Immune-based combination therapy for esophageal cancer

Esophageal cancer (EC) is an aggressive malignancy raising a healthcare concern worldwide. Standard treatment options include surgical resection, chemotherapy, radiation therapy, and targeted molecular therapy. The five-year survival rate for all stages of EC is approximately 20%, ranging from 5% to 47%, with a high recurrence rate and poor prognosis after treatment. Immunotherapy has shown better efficacy and tolerance than conventional therapies for several malignancies. Immunotherapy of EC, including immune checkpoint inhibitors, cancer vaccines, and adoptive cell therapy, has shown clinical advantages. In particular, monoclonal antibodies against PD-1 have a satisfactory role in combination therapy and are recommended for first- or second-line treatments. Here, we present a systematic summary and analysis of immunotherapy-based combination therapies for EC.

Pembrolizumab versus paclitaxel for previously treated PD-L1-positive advanced gastric or gastroesophageal junction cancer: 2-year update of the randomized phase 3 KEYNOTE-061 trial

BACKGROUND

In the phase 3 KEYNOTE-061 study (cutoff: 10/26/2017), pembrolizumab did not significantly prolong OS vs paclitaxel as second-line (2L) therapy in PD-L1 combined positive score (CPS) ≥ 1 gastric/GEJ cancer. We present results in CPS ≥ 1, ≥ 5, and ≥ 10 populations after two additional years of follow-up (cutoff: 10/07/2019).

METHODS

Patients were randomly allocated 1:1 to pembrolizumab 200 mg Q3W for ≤ 35 cycles or standard-dose paclitaxel. Primary endpoints: OS and PFS (CPS ≥ 1 population). HRs were calculated using stratified Cox proportional hazards models.

RESULTS

366/395 patients (92.7%) with CPS ≥ 1 died. Pembrolizumab demonstrated a trend toward improved OS vs paclitaxel in the CPS ≥ 1 population (HR, 0.81); 24-month OS rates: 19.9% vs 8.5%. Pembrolizumab incrementally increased the OS benefit with PD-L1 enrichment (CPS ≥ 5: HR, 0.72, 24-month rate, 24.2% vs 8.8%; CPS ≥ 10: 0.69, 24-month rate, 32.1% vs 10.9%). There was no difference in median PFS among treatment groups (CPS ≥ 1: HR, 1.25; CPS ≥ 5: 0.98; CPS ≥ 10: 0.79). ORR (pembrolizumab vs paclitaxel) was 16.3% vs 13.6% (CPS ≥ 1), 20.0% vs 14.3% (CPS ≥ 5), and 24.5% vs 9.1% (CPS ≥ 10); median DOR was 19.1 months vs 5.2, 32.7 vs 4.8, and NR vs 6.9, respectively. Fewer treatment-related AEs (TRAEs) occurred with pembrolizumab than paclitaxel (53% vs 84%).

CONCLUSION

In this long-term analysis, 2L pembrolizumab did not significantly improve OS but was associated with higher 24-month OS rates than paclitaxel. Pembrolizumab also increased OS benefit with PD-L1 enrichment among patients with PD-L1-positive gastric/GEJ cancer and led to fewer TRAEs than paclitaxel.

TRIAL REGISTRATION

ClinicalTrials.gov, NCT02370498.

Immunotherapy for gastric cancer: a 2021 update

Gastric cancer, the fifth most frequent cancer and the fourth leading cause of cancer deaths, accounts for a devastating death rate worldwide. Since the majority of patients with gastric cancer are diagnosed at advanced stages, they are not suitable for surgery and present with locally advanced or metastatic disease. Recent advances in immunotherapy have elicited a considerable amount of attention as viable therapeutic options for several cancer types. This work presents a summary of the currently ongoing clinical trials and critically addresses the efficacy of a large spectrum of immunotherapy approaches in the general population for gastric cancer as well as in relation to tumor genetic profiling.

