Targeted therapies for renal cell carcinoma: understanding their impact on survival

Melatonin-triggered post-transcriptional and post-translational modifications of ADAMTS1 coordinately retard tumorigenesis and metastasis of renal cell carcinoma

A disintegrin and metalloprotease with thrombospondin motifs (ADAMTS) family are widely implicated in tissue remodeling events manifested in cancer development. ADAMTS1, the most fully characterized ADAMTS, plays conflicting roles in different cancer types; however, the role of ADAMTS1 in renal cell carcinoma (RCC) remains unclear. Herein, we found that ADAMTS1 is highly expressed in RCC tissues compared to normal renal tissues, and its expression was correlated with an advanced stage and a poor prognosis of RCC patients. In vitro, we observed higher expression of ADAMTS1 in metastatic (m)RCC cells compared to primary cells, and manipulation of ADAMTS1 expression affected cell invasion and clonogenicity. Results from protease array showed that ADAMTS1 is modulated by melatonin through mechanisms independent of the MT1 receptor in mRCC cells, and overexpression of ADAMTS1 relieved the invasion/clonogenicity and growth/metastasis inhibition imposed by melatonin treatment in vitro and in an orthotopic xenograft model. The human microRNA (miR) OneArray showed that miR-181d and miR-let-7f were induced by melatonin and, respectively, targeted the 3'-UTR and non-3'-UTR of ADAMTS1 to suppress its expression and mRCC invasive ability. Clinically, RCC patients with high levels of miR-181d or miR-let-7f and a low level of ADAMTS1 had the most favorable prognoses. In addition, ubiquitin/proteasome-mediated degradation of ADAMTS1 can also be triggered by melatonin. Together, our study indicates that ADAMTS1 may be a useful biomarker for predicting RCC progression. The novel convergence between melatonin and ADAMTS1 post-transcriptional and post-translational regulation provides new insights into the role of melatonin-induced molecular regulation in suppressing RCC progression.

Exploring serum metabolic markers for the discrimination of ccRCC from renal angiomyolipoma by metabolomics

Aim: The discrimination of renal cell carcinoma from renal angiomyolipoma (RAML) is crucial for the effective treatment of each. Materials & methods: Serum samples were analyzed by nuclear magnetic resonance spectroscopy-based metabolomics and a number of metabolites were further quantified by HPLC-UV. Results: Clear-cell renal carcinoma (ccRCC) was characterized by drastic disruptions in energy, amino acids, creatinine and uric acid metabolic pathways. A logistic model for the differential diagnosis of RAML from ccRCC was established using the combination of serum levels of uric acid, the ratio of uric acid to hypoxanthine and the ratio of hypoxanthine to creatinine as variables with area under the curve of the receiver operating characteristic curve value of 0.907. Conclusion: Alterations in serum purine metabolites may be used as potential metabolic markers for the differential diagnosis of ccRCC and RAML.

Metastasis in renal cell carcinoma: Biology and implications for therapy

Although multiple advances have been made in systemic therapy for renal cell carcinoma (RCC), metastatic RCC remains incurable. In the current review, we focus on the underlying biology of RCC and plausible mechanisms of metastasis. We further outline evolving strategies to combat metastasis through adjuvant therapy. Finally, we discuss clinical patterns of metastasis in RCC and how distinct systemic therapy approaches may be considered based on the anatomic location of metastasis.

Which Metrics Are Appropriate to Describe the Value of New Cancer Therapies?

Patients with certain cancers are treated with curative intent, but for others the results are less favorable and different therapeutic approaches are needed. Early data suggest that new therapies, which modulate immune responses to cancers, may have potential for long-term survival in a proportion of cases. Therefore, it is timely to consider whether metrics generally used to describe the medical value of therapies for patients with common solid tumors remain appropriate for therapies with curative potential. Literature reviews were conducted to define how various stakeholders describe cure in oncology and to identify the endpoints used in clinical trials for selected solid tumors. The results showed that “cure” is described using various terms that can be divided broadly into lack of disease progression, eradication of cancerous cells, and survival. The review of trial endpoints showed frequent use of median overall survival (OS) and progression- and response-related endpoints. Because these endpoints were mainly described in the context of chemotherapies that are not generally curative, they may not adequately capture outcomes of new therapeutic modalities with potential for long-term survival. More appropriate endpoints may include mean OS, cure fraction, and OS rate at landmark time points.

Prognostic factors in patients receiving third line targeted therapy for metastatic renal cell carcinoma

PURPOSE

Several prognostic models have been proposed for metastatic renal cell carcinoma but none has been validated in patients who receive third line targeted agents. We evaluated prognostic factors in patients with metastatic renal cell carcinoma who received a third line targeted agent.

