Radiation and Immunotherapy in Upper Gastrointestinal Cancers: The Current State of Play

Roles of cGAS-STING Pathway in Radiotherapy Combined with Immunotherapy for Hepatocellular Carcinoma

Although great strides have been made in the management and treatment of hepatocellular carcinoma (HCC), its prognosis is still poor yielding a high mortality. Immunotherapy is recommended for treating advanced HCC, but its efficiency is hampered because of hepatic immunosuppression. Stimulator of interferon genes (STING) pathway, serving as a critical cytoplasmic DNA-sensing process, is reported to initiate the antitumor immune response, and link the innate immunity to the adaptive immune system. Radiotherapy has been well acknowledged to induce destruction and release of tumor-derived DNA into the cytoplasm, which then activates the cGAS-STING pathway. On this basis, radiotherapy can be used as a sensitizer for immunotherapy, and its combination with immunotherapy may bring in changes to the suboptimal efficacy of immune checkpoint inhibitor monotherapy. In this review, we summarized the roles of cGAS-STING pathway in regulation of radiotherapy combined with immunotherapy for treating HCC.

Non-coding RNAs in radiotherapy resistance: Roles and therapeutic implications in gastrointestinal cancer

Radiotherapy has become an indispensable and conventional means for patients with advanced solid tumors including gastrointestinal cancer. However, innate or acquired radiotherapy resistance remains a significant challenge and greatly limits the therapeutic effect, which results in cancer relapse and poor prognosis. Therefore, it is an urgent need to identify novel biomarkers and therapeutic targets for clarify the biological characteristics and mechanism of radiotherapy resistance. Recently, lots of studies have revealed that non-coding RNAs (ncRNAs) are the potential indicators and regulators of radiotherapy resistance via the mediation of various targets/pathways in different cancers. These findings may serve as a potential therapeutic strategy to overcome radiotherapy resistance. In this review, we will shed light on the recent findings regarding the functions and regulatory mechanisms of ncRNAs following radiotherapy, and comprehensively discuss their potential as biomarkers and therapeutic targets in radiotherapy resistance of gastrointestinal cancer.

Visceral adipose tissue secretome from early and late-stage oesophageal cancer patients differentially affects effector and regulatory T cells

AIM

Visceral obesity is a key risk factor in the development of oesophagogastric junctional adenocarcinoma (OGJ), predominantly via generation of systemic low grade inflammation. Obesity-induced inflammation promotes resistance to current standards of care, enhancing tumour cell growth and survival. This study investigates the effect of the visceral adipose tissue secretome from OGJ patients with early versus advanced tumours on T-cell immunity and the role of immune checkpoint blockade in enhancing anti-tumour immunity.

METHODS AND RESULTS

Visceral adipose conditioned media (ACM) from both early and late-stage OGJ patients significantly altered T cell activation status, upregulating co-stimulatory marker CD27 on T cells. ACM from both early and late-stage OGJ patients significantly altered immune checkpoint expression profiles downregulating immune checkpoints (ICs) on the surface of dual Th1/17-like and Th17-like cells and upregulating ICs on the surface of Th1-like cells and Treg cells. ACM derived from early-stage OGJ patients but not late-stage OGJ patients increased IFN-γ production by T cells. The addition of immune checkpoint blockers (ICBs) did not increase IFN-γ production by T cells in the presence of late-stage ACM, collectively highlighting the dichotomous immunostimulatory effect of early-stage ACM and immune-inhibitory effect of late-stage ACM. Interestingly, ACM from early-stage OGJ patients was more pro-inflammatory than ACM from late-stage patients, reflected by decreased levels of IL-17A/F, TNF-α, IL-1RA and IL-5.

