Combination or sequencing strategies to improve the outcome of metastatic renal cell carcinoma patients: a critical review

Survival outcomes of double- and triple-sequential targeted therapy in patients with metastatic renal cell carcinoma: a retrospective comparison

Objective

To evaluate the progression-free survival (PFS) and overall survival (OS) in patients with metastatic renal cell carcinoma (mRCC) treated with double- and triple-sequence targeted therapy (TT) using tyrosine kinase inhibitors (TKIs) and mammalian target of rapamycin inhibitors (mTORi).

Materials and Methods

Records of 292 patients with mRCC, treated with TT between January 2005 and July 2015, were analyzed retrospectively. Kaplan-Meier and log-rank analyses were used to calculate and compare the total PFS (tPFS) and OS when patients underwent double- or triple-TT using TKIs or mTORi.

Results

Eighty-one (27.7%) patients who underwent second-line TT were enrolled; 30 (10.3%) of whom underwent third-line TT. The tPFS and OS of double-TT using TKI-mTORi (5.4 and 30 months, respectively) were significantly better compared with TKI-TKI (0.3 and 2 months) or mTORi-TKI (2 and 6 months) (p <0.001). For triple-TT, the tPFS and OS of TKI-mTORi-TKI (22.8 and 25 months, respectively) were significantly superior compared with those for TKI-TKI-mTORi (4 and 9 months) (p <0.05).

For patients with intermediate-risk according to the Heng or Memorial Sloan-Kettering Cancer Center risk models, TKI-mTORi was associated with a significantly longer tPFS and OS compared with TKI-TKI [expect for OS in the Heng group (p = 0.086)]. For the triple TT group, TKI-mTORi-TKI resulted in improved tPFS and OS compared with TKI-TKI-TKI or TKI-TKI-mTORi (p <0.05).

Conclusion

In patients with mRCC, sequential administration of TKI-mTORi led to a significantly superior tPFS compared with any other TT sequence. By contrast, OS did not differ significantly according to TT sequence.

Efficacy of sequential therapies with sorafenib-sunitinib versus sunitinib-sorafenib in metastatic renal cell carcinoma: A systematic review and meta-analysis

The most efficient sequence of targeted agents for metastatic renal cell carcinoma patients has yet to be identified. Whether the sequence of sorafenib and sunitinib really matters is controversial and not answered clearly until now. This meta-analysis aims to estimate the efficacy of receptor tyrosine kinase inhibitors sorafenib-sunitinib and sunitinib-sorafenib for metastatic renal cell carcinoma, on the outcome of first-line progression-free survival, second-line progression-free survival, total progression-free survival and overall survival.

We searched PubMed, Embase, Cochrane Library and ClinicalTrails.gov for eligible studies. Data were analyzed using random or fixed effects model depending on the heterogeneity of the eligible studies. Heterogeneity across studies were analyzed using Q and I2 statistics.

Of 902 identified studies, ten were qualified in our analysis (N = 1732 patients). Sorafenib-sunitinib yielded no statistically significant benefit in first-line progression-free survival (fixed effects; HR = 0.95; 95%CI 0.75-1.21; p = 0.702), total progression-free survival (random effects; HR = 0.92; 95%CI 0.71-1.19; p = 0.531) and overall survival (fixed effects; HR = 0.89; 95%CI 0.72-1.09; p = 0.257), compared with sunitinib-sorafenib. Second-line progression-free survival was longer for sorafenib-sunitinib than sunitinib-sorafenib (fixed effects; HR = 0.55; 95%CI 0.44-0.68; p = 0.000).

Sequential therapies with sorafenib and sunitinib is well tolerated and efficient in mRCC. However, there are no evidence supported that sorafenib–sunitinib has the superiority to sunitinib-sorafenib in sequence. The ideal sequence of targeted agents requires further elucidation.

