Vascular endothelial growth factor and mTOR pathways in renal cell carcinoma: differences and synergies of two targeted mechanisms

Current status and novel insights into the role of metastasectomy in the era of immunotherapy

INTRODUCTION

New perspectives on the role of metastasectomy have emerged along with the advances in cancer immunotherapy. Despite accumulating evidence that encourages the use of immunotherapy in the metastatic setting, current data regarding its combination with surgical resection of secondary lesions, as well as the best timeline and sequence of such a therapeutic approach is limited.

AREAS COVERED

We review the currently available literature on the role of metastasectomy in the era of novel immunotherapeutic agents and provide comprehensive evidence from ongoing trials about the available treatment strategies. In metastatic melanoma, immune checkpoint inhibitors (ICIs) play a key role both in the neoadjuvant and adjuvant setting to achieve long-term disease control. In metastatic renal cell carcinoma, investigation is ongoing regarding the emerging role of ICIs before metastasectomy. ICIs have improved outcomes in patients with metastatic colorectal and head and neck cancer.

EXPERT OPINION

In the neoadjuvant setting, the high response rates and the durability of responses to immunotherapy may enable the resectability of metastatic lesions. In the adjuvant setting post metastasectomy, immunotherapy constitutes a safe and efficacious approach to support immune tumor surveillance and delay or even prevent disease relapse. Patient participation in relevant clinical trials should be encouraged.

Gene Expression Signature Correlates with Outcomes in Metastatic Renal Cell Carcinoma Patients Treated with Everolimus Alone or with a Vascular Disrupting Agent

Everolimus monotherapy use for metastatic renal cell carcinoma (mRCC) has diminished due to recent approvals of immune checkpoint and VEGF inhibitors. We hypothesized that gene expression associated with everolimus benefit may provide rationale to select appropriate patients. To address this hypothesis, tumors from a phase I/II trial that compared everolimus alone or with BNC105P, a vascular disrupting agent, were profiled using Nanostring as a discovery cohort. A phase III trial (CheckMate 025) was used for validation. Clinical benefit (CB) was defined as response or stable disease for ≥6 months. A propensity score covariate adjustment was used, and model discrimination performance was assessed using the area under the ROC curve (AUC). In a discovery cohort of 82 patients, 35 (43%) were treated with everolimus alone and 47 (57%) received everolimus + BNC105P. Median PFS (mPFS) was 4.9 (95% CI, 2.8-6.2) months. A four-gene signature (ASXL1, DUSP6, ERCC2, and HSPA6) correlated with CB with everolimus ± BNC105P [AUC, 86.9% (95% CI, 79.2-94.7)]. This was validated in 130 patients from CheckMate 025 treated with everolimus [AUC, 60.2% (95% CI, 49.7-70.7)]. Among 43 patients (52.4%) with low expression of an 18-gene signature, everolimus + BNC105P was associated with significantly longer mPFS compared with everolimus alone (10.4 vs. 6.9 months; HR, 0.49; 95% CI, 0.24-1.002; P = 0.047). These signatures warrant further validation to select patients who may benefit from everolimus alone or with a vascular disrupting agent.

Improved Treatment Outcomes by Using Patient Specific Drug Combinations in Mammalian Target of Rapamycin Activated Advanced Metastatic Cancers

Background: Activation of the mTOR signaling pathway is ubiquitous in cancers and a favourable therapeutic target. However, presently approved mTOR inhibitor monotherapies have modest benefits in labeled indications while poor outcomes have been reported for mTOR inhibitor monotherapy when administered in a label-agnostic setting based on univariate molecular indications. The present study aimed to determine whether patient-specific combination regimens with mTOR inhibitors and other anticancer agents selected based on multi-analyte molecular and functional tumor interrogation (ETA: Encyclopedic Tumor Analysis) yields significant treatment response and survival benefits in advanced or refractory solid organ cancers. Methods: We evaluated treatment outcomes in 49 patients diagnosed with unresectable or metastatic solid organ cancers, of whom 3 were therapy naïve and 46 were pre-treated in whom the cancer had progressed on 2 or more prior systemic lines. All patients received mTOR inhibitor in combination with other targeted, endocrine or cytotoxic agents as guided by ETA. Patients were followed-up to determine Objective Response Rate (ORR), Progression Free Survival (PFS) and Overall Survival (OS). Results: The Objective Response Rate (ORR) was 57.1%, the disease Control rate (DCR) was 91.8%, median Progression Free Survival (mPFS) was 4.9 months and median Overall Survival (mOS) was 9.4 months. There were no Grade IV treatment related adverse events (AEs) or any treatment related deaths. Conclusion: Patient-specific combination regimens with mTOR inhibition and other anti-neoplastic agents, when selected based on multi-analyte molecular and functional profiling of the tumor can yield meaningful outcomes in advanced or refractory solid organ cancers. Trial Registration: Details of all trials are available at WHO-ICTRP: https://apps.who.int/trialsearch/. RESILIENT ID CTRI/2018/02/011808. ACTPRO ID CTRI/2018/05/014178. LIQUID IMPACT ID CTRI/2019/02/017548.