Clinical and Recent Patents Applications of PD-1/PD-L1 Targeting Immunotherapy in Cancer Treatment-Current Progress, Strategy, and Future Perspective

Targeting PD-L1 and PD-1 interactions is a relatively new therapeutic strategy used to treat cancer. Inhibitors of PD-1/PD-L1 include peptides, small molecule chemical compounds, and antibodies. Several approved antibodies targeting PD-1 or PD-L1 have been patented with good curative effect in various cancer types in clinical practices. While the current antibody therapy is facing development bottleneck, some companies have tried to develop PD-L1 companion tests to select patients with better diagnosis potential. Meanwhile, many companies have recently synthesized small molecule inhibitors of PD-1/PD-L1 interactions and focused on searching for novel biomarker to predict the efficacy of anti-PD-1/PD-L1 drugs. This review summarized clinical studies and patent applications related to PD-1/PD-L1 targeted therapy and also discussed progress in inhibitors of PD-1/PD-L1.

Overcoming resistance to anti-PD1 and anti-PD-L1 treatment in gastrointestinal malignancies

In the last few years, the unprecedented results of immune checkpoint inhibitors have led to a paradigm shift in clinical practice for the treatment of several cancer types. However, the vast majority of patients with gastrointestinal cancer do not benefit from immunotherapy. To date, microsatellite instability high and DNA mismatch repair deficiency are the only robust predictive biomarkers of response to immune checkpoint inhibitors. Unfortunately, these patients comprise only 5%-10% of all gastrointestinal cancers. Several mechanisms of both innate and adaptive resistance to immunotherapy have been recognized that may be at least in part responsible for the failure of immune checkpoint inhibitors in this population of patients. In the first part of this review article, we provide an overview of the main clinical trials with immune checkpoint inhibitors in patients with gastrointestinal cancer and the role of predictive biomarkers. In the second part, we discuss the actual body of knowledge in terms of mechanisms of resistance to immunotherapy and the most promising approach that are currently under investigation in order to expand the population of patients with gastrointestinal cancer who could benefit from immune checkpoint inhibitors.

The safety and efficacy of anti-PD-1/anti-PD-L1 antibody therapy in the treatment of previously treated, advanced gastric or gastro-oesophageal junction cancer: A meta-analysis of prospective clinical trials

INTRODUCTION

So far, anti-PD-1/anti-PD-L1 antibody therapy is reportedly in treating gastric cancer or gastro-oesophageal junction cancer (GC/GEJC) in a number of clinical trials. Based on this, we conducted current meta-analysis to assess the safety and efficacy of anti-PD-1/anti-PD-L1 antibody for previously treated advanced GC/GEJC patients.

METHODS

We searched five electronic databases for eligible records. Outcomes were presented and analyzed by objective response rate (ORR), disease control rate (DCR), progression-free survival (PFS), overall survival (OS) and adverse effects (AEs).

RESULTS

Nine records involving 1388 participants were selected in our study. The pooled ORR, DCR, OS rate (6 month), PFS rate (6 month), OS rate (12 month) and PFS rate (12 month) were 10% (95% confidence interval [CI]: 6%-14%), 32% (95%CI: 25%-38%), 52% (95%CI: 44%-61%), 18% (95%CI: 13%-24%), 40% (95%CI: 31%-48%) and 8% (95%CI: 5%-10%), respectively. Meanwhile, grade≥3 AEs rate was 12% (95% CI: 10%-15%). Programmed death ligand 1 (PD-L1) positive cases had higher rate of ORR (odds ratio [OR]: 3.75, 95%CI: 2.09-6.74, P=0.58) compared with negative cases.

CONCLUSION

The results indicated that anti-PD-1/anti-PD-L1 antibody therapy has an effectual anti-tumor activity and controllable AEs in advanced GC/GEJC patients. Furthermore, overexpression of PD-L1 in advanced GC/GEJC patients had better ORR from anti-PD-1/anti-PD-L1 antibody therapy (PROSPERO registration number: CRD42018116480).

Differences in immune contextures among different molecular subtypes of gastric cancer and their prognostic impact

BACKGROUND

Gastric cancers have been recently classified in accordance with their molecular characteristics, thus demonstrating the complex nature of cancers and an association with the immune contexture within the tumor microenvironment. This study aimed to investigate the correlation between the molecular subtype and immune contexture of gastric cancers.

