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
5203 - Novel fusion genes identified from matched primary and recurred breast cancers by RNA-sequencing
Presenter: Soojeong Choi
Session: Poster Display session 2
Resources:
Abstract
5873 - Association between PIK3CA mutation status and development of brain metastases in HR+/HER2- metastatic breast cancer
Presenter: Donna Fitzgerald
Session: Poster Display session 2
Resources:
Abstract
3588 - The role of AXL as mechanism of resistance to trastuzumab and a prognostic factor in breast cancer HER2 positive: a translational approach.
Presenter: Anna Adam-Artigues
Session: Poster Display session 2
Resources:
Abstract
5640 - Untargeted assessment of tumor fractions in plasma for monitoring and prognostication from metastatic breast cancer patients undergoing systemic treatment
Presenter: Marija Balic
Session: Poster Display session 2
Resources:
Abstract
2616 - Clinical application of mutational analysis in breast cancer patients: the relevance of PIK3CA analysis for precision medicine.
Presenter: Juan Miguel Cejalvo
Session: Poster Display session 2
Resources:
Abstract
3870 - A retrospective gene expression analysis of surgically-removed Breast Cancer Brain Metastasis (BCBM)
Presenter: Meritxell Mallafré-Larrosa
Session: Poster Display session 2
Resources:
Abstract
1240 - Endocrine therapy alone versus targeted combination strategy as first line treatment in elderly patients with hormone receptor-positive advanced breast cancer: meta-analysis of Phase II and III randomized clinical trials
Presenter: Claudia Omarini
Session: Poster Display session 2
Resources:
Abstract
5535 - Alpelisib (ALP) + fulvestrant (FUL) for patients with hormone receptor–positive (HR+), HER2− advanced breast cancer (ABC): management and time course of key adverse events of special interest (AESIs) in SOLAR-1
Presenter: Hope Rugo
Session: Poster Display session 2
Resources:
Abstract
3093 - Changes in Hormone-Receptor status in Luminal breast cancers between primary tumor and metastases: results of the observational cohort GIM-13 AMBRA Study
Presenter: Marina Cazzaniga
Session: Poster Display session 2
Resources:
Abstract
1378 - MONARCH 3: Updated time to chemotherapy and disease progression following abemaciclib plus aromatase inhibitor (AI) in HR+, HER2- advanced breast cancer (ABC)
Presenter: Miguel Martín
Session: Poster Display session 2
Resources:
Abstract