The Role of Hypoxia and Cancer Stem Cells in Renal Cell Carcinoma Pathogenesis

The cancer stem cell (CSC) model has recently been approached also in renal cell carcinoma (RCC). A few populations of putative renal tumor-initiating cells (TICs) were identified, but they are indifferently understood; however, the first and most thoroughly investigated are CD105-positive CSCs. The article presents a detailed comparison of all renal CSC-like populations identified by now as well as their presumable origin. Hypoxic activation of hypoxia-inducible factors (HIFs) contributes to tumor aggressiveness by multiple molecular pathways, including the governance of immature stem cell-like phenotype and related epithelial-to-mesenchymal transition (EMT)/de-differentiation, and, as a result, poor prognosis. Due to intrinsic von Hippel-Lindau protein (pVHL) loss of function, clear-cell RCC (ccRCC) develops unique pathological intra-cellular pseudo-hypoxic phenotype with a constant HIF activation, regardless of oxygen level. Despite satisfactory evidence concerning pseudo-hypoxia importance in RCC biology, its influence on putative renal CSC-like largely remains unknown. Thus, the article discusses a current knowledge of HIF-1α/2α signaling pathways in the promotion of undifferentiated tumor phenotype in general, including some experimental findings specific for pseudo-hypoxic ccRCC, mostly dependent from HIF-2α oncogenic functions. Existing gaps in understanding both putative renal CSCs and their potential connection with hypoxia need to be filled in order to propose breakthrough strategies for RCC treatment.

Beyond evidence-based data: scientific rationale and tumor behavior to drive sequential and personalized therapeutic strategies for the treatment of metastatic renal cell carcinoma

The recent advances in identification of the molecular mechanisms related to tumorigenesis and angiogenesis, along with the understanding of molecular alterations involved in renal cell carcinoma (RCC) pathogenesis, has allowed the development of several new drugs which have revolutionized the treatment of metastatic renal cell carcinoma (mRCC).This process has resulted in clinically significant improvements in median overall survival and an increasing number of patients undergoes two or even three lines of therapy. Therefore, it is necessary a long-term perspective of the treatment: planning a sequential and personalized therapeutic strategy to improve clinical outcome, the potential to achieve long-term response, and to preserve quality of life (QOL), minimizing treatment-related toxicity and transforming mRCC into a chronically treatable condition.Because of the challenges still encountered to draw an optimal therapeutic sequence, the main focus of this article will be to propose the optimal sequencing of existing, approved, oral targeted agents for the treatment of mRCC using evidence-based data along with the knowledge available on the tumor behavior and mechanisms of resistance to anti-angiogenic treatment to provide complementary information and to help the clinicians to maximize the effectiveness of targeted agents in the treatment of mRCC.

Suppression of mTOR pathway in solid tumors: lessons learned from clinical experience in renal cell carcinoma and neuroendocrine tumors and new perspectives

The PI3K-AKT-mTOR pathway plays role in the regulation of many cellular processes. Hyperactivation of mTOR signaling has been implicated in human carcinogenesis, representing an attractive target for cancer therapy. Among other cancer subtypes, renal cell carcinoma (RCC) and neuroendocrine tumors are relevant settings in which the deregulation of mTOR pathway is of crucial importance. Different mTOR-inhibitory agents have been developed in recent years. Temsirolimus is approved for advanced RCC; everolimus is registered for the treatment of advanced RCC, pancreatic neuroendocrine tumors and postmenopausal, hormone receptor-positive/HER2-negative, advanced breast cancer. This review is focused on the description of the clinical experience with mTOR-inhibitor agents for the treatment of advanced RCC and neuroendocrine tumors, followed by an excursus on the landscape of the ongoing research in this field.