METHODS

The immune contexture, including the type, density, and location of tumor-infiltrating lymphocytes (TILs), of gastric cancer patients was examined and immune subtypes were classified based on it. In particular, PD-L1 expression on tumor cells and TILs and Foxp3⁺ TILs was assessed in accordance with molecular subtypes.

RESULTS

High levels of visual TIL estimates and Foxp3⁺ TILs were markedly associated with increased overall survival (P = 0.001, P < 0.001, separately). Immune subtypes were associated with tumor size, gross type, depth of invasion, lymph node metastatic status, lymphovascular invasion, perineural invasion, and microsatellite instability status. EBV-positive (C1) and MSI (C2) gastric cancers, considered subtypes with better prognosis, were significantly associated with high TIL levels (P < 0.05). In contrast, epithelial-mesenchymal transition (EMT, C3) gastric cancers with poor overall survival displayed low levels of Foxp3⁺ TILs. Type II tumors (low level of TILs/low PD-L1 expression) displayed a significant correlation with poor overall survival (P = 0.004) and accounted for the highest proportion in the aberrant p53-expressing (C4) gastric cancers.

CONCLUSION

The molecular subtype of gastric cancers is correlated with the immune subtype, including immune contexture and PD-L1 expression, within the tumor microenvironment.

Targeted and novel therapy in advanced gastric cancer

The systemic treatment options for advanced gastric cancer (GC) have evolved rapidly in recent years. We have reviewed the recent data of clinical trial incorporating targeted agents, including inhibitors of angiogenesis, human epidermal growth factor receptor 2 (HER2), mesenchymal-epithelial transition, epidermal growth factor receptor, mammalian target of rapamycin, claudin-18.2, programmed death-1 and DNA. Addition of trastuzumab to platinum-based chemotherapy has become standard of care as front-line therapy in advanced GC overexpressing HER2. In the second-line setting, ramucirumab with paclitaxel significantly improves overall survival compared to paclitaxel alone. For patients with refractory disease, apatinib, nivolumab, ramucirumab and TAS-102 have demonstrated single-agent activity with improved overall survival compared to placebo alone. Pembrolizumab has demonstrated more than 50% response rate in microsatellite instability-high tumors, 15% response rate in tumors expressing programmed death ligand 1, and non-inferior outcome in first-line treatment compared to chemotherapy. This review summarizes the current state and progress of research on targeted therapy for advanced GC.

Immune Checkpoint Blockade: The New Frontier in Cancer Treatment

Immune checkpoint blockers have revolutionized cancer treatment in recent years. These agents are now approved for the treatment of several malignancies, including melanoma, squamous and non-squamous non-small cell lung cancer, renal cell carcinoma, urothelial carcinoma, and head and neck squamous cell carcinoma. Studies have demonstrated the significant impact of immunotherapy versus standard of care on patient outcomes, including durable response and extended survival. The use of immunotherapy-based combination therapy has been shown to further extend duration of response and survival. Immunotherapies function through modulation of the immune system, which can lead to immune-mediated adverse events (imAEs). These include a range of dermatologic, gastrointestinal, endocrine, and hepatic toxicities, as well as other less common inflammatory events. ImAEs are typically low grade and manageable when identified early and treated with appropriate measures. Identifying the right patient for the right therapy will become more important as new immunotherapies and immunotherapy-based combinations are approved and costs of cancer care continue to rise.

Efficacy and safety of immune checkpoint inhibitors in advanced gastric or gastroesophageal junction cancer: a systematic review and meta-analysis

