Immune checkpoint inhibitors in resectable gastroesophageal cancers - a review

Gastroesophageal cancers (GEC) have a poor survival rate of 20–30% at 5 years, often due to delayed presentations. Neoadjuvant chemoradiotherapy (CRT) followed by surgery or peri-operative chemotherapy and surgery are widely used as the standard of care for patients with resectable GEC. Immune checkpoint inhibitors (ICIs) have improved survival in metastatic and recurrent GEC which led to their application in resectable GEC. Based on the pivotal CheckMate 577 study results, the Food and Drug Administration (FDA) approved nivolumab for patients with completely resected high-risk esophageal or gastroesophageal junction cancer (GEJC). Several ongoing trials with many ICIs could potentially improve resectable GEC outcomes. This review explores the rationale for using ICIs in resectable GEC and discusses the significance of reported clinical trials. Finally, we will examine some ongoing clinical trials and the challenges as well as prospects of ICIs in resectable GEC.

Immunotherapy in Gastroesophageal Cancers: Current Evidence and Ongoing Trials

OPINION STATEMENT

Data supporting the use of immunotherapy in the treatment of gastroesophageal cancer continues to evolve. The promising results from adjuvant immunotherapy and trials combining immunotherapy plus chemotherapy in the 1L setting have led to broad US FDA approvals. Among the PD-L1 negative subgroups, the magnitude of benefit is diminished; effective therapy for this population remains an unmet need. A detailed biologic understanding of the PD-L1 negative (and low) population represents a barrier to developing effective combination therapies, although combination angiogenesis inhibitors and immunotherapy look encouraging. Early phase clinical trials, particularly with pembrolizumab plus lenvatinib (EPOC 1706), demonstrated a clear signal independent of PD-L1, and a confirmatory phase III trial of pembrolizumab plus lenvatinib is planned. Conceptually, it is important to think of immune checkpoint inhibitor therapy as targeted therapy, most active in clearly defined biomarker-selected populations. Pre-planned analyses have reliably shown a clear trend toward a greater magnitude of benefit in patients with higher PD-L1 expression, particularly CPS ≥ 5 and ≥ 10. Whether there is a linear relationship at higher cutoffs is not well known, though it likely represents smaller and smaller populations. Although beyond the scope of this clinically oriented review, recognition of the spatial and temporal heterogeneity in PD-L1 expression is important and repeat testing from progression samples across lines of therapy should be considered. Questions about additional predictive biomarkers, particularly plasma-derived, remain. Responses by tumor histology and location also differ, and special attention to these factors as well as MSI-H, HER2, and EBV subgroups in future trials is warranted. Questions regarding the incorporation of immunotherapy after progression on 1L immunotherapy plus chemotherapy combinations will arise as these combinations are used more frequently, and this represents a key area of future investigation. Overall, the role of immunotherapy continues to expand in GEA, and we welcome any additional tools for this difficult-to-treat group of cancers.

Comparative Dosimetric Analysis and Normal Tissue Complication Probability Modelling of Four-Dimensional Computed Tomography Planning Scans Within the UK NeoSCOPE Trial

AIMS

NeoSCOPE is a trial of two different neoadjuvant chemoradiotherapy regimens for resectable oesophageal cancer and was the first multicentre trial in the UK to incorporate four-dimensional computed tomography (4D-CT) into radiotherapy planning. Despite 4D-CT being increasingly accepted as a standard of care for lower third and junctional oesophageal tumours, there is limited evidence of its benefit over standard three-dimensional computed tomography (3D-CT).

MATERIALS

Using NeoSCOPE 4D-CT cases, we undertook a dosimetric comparison study of 3D-CT versus 4D-CT plans comparing target volume coverage and dose to organs at risk. We used established normal tissue complication probability models to evaluate the potential toxicity reduction of using 4D-CT plans in oesophageal cancer.

RESULTS

4D-CT resulted in a smaller median absolute PTV volume and lower dose levels for all reported constraints with comparable target volume coverage. NTCP modelling suggests a significant relative risk reduction of cardiac and pulmonary toxicity endpoints with 4D-CT.

CONCLUSION

Our work shows that incorporating 4D-CT into treatment planning may significantly reduce the toxicity burden from this treatment.

The Cancer-Immune Set Point in Oesophageal Cancer

Immunotherapy has achieved long-term disease control in a proportion of cancer patients, but determinants of clinical benefit remain unclear. A greater understanding of antitumor immunity on an individual basis is needed to facilitate a precision oncology approach. A conceptual framework called the "cancer-immune set point" has been proposed to describe the equilibrium between factors that promote or suppress anticancer immunity and can serve as a basis to understand the variability in clinical response to immune checkpoint blockade. Oesophageal cancer has a high mutational burden, develops from pre-existing chronic inflammatory lesions and is therefore anticipated to be sensitive to immune checkpoint inhibition. However, both tumour- and patient-specific factors including the immune microenvironment, the microbiome, obesity, and host genetics contribute to an immune set point that confers a lower-than-expected response to checkpoint blockade. Immunotherapy is therefore currently confined to latter lines of treatment of advanced disease, with no reliable predictive biomarker of response. In this review, we examine oesophageal cancer in the context of the cancer-immune set point, discuss factors that contribute to response to immunotherapeutic intervention, and propose areas requiring further investigation to improve treatment response.

Immunotherapy for esophageal cancer: a 2019 update

Esophageal cancer remains a global health concern with a dismal prognosis and an estimated 5-year survival rate of approximately 10-15%. Immunotherapy is a novel treatment approach representing an effective and promising option against several types of cancer. The development of new and efficacious immunotherapeutic strategies, such as adoptive cell therapy-based, antibody-based and vaccine-based therapies, aims to prevent immunological escape and modify immunological responses. In this review, we discuss the theoretical background and current status of immunotherapy for patients with esophageal cancer. We also present ongoing clinical trials and summarize key findings concerning survival and safety analyses.

Immune Checkpoint Inhibitors in Esophageal Cancers: are we Finally Finding the Right Path in the Mist?

Esophageal cancer remains a challenging disease due to limited treatment options and poor prognosis. In recent years, immune checkpoint inhibitors (ICI) have been proven to be safe and effective in the treatment of highly lethal malignancies, such as non-small cell lung cancer and melanoma. Recent clinical trials also showed promising activity in immune checkpoint inhibitors in pretreated advanced esophageal carcinoma and a potentially significant impact on the outcome of selected patients, independently of histology. Combination studies evaluating immunotherapy and chemotherapy and, in localized disease, radiotherapy are in progress and will hopefully confirm their promises in the near future. However, reliable predictive biomarkers are still lacking. Indeed, at present, the role of programmed cell death ligand 1 expression and other factors (such as microsatellite instability and tumor mutational burden) as predictive biomarkers of benefit to immune checkpoint inhibitors is still controversial. Our aim was to explore the rationale of ICIs in esophageal cancer, review the results already available in multiple settings, and investigate future perspectives with single-agent and combination strategies.