Effectiveness of immunochemotherapy for gastric cancer: a review of the current status

Combination immunotherapy and active-specific tumor cell vaccination augments anti-cancer immunity in a mouse model of gastric cancer

Background

Active-specific immunotherapy used as an adjuvant therapeutic strategy is rather unexplored for cancers with poorly characterized tumor antigens like gastric cancer. The aim of this study was to augment a therapeutic immune response to a low immunogenic tumor cell line derived from a spontaneous gastric tumor of a CEA424-SV40 large T antigen (CEA424-SV40 TAg) transgenic mouse.

Methods

Mice were treated with a lymphodepleting dose of cyclophosphamide prior to reconstitution with syngeneic spleen cells and vaccination with a whole tumor cell vaccine combined with GM-CSF (a treatment strategy abbreviated as LRAST). Anti-tumor activity to subcutaneous tumor challenge was examined in a prophylactic as well as a therapeutic setting and compared to corresponding controls.

Results

LRAST enhances tumor-specific T cell responses and efficiently inhibits growth of subsequent transplanted tumor cells. In addition, LRAST tended to slow down growth of established tumors. The improved anti-tumor immune response was accompanied by a transient decrease in the frequency and absolute number of CD4⁺CD25⁺FoxP3⁺ T cells (Tregs).

Conclusions

Our data support the concept that whole tumor cell vaccination in a lymphodepleted and reconstituted host in combination with GM-CSF induces therapeutic tumor-specific T cells. However, the long-term efficacy of the treatment may be dampened by the recurrence of Tregs. Strategies to counteract suppressive immune mechanisms are required to further evaluate this therapeutic vaccination protocol.

Anti-tumor effects of CIK combined with oxaliplatin in human oxaliplatin-resistant gastric cancer cells in vivo and in vitro

BACKGROUND

Drug resistance remains a great challenge in the treatment of gastric cancer. The goal of this study was to explore the anti-tumor effects and mechanism of cytokine-induced killer (CIK) cell combined with oxaliplatin (L-OHP) in human oxaliplatin-resistant gastric cancer cells.

METHODS

After producing oxaliplatin-resistant gastric cancer cells, cell morphology, growth and doubling time were observed, followed by detection of cell cycle distribution and apoptosis, drug sensitivity (e.g., L-OHP) and expression of P-gp and livin. MTT assay, in vivo pharmacodynamics and pathomorphology experiments were used to detect killing activities of CIK combined with L-OHP.

RESULTS

Compared with parental gastric cancer cells, oxaliplatin-resistant gastric cancer cells in S phase were reduced and cell apoptosis rate was increased (P < 0.05), the inhibition rate of 10 chemotherapeutics on oxaliplatin-resistant gastric cancer cells was significantly lower and the expression of P-gp was significantly higher (P < 0.05). However, there was no significant difference in livin expression between parental gastric cancer cells and oxaliplatin-resistant gastric cancer cells (P > 0.05). The in vitro killing activity of CIK combined with L-OHP on parental cells and oxaliplatin-resistant cells were significantly enhanced compared with L-OHP or CIK alone. And it showed greater synergetic effects against oxaliplatin-resistant cells compared with parental cells (P < 0.05). In addition, survival rate, abdominal circumference and pathomorphology results revealed stronger in vivo anti-tumor effects when the two therapies were combined.

CONCLUSIONS

The mechanism of oxaliplatin-resistant cell secondary multidrug resistance was correlated with the variation of cell cycle distribution, extension of doubling time and upregulation of P-gp expression. The synergistic effect of CIK in combination with L-OHP on killing activity against oxaliplatin-resistant cells was shown in vivo and in vitro.

Recent advances in molecular diagnosis and therapy of gastric cancer

Gastric cancer is the fourth most common malignancy and the second most frequent cause of cancer-related death in the world. It is often diagnosed in advanced stages when treatment options are limited, leading to a poor prognosis. During the past 15 years, much has been learnt about the molecular mechanisms of gastric carcinogenesis and the development of metastases. This coincided with the development of new techniques for functional genomics, including both transcriptomics and proteomics, which significantly improve the ability to explore new molecular alterations involved in carcinogenesis and tumor progression. An improved understanding of the molecular pathology and pathogenesis of gastric cancer may lead to a more rapid development of molecular diagnostic and patient tailored therapeutic targets.

Preoperative staging of gastric cancer by endoscopic ultrasound: the prognostic usefulness of ascites detected by endoscopic ultrasound

BACKGROUND

Endoscopic ultrasound (EUS) is the standard modality in local preoperative staging of gastric cancers and is reputedly able to detect ascites. However, the association between ascites detected by EUS and local tumor staging, peritoneal carcinomatosis, or survival after surgery is not well documented.