Sequence of treatment in locally advanced and metastatic renal cell carcinoma

The spectrum of drugs that have shown activity in advanced or metastatic renal cell carcinoma (RCC) has led to a debate on the optimal sequence of treatments. There is agreement on recommending targeted agents as the standard of care in this disease. Uncertainty, however, remains on the best first-line drug choice. Physicians and patients may select sunitinib, bevacizumab in combination with interferon-alpha (IFN-α), pazopanib, or-in poor risk patients-temsirolimus. There are also a variety of therapies with proven efficacy on hand in the second-line setting: sorafenib, pazopanib, axitinib, and everolimus. While most randomized RCC trials assessed progression free survival (PFS) as primary endpoint, some agents were shown to improve median overall survival (OS), and given in sequence they have extended the life expectancy of RCC patients from 13 months in the cytokine era to over 30 months. Despite the progress made, there are sobering aspects to the oncologic success story in RCC, as the new treatments do not obtain an objective response or disease stabilization (SD) in all patients. There are also as yet no predictors to select patients who might benefit and those who are primary resistant to specific drugs, and ultimately almost all patients will experience disease progression. Bearing inevitable treatment failure in mind, availability of further drugs and switching therapy while the patient is in a condition to continue pharmacotherapy is essential. Of note, depending on the setting, only 33-59% of patients receive second-line treatment. In this review we present data on first-, second-, and third-line treatment in RCC, and discuss the difficulties in their interpretation in the context of treatment sequence. We summarize biological aspects and discuss mechanisms of resistance to anti-angiogenic therapy and their implications for treatment selection.

Future perspectives for mTOR inhibitors in renal cell cancer treatment

ABSTRACT 

Everolimus is a mTOR inhibitor that demonstrates antitumor and antiangiogenic activities. In a randomized Phase III trial, patients with metastatic renal cell carcinoma who progressed on sunitinib/sorafenib were treated with everolimus and showed significant improvement in progression-free survival compared with best supportive care. Novel approaches in treatment are expected to ensure less toxic therapies and increase efficacy of everolimus. To provide a new perspective for mTOR inhibitor research and therapy, we discuss renal cell carcinoma cancer stem cells as a potential target for mTOR inhibitors and present new concepts on emerging antiangiogenic therapies. Finally, we point why systems biology approach with reverse molecular engineering may also contribute to the field of drug discovery in renal cell carcinoma.

Mammalian Target of Rapamycin Inhibitors Resistance Mechanisms in Clear Cell Renal Cell Carcinoma

Mammalian target of rapamycin (mTOR) is a kinase protein involved in PI3K/AKT signaling with a central role in the processes of cell growth, survival and angiogenesis. Frequent mutations of this pathway make upstream and downstream components novel targets for tailored therapy design. Two mTOR inhibitors - everolimus and temsirolimus - enable an increase in overall survival (OS) or progression-free survival (PFS) time in a treatment of renal cancer. Despite recent advances in renal cancer treatment, resistance to targeted therapy is common. Understanding of molecular mechanisms is the basis of drug resistance which can facilitate prediction of success or failure in combinational or sequential targeted therapy. The article provides current knowledge on the mTOR signaling network and gives insight into the mechanisms of resistance to mTOR inhibitors from the complex perspective of RCC biology. The mechanisms of resistance developed not only by cancer cells, but also by interactions with tumor microenvironment are analyzed to emphasize the role of angiogenesis in ccRCC pathogenesis. As recent studies have shown the role of PI3K/AKT-mTOR pathway in proliferation and differentiation of cancer stem cells, we discuss cancer stem cell hypothesis and its possible contribution to ccRCC resistance. In the context of drug resistance, we also elaborate on a new approach considering ccRCC as a metabolic disease. In conclusion we speculate on future developments in agents targeting the mTOR pathway taking into consideration the singular biology of ccRCC.

Clinical and molecular prognostic and predictive biomarkers in clear cell renal cell cancer

ABSTRACT 

The natural history of clear cell renal cell cancer is highly unpredictable with various progressors and with populations where small renal masses may be accompanied by metastatic disease. Currently, there is a critical need to determine patient risk and optimize treatment regimes. For these patients, molecular markers may offer significant information in terms of prognostic and predictive values, as well as determination of valid therapeutic targets. Until now, only a few of the many identified clear cell renal cell cancer biomarkers have been clinically validated in large cohorts. And only several biomarkers are integrated in predictive or prognostic models. Therefore, a large cohesive effort is required to advance the field of clear cell renal cell cancer prognostic biomarkers through systematic discovery, verification, validation and clinical implementation.

