Treatment for metastatic adenocarcinoma of the stomach and gastroesophageal junction: 2020

CRP and soluble CTLA4 are determinants of anti-PD1 resistance in gastrointestinal cancer

Targeting immune inhibitory checkpoint (IC) pathways have attracted great attention as a promising strategy for treating gastrointestinal (GI) cancer. However, the therapeutic efficacy is low in most cases, and little progress has been made in establishing biomarkers that predict the possible responses, and combination regimens that enhance the therapeutic efficacy. As a predictive biomarker, soluble forms of IC molecules have been recently highlighted. However, little is known about which IC molecules is most critically associated with the treatment resistance, and also about the biological and immunological roles of the IC molecules in GI cancer. In this study, we analyzed sera obtained from advanced gastric cancer patients before and one month after treatment with anti-PD1 nivolumab for soluble IC molecules by ELISA. We found that decrease of soluble CTLA4 (sCTLA4) at posttreatment were significantly associated with a better prognosis, and combination with low level of CRP at posttreatment more clearly defined anti-PD1 responders with long-term survival. Indeed, in the in vitro setting, CRP stimulation upregulated CTLA4 expression in tumor cells followed by generation of sCTLA4 that suppressed CTL induction, and simultaneously conferred high self-renewal and invasive abilities on the tumor cells accompanied by increase of EMT-related gene expressions. In the in vivo setting, CRP injection elevated sCTLA4 level in sera of mouse tumor metastasis models, leading to failure of anti-PD1 therapy. However, treatment with anti-CTLA4 mAb or a PPARγ agonist that can reduce in vivo CRP successfully elicited anti-tumor efficacy in the anti-PD1 resistant models. These suggest that targeting CRP and sCTLA4 may be a promising strategy for improving clinical outcomes in the treatments, including anti-PD1 therapy, of GI cancer.

Global Ring Study to Investigate the Comparability of Total Assay Performance of Commercial Claudin 18 Antibodies for Evaluation in Gastric Cancer

Claudin 18.2 (CLDN18.2), the dominant isoform of CLDN18 in gastric tissues, is a highly specific tight junction protein of the gastric mucosa with variably retained expressions in gastric and gastroesophageal junction cancers. Additionally, CLDN18.2-targeted treatment with zolbetuximab, in combination with chemotherapy, has recently been assessed in 2 phase-III studies of patients with HER2-negative, locally advanced, unresectable, or metastatic gastric or gastroesophageal junction adenocarcinoma. These trials used the investigational VENTANA CLDN18 (43-14A) RxDx immunohistochemistry (IHC) assay on the Ventana BenchMark platform to identify patients eligible for CLDN18.2-targeted treatment. We report the findings of a global ring study evaluating the analytical comparability of concordance of the results of 3 CLDN18 antibodies (Ventana, LSBio, and Novus) stained on 3 IHC-staining platforms (Ventana, Dako, and Leica). A tissue microarray (TMA), comprising 15 gastric cancer cases, was stained by 27 laboratories across 11 countries. Each laboratory stained the TMAs using at least 2 of the 3 evaluated CLDN18 antibodies. Stained TMAs were assessed and scored using an agreed IHC-scoring algorithm, and the results were collated for statistical analysis. The data confirmed a high level of concordance for the VENTANA CLDN18 (43-14A; Ventana platform only) and LSBio antibodies on both the Dako and Leica platforms, with accuracy, precision, sensitivity, and specificity rates all reaching a minimum acceptable ≥85% threshold and good-to-excellent levels of concordance as measured by Cohen's kappa coefficient. The Novus antibody showed the highest level of variability against the reference central laboratory results for the same antibody/platform combinations. It also failed to meet the threshold for accuracy and sensitivity when used on either the Dako or Leica platform. These results demonstrated the reliability of IHC testing for CLDN18 expression in gastric tumor samples when using commercially available platforms with an appropriate methodology and primary antibody selection.

Effects of prior therapies on outcomes with trifluridine/tipiracil in patients with metastatic gastric/gastroesophageal junction cancer in a randomized phase III trial (TAGS)

BACKGROUND

In the phase III TAGS trial, trifluridine/tipiracil showed survival benefit versus placebo in patients with metastatic gastric/gastroesophageal junction cancer and ≥ 2 prior chemotherapies. This post hoc exploratory analysis assessed the impact of prior therapy type on outcomes.