Background: Immune checkpoint inhibitors (ICI) have shown promising prospects in gastroesophageal junction (G/GEJ) cancer immunotherapy, many clinical trials have been carried out. Objective: To evaluate the efficacy and safety of ICI in G/GEJ cancer. Methods: The published English articles of PubMed, Cochrane Library, Embase, Web of Science were searched up to 30/09/2018. The efficacy and safety of ICI were analyzed by meta-analysis. Results: A total of 2003 patients from nine clinical trials were included. Anti-PD-1 treatment improved the 12-month, 18-month overall survival (OS) rate (RR, 1.79 p = 0.013; 2.20 p = 0.011) and prolonged the duration of response (DOR) (MSR, 3.27 p < 0.001). The objective response rate (ORR) in PD-L1+ patients was greater than PD-L1- (RR, 4.31 p < 0.001). Microsatellite instability-high (MSI-H) patients had higher ORR and disease control rate (DCR) than microsatellite stability (MSS) (RR, 3.40 p< 0.001; 2.26 p= 0.001). The most common grade ≥3 treatment-related adverse events (TRAEs) were fatigue, aspartate aminotransferase increased, hepatitis, pneumonitis, colitis, hypopituitarism. The TRAE incidence of anti-PD-1/PD-L1 was less than chemotherapy (TRAE RR = 0.64 p< 0.001; ≥3 TRAE RR = 0.37 p < 0.001). The incidence of ≥3 TRAEs of anti-PD-1/PD-L1 treatment was less than that of anti-CTLA-4 (11.7% vs 43.9%). Conclusions: ICI treatment could improve some but not all survival endpoints to advanced or metastatic G/GEJ cancer patients suggesting modest benefit and less adverse reactions. Anti-PD-1/PD-L1 therapy was more effective to PD-L1+, MSI-H, EBV+, or high tumor mutational burden patients.

KEYNOTE-585: Phase III study of perioperative chemotherapy with or without pembrolizumab for gastric cancer

BACKGROUND

Surgical resection is the only curative treatment option for gastric cancer. Despite widespread adoption of multimodality perioperative treatment strategies, 5-year overall survival rates remain low. In patients with advanced gastric or gastroesophageal junction adenocarcinoma, pembrolizumab has demonstrated promising efficacy and manageable safety as monotherapy in previously treated patients and as first-line therapy in combination with cisplatin and 5-fluorouracil. Combining chemotherapy with pembrolizumab in the neoadjuvant/adjuvant setting may benefit patients with locally advanced, resectable disease.

AIM

To describe the design and rationale for the global, multicenter, randomized, double-blind, Phase III KEYNOTE-585 study to evaluate the efficacy and safety of pembrolizumab plus chemotherapy compared with placebo plus chemotherapy as neoadjuvant/adjuvant treatment for localized gastric or gastroesophageal junction adenocarcinoma. ClinicalTrials.gov : NCT03221426.

Avelumab (anti-PD-L1) as first-line switch-maintenance or second-line therapy in patients with advanced gastric or gastroesophageal junction cancer: phase 1b results from the JAVELIN Solid Tumor trial

Background

We evaluated the antitumor activity and safety of avelumab, a human anti–PD-L1 IgG1 antibody, as first-line switch-maintenance (1 L-mn) or second-line (2 L) treatment in patients with advanced gastric/gastroesophageal cancer (GC/GEJC) previously treated with chemotherapy.

Methods

In a phase 1b expansion cohort, patients without (1 L-mn) or with (2 L) disease progression following first-line chemotherapy for advanced GC/GEJC received avelumab 10 mg/kg intravenously every 2 weeks. Endpoints included best overall response, progression-free survival (PFS), overall survival (OS), and safety.

Results

Overall, 150 patients were enrolled (1 L-mn, n = 90; 2 L, n = 60) and median follow-up in the 1 L-mn and 2 L subgroups was 36.0 and 33.7 months, respectively. The confirmed objective response rate was 6.7% in both subgroups (95% CI, 2.5–13.9% and 1.8–16.2%, respectively), including complete responses in 2.2% of the 1 L-mn subgroup (n = 2). In the 1 L-mn and 2 L subgroups, median duration of response was 21.4 months (95% CI, 4.0–not estimable) and 3.5 months (95% CI, 2.8–8.3) and disease control rates were 56.7 and 28.3%, respectively. Median PFS in the 1 L-mn and 2 L subgroups was 2.8 months (95% CI, 2.3–4.1) and 1.4 months (95% CI, 1.3–1.5), with 6-month PFS rates of 23.0% (95% CI, 14.7–32.4%) and 7.9% (95% CI, 2.6–17.2%), and median OS was 11.1 months (95% CI, 8.9–13.7) and 6.6 months (95% CI, 5.4–9.4), respectively. In the 1 L-mn subgroup, median OS measured from start of 1 L chemotherapy was 18.7 months (95% CI, 15.4–20.6). Across both subgroups, 20.7% had an infusion-related reaction of any grade. Other common treatment-related adverse events (TRAEs) of any grade included fatigue (10.0%) and nausea (6.7%). Treatment-related serious adverse events occurred in 4.0% of patients. Overall, 8.7% had a grade ≥3 TRAE, including 1 treatment-related death.

