Optimal locoregional treatment in gastric cancer

Mammalian target of rapamycin is activated in human gastric cancer and serves as a target for therapy in an experimental model

The mammalian target of rapamycin (mTOR) has become an interesting target for cancer therapy through its influence on oncogenic signals, which involve phosphatidylinositol-3-kinase and hypoxia-inducible factor-1alpha (HIF-1alpha). Since mTOR is an upstream regulator of HIF-1alpha, a key mediator of gastric cancer growth and angiogenesis, we investigated mTOR activation in human gastric adenocarcinoma specimens and determined whether rapamycin could inhibit gastric cancer growth in mice. Expression of phospho-mTOR was assessed by immunohistochemical analyses of human tissues. For in vitro studies, human gastric cancer cell lines were used to determine S6K1, 4E-BP-1 and HIF-1alpha activation and cancer cell motility upon rapamycin treatment. Effects of rapamycin on tumor growth and angiogenesis in vivo were assessed in both a subcutaneous tumor model and in an experimental model with orthotopically grown tumors. Mice received either rapamycin (0.5 mg/kg/day or 1.5 mg/kg/day) or diluent per intra-peritoneal injections. In addition, antiangiogenic effects were monitored in vivo using a dorsal-skin-fold chamber model. Immunohistochemical analyses showed strong expression of phospho-mTOR in 60% of intestinal- and 64% of diffuse-type human gastric adenocarcinomas. In vitro, rapamycin-treatment effectively blocked S6K1, 4E-BP-1 and HIF-1alpha activation, and significantly impaired tumor cell migration. In vivo, rapamycin-treatment led to significant inhibition of subcutaneous tumor growth, decreased CD31-positive vessel area and reduced tumor cell proliferation. Similar significant results were obtained in an orthotopic model of gastric cancer. In the dorsal-skin-fold chamber model, rapamycin-treatment significantly inhibited tumor vascularization in vivo. In conclusion, mTOR is frequently activated in human gastric cancer and represents a promising new molecular target for therapy.

VEGF/VEGFR signalling as a target for inhibiting angiogenesis

VEGFs and a respective family of tyrosine kinases receptors (VEGFRs) are key proteins modulating angiogenesis, the formation of new vasculature from an existing vascular network. There has been considerable evidence in vivo, including clinical observations, that abnormal angiogenesis is implicated in a number of disease conditions, which include rheumatoid arthritis, inflammation, cancer, psoriasis, degenerative eye conditions and others. Antiangiogenic therapies based on inhibition of VEGF/VEGFR signalling were reported to be powerful clinical strategies in oncology and ophthalmology. Current efforts have yielded promising clinical data for several antiangiogenic therapeutics. In this review, the authors elucidate key aspects of VEGFR signalling, as well as clinically relevant strategies for the inhibition of VEGF-induced angiogenesis, with an emphasis on small-molecule VEGFR inhibitors.

Therapeutic options to target angiogenesis in human malignancies

The critical role of angiogenesis in tumour growth and metastasis is now well established in the literature. Growing tumours stimulate neovascularisation through the secretion of pro-angiogenic growth factors, in particular, basic fibroblast growth factor and VEGF. Several lines of evidence have implicated VEGF in tumourigenesis, and understanding the role of VEGF in tumour angiogenesis has facilitated the development of novel targeting agents that specifically interfere with angiogenesis. Different approaches to disrupting tumour-induced angiogenesis encompass tyrosine kinase inhibitor, monoclonal antibodies, small-molecule inhibitors and transcription inhibitors. However, monoclonal antibody and tyrosine kinase inhibitors are the most advanced drug classes currently being investigated in clinical trials. So far, three anti-VEGF inhibitors, bevacizumab, sunitinib and sorafenib, have been approved for the treatment of solid human malignancies including colorectal cancer, gastrointestinal stromal tumours and renal cell carcinoma. Other antiangiogenic drugs are being investigated in various types of cancer. This review summarises the current literature on the use of these agents to interfere with VEGF, VEGF receptor, the matrix breakdown or other mechanisms involved in angiogenesis.