GOALS

To assess the accuracy, sensitivity, and specificity of EUS in the preoperative staging and detection of ascites in gastric cancers. We also try to correlate ascites with histologic staging, tumor differentiation, and survival rate of gastric carcinoma after surgery.

STUDY

The retrospective analysis was made in 57 consecutive patients with histologically confirmed gastric adenocarcinomas that underwent EUS before surgery. The accuracy of EUS was compared with the final surgical-pathologic findings. We estimated the prognostic usefulness by analyzing the clinicopathologic features of gastric adenocarcinomas and following up their survival rates.

RESULTS

The overall T staging was 88% accurate by EUS. The accuracy for T staging was as follows: T1, 100%; T2, 33%; T3, 93%; and T4, 100%. About 50% of T2 cases were overstaged. The overall accuracy, sensitivity, and specificity of detecting lymph node metastasis by EUS were 79%, 79%, and 80%, respectively. One of the seven T1 cancers had regional lymph node metastasis, and it was missed by EUS, although the T classification was precisely staged based on finding submucosal invasion. A total of 22 patients (39%) had ascites detected by EUS; both the sensitivity and specificity of EUS in demonstrating ascites were 100% in our study. Ascites was significantly correlated with the depth of tumor invasion ( = 0.036), lymph node metastasis ( = 0.008), and poor cellular differentiation ( = 0.007), but it was not significantly correlated with macroscopic peritoneal carcinomatosis. The survival rate after surgical treatment was poor in those with gastric cancers with lymph node metastasis, ascites, or poorly differentiated tumors ( < 0.05). However, multivariate analysis showed that lymph node metastasis was the only significant prognostic predictor ( = 0.004).

CONCLUSIONS

Endoscopic ultrasound is a valuable diagnostic tool in the local staging of gastric cancers and demonstration of ascites. Although the surgical treatment of gastric cancers with lymph node metastasis, ascites, or poor differentiation had poorer survival rate, only lymph node metastasis was proved to be a significant prognostic predictor in multivariate analysis.

The difference in gastric cancer between Japan, USA and Europe: what are the facts? what are the suggestions?

In Japan the survival rate for gastric cancer has steadily improved over the last 30 years whilst that in the West has remained static and inferior. In this review three hypotheses are examined to explain the difference. There is little evidence to suggest genetic differences, which might result in a less aggressive cancer in Japan. Recently there has been a rise in the proportion of cancers of the gastro-oesophageal junction in the West and this has not been seen in Japan. The comparison of survival data from these two regions is problematic with different staging systems and a stage migration effect. The established surgical treatment of gastric cancer in Japan is radical gastrectomy and regional lymphadenectomy and this has been proposed as a superior treatment to the standard gastrectomy common in the West. The results for survival benefit however, have not been reproduced in randomized clinical trials. The heterogeneity of adjuvant and neoadjuvant treatment regimens in Japan and the West has led to difficulties in the interpretation of their effects. There is considerable scope for future collaboration between clinicians in the West and Japan.

The role of pretherapeutic laparoscopy in the selection of treatment for patients with gastric carcinoma: a proposal for a laparoscopic staging system

BACKGROUND

A pretherapeutic staging system to design nonoperative or neoadjuvant treatments in gastric cancer is required. In this study, a simple staging system based on laparoscopic findings to define a treatment algorithm was developed.

METHODS

A retrospective cohort study was conducted of 151 patients allocated into four stages based on laparoscopic findings. The depth of tumor invasion and the presence of metastasis based on laparoscopic findings were used to construct these stages. Laparoscopic findings were compared with histopathology.

RESULTS

An excellent agreement of the laparoscopy-defined depth of invasion and the surgical pathology standard was found (weighted kappa 0.85). The likelihood ratios for a positive and negative laparoscopic diagnosis of metastasis were 40.4 and 0.015, respectively (98.5% sensitivity, 97.6% specificity). Those for positive and negative diagnosis of resectability were 2.6 and 0.03, respectively (98.4% sensitivity, 62% specificity). The laparoscopic stages presented significant prognostic value. Two-year survival was 93%, 69%, 60%, and 17%, respectively. Surgical resection was possible in 100%, 100%, 49%, and 12%, respectively.

CONCLUSIONS

The proposed laparoscopic staging system is a simple and reproducibLe way for selection of a suitable therapy. It allows for adequate stratification of the main risk factors in the setting of clinical trials evaluating preoperative treatments.