CONCLUSION

The ACM-induced upregulation of ICs on T cells highlights a therapeutic vulnerability that could be exploited by ICBs to harness anti-cancer immunity and improve clinical outcomes for OGJ patients. Schematic workflow - (A) visceral adipose tissue was taken from OAC patients at time of surgery and cultured for 72 h in media. (B) The harvested ACM was co-cultured with healthy donor PBMCs that were concurrently activated with anti-CD3/28 for 48 h and T cell immunophenotyping was carried out by flow cytometry. Key findings - (A) Early and late stage ACM enhanced a Th1-like phenotype and upregulated CTLA-4 on Th1-like cells. A Th17-like phenotype was also enhanced in addition with a Treg-like phenotype. CTLA-4 and PD-L1 were upregulated on the surface of Treg-like cells. (B) ICB-attenuated IL-17 production by T cells. However, ACM attenuated ICB-mediated reduction in IL-10 production by T cells. Higher levels of pro-inflammatory factors were found in early stage ACM compared with late stage ACM.

FLOT and CROSS chemotherapy regimens alter the frequency of CD27+ and CD69+ T cells in oesophagogastric adenocarcinomas: implications for combination with immunotherapy

Combining immunostimulatory chemotherapies with immunotherapy is an attractive strategy to enhance treatment responses in oesophagogastric junctional adenocarcinoma (OGJ). This study investigates the immunostimulatory properties of FLOT, CROSS and MAGIC chemotherapy regimens in the context of OGJ using in vitro and ex vivo models of the treatment-naïve and post-chemotherapy treated tumour microenvironment. FLOT and CROSS chemotherapy regimens increased surrogate markers of immunogenic cell death (HMGB1 and HLA-DR), whereas the MAGIC treatment regimen decreased HMGB1 and HLA-DR on OGJ cells (markedly for epirubicin). Tumour-infiltrating and circulating T cells had significantly lower CD27 expression and significantly higher CD69 expression post-FLOT and post-CROSS treatment. Similarly, the supernatant from FLOT- and CROSS-treated OGJ cell lines and from FLOT- and CROSS-treated OGJ biopsies cultured ex vivo also decreased CD27 and increased CD69 expression on T cells. Following 48 h treatment with post-FLOT and post-CROSS tumour conditioned media the frequency of CD69+ T cells in culture negatively correlated with the levels of soluble immunosuppressive pro-angiogenic factors in the conditioned media from ex vivo explants. Supernatant from FLOT- and CROSS-treated OGJ cell lines also increased the cytotoxic potential of healthy donor T cells ex vivo and enhanced OGJ patient-derived lymphocyte mediated-killing of OE33 cells ex vivo. Collectively, this data demonstrate that FLOT and CROSS chemotherapy regimens possess immunostimulatory properties, identifying these chemotherapy regimens as rational synergistic partners to test in combination with immunotherapy and determine if this combinatorial approach could boost anti-tumour immunity in OGJ patients and improve clinical outcomes.

PD-1 inhibitors in esophageal cancer: a systematic review of the oncological outcomes associated with PD-1 blockade and the evolving therapeutic paradigm

Patients with esophageal or gastroesophageal junction (GEJ) cancer who fail to respond to chemoradiotherapy have a poor clinical prognosis. Recent clinical trials have investigated the use of immune checkpoint inhibitors in these patients. The use of programmed cell death protein 1 (PD-1) inhibitors has emerged as exciting therapeutic options in the curative and palliative setting of other solid tumors. We assessed the efficacy and safety of PD-1 inhibitors in esophageal and GEJ cancers. This systematic review was performed in accordance with the PRISMA guidelines. A comprehensive electronic literature search from the EMBASE, Pubmed, Scopus, MEDLINE, and Google Scholar databases was conducted up to 25 July 2021. This review identified 11 eligible studies reporting outcomes of 3451 patients treated with PD-1 blockade compared with 2286 patients treated with either a placebo or the standard regimen of chemotherapy. Clinically significant improvements in median overall survival have been demonstrated in advanced and metastatic esophageal and GEJ cancer while maintaining acceptable safety profiles. Promising survival data have also recently emerged from PD-1 blockade in the adjuvant setting. PD-1 blockade in esophageal and GEJ cancer has delivered impressive survival benefit while remaining well tolerated. Its use in the adjuvant setting will further advance treatment options, and more advancements in this area of therapy are highly anticipated. However, further characterization of the PD-1/programmed death ligand-1 pathway and elucidation of biomarkers to predict response are required to optimize patient selection.