Prospective study on late renal toxicity following postoperative chemoradiotherapy in gastric cancer

PURPOSE

Postoperative chemoradiotherapy in gastric cancer improves locoregional control and survival. Reports on late toxicity, however, have been scarce thus far. Because renal toxicity is one of the most serious late complications in upper abdominal radiotherapy, we prospectively analyzed kidney function in patients who underwent postoperative chemoradiotherapy for gastric cancer.

PATIENTS AND METHODS

In 44 patients, Tc99m-thiatide renography was performed before and at regular intervals after postoperative chemoradiotherapy. The left-to-right (L/R) ratio was used as an index of the relative kidney function. Mean L/R values were calculated for four follow-up time intervals. For all patients, kidney V20 (percentage of the volume of the kidney that received more than 20 Gy) and mean dose of both kidneys were retrieved from the three-dimensional dose-volume histograms.

RESULTS

We observed a progressive decrease in left renal function of 11% (p = 0.012) after 6 months, up to 52% (p < 0.001) after >18 months. The V20 (left kidney) and mean left kidney dose were identified as parameters associated with decreased kidney function. Mean serum creatinine was increased from 74.6 micromol/L before treatment to 86.1 micromol/L at 1 year after chemoradiotherapy (p < 0.001). In patients with a follow-up of 18-28 months, one case of severe renovascular hypertension was observed.

CONCLUSION

A progressive relative functional impairment of the left kidney in patients after postoperative chemoradiotherapy for gastric cancer is demonstrated. To optimize the survival benefit that can be established with adjuvant regimens, strategies to minimize the dose to the kidneys and other critical organs should be explored.

Gene expression profile of primary gastric cancer: towards the prediction of lymph node status

BACKGROUND

The identification of gastric tumors associated with a higher risk of lymph node metastasis could help surgeons select patients who may benefit from extended lymph node dissection. The aim of this study was to screen the genome in the search of primary gastric cancer gene expression profiles that might predict lymph node status.

METHODS

The gene expression profile was evaluated in frozen tumor samples obtained from 32 patients with primary gastric adenocarcinomas. The array consisted of a duplicated spot panel of 5,541 human genes. To classify node-positive (N+) and node-negative (N-) cases, a logistic regression model was fitted optimizing the Akaike Information Criteria after a stepwise gene selection. The accuracy was evaluated by means of leave-one-out cross validation.

RESULTS

All patients underwent radical gastrectomy and extended lymphadenectomy. Of all the cases, 21 were N+ and 11 demonstrated no lymph node involvement (N-). After quality filtering, the analysis of variance selected a set of 136 genes potentially correlated with nodal involvement (P value <.05). Of these 136 genes, 5 were differentially expressed (adjusted P value <.05). After a stepwise gene selection, only three genes (Bik, aurora kinase B, eIF5A2) were retained in the logistic model, which could correctly predict lymph node status in 30 of 32 cases.

CONCLUSIONS

If our findings were confirmed, the identified gene pattern might be used to tailor the extent of lymph node dissection on a single patient basis.

Aggressive D2 Lymphadenectomy is Required for Accurate Pathologic Staging of Gastric Adenocarcinoma