Renal cell carcinoma with intramyocardial metastases

Background

Cardiac metastases from renal cell carcinoma without vena caval involvement are extremely rare with a limited number of cases reported in the worldwide literature until now. Nevertheless, this rare location of metastasis may significantly influence patient treatment and prognosis. Cooperation between oncology, cardiology, and urology teams are indispensable in cases of patients suffering from intramyocardial tumors. For these individuals, treatment guidelines based on large-scale studies are unavailable and only case/case series analysis may provide clinicians with decision assistance.

Case presentation

In this paper, we report a case of a 50-year-old Caucasian male diagnosed with a 10.2 × 10.3 × 10.0 cm lower pole left renal mass in January 2002. He was subsequently treated with immunochemotherapy, tyrosine kinase inhibitors (TKIs), and mTOR inhibitors (mTORIs) - that is sunitinib, everolimus, and sorafenib. In March 2012, contrast-enhancing tumors in the left myocardium (∅22 mm) and in the interventricular septum (∅26 mm) were seen on CT. Cardiology testing was conducted and the patient was treated with pazopanib with a profound response. Overall survival since the clear cell renal cell carcinoma (ccRCC) diagnosis was 11 years 2 months and since diagnosis of multiple heart metastases was 1 year.

Conclusions

Cardiac metastases present a unique disease course in renal cell carcinoma. Cardiac metastases may remain asymptomatic, as in the case of this patient at the time of diagnosis. The most common cardiac presentation of renal cell carcinoma is hypertension, but other cardiac presentations include shortness of breath, cough, and arrhythmias. Targeted systemic therapy with tyrosine kinase inhibitors may be useful for this group of patients, but necrosis in the myocardium can result in tamponade and death. Regular cardiac magnetic resonance imaging scans are required for treatment monitoring.

Tracheal adenoid cystic carcinoma mimicking a thyroid tumor: A case report

At present, only eight cases of tracheal adenoid cystic carcinomas (ACCs) mimicking thyroid tumors have been reported. Since there are no guidelines available regarding their diagnosis and treatment, they present a significant clinical challenge. In the present study, patient treatment was analyzed to deliver the first concise summary of treatment options in patients with ACC mimicking a thyroid tumor. In addition, all available data regarding molecular abnormalities of this disease have been discussed. The current study presents a case of a 17-year-old patient with a tracheal ACC mimicking a thyroid tumor. The patient was diagnosed in 2007 with a pathological mass between the left lobe of the thyroid and the trachea, and underwent surgery and radiotherapy. In 2010, multiple lesions in the lungs were diagnosed and pulmonary metastasectomy was performed. Following surgery, the patient has been disease-free for almost 30 months. Thyroid tumor biopsy may reveal ACCs. This pathological report requires further investigation of the head and neck in order to confirm if the disease is of tracheal origin. Patients may present with a neck swelling, hoarseness of voice or dysphagia. Surgery must be considered as first-line therapy for all patients with local disease as it may be curative. For palliative treatment chemoradiotherapy based on cisplatin may be effective. The identification of cytogenetics, tumor suppressor genes, oncogenes, epigenetic alterations and mitochondrial abnormalities specific for ACCs is critical to the development of targeted therapies. Thus far, large studies have only reported the transcriptional activator Myb and mammalian target of rapamycin signaling pathway to be disrupted in ACCs.

Management of metastatic renal cell carcinoma patients with poor-risk features: current status and future perspectives

With seven agents approved for renal cell carcinoma within the past few years, there has undoubtedly been progress in treating this disease. However, patients with poor-risk features remain a challenging and difficult-to-treat population, with the mTOR inhibitor, temsirolimus, the only agent approved in the first-line setting. Phase III trial data are still lacking VEGF-pathway inhibitors in patients with poor prognostic features. Poor-risk patients need to be considered as a heterogeneous population. Further understanding of biomarkers can lead to a better selection of patients who may benefit the most from treatment and improvements in prognosis. The presence of poor Karnofsky scores and liver or CNS disease may affect the outcome of these patients much more than other identified factors. This consideration may provide the rationale to further stratify poor-risk patients further subgroups destined to receive either cure or palliation.

