Abstract 4331
Background
Esophageal adenocarcinoma (EAC) is a lethal disease with poor prognosis due to the limited treatment options. STING is a transmembrane protein that activates transcription of type I IFN genes, resulting in stimulation of APCs and enhanced CD8+ T cell infiltration. Recently, STING agonists have demonstrated not only potent efficacy against the primary tumor but also in the distant metastasis and recurrences. Interestingly, combining the STING agonist with radiotherapy and immune checkpoint inhibitors has demonstrated durable anticancer activity in solid tumors. Hence, the aim of the study was to specifically evaluate the efficacy and immunologic regulatory effects of STING agonist +/- radiation in an established EAC model.
Methods
Esophagojejunostomy was performed on rats to induce gastroduodenojejunal reflux leading to the development EAC. At 32 weeks post operatively, rats received either 50μg STING (ADU-S100) +/- 16Gy radiation or placebo (PBS) +/- 16Gy radiation. Drug or placebo control was delivered intratumorally twice via endoscopy, 3 weeks apart. Drug efficacy was evaluated by pre- and post- treatment MRI, serial biopsies, histology and RT-PCR. Additionally, IHC was performed using CD8 and PD-L1 antibodies.
Results
There was no difference in observed mortality among the groups (p = 0.3). Mean MRI tumor volume decreased by 19.7% and 18.6% in ADU-S100 and ADU-S100 + radiation animals and increased by 34.7% and 90.3% in placebo and placebo + radiation animals, respectively (P = 0.0006). Downstream gene expression, pre- to on- treatment, demonstrated upregulation of IFNγ (p = 0.0003) and TNFα (p = 0.02) in the treatment groups vs. placebo. The most remarkable change was observed in ADU-S100 group (5.5X IFNγ and 10.9X TNFα; p < 0.01). On- or post- treatment, radiation alone, ADU-S100 alone and ADU-S100 + radiation groups demonstrated significantly elevated densities of CD8+ T cells and PD-L1+ tumor and immune stromal cells compared to placebo (p < 0.01).
Conclusions
ADU-S100 exhibits potent antitumor efficacy and a promising immunomodulatory profile in a de novo EAC model providing the rationale for clinical strategies, likely in combination with immune checkpoint inhibitors.
Clinical trial identification
Editorial acknowledgement
Legal entity responsible for the study
The authors.
Funding
Has not received any funding.
Disclosure
A.H. Zaidi: Shareholder / Stockholder / Stock options: Array Biopharma; Research grant / Funding (institution): Eli Lilly & Co. All other authors have declared no conflicts of interest.
Resources from the same session
3240 - Efficacy and safety of trifluridine/tipiracil (FTD/TPI) in European patients with heavily pretreated metastatic gastric cancer (mGC): an analysis of the TAGS study
Presenter: Maria Alsina
Session: Poster Display session 2
Resources:
Abstract
733 - Clinical experience: ramucirumab with FOLFIRI/XELIRI as a second line for patients with metastatic gastric cancer
Presenter: Tatiana Titova
Session: Poster Display session 2
Resources:
Abstract
2186 - Efficacy and safety of apatinib for the treatment of AFP-producing gastric cancer
Presenter: Ningning Li
Session: Poster Display session 2
Resources:
Abstract
3172 - Apatinib in combination with docetaxol and S1 chemotherapy in the first line treatment of metastatic gastric cancer
Presenter: Ling Xia
Session: Poster Display session 2
Resources:
Abstract
3982 - Parameters of local cellular immunity in metastatic gastric cancer
Presenter: Aleksandr Sagakyants
Session: Poster Display session 2
Resources:
Abstract
5102 - Germline pathogenic mutations in Chinese patients with gastric cancer identified by next-generation sequencing (NGS)
Presenter: Xiaotian Zhang
Session: Poster Display session 2
Resources:
Abstract
5012 - Inhibition of the PI3K pathway in HER2-positive gastric cancer
Presenter: Sinead Toomey
Session: Poster Display session 2
Resources:
Abstract
4803 - Investigation on gastric cancer susceptibility genes in Chinese early-onset diffuse gastric cancer
Presenter: Yi Feng
Session: Poster Display session 2
Resources:
Abstract
4778 - A correlation analysis between survival rate and the characteristic gene of gastric cancer based on bioinformatics analysis
Presenter: Yi-wen Zhang
Session: Poster Display session 2
Resources:
Abstract
4805 - Phase I study of apatinib combined with POF (paclitaxel plus FOLFOX) in patients (pts) with treatment-naïve advanced gastric cancer (TNAGC)
Presenter: Rongbo LIN
Session: Poster Display session 2
Resources:
Abstract