METHODS

Based on prior treatment, patients in TAGS (N = 507) were categorized into overlapping subgroups: ramucirumab ± other agents (n = 169), no ramucirumab (n = 338), paclitaxel but no ramucirumab (n = 136), ramucirumab + paclitaxel sequentially or in combination (n = 154), neither paclitaxel nor ramucirumab (n = 202), irinotecan (n = 281), and no irinotecan (n = 226). Overall and progression-free survival, time to Eastern Cooperative Oncology Group performance status (ECOG PS) ≥ 2, and safety were assessed.

RESULTS

Baseline characteristics and prior therapy patterns were generally well balanced between trifluridine/tipiracil and placebo arms across subgroups. Trifluridine/tipiracil was associated with survival benefits versus placebo regardless of prior treatment: across subgroups, median overall survival was 4.6-6.1 versus 3.0-3.8 months (hazard ratios, 0.47-0.88), median progression-free survival was 1.9-2.3 versus 1.7-1.8 months (hazard ratios, 0.49-0.67), and median time to ECOG PS ≥ 2 was 4.0-4.7 versus 1.9-2.5 months (hazard ratios, 0.56-0.88). Among trifluridine/tipiracil-randomized patients, median overall and progression-free survival trended longer in those who had not received ramucirumab, paclitaxel and ramucirumab, or irinotecan (6.0-6.1 and 2.1-2.3 months, respectively) than in those who previously received these agents (4.6-5.7 and 1.9 months). The trifluridine/tipiracil safety profile was consistent across subgroups, with similar overall incidences of grade ≥ 3 adverse events. Minor variations in hematologic toxicities were noted.

CONCLUSIONS

In TAGS, third- or later-line trifluridine/tipiracil treatment demonstrated overall and progression-free survival and functioning benefits versus placebo and a consistent safety profile in patients with metastatic gastric/gastroesophageal junction cancer, regardless of prior treatment type.

CLINICAL TRIALS REGISTRATION

clinicaltrials.gov NCT02500043.

Pembrolizumab or pembrolizumab plus chemotherapy versus standard of care chemotherapy in patients with advanced gastric or gastroesophageal junction adenocarcinoma: Asian subgroup analysis of KEYNOTE-062

OBJECTIVE

First-line pembrolizumab with/without chemotherapy versus chemotherapy was evaluated in programmed death ligand 1 combined positive score ≥1, locally advanced/unresectable or metastatic gastric cancer/gastrooesophageal junction cancer in the KEYNOTE-062 study. We present results for patients enrolled in Asia.

METHODS

Eligible patients were randomly assigned 1:1:1 to pembrolizumab 200 mg, pembrolizumab plus chemotherapy (cisplatin + 5-fluorouracil or capecitabine) or placebo plus chemotherapy Q3W. End points included overall survival (primary) in combined positive score ≥1 and combined positive score ≥10 populations and safety and tolerability (secondary).

RESULTS

A total of 187 patients were enrolled in Asia (pembrolizumab, n = 62; pembrolizumab plus chemotherapy, n = 64; chemotherapy, n = 61). Compared with the global population, higher proportions of patients had Eastern Cooperative Oncology Group performance status 0 and a diagnosis of stomach cancer. In the programmed death ligand 1 combined positive score ≥1 population, median overall survival was numerically longer with pembrolizumab versus chemotherapy (22.7 vs 13.8 months; hazard ratio, 0.54; 95% confidence interval, 0.35-0.82) and pembrolizumab plus chemotherapy versus chemotherapy (16.5 vs 13.8 months; hazard ratio, 0.78; 95% confidence interval, 0.53-1.16). In the programmed death ligand 1 combined positive score ≥10 population, median overall survival was also numerically longer with pembrolizumab versus chemotherapy (28.5 vs 14.8 months; hazard ratio, 0.43; 95% confidence interval, 0.21-0.89) and pembrolizumab plus chemotherapy versus chemotherapy (17.5 vs 14.8 months; hazard ratio, 0.86; 95% confidence interval, 0.45-1.64). The grade 3-5 treatment-related adverse event rate was 19.4%, 75.8% and 64.9% for patients receiving pembrolizumab, pembrolizumab plus chemotherapy and chemotherapy, respectively.