Management of metastatic kidney cancer in the era of personalized medicine

Patients with localized renal cell cancer (RCC) are often cured following surgical resection. However, a significant proportion of patients will experience recurrence or present with metastatic disease at distant sites and may be deemed incurable. The worldwide incidence of RCC is rising, affecting more than 271,000 people and resulting in 116,000 deaths each year. Unfortunately, advanced RCC is typically resistant to classical chemotherapy and radiotherapy. Previously, non-specific immunotherapies such as interleukin-2 and interferon were used in hopes of improving cancer immunity, leading to rare but durable responses. However, enthusiasm for these immunotherapies has waned due to limited patient responses, their excessive toxicities, and the emergence of alternative targeted therapies that have resulted in improved clinical endpoints for patients with metastatic RCC (mRCC). Strides in targeted treatment can be attributed to an improved understanding of the molecular underpinnings that cause and drive the progression of renal cell cancers. More recently, interest in immunotherapies has resurfaced, as agents inhibiting specific checkpoints involved in cancer immune evasion have demonstrated promising activity in patients with mRCC. Here we review the novel targeted agents, biomarkers and immunotherapies that promise to change the clinical outcomes for patients with advanced RCC.

Microvessel area as a predictor of sorafenib response in metastatic renal cell carcinoma

Background

Sorafenib was the first Food and Drug Administration approved anti-angiogenic therapy for renal cell carcinoma (RCC). Currently, there are no validated predictive biomarkers for sorafenib. Our purpose was to determine if sorafenib target expression is predictive of sorafenib sensitivity.

Methods

We used an automated, quantitative immunofluorescence-based method to determine expression levels of sorafenib targets VEGF, VEGF-R1, VEGF-R2, VEGF-R3, c-RAF, B-RAF, c-Kit, and PDGFR-β in a cohort of 96 patients treated with sorafenib. To measure vasculature in the tumor samples, we measured microvessel area (MVA) by CD-34 staining.

Results

Of the markers studied, only high MVA was predictive of response (p = 0.005). High MVA was associated with smaller primary tumors (p = 0.005). None of the biomarkers studied was predictive of overall or progression-free survival. Using the Bonferroni adjustment correcting for 9 variables with an alpha of 0.05, MVA remained significantly associated with sorafenib response.

Conclusions

Our results suggest that high MVA in tumor specimens might be associated with a greater likelihood of response to therapy. Further studies are needed to confirm these results in additional patients and in patients receiving other VEGF-R2 inhibitors, as MVA might be useful to improve patient selection for VEGF-R2 inhibitors.

Metastatic renal cell carcinoma: how to make the best sequencing decision after withdrawal for intolerance to a tyrosine kinase inhibitor

With seven agents approved for metastatic renal cell carcinoma (RCC) within the past few years, there has undoubtedly been progress in treating this disease. The treatment safety of these new agents, however, now represents a crucial concern, which requires a search for the best possible balance between the minimization of the treatment burden and the need for maintaining appropriate drug dosages able to induce the best clinical benefit. In this review we have analyzed safety data of all approved targeted agents for metastatic RCC available as first- or second-line therapy to provide suggestions aimed at establishing the most appropriate second-line or later treatment on the basis of toxicities that have arisen in therapy. Based on the characteristics and comorbidities of the patients and on the toxicity profile of each treatment, it is possible to plan different therapeutic options. We, therefore, have compiled a list of points that are important to keep in mind when considering the use of the targeted drugs for the treatment of advanced RCC.

Suppression of renal cell carcinoma growth in vivo by forced expression of vascular endothelial growth inhibitor