Conclusion

Avelumab showed clinical activity and an acceptable safety profile in patients with GC/GEJC.

Trial registration

ClinicalTrials.govNCT01772004; registered 21 January 2013.

Electronic supplementary material

The online version of this article (10.1186/s40425-019-0508-1) contains supplementary material, which is available to authorized users.

Discordancy and changes in the pattern of programmed death ligand 1 expression before and after platinum-based chemotherapy in metastatic gastric cancer

BACKGROUND

Our goal was to evaluate changes in PD-L1 expression in primary tumours of metastatic gastric cancer before and after chemotherapy.

METHODS

We evaluated the PD-L1 expression of 72 patients with primary gastric cancer, before and after palliative first-line platinum-based chemotherapy, between January 2015 and March 2017. The PD-L1 ratio was defined as pre-chemotherapy PD-L1 expression divided by the post-chemotherapy PD-L1 expression.

RESULTS

In 30 patients with PD-L1 negative pre-chemotherapy, 12 (40%) were positive post-chemotherapy; among the 42 patients with PD-L1 positive pre-chemotherapy, 24 (57.1%) were negative post-chemotherapy. The degree of PD-L1 expression decreased from 58.3% before chemotherapy to 41.7% after chemotherapy (P = 0.046). Among patients with complete response/partial response (CR/PR), the degree of PD-L1 expression decreased (P = 0.002), as well as PD-L1 positivity with statistical significance (P = 0.013) after chemotherapy, but not among patients with stable disease/progressive disease (SD/PD). Higher disease control rates (CR/PR/SD) were observed in patients with an elevated PD-L1 ratio (P = 0.043). Patients with a high PD-L1 ratio (> 1) were found to be associated with a better progression-free survival (HR 0.34, 95% CI 0.17-0.67, P = 0.002).

CONCLUSIONS

PD-L1 expression can change during chemotherapy. Moreover, changes in patterns of PD-L1 expression might be associated with patient prognosis and response to chemotherapy.

Resolution of Gastric Cancer-Promoting Inflammation: A Novel Strategy for Anti-cancer Therapy

The connection between inflammation and cancer was initially recognized by Rudolf Virchow in the nineteenth century. During the last decades, a large body of evidence has provided support to his hypothesis, and now inflammation is recognized as one of the hallmarks of cancer, both in etiopathogenesis and ongoing tumor growth. Infection with the pathogen Helicobacter pylori is the primary causal factor in 90% of gastric cancer (GC) cases. As we increase our understanding of how chronic inflammation develops in the stomach and contributes to carcinogenesis, there is increasing interest in targeting cancer-promoting inflammation as a strategy to treat GC. Moreover, once cancer develops and anti-cancer immune responses are suppressed, there is evidence of a substantial shift in the microenvironment and new targets for immune therapy emerge. In this chapter, we provide insight into inflammation-related factors, including T lymphocytes, macrophages, pro-inflammatory chemokines, and cytokines, which promote H. pylori-associated GC initiation and growth. While intervening with chronic inflammation is not a new practice in rheumatology or gastroenterology, this approach has not been fully explored for its potential to prevent carcinogenesis or to contribute to the treatment of GC. This review highlights current and possible strategies for therapeutic intervention including (i) targeting pro-inflammatory mediators, (ii) targeting growth factors and pathways involved in angiogenesis in the gastric tumor microenvironment, and (iii) enhancing anti-tumor immunity. In addition, we highlight a significant number of clinical trials and discuss the importance of individual tumor characterization toward offering personalized immune-related therapy.