Cooperation between chemotherapy and immune checkpoint blockade to enhance anti-tumour T cell immunity in oesophageal adenocarcinoma

Response rates to immune checkpoint blockade (ICB) remain low in oesophageal adenocarcinoma (OAC). Combining ICB with immunostimulatory chemotherapies to boost response rates is an attractive approach for converting 'cold' tumours into 'hot' tumours. This study profiled immune checkpoint (IC) expression on circulating and tumour-infiltrating T cells in OAC patients and correlated these findings with clinical characteristics. The effect of first-line chemotherapy regimens (FLOT and CROSS) on anti-tumour T cell immunity was assessed to help guide design of ICB and chemotherapy combinations in the first-line setting. The ability of ICB to enhance lymphocyte-mediated cytolysis of OAC cells in the absence and presence of post-FLOT and post-CROSS chemotherapy tumour cell secretome was assessed by a CCK-8 assay. Expression of ICs on T cells positively correlated with higher grade tumours and a subsequent poor response to neoadjuvant treatment. First-line chemotherapy regimens substantially altered IC expression profiles of T cells increasing PD-1, A2aR, KLRG-1, PD-L1, PD-L2 and CD160 and decreasing TIM-3 and LAG-3. In addition, pro-inflammatory T cell cytokine profiles were enhanced by first-line chemotherapy regimens. T cell activation status was significantly altered; both chemotherapy regimens upregulated co-stimulatory markers ICOS and CD69 yet downregulated co-stimulatory marker CD27. However, ICB attenuated chemotherapy-induced downregulation of CD27 on T cells and promoted differentiation of effector memory T cells into a terminally differentiated state. Importantly, dual nivolumab-ipilimumab treatment increased lymphocyte-mediated cytolysis of OAC cells, an effect further enhanced in the presence of post-FLOT tumour cell secretome. These findings justify a rationale to administer ICBs concurrently with first-line chemotherapies.

The Prognostic Value of the Lymph Node in Oesophageal Adenocarcinoma; Incorporating Clinicopathological and Immunological Profiling

Simple Summary

Oesophageal cancer rates are increasing rapidly with patients often presenting at an advanced stage. The current approach to treatment involves radiotherapy, chemotherapy, or combination chemoradiotherapy with surgery; however, only a fraction of these patients will achieve meaningful responses. Therefore, there is a need to better understand the tumour and lymph node microenvironments to inform future treatment strategies. This study measured immune markers including immune checkpoint expression in tumour and lymph node tissue in oesophageal cancer patients and patient clinical outcomes, including survival time, response to treatment, and adverse events. We report herein that nodal metastases is of equal prognostic importance to clinical tumour stage and tumour regression grade in OAC and we observed a more immunosuppressive microenvironment in the tumour compared with the lymph node.

Abstract

Response rates to the current gold standards of care for treating oesophageal adenocarcinoma (OAC) remain modest with 15–25% of patients achieving meaningful pathological responses, highlighting the need for novel therapeutic strategies. This study consists of immune, angiogenic, and inflammatory profiling of the tumour microenvironment (TME) and lymph node microenvironment (LNME) in OAC. The prognostic value of nodal involvement and clinicopathological features was compared using a retrospective cohort of OAC patients (n = 702). The expression of inhibitory immune checkpoints by T cells infiltrating tumour-draining lymph nodes (TDLNs) and tumour tissue post-chemo(radio)therapy at surgical resection was assessed by flow cytometry. Nodal metastases is of equal prognostic importance to clinical tumour stage and tumour regression grade (TRG) in OAC. The TME exhibited a greater immuno-suppressive phenotype than the LNME. Our data suggests that blockade of these checkpoints may have a therapeutic rationale for boosting response rates in OAC.