Kidney cancer therapy: new perspectives and avenues

Optimal Management of First-Line Advanced Renal Cell Carcinoma: Focus on Pembrolizumab

Renal cell carcinoma (RCC) is among the 10 most common cancers in the USA. One-third of the patients diagnosed with this cancer present with locally advanced or metastatic disease. In the past, advanced disease conferred poor survival outcomes; however, the treatment paradigm for RCC has been revolutionized twice since 2005. The initial wave of revolution came with the emergence of vascular endothelial growth factor (VEGF) inhibitors and a second wave arose more recently with the emergence and unprecedented success of checkpoint inhibitors in RCC. A third wave combining these two strategies is well underway and likely represents the new paradigm to improve survival outcomes for afflicted patients. In this review, we discuss the current treatment landscape for patients with advanced RCC, focusing on approved VEGF and checkpoint inhibitors in the first-line setting as well as highlighting landmark combination clinical trials.

G3BP1 promotes tumor progression and metastasis through IL-6/G3BP1/STAT3 signaling axis in renal cell carcinomas

The chronic inflammatory microenvironment within or surrounding the primary renal cell carcinoma (RCC) site promotes oncogenic transformation as well as contributes to the development of metastasis. G3BP stress granule assembly factor 1 (G3BP1) was found to be involved in the regulation of multiple cellular functions. However, its functions in RCC have not been previously explored. Here, we first showed that the expression of G3BP1 is elevated in human RCC and correlates with RCC progression. In cultured RCC cells, knockdown of G3BP1 results in inhibition of tumor cell proliferation, migration, and invasion, consistently with the alteration of epithelial–mesenchymal transition (EMT) and cell proliferative markers, including Cadherins, Vimentin, Snail, Slug, c-Myc, and cyclin D1. Remarkably, knockdown of G3BP1 dramatically impaired the signaling connection of pro-inflammatory cytokine IL-6 stimulation and downstream STAT3 activation in RCC, thus eventually contributing to the disruption of IL-6-elicited RCC migration and metastasis. In addition, in vivo orthotopic tumor xenografts results confirmed that knockdown of G3BP1 suppressed RCC tumor growth and metastasis in mice. Collectively, our findings support the notion that G3BP1 promotes tumor progression and metastasis through IL-6/G3BP1/STAT3 signaling axis in RCC.

Interleukin-6 as an emerging regulator of renal cell cancer

BACKGROUND

Our knowledge on the molecular basis of kidney cancer metastasisis still relatively low. About 25-30% of patients suffering from clear cell renal cell carcinoma (ccRCC)present metastatic disease at the time of primary diagnosis. Only 10% of patients diagnosed with stage IV disease survive 5 years and 20-50% of patients diagnosed with localized tumor develop metastases within 3 years. High mortality of patients with this cancer is associated with a large potential for metastasis and resistance to oncologic treatments such as chemo- and radiotherapy. Literature data based on studies conducted on other types of cancers suggest that in metastatic ccRCC, the complex of interleukin-6 (IL-6) and its soluble receptor (sIL-6R; complex IL-6/sIL-6R) and the signal transduction pathway (gp130/STAT3) might play a key role in this process.

PURPOSE

Therefore, in this review we focus on the role of IL-6 and its signaling pathways as a factor for development and spread of RCC. Analyzing the molecular basis of cancer spreading will enable the development of prognostic tests, evaluate individual predisposition for metastasis, and produce drugs that target metastases. As the development of effective systemic treatments evolve from advancements in molecular biology, continued studies directed at understanding the genetic and molecular complexities of this disease are critical to improve RCC treatment options.

Temsirolimus

Temsirolimus, an ester of sirolimus (rapamycin), selectively inhibits the kinase mammalian target of rapamycin (mTOR) and consequently blocks the translation of cell cycle regulatory proteins and prevents overexpression of angiogenic growth factors. It has been found to have antitumour activity in patients with relapsed or refractory mantle cell lymphoma (MCL). In addition, patients with advanced renal cell carcinoma (RCC) and a poor prognosis who received a once-weekly intravenous (IV) infusion of temsirolimus 25 mg experienced significant survival benefits compared with patients receiving standard interferon-α (IFN-α) therapy in a large phase III clinical study. In this study, median overall survival was 10.9 versus 7.3 months and objective response rates were 8.6% in temsirolimus recipients versus 4.8% IFN-α recipient group. Temsirolimus monotherapy recipients experienced significantly fewer grade 3 or 4 adverse events and had fewer withdrawals for adverse events than patients receiving IFN-α. The role of temsirolimus in sequential and combination therapy is yet to be found.

Pre-treatment neutrophil-to-lymphocyte ratio may be associated with the outcome in patients treated with everolimus for metastatic renal cell carcinoma

Background:

Everolimus is a mammalian target of rapamycin inhibitor approved for the treatment of metastatic renal cell carcinoma (mRCC). We aimed to assess the association between pre-treatment neutrophil-to-lymphocyte ratio (NLR) and the outcome of patients treated with everolimus for mRCC.

Methods:

Ninety-seven patients with mRCC were treated with everolimus till April 2013 in our institutions. Patients were stratified in two groups with NLR >3 (Group A) vs <3 (Group B). Progression-free survival (PFS) and overall survival (OS) were estimated using Kaplan–Meier method. Gender, age, Motzer prognostic group, PFS on first-line therapy, neutrophilia and NLR were included in the Cox analysis to investigate their prognostic relevance.