The therapeutic efficacy of aggressive regional D2 lymphadenectomy as an adjunct to gastrectomy for adenocarcinoma of the stomach remains controversial. It is hypothesized that D2 lymphadenectomy compared with limited D1 lymphadenectomy increases nodal yield without adding to operative morbidity or mortality, and is necessary to allow accurate pathologic staging according to current American Joint Committee on Cancer (AJCC) criteria. A 10-year retrospective review of a consecutive series of 105 gastrectomies for adenocarcinoma at an urban public teaching hospital was performed. Of 69 intended curative gastrectomies, 55 (80%) included D2 lymphadenectomies, whereas of 36 palliative gastrectomies, only 9 (25%) included D2 lymphadenectomies (P = 0.0041). Only D2 and not D1 lymphadenectomy achieved the AJCC minimum guideline of the 15 lymph nodes required for accurate pathologic staging (mean 25.2 vs 12.4 nodes, respectively; P = 0.0001). For D2 cases, 86 per cent had greater than 15 nodes excised compared with only 20 per cent for D1 cases (P = 0.0002). The morbidity and mortality rates for D2 and D1 operations were 22 per cent and 2 per cent, and 41 per cent and 2 per cent, respectively. We conclude that there was no increased morbidity or mortality associated with D2 lymphadenectomy; that reliable harvesting of an adequate number of lymph nodes for accurate AJCC pathologic tumor staging requires D2 lymphadenectomy; and that D2 lymphadenectomy should be performed as part of virtually all gastrectomies for invasive adenocarcinoma having curative intent.

Clinical response to therapy targeted at vascular endothelial growth factor in metastatic renal cell carcinoma: impact of patient characteristics and Von Hippel-Lindau gene status

OBJECTIVE

To describe the relationship among patient characteristics, Von Hippel-Lindau (VHL) gene status and clinical outcome in metastatic renal cell carcinoma (RCC) in patients receiving vascular endothelial growth factor (VEGF)-targeted therapy.

PATIENTS AND METHODS

All patients with metastatic RCC who received therapy with interferon-alpha plus bevacizumab, SU11248 or AG013736 at the authors' institution were considered. Clinical features were collected and activation status of the VHL gene (VHL) was determined from baseline paraffin-embedded tumour samples. Tumour response, time to tumour progression (TTP) and overall survival were recorded.

RESULTS

Forty-three patients were evaluable for determination of VHL status and clinical response. There was an objective response in 18 patients (43%; 95% confidence interval 28-59%). The median TTP for the entire cohort was 8.1 months. There was an improved clinical outcome in patients with the following clinical features: male gender, lack of hepatic metastases, no previous radiation therapy and higher baseline haemoglobin level. Twenty-six patients (60%) had evidence of VHL mutation or promoter methylation; such patients had an objective response rate of 48%, vs 35% in patients with no VHL mutation or methylation. Patients with VHL methylation or a mutation predicted to truncate or shift the VHL reading frame had a median TTP of 13.3 months, vs 7.4 months in patients with none of these features (P = 0.06).

CONCLUSION

VEGF-targeted therapy is active in metastatic RCC and the response can be associated with certain clinical features. The TTP with VEGF-targeted therapy might be prolonged in patients with VHL methylation or mutations that truncate or shift the VHL reading frame. Further investigation of VHL pathway components is needed to understand the biology of the response to VEGF-targeted agents in metastatic RCC.

Selecting a specific pre- or postoperative adjuvant therapy for individual patients with operable gastric cancer

Although the very high locoregional recurrence rates reported with limited D0/D1 surgery can be reduced with extended D2 gastrectomy for operable gastric cancer, overall relapse and survival rates remain poor and can only be improved with adequate perioperative adjuvant treatment. However, despite intensive research, no regimen has been established as standard. Meta-analyses have demonstrated a marginal survival benefit with adjuvant chemotherapy. Two recent large randomized trials for operable gastric cancer, the MAGIC trial and the INT-0116 trial, provide evidence that some patients may benefit from perioperative chemotherapy and chemoradiation, respectively. However, while both trials suggest an overall survival benefit with adjuvant treatment, they don't provide the harm-benefit ratio for specific subsets of patients wih different extent of surgery (D1 or D2) and tumor stage (early [T1,2]/advanced [T3,4]). This lack of evidence complicates current therapeutic adjuvant decisions. Estimating the risk of local and distant recurrence (high, moderate or low) after D1 or D2 surgery in various tumor stages and the expected harm-benefit ratio, the authors provide useful information for decisions on adjuvant chemotherapy with or withour radiotherapy in individual patients. Research on newer cytotoxic and targeted agents may improve treatment efficacy. Simultaneously, advances with microarray-based gene-expression profiling signatures may improve individualized treatment decisions. However, the validation and translation of these genomic classifiers as biomarkers into a completed 'bench-to-bedside' cycle for tailoring treatment to individuals is a major challenge and limits inflated expectations.

