session: Poster Display session 2
Resources:
Abstract
2575 - Next-generation DNA Sequencing (NGS) Results for Tumors From Phase 2 ABRAZO Study of Talazoparib After Platinum or Cytotoxic Non-Platinum Regimens in Patients (pts) With Advanced Breast Cancer (ABC) and Germline BRCA1/2 (gBRCA) Mutations
Presenter: Nicholas C. Turner
Session: Poster Display session 2
Resources:
Abstract
4499 - FGFR1 and CCND1 gene amplifications are associated with breast cancer resistance to aromatase inhibitors
Presenter: Evgeny Imyanitov
Session: Poster Display session 2
Resources:
Abstract
4110 - Clinicopathologic features of BRCA mutated breast cancer patients: Hacettepe Experience
Presenter: Sercan Aksoy
Session: Poster Display session 2
Resources:
Abstract