Results:

Median OS and PFS were 10.6 and 5.3 months, respectively. Median OS was 12.2 months in Group A and 24.4 months in Group B (P=0.001). Median PFS was 3.4 months in Group A and 9.9 months in Group B (P<0.001). At multivariate analysis, only Motzer prognostic group and NLR were independent prognostic factors for OS and PFS.

Conclusion:

Pre-treatment NLR is an independent prognostic factor for patients with mRCC treated with second- or third-line everolimus. This should be investigated and validated in prospective studies.

Intrinsic immune alterations in renal cell carcinoma and emerging immunotherapeutic approaches

INTRODUCTION

Individuals affected by kidney cancer present a variety of immune abnormalities including cellular immune dysfunction, cytokine alterations and antigen presentation defects. On the other hand, spontaneous remissions are seen in up to 4% of renal cell carcinoma (RCC) patients and they are thought to occur via immune mechanisms.

AREAS COVERED

The authors comprehensively review the immune abnormalities in RCC patient and describe the kidney cancer immunotherapy candidates that are most advanced in their clinical development. Most relevant publications were identified through searching the PubMed database; the obtained information was thoroughly analyzed and synthesized.

EXPERT OPINION

As cure in advanced RCC cannot be accomplished with the current therapy standards such as tyrosine kinase inhibitors and mammalian target of rapamycin inhibitors, new treatment strategies are being sought. Enhancing the immune system represents an appealing avenue for kidney cancer therapy. Disappointingly, high-dose interleukin-2 and interferon-α cause severe toxicity and produce a questionable clinical benefit. The authors postulate that the 'durable responses' seen with these agents in only a handful of RCC patients represent spontaneous remissions. Promising immune strategies in RCC such as anti-cytotoxic T-lymphocyte-associated protein antibodies, anti-programmed cell death 1 (PD1)/PD1 ligand and tumor vaccines may expand the existing options for kidney cancer in future years.

Immunotherapy for renal cell carcinoma

Immunotherapy plays a significant role in the management of renal cell carcinoma (RCC) patients with metastatic disease because RCC is highly resistant to both chemotherapy and radiation therapy. Many reports illustrate various approaches to the treatment of RCC, such as cytokine-, antigen- or dendritic cell- (DC-) based immunotherapy, and the safety and effectiveness of immunotherapy have been highlighted by multiple clinical trials. Although antitumor immune responses and clinically significant outcomes have been achieved in these trials, the response rate is still low, and very few patients show long-term clinical improvement. Recently, the importance of immune regulation by antigen-presenting cells (APC) and regulatory T cells (Treg cells) has also been discussed. The authors outline the principles of cell-mediated tumor immunotherapy and discuss clinical trials of immunotherapy for RCC.

Temsirolimus

Temsirolimus, an ester of sirolimus (rapamycin), selectively inhibits the kinase mammalian target of rapamycin and consequently blocks the translation of cell cycle regulatory proteins and prevents overexpression of angiogenic growth factors. Patients with advanced renal cell carcinoma (RCC) and a poor prognosis who received a once-weekly intravenous (IV) infusion of temsirolimus 25 mg, experienced significant survival benefits when compared with patients receiving standard interferon-alpha (IFNalpha) therapy in a large phase III clinical study. In this study, median overall survival was 10.9 vs. 7.3 months and objective response rates were 8.6% in temsirolimus recipients vs. 4.8% IFNalpha recipient group.Temsirolimus monotherapy recipients experienced significantly fewer grade 3 or 4 adverse events and had fewer withdrawals for adverse events than patients receiving IFNalpha.

Structure, expression and function of HLA-G in renal cell carcinoma

Tumors have developed different strategies to escape from immune cell recognition which include the downregulation or loss of the classical HLA class I antigens as well as aberrant expression of non-classical HLA antigens like HLA-G. Abnormalities in MHC class surface expression have also been described in renal cell carcinoma (RCC) and represent mechanisms to avoid elimination by immune effector cells. We here review the structure/polymorphism, mRNA and protein expression profile of HLA-G in RCC and corresponding normal kidney epithelium, its mode of regulation and its functional consequences on immune responses. A heterogeneous constitutive HLA-G mRNA and/or protein expression was found in both RCC lesions and RCC cell lines, whereas normal kidney epithelium totally lack HLA-G mRNA and protein expression. In comparison to other tumor entities, the frequency of HLA-G expression is relatively high in RCC. Since HLA-G expression is lost during cultivation of RCC cells, the tumor microenvironment and/or endothelium appear to be involved in the regulation of HLA-G expression in this disease. HLA-G expression could be transcriptionally upregulated in RCC by interferons, IL-10 and gangliosides. Silencing of HLA-G expression in RCC is often associated with methylation of the HLA-G promoter which could be reverted by the treatment with demethylating agents. Functional studies using natural killer cells, lymphokine activated killer cells as well as antigen-specific CD8+ cytotoxic T lymphocytes demonstrated that HLA-G expression prevents lysis of RCC cells by these different immune effector cells. In contrast, HLA-G-negative normal kidney cells as well as HLA-G-negative RCC cells were not recognized by NK and T cells. Thus, HLA-G represents one important immune escape mechanism of human RCC which has an impact on the design of T and NK cell-based immunotherapies in this disease.