Adjuvant therapy in gastric and cardia cancer: should we irradiate?

PURPOSE OF REVIEW

The purpose of this review is to comment on the current status and the place of the (neo)adjuvant therapy of gastric cancer, and on the standardization of care in this setting.

RECENT FINDINGS

The definition of optimal surgery remains controversial in gastric cancer. A recent review by the Dutch Gastric Cancer Group supports the so-called 'over-D1' extended lymphadenectomy, without pancreatectomy and splenectomy, as the optimal procedure, avoiding an increased postoperative mortality. The results from the phase III INT 116 trial should not definitively assign adjuvant chemoradiation as a robust standard of care, mainly due to the lack of optimal surgery in this trial. However, the concept of adjuvant chemoradiation will likely become more and more used, and will influence the design of future studies, reinforced by the incorporation of novel agents. If adjuvant chemotherapy failed to significantly increase survival, the use of perioperative chemotherapy (ECF regimen x 3 pre- and postoperative) was recently reported to improve survival, without affecting postoperative mortality and morbidity; mature results from this large phase III Medical Research Council Adjuvant Gastric Cancer Infusional Chemotherapy trial should be considered as an important step implementing neoadjuvant chemotherapy as a new standard of care. Neoadjuvant therapy of locally advanced tumors also offers an ideal setting to assess new combinations, including cytotoxics, biologics and conformational radiation, coupled with translational research.

SUMMARY

Much remains to be done before anticipating an incontestable standard of care in gastric cancer, although the recent phase III trials indicate that multimodality therapy could impact on the prognosis of gastric cancer.

Renal cell carcinoma

PURPOSE OF REVIEW

In this review we will highlight the recent novel contributions to the treatment of renal cell carcinoma in the fields of anti-angiogenesis, immunotherapeutics, and surgical management. In addition, this review will update recent advances in diagnostic and imaging modalities for renal cell carcinoma and dietary and environmental relationships to the epidemiology of this growing disease.

RECENT FINDINGS

Advancements in the use of innovative treatment strategies for the management of localized renal cell carcinoma and the introduction of new targeted therapeutics with benefit in the metastatic setting has produced a major impact on the treatment of this disease.

SUMMARY

The management of metastatic renal cell carcinoma has undergone a revolution in the past year with groundbreaking treatment strategies encompassing a broad range of therapeutic modalities. At the other end of the spectrum, emerging data is beginning to change our perspective about the management of small, localized renal tumors that are being discovered with increasing frequency. This review will update recent findings supporting diet and tobacco exposure as etiologic factors in the development of renal cell carcinoma, the molecular concepts that underlie the disease and the targeted therapeutics designed to inhibit specific kinase activities, and emerging use of minimally invasive therapies for localized disease.

Chemotherapy as a component of multimodal therapy for gastric carcinoma

Prognosis of locally advanced gastric cancer remains poor, and several multimodality strategies involving surgery, chemotherapy, and radiation have been tested in clinical trials. Phase III trial testing the benefit of postoperative adjuvant chemotherapy over treatment with surgery alone have revealed little impact on survival, with the exception of some small trials in Western nations. A large trial from the United States exploring postoperative chemoradiation was the first major success in this category. Results from Japanese trials suggest that moderate chemotherapy with oral fluoropyrimidines may be effective against less-advanced (T2-stage) cancer, although another confirmative trial is needed to prove this point. Investigators have recently turned to neoadjuvant chemotherapy, and some promising results have been reported from phase II trials using active drug combinations. In 2005, a large phase III trial testing pre- and postoperative chemotherapy has proven its survival benefit for resectable gastric cancer. Since the rate of pathologic complete response is considered to affect treatment results of this strategy, neoadjuvant chemoradiation that further increases the incidence of pathologic complete response could be a breakthrough, and phase III studies testing this strategy may be warranted in the near future.