MATERIALS AND METHODS

We retrospectively reviewed data on 2,065 patients with clear cell metastatic renal cell carcinoma who were treated with targeted therapy at a total of 23 centers in Italy. Included in final analysis were 281 patients treated with 3 targeted agents. Overall survival was the main outcome. Cox proportional hazards regression followed by bootstrap validation was used to identify independent prognostic factors.

RESULTS

Three clinical characteristics (ECOG performance status greater than 1, metastasis at diagnosis and liver metastasis) and 2 biochemical factors (hemoglobin less than the lower limit of normal and neutrophil count greater than the upper limit of normal, respectively) were prognostic. Patients were classified into 3 risk categories, including low-zero or 1, intermediate-2 and high risk-more than 2 risk factors. Median overall survival was 19.7, 10.1 and 5.5 months, and 1-year overall survival was 71%, 43% and 15%, respectively. The major limitation was the retrospective nature of this study and absent external validation.

CONCLUSIONS

This nomogram included clinical and biochemical prognostic factors. In clinical trials it may be useful to select patients and define the prognosis.

Meta-analysis identifies NF-κB as a therapeutic target in renal cancer

OBJECTIVE

To determine the expression patterns of NF-κB regulators and target genes in clear cell renal cell carcinoma (ccRCC), their correlation with von Hippel Lindau (VHL) mutational status, and their association with survival outcomes.

METHODS

Meta-analyses were carried out on published ccRCC gene expression datasets by RankProd, a non-parametric statistical method. DEGs with a False Discovery Rate of < 0.05 by this method were considered significant, and intersected with a curated list of NF-κB regulators and targets to determine the nature and extent of NF-κB deregulation in ccRCC.

RESULTS

A highly-disproportionate fraction (~40%; p < 0.001) of NF-κB regulators and target genes were found to be up-regulated in ccRCC, indicative of elevated NF-κB activity in this cancer. A subset of these genes, comprising a key NF-κB regulator (IKBKB) and established mediators of the NF-κB cell-survival and pro-inflammatory responses (MMP9, PSMB9, and SOD2), correlated with higher relative risk, poorer prognosis, and reduced overall patient survival. Surprisingly, levels of several interferon regulatory factors (IRFs) and interferon target genes were also elevated in ccRCC, indicating that an 'interferon signature' may represent a novel feature of this disease. Loss of VHL gene expression correlated strongly with the appearance of NF-κB- and interferon gene signatures in both familial and sporadic cases of ccRCC. As NF-κB controls expression of key interferon signaling nodes, our results suggest a causal link between VHL loss, elevated NF-κB activity, and the appearance of an interferon signature during ccRCC tumorigenesis.

CONCLUSIONS

These findings identify NF-κB and interferon signatures as clinical features of ccRCC, provide strong rationale for the incorporation of NF-κB inhibitors and/or and the exploitation of interferon signaling in the treatment of ccRCC, and supply new NF-κB targets for potential therapeutic intervention in this currently-incurable malignancy.

Interferon-γ-induced necrosis: an antitumor biotherapeutic perspective

Interferon (IFN)-γ-like the well-known antitumor biotherapeutic IFN-α-is a powerful antiproliferative and immune modulatory cytokine, but mixed results from clinical trials, together with issues of systemic toxicity, have dampened enthusiasm for its use in the treatment of cancer. We suggest that at least 2 factors reduce the antitumor efficacy of IFN-γ: (1) poorly understood survival mechanisms that protect most tumor cells from IFN-γ-induced direct cytotoxicity, and (2) the short half-life of IFN-γ in serum. In this review, we outline avenues to overcome both these limitations. First, we have identified the transcription factor nuclear factor-kappa B (NF-κB) as a protective mechanism against IFN-γ-induced necrosis, and disabling NF-κB allows IFN-γ to trigger RIP1 kinase-dependent programmed necrosis (or necroptosis) in otherwise resistant cells. Second, we propose that fusing IFN-γ to tumor-specific antibodies will stabilize IFN-γ in serum and target this cytokine to tumor cells. We expect that such IFN-γ-antibody chimeras (called immunocytokines), when combined with agents that neutralize tumor-intrinsic survival signals such as NF-κB, will exert potent tumoricidal activity with minimized systemic side effects. Although this review will focus on exploiting IFN-γ-induced necrosis for treatment of renal cell carcinoma, these approaches are also directly applicable to several human cancers in which IFNs have shown therapeutic potential.