Polycystin-1 induces activation of the PI3K/AKT/mTOR pathway and promotes angiogenesis in renal cell carcinoma

In the present study we investigated the expression and the functional role of mechanosensitive polycystins in renal cell carcinoma (RCC). In 115 RCC patients we evaluated the protein expression of polycystin-1 (PC1), polycystin-2 (PC2), VEGF and protein components of the PI3K/Akt/mTOR pathway, which have been implicated both in RCC and polycystic kidney disease. PC1 and PC2 demonstrated reduced expression throughout the RCC tissue compared to the adjacent normal tissue. PC1 and PC2 revealed high expression when they were associated with higher grade and decreased 5-year survival respectively. PC1 and PC2 were positively correlated with p110γ subunit of PI3K and high PC1 expressing cells tended to display activation/phosphorylation of Akt. There was also a positive association between PC1 and VEGF expression, whereas PC1 augmented the tumor's microvascular network in stage IV carcinomas. In human RCC cells, functional inhibition of PC1 resulted in upregulation of the PI3K/Akt/mTOR pathway, enhanced cell proliferation and led to inhibition of cell migration. Conclusively, aberrant PC1 regulation is associated with increased angiogenesis and features of advanced disease in RCC tissues.

Decreased capillary density in renal cell carcinoma: Evidence from a case report with micro-computerized tomography

RATIONALE

Conventional computerized tomography (CT) examination can differentiate renal cortical tumor from urothelial carcinoma on the basis of the highly contrast-enhanced vessels in renal cortical tumors. However, the capillary distribution of renal cell carcinoma (RCC) has been under-investigated. Here, we present a micro-CT image of tumor tissue in a patient with RCC.

PATIENT CONCERNS

The patient was a 72-year-old woman with a past history of diabetes mellitus and hypertension. She did not have tumor-related symptoms.

DIAGNOSIS AND INTERVENTIONS

The tumor was diagnosed using abdominal CT during her yearly routine health check. After radical nephrectomy, the tumor was subjected to pathological examination and micro-CT imaging. Pathological analysis confirmed a clear cell renal carcinoma. The capillary distribution of the tumor was significantly lesser than that of the normal cortex on micro-CT image.

LESSONS

Microvessels of RCC can be detected by micro-CT. We also found that the distribution of microvessels was uneven and lower than that in the normal cortex in this case. For a more general diagnosis, more micro-CT images of RCC tumors are needed.

mTOR inhibitor and bone-targeted drugs break the vicious cycle between clear-cell renal carcinoma and osteoclasts in an in vitro co-culture model

The skeleton is one of the most common sites of metastatic spread from advanced clear-cell renal carcinoma (ccRCC). Most of the bone lesions observed in RCC patients are classified as osteolytic, causing severe pain and morbidity due to pathological bone destruction. Nowadays, it is well known that cancer induced bone loss in lytic metastasis is caused by the triggering of a vicious cycle between cancer and bone resident cells that leads to an imbalance between bone formation and degradation. Targeting the mammalian target of rapamycin (mTOR) is an efficient treatment option for metastatic renal carcinoma patients. Moreover, bone targeted therapy could benefit bone metastatic cancer patients caused by advanced RCC. However, more data is needed to support the hypothesis of the beneficial effect of a combined therapy. The aim of this work is to investigate the effect of targeting mTOR and the sequential combination with bone targeted therapy as a strategy to break the vicious cycle between ccRCC cells and osteoclasts. A previously optimized fully human co-culture model is used to mimic the crosstalk between Caki-2 cells (ccRCC) and osteoclasts. Cells are treated at fixed timing with everolimus, zoledronic acid and denosumab as single or sequential combined treatment. We show that Caki-2 cells can induce osteoclast cells differentiation from isolated human monocytes, as demonstrated by specific tartrate-resistant acid phosphatase (TRAP) staining and f-actin ring formation, in a statistically significant manner. Moreover, differentiated osteoclasts proved to be functionally active by pit formation assay. Caki-2 cells co-cultured with osteoclasts acquire a more aggressive phenotype based on gene expression analysis. Interestingly, the sequential combined treatment of everolimus and zoledronic acid is the most effective in the inhibition of both Caki-2 cells survival and osteoclastogenic potential, making it an effective strategy to inhibit the vicious cycle of bone metastasis. At preclinical level, this observation confirms the value of our co-culture model as a useful tool to mimic the bone microenvironment and to assess drug sensitivity in vitro. A better understanding of the molecular mechanisms involved in tumor-bone cells crosstalk will be investigated next.

Efficacy of targeted therapy for advanced renal cell carcinoma: a systematic review and meta-analysis of randomized controlled trials

We conducted a systematic review and meta-analysis of the literature on the efficacy of the targeted therapies in the treatment of advanced RCC and, via an indirect comparison, to provide an optimal treatment among these agents. A systematic search of Medline, Scopus, Cochrane Library and Clinical Trials unpublished was performed up to Jan 1, 2015 to identify eligible randomized trials. Outcomes of interest assessing a targeted agent included progression free survival (PFS), overall survival (OS) and objective response rate (ORR). Thirty eligible randomized controlled studies, total twentyfourth trails (5110 cases and 4626 controls) were identified. Compared with placebo and IFN-α, single vascular epithelial growth factor (receptor) tyrosine kinase inhibitor and mammalian target of rapamycin agent (VEGF(r)-TKI & mTOR inhibitor) were associated with improved PFS, improved OS and higher ORR, respectively. Comparing sorafenib combination vs sorafenib, there was no significant difference with regard to PFS and OS, but with a higher ORR. Comparing single or combination VEGF(r)-TKI & mTOR inhibitor vs BEV + IFN-α, there was no significant difference with regard to PFS, OS, or ORR. Our network ITC meta-analysis also indicated a superior PFS of axitinib and everolimus compared to sorafenib. Our data suggest that targeted therapy with VEGF(r)-TKI & mTOR inhibitor is associated with superior efficacy for treating advanced RCC with improved PFS, OS and higher ORR compared to placebo and IFN-α. In summary, here we give a comprehensive overview of current targeted therapies of advanced RCC that may provide evidence