Vascular endothelial growth inhibitor (VEGI) has been associated with tumor-related vasculature in certain malignancies. However, its implication in renal cell carcinoma (RCC), an angiogenesis-dependent tumor, remains unknown. In the present study, we investigated the role played by VEGI in RCC. The expression of VEGI was examined in human renal tissue and RCC cell lines using immunohistochemical staining and RT-PCR, respectively. The biological impact of modifying the expression of VEGI in RCC cells was evaluated using in vitro and in vivo models. We show that VEGI mRNA is expressed in a wide variety of human RCC cell lines, all of normal renal and most of RCC tissue specimens. VEGI protein expression was observed in normal renal tubular epithelial cells, but was decreased or absent in RCC specimens, particularly in tumors with high grade. Moreover, forced expression of VEGI led to an inhibition of vascular endothelial tube formation, decrease in the motility and adhesion of RCC cells in vitro. Interestingly, forced expression of VEGI had no bearing on growth, apoptosis and invasive capacity of RCC cells. However, tumor growth was reduced in xenograft models. Immunohistochemical staining showed that microvessel density decreased in VEGI forced expression xenograft tumor samples. Taken together, our findings showed that the expression of VEGI is decreased in RCC, particularly in tumors with higher grade. Together with its inhibitory effect on cellular motility, adhesion, vascular endothelial tube formation and tumor growth in vivo, this suggests that VEGI functions mainly through inhibition of angiogenesis and is a negative regulator of aggressiveness during the development and progression of RCC.

mTOR inhibitors in advanced renal cell carcinomas: from biology to clinical practice

To date, oral everolimus is indicated for the treatment of patients with advanced renal cell carcinoma, whose disease has progressed on or after treatment with vascular endothelial growth factor-targeted therapy, and intravenous temsirolimus for the first-line treatment of patients with poor prognosis metastatic renal cell carcinoma. However, some factors could guide the treatment choice aiming to individualize a treatment plan. Besides the crucial issue of treatment efficacy, other factors are to be considered such as disease status, histological subtype, extent of the disease, patient-specific factors, and agent-specific factors. All of these considerations have to stay in the frame of guideline recommendations which represent evidence-based medicine. The purpose of this article is to summarize the main pharmacological and pharmacokinetic characteristics of mTOR inhibitors, and to define targeted populations according to prognostic indexes.

Second line treatment of metastatic renal cell carcinoma: The Institut Gustave Roussy experience with targeted therapies in 251 consecutive patients

BACKGROUND

Sequential treatment is currently the standard of care in metastatic renal cell carcinoma (mRCC). However, very little is known on how many patients (pts) can receive second line or further, and on how to predict those pts. The goal of this study was to evaluate these questions in a large series of pts treated in our institution.

PATIENTS AND METHODS

Data from all mRCC patients treated at the IGR from 2005 to 2009 with first line targeted therapy (sunitinib (SU), sorafenib (SO), bevacizumab (B), temsirolimus or everolimus (pooled together as mammalian target of rapamycin - mTOR)) were analysed. Only patients with subsequent follow-up have been included in this analysis. Patients were defined as 'non-eligible' for second treatment if: they were (i) still on first line treatment, (ii) not showing progressive (durable stable disease or partial response or complete response) or (iii) if they refused a second line treatment.

RESULTS

251 patients, median age 60 years, median follow-up 20.2 months were treated with targeted therapy with a median overall survival (OS) of 25.8 months. Median OS with SU (127), SO (60) or B (61) were 26.3, 16.4 and 32.5 months respectively. Only three patients received an mTOR inhibitor as first line. According to the eligibility criteria, the percentage of patients who received a second line was 59% (n=61/103), 52% (n=30/58) and 79% (n=38/48) for Su, So and B, respectively. Memorial Sloan-Kettering Cancer Centre (MSKCC) classification (P=0.02) and first line agent (P=0.001) were significant predictive factor for receiving a second line of treatment. Overall, patients receiving B were in better general condition, with 77% of performance status score (PS)=0 compared to SO (53%) and SU (48%) (P=0.005). Among the 131 patients who received a second line, the median OS from the start of second line treatment was 20.8 months for a tyrosine kinase inhibitor (TKI) (n=98; 75%) and 16.6 months for an mTOR (n=32; 42%) (P=0.12). Furthermore, the percentage of patients who received a third line was 56% (27/48), 28% (7/25) and 65% (13/20) for SU, SO and B, respectively.

CONCLUSION

The median OS in patients treated with targeted therapies for mRCC in The Institut Gustave Roussy exceeds 2 years. The use of second line varies from 52% to 79%. Further studies are needed to validate the MSKCC groups and first line therapy as predictive factor for second line treatment.