NF-κB inhibition by bortezomib permits IFN-γ-activated RIP1 kinase-dependent necrosis in renal cell carcinoma

Advanced renal cell carcinoma (RCC) is an invariably fatal cancer. Currently, small-molecule inhibitors that target cell growth, angiogenesis, or nutrient-sensing pathways represent the primary pharmacologic interventions for this disease, but these inhibitors only delay tumor progression and are not curative. The cytokine IFN-γ showed the potential to provide lasting remission in several phase I/II trials for advanced RCCs, but subsequent trials, including a multicenter phase III study using IFN-γ as a monotherapy for RCCs, were less promising. Notably, these trials were designed to exploit the indirect immunomodulatory effects of IFN-γ, whereas its direct antitumor properties--including its ability to trigger programmed cell death in tumors-remain mostly untapped. Here, we show that the proteasome inhibitor bortezomib (PS-341, Velcade) sensitizes otherwise resistant RCC cells to direct necrotic death by IFN-γ. Mechanistically, we show that bortezomib functions, at least in part, by inhibiting prosurvival NF-κB signaling. In the absence of this signal, IFN-γ triggers programmed necrosis (or "necroptosis") dependent on the kinase RIP1. When taken together with the observation that NF-κB signaling is elevated in RCCs, these results provide rationale for the combined use of IFN-γ and bortezomib in the treatment of metastatic RCCs.

Anti-CD70 immunocytokines for exploitation of interferon-γ-induced RIP1-dependent necrosis in renal cell carcinoma

Metastatic renal cell carcinoma (RCC) is an incurable disease in clear need of new therapeutic interventions. In early-phase clinical trials, the cytokine IFN-γ showed promise as a biotherapeutic for advanced RCC, but subsequent trials were less promising. These trials, however, focused on the indirect immunomodulatory properties of IFN-γ, and its direct anti-tumor effects, including its ability to kill tumor cells, remains mostly unexploited. We have previously shown that IFN-γ induces RIP1 kinase-dependent necrosis in cells lacking NF-κB survival signaling. RCC cells display basally-elevated NF-κB activity, and inhibiting NF-κB in these cells, for example by using the small-molecule proteasome blocker bortezomib, sensitizes them to RIP1-dependent necrotic death following exposure to IFN-γ. While these observations suggest that IFN-γ-mediated direct tumoricidal activity will have therapeutic benefit in RCC, they cannot be effectively exploited unless IFN-γ is targeted to tumor cells in vivo. Here, we describe the generation and characterization of two novel ‘immunocytokine’ chimeric proteins, in which either human or murine IFN-γ is fused to an antibody targeting the putative metastatic RCC biomarker CD70. These immunocytokines display high levels of species-specific IFN-γ activity and selective binding to CD70 on human RCC cells. Importantly, the IFN-γ immunocytokines function as well as native IFN-γ in inducing RIP1-dependent necrosis in RCC cells, when deployed in the presence of bortezomib. These results provide a foundation for the in vivo exploitation of IFN-γ-driven tumoricidal activity in RCC.

Impact of age on treatment trends and clinical outcome in patients with metastatic renal cell carcinoma

OBJECTIVES

Clinical outcomes in older adults with metastatic renal cell carcinoma (mRCC) are poorly understood, particularly in the era of targeted therapies. We characterize survival and relevant treatment-related variables in a modern series.

MATERIALS AND METHODS

From an institutional database including 562 patients with RCC, a total of 219 patients with metastatic disease were identified for the current analysis. Survival was assessed in four age-based cohorts: (1) age<55, (2) age 55–64, (3) age 65–74, and(4) age≥75. The number of lines of therapy rendered was collected for each patient, and the reason for treatment discontinuation was characterized.

RESULTS

Of the 219 patients assessed, median age was 58 (range, 26–87), and most patients had clear cell histology (82%) and prior nephrectomy (70.9%). The majority of patients were characterized as intermediate-risk (53%) by MSKCC criteria. Median survival in patients age≥75 was 12.5 months, as compared to 26.4 months for patients age<75 (P=0.003). Patients age≥75 received fewer lines of systemic therapy as compared to other age-based subsets, and more frequently discontinued therapies due to toxicity.

CONCLUSIONS

Older adults represent a unique subpopulation of patients with mRCC, with distinct clinical outcomes. Further research is warranted to better understand the safety and tolerability of current therapies for mRCC in this group.

