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
3180 - Genomic analysis of hepatobiliary lithiasis associated cholangiocarcinoma revealed a distinct subtype feature.
Presenter: Lunda Gu
Session: Poster Display session 2
Resources:
Abstract
4891 - Comparison of the impact of stereotactic body radiation therapy vs. radiofrequency ablation on liver function in patients with single hepatocellular carcinoma: A propensity score matching analysis
Presenter: Masayuki Ueno
Session: Poster Display session 2
Resources:
Abstract
3203 - Exploratory analysis based on tumor location and early metabolic tumor response of REACHIN, a randomized double-blinded placebo-controlled phase II trial of regorafenib after failure of gemcitabine/platinum-based chemotherapy for advanced and metastatic biliary tract tumors.
Presenter: Anne Demols
Session: Poster Display session 2
Resources:
Abstract
1602 - Predictive Value of Neutrophil-Lymphocyte Ratio (NLR) And Platelet-Lymphocyte Ratio (PLR) In Hepatocellular Carcinoma (HCC) Patients Treated with Nivolumab (N)
Presenter: Sirish Dharmapuri
Session: Poster Display session 2
Resources:
Abstract
2848 - Preliminary Safety and Pharmacokinetics of a New Lysosomotropic Oral Agent, GNS561, in a First-in-Human Study in Advanced Primary Liver Cancer Patients
Presenter: Ahmad Awada
Session: Poster Display session 2
Resources:
Abstract
1396 - A phase 1b trial of lenvatinib (LEN) plus pembrolizumab (PEMBRO) in unresectable hepatocellular carcinoma (uHCC): updated results
Presenter: Josep Llovet
Session: Poster Display session 2
Resources:
Abstract
1139 - Multicentric prospective study of validation of angiogenesis-related gene polymorphisms in HCC patients treated with sorafenib: Final results of INNOVATE study
Presenter: Andrea Casadei-gardini
Session: Poster Display session 2
Resources:
Abstract
4688 - Prognostic and predictive factors from the phase 3 CELESTIAL trial of cabozantinib (C) versus placebo (P) in previously treated advanced hepatocellular carcinoma (aHCC)
Presenter: Tim Meyer
Session: Poster Display session 2
Resources:
Abstract
1492 - A phase Ib study of pembrolizumab following trans-arterial chemoembolization (TACE) in hepatocellular carcinoma (HCC): PETAL.
Presenter: David Pinato
Session: Poster Display session 2
Resources:
Abstract
3159 - Anlotinib for advanced hepatocellular carcinoma: interim results from the phase II ALTER0802 study
Presenter: AiPing Zhou
Session: Poster Display session 2
Resources:
Abstract