CONCLUSIONS

This post hoc analysis showed pembrolizumab monotherapy was associated with numerically improved overall survival and a favourable tolerability profile versus chemotherapy in Asians with programmed death ligand 1-positive advanced gastric cancer/gastrooesophageal junction cancer.This study is registered with ClinicalTrials.gov, NCT02494583.

Clinicopathologic and survival differences between adenocarcinoma of the distal oesophagus and gastro-oesophageal junction

BACKGROUND

The incidence of adenocarcinoma of the distal oesophagus (DO) and gastro-oesophageal junction (GOJ) are increasing. They may represent differing disease processes. This study aimed to assess clinicopathological and survival differences between patients with DO and GOJ adenocarcinomas.

METHODS

Data were extracted from a prospective single-surgeon database of consecutive patients undergoing an open Ivor-Lewis oesophagectomy for oesophageal adenocarcinoma (distal oesophagus, Siewert type I and II). Differences in clinicopathological characteristics and survival were evaluated and prognostic factors examined using univariate and multivariate survival analyses.

RESULTS

The data were available for 234 patients who underwent an oesophagectomy between 1992 and 2019. DO tumours had higher rates of Barrett's oesophagus (P < 0.001), presented with lower tumour stage (P = 0.02) and were more likely to be associated with fewer lymph nodes resected (P = 0.003) than GOJ tumours. The median overall survival for distal oesophageal tumours was 29.2 months, while gastro-oesophageal tumours was 38.6 months. Kaplan Meier analysis did not show a difference in overall survival between the two groups (P = 0.08). However, when adjusted for potential confounders, GOJ tumours were associated with a reduced adjusted hazard of death (adjusted HR 0.58, 95% CI 0.36-0.92, P = 0.022) compared with DO tumours.

CONCLUSION

This study suggests that GOJ cancers have different clinicopathological characteristics and improved survival compared to DO tumours.

The Emerging Roles of Circular RNAs in the Chemoresistance of Gastrointestinal Cancer

Gastrointestinal (GI) cancer represents a major global health problem due to its aggressive characteristics and poor prognosis. Despite the progress achieved in the development of treatment regimens, the clinical outcomes and therapeutic responses of patients with GI cancer remain unsatisfactory. Chemoresistance arising throughout the clinical intervention is undoubtedly a critical barrier for the successful treatment of GI cancer. However, the precise mechanisms associated with chemoresistance in GI cancer remain unclear. In the past decade, accumulating evidence has indicated that circular RNAs (circRNAs) play a key role in regulating cancer progression and chemoresistance. Notably, circRNAs function as molecular sponges that sequester microRNAs (miRNAs) and/or proteins, and thus indirectly control the expression of specific genes, which eventually promote or suppress drug resistance in GI cancer. Therefore, circRNAs may represent potential therapeutic targets for overcoming drug resistance in patients with GI cancer. This review comprehensively summarizes the regulatory roles of circRNAs in the development of chemoresistance in different GI cancers, including colorectal cancer, gastric cancer and esophageal cancer, as well as deciphers the underlying mechanisms and key molecules involved. Increasing knowledge of the important functions of circRNAs underlying drug resistance will provide new opportunities for developing efficacious therapeutic strategies against GI cancer.

Roles of microRNAs in Gastrointestinal Cancer Stem Cell Resistance and Therapeutic Development

Resistance to cancer treatment is one of the major challenges currently faced when treating gastrointestinal (GI) cancers. A major contributing factor to this resistance is the presence of cancer stem cells (CSCs) in GI cancers (e.g., colorectal, pancreatic, gastric, liver cancer). Non-coding RNAs, such as microRNAs (miRNAs), have been found to regulate several key targets that are responsible for cancer stemness, and function as oncogenic miRNAs (oncomiRs) or tumor suppressor miRNAs. As a result, several miRNAs have been found to alter, or be altered by, the expression of CSC-defining markers and their related pathways. These miRNAs can be utilized to affect stemness in multiple ways, including directly targeting CSCs and enhancing the efficacy of cancer therapeutics. This review highlights current studies regarding the roles of miRNAs in GI CSCs, and efforts towards the development of cancer therapeutics.