Update on targeted therapies for clear cell renal cell carcinoma

PURPOSE OF REVIEW

The article reviews the evolution of targeted therapies for clear cell renal cell carcinoma (RCC) and recent developments in the field. The vast majority of work in kidney cancer deals with clear cell RCC, which is the most common variant of this malignancy. The identification of loss of function of the von Hippel-Lindau protein as the basis for clear cell RCC, in addition to the well designed clinical trials that have ensued, provide an outstanding model for the development of mechanism-based targeted therapy in cancer.

RECENT FINDINGS

The treatment of advanced and metastatic RCC continues to be a major challenge for uro-oncologists despite the approval of six targeted therapies over the past 5 years. This rapid growth in therapeutic options has brought much needed improvements in overall and progression-free survival, although durable complete responses are rare. However, the plurality of treatments also poses challenges in terms of selecting the best therapy for a given patient, designing trials with appropriate comparison arms and endpoints, identifying well tolerated and effective drug combinations or sequences, and determining the role of targeted therapies in the neoadjuvant and adjuvant settings.

SUMMARY

Vascular endothelial growth factor and mammalian target of rapamycin-targeted therapies continue to play a critical role in the management of advanced and metastatic RCC. Ongoing research to identify novel agents continues to build upon the work done during the elucidation of the von Hippel-Lindau/clear cell RCC pathway. It is hoped that ongoing and planned studies will enable development of therapeutic regimens that will incorporate agents with improved toxicity and better efficacy as well as defining a role for a multidisciplinary approach to the management of advanced RCC.

Targeted therapy for advanced renal cell carcinoma

BACKGROUND

Advanced renal cell carcinoma has been resistant to drug therapy of different types and new types of drug therapy are needed. Targeted agents inhibit known molecular pathways involved in cellular proliferation and neoangiogenesis, the induction by the tumour of host microvascular networks. Angiogenesis is of special interest in the clear cell histologic subtype of renal cancer because of its vascularity and constitutively activated hypoxia-inducible path in the majority of tumours.

OBJECTIVES

1) To provide a systematic review of studies testing targeted agents.2) To identify the type and degree of clinical benefit, if any, of targeted agents over the prior standard of care, particularly any impact on overall survival.

SEARCH STRATEGY

1) Electronic search of CENTRAL, MEDLINE and EMBASE databases.2) Hand search of international cancer meeting abstract and other sources specified in the protocol.

SELECTION CRITERIA

Randomized controlled studies of targeted agents in patients with advanced renal cell cancer reporting major remission rate or overall survival by allocation. Progression-free survival (PFS) was adopted as an additional outcome because PFS was a commonly chosen primary outcome, and because several pivotal studies allowed crossover from the control to the investigational arm after closure to accrual thereby making overall survival a problematic endpoint.

DATA COLLECTION AND ANALYSIS

Nineteen fully eligible studies tested ten different targeted agents (Table 04). One additional study was excluded because no outcome data by allocation have been reported (Hutson 2007). For purposes of comparison, the studies were divided into three groups: Group 1 studies compared different doses of the same agents; Group 2 studies examined the impact of targeted agents in patients who had received prior cytokine or other systemic therapy; and Group 3 studies tested targeted agents in systemically naive patients, either against standard interferon-alfa or against another control therapy. Meta-analysis was not utilized because there were very few situations where the same agents had been tested in the same group in more than one study.

MAIN RESULTS

In systemically untreated patients in studies using subcutaneous interferon-alfa as control therapy, the major findings were: 1) An improvement in overall survival has been demonstrated only with the use of weekly intravenous temsirolimus in patients with unselected renal cancer histology and adverse prognostic features (median survival 10.9 months versus 7.3 months for temsirolimus or interferon-alfa respectively, HR 0.73, P = 0.008 log rank, Hudes 2007). However, the chance of major remission was low and not improved with temsirolimus. 2) In patients with mostly good or intermediate prognostic risk with clear cell renal cancer, oral sunitinib improves the chance of major remission, the probability of symptomatic improvement, and freedom from disease progression (Motzer 2007); in a similar setting, the addition of biweekly intravenous bevacizumab to interferon-alfa also improved the chance of major remission and prolonged progression-free survival (Escudier 2007b); overall survival had not changed at the time of interim reporting of either study. In patients with clear cell renal cancers who had failed prior cytokine therapy, oral sorafenib gives a better quality of life than placebo as well as improved chance of being free of disease progression; overall survival may have improved but is hard to evaluate because of crossover of placebo-assigned patients after the study closed to accrual (Escudier 2007a).

AUTHORS' CONCLUSIONS

Based on less than a decade of experience, some targeted agents with specified molecular targets have demonstrated clinically useful benefits over the previous standard of care for patients with advanced renal cancer. Much more research is required to fully establish the role of targeted agents in this condition.