T-Cell-Inflamed Gene-Expression Profile, Programmed Death Ligand 1 Expression, and Tumor Mutational Burden Predict Efficacy in Patients Treated With Pembrolizumab Across 20 Cancers: KEYNOTE-028

PURPOSE

Biomarkers that can predict response to anti-programmed cell death 1 (PD-1) therapy across multiple tumor types include a T-cell-inflamed gene-expression profile (GEP), programmed death ligand 1 (PD-L1) expression, and tumor mutational burden (TMB). Associations between these biomarkers and the clinical efficacy of pembrolizumab were evaluated in a clinical trial that encompassed 20 cohorts of patients with advanced solid tumors.

METHODS

KEYNOTE-028 ( ClinicalTrials.gov identifier: NCT02054806) is a nonrandomized, phase Ib trial that enrolled 475 patients with PD-L1-positive advanced solid tumors who were treated with pembrolizumab 10 mg/kg every 2 weeks for 2 years or until confirmed disease progression or unacceptable toxicity occurred. The primary end point was objective response rate (ORR; by RECIST v1.1, investigator review). Secondary end points included safety, progression-free survival (PFS), and overall survival (OS). Relationships between T-cell-inflamed GEP, PD-L1 expression, and TMB and antitumor activity were exploratory end points.

RESULTS

ORRs (with 95% CIs) ranged from 0% (0.0% to 14.2%) in pancreatic cancer to 33% (15.6% to 55.3%) in small-cell lung cancer. Across cohorts, median (95% CI) PFS ranged from 1.7 months (1.5 to 2.9 months) to 6.8 months (1.9 to 14.1 months) in pancreatic and thyroid cancers, respectively, and median OS from 3.9 months (2.8 to 5.5 months) to 21.1 months (9.1 to 22.4 months) in vulvar and carcinoid tumors, respectively. Higher response rates and longer PFS were demonstrated in tumors with higher T-cell-inflamed GEP, PD-L1 expression, and/or TMB. Correlations of TMB with GEP and PD-L1 were low. Response patterns indicate that patients with tumors that had high levels of both TMB and inflammatory markers (GEP or PD-L1) represent a population with the highest likelihood of response. Safety was similar and consistent with prior pembrolizumab reports.

CONCLUSION

A T-cell--inflamed GEP, PD-L1 expression, and TMB predicted response to pembrolizumab in multiple tumor types. These biomarkers (alone/in combination) may help identify patients who have a higher likelihood of response to anti-PD-1 therapies across a broad spectrum of cancers.

Targeting Programmed Cell Death -1 (PD-1) and Ligand (PD-L1): A new era in cancer active immunotherapy

Improved understanding of the immune system and its role in cancer development and progression has led to impressive advances in the field of cancer immunotherapy over the last decade. Whilst the field is rapidly evolving and the list of drugs receiving regulatory approval for the treatment of various cancers is fast growing, the group of PD1- PDL-1 inhibitors is establishing a leading role amongst immunomodulatory agents. PD1- PDL-1 inhibitors act against pathways involved in adaptive immune suppression resulting in immune checkpoint blockade. Within the last four years two PD-1 and three PD-L1 inhibitors have been utilized in clinical practice against a variety of malignancies. Focus was initially placed on targeting cancers considered immunogenic such as melanoma, renal and lung cancers but subsequently the application expanded to include amongst others Hodgkin Lymphoma, urothelial as well as head and neck cancer. This article provides a comprehensive review of the early and late phase trials that led to the regulatory approval of all five PD1- PDL-1 inhibitors in the corresponding cancer types. It presents available data on the combinations of PD1- PDL-1 inhibitors with other therapies (immunotherapy, targeted therapy and chemotherapy), the toxicity profile of the PD1- PDL-1 inhibitors and ongoing trials testing the efficacy of these agents in cancer types beyond those that have been addressed already. Finally, current and future challenges in the application of PD-1 and PD-L1 inhibitors are discussed with emphasis on the role of predictive biomarkers.

Molecular biomarkers in gastro-esophageal cancer: recent developments, current trends and future directions

Gastro-esophageal adenocarcinomas (GEA) represent a severe global health burden and despite improvements in the multimodality treatment of these malignancies the prognosis of patients remains poor. HER2 overexpression/amplification has been the first predictive biomarker approved in clinical practice to guide patient selection for targeted treatment with trastuzumab in advanced gastric and gastro-esophageal junction cancers. More recently, immunotherapy has been approved for the treatment of GEA and PD-L1 expression is now a biomarker required for the administration of pembrolizumab in these diseases. Significant progress has been made in recent years in dissecting the genomic makeup of GEA in order to identify distinct molecular subtypes linked to distinct patterns of molecular alterations. GEA have been found to be highly heterogeneous malignances, representing a challenge for biomarkers discovery and targeted treatment development. The current review focuses on an overview of established and novel promising biomarkers in GEA, covering recent molecular classifications from TCGA and ACRG. Main elements of molecular heterogeneity are discussed, as well as emerging mechanisms of primary and secondary resistance to HER2 targeted treatment and recent biomarker-driven trials. Future perspectives on the role of epigenetics, miRNA/lncRNA and liquid biopsy, and patient-derived xenograft models as a new platform for molecular-targeted drug discovery in GEA are presented. Our knowledge on the genomic landscape of GEA continues to evolve, uncovering the high heterogeneity and deep complexity of these tumors. The availability of new technologies and the identification of promising novel biomarker will be critical to optimize targeted treatment development in a setting where therapeutic options are currently lacking. Nevertheless, clinical validation of novel biomarkers and treatment strategies still represents an issue.

Advances in immuno-oncology biomarkers for gastroesophageal cancer: Programmed death ligand 1, microsatellite instability, and beyond

Blockade of the programmed death ligand 1 (PD-L1) and programmed cell death 1 (PD-1) receptor axis represents an effective form of cancer immunotherapy. Preclinical evidence initially suggested that gastric and gastroesophageal junction (GEJ) cancers are potentially immunotherapy-sensitive tumors. Early phase clinical trials have demonstrated promising antitumor activity with PD-1/PD-L1 blockade in advanced or metastatic gastric/GEJ cancer. Microsatellite instability (MSI) and PD-L1 expression have been shown to predict higher response to PD-1 inhibitors as highlighted by the recent approvals of pembrolizumab in treatment-refractory solid tumors with MSI status and the third-line or greater treatment of PD-L1 positive advanced gastric/GEJ cancers. However, predictive and prognostic biomarkers remain an ongoing need. In this review, we detail the preclinical evidence and early tissue biomarker analyses illustrating potential predictive biomarkers to PD-1/PD-L1 blockade in gastric/GEJ cancer. We also review the clinical development of PD-1/PD-L1 inhibitors in gastric/GEJ cancer and highlight several areas in need of future investigation in order to optimize the efficacy of PD-1/PD-L1 blockade in gastric/GEJ cancer.

Checkpoint blockade in esophagogastric cancer

There are few effective treatment options for metastatic esophagogastric adenocarcinomas after progression on second-line chemotherapy. Immune checkpoint blockade therapy is a promising treatment strategy for selected advanced esophagogastric cancer, and the PD-1 inhibitor pembrolizumab has recently been approved for metastatic or recurrent gastric or gastroesophageal junction cancer that has progressed beyond second-line systemic therapy. We review the current data supporting immune checkpoint blockade therapy in advanced esophagogastric adenocarcinoma.

Immunotherapy in Advanced Gastric Cancer: An Overview of the Emerging Strategies

Gastric cancer (GC) remains a public health problem, being the fifth most common cancer worldwide. In the western countries, the majority of patients present with advanced disease. Additionally, 65 to 75% of patients treated with curative intent will relapse and develop systemic disease. In metastatic disease, systemic treatment still represents the state of the art, with less than a year of median overall survival. The new molecular classification of GC was published in 2014, identifying four distinct major subtypes of gastric cancer, and has encouraged the investigation of new and more personalized treatment strategies. This paper will review the current evidence of immunotherapy in advanced gastric cancer.