Safety and Efficacy of Sorafenib in Renal Cell Carcinoma

This article reviews data on sorafenib use in renal cell carcinoma. Mechanisms of actions and pharmacokinetics are briefly described. Major clinical trials are presented, summarizing efficacy and safety of sorafenib. Its place in current treatment of renal cell carcinoma is discussed. Sorafenib is likely to remain one of the mainstays of RCC treatment in coming years.

Store-operated Ca2+ entry is remodelled and controls in vitro angiogenesis in endothelial progenitor cells isolated from tumoral patients

BACKGROUND

Endothelial progenitor cells (EPCs) may be recruited from bone marrow to sustain tumor vascularisation and promote the metastatic switch. Understanding the molecular mechanisms driving EPC proliferation and tubulogenesis could outline novel targets for alternative anti-angiogenic treatments. Store-operated Ca(2+) entry (SOCE), which is activated by a depletion of the intracellular Ca(2+) pool, regulates the growth of human EPCs, where is mediated by the interaction between the endoplasmic reticulum Ca(2+)-sensor, Stim1, and the plasmalemmal Ca(2+) channel, Orai1. As oncogenesis may be associated to the capability of tumor cells to grow independently on Ca(2+) influx, it is important to assess whether SOCE regulates EPC-dependent angiogenesis also in tumor patients.

METHODOLOGY/PRINCIPAL FINDINGS

The present study employed Ca(2+) imaging, recombinant sub-membranal and mitochondrial aequorin, real-time polymerase chain reaction, gene silencing techniques and western blot analysis to investigate the expression and the role of SOCE in EPCs isolated from peripheral blood of patients affected by renal cellular carcinoma (RCC; RCC-EPCs) as compared to control EPCs (N-EPCs). SOCE, activated by either pharmacological (i.e. cyclopiazonic acid) or physiological (i.e. ATP) stimulation, was significantly higher in RCC-EPCs and was selectively sensitive to BTP-2, and to the trivalent cations, La(3+) and Gd(3+). Furthermore, 2-APB enhanced thapsigargin-evoked SOCE at low concentrations, whereas higher doses caused SOCE inhibition. Conversely, the anti-angiogenic drug, carboxyamidotriazole (CAI), blocked both SOCE and the intracellular Ca(2+) release. SOCE was associated to the over-expression of Orai1, Stim1, and transient receptor potential channel 1 (TRPC1) at both mRNA and protein level The intracellular Ca(2+) buffer, BAPTA, BTP-2, and CAI inhibited RCC-EPC proliferation and tubulogenesis. The genetic suppression of Stim1, Orai1, and TRPC1 blocked CPA-evoked SOCE in RCC-EPCs.

CONCLUSIONS

SOCE is remodelled in EPCs from RCC patients and stands out as a novel molecular target to interfere with RCC vascularisation due to its ability to control proliferation and tubulogenesis.

Hypoxia promotes tumor growth in linking angiogenesis to immune escape

Despite the impressive progress over the past decade, in the field of tumor immunology, such as the identification of tumor antigens and antigenic peptides, there are still many obstacles in eliciting an effective immune response to eradicate cancer. It has become increasingly clear that tumor microenvironment plays a crucial role in the control of immune protection. Tumors have evolved to utilize hypoxic stress to their own advantage by activating key biochemical and cellular pathways that are important in progression, survival, and metastasis. Hypoxia-inducible factor (HIF-1) and vascular endothelial growth factor (VEGF) play a determinant role in promoting tumor cell growth and survival. Hypoxia contributes to immune suppression by activating HIF-1 and VEGF pathways. Accumulating evidence suggests a link between hypoxia and tumor tolerance to immune surveillance through the recruitment of regulatory cells (regulatory T cells and myeloid derived suppressor cells). In this regard, hypoxia (HIF-1α and VEGF) is emerging as an attractive target for cancer therapy. How the microenvironmental hypoxia poses both obstacles and opportunities for new therapeutic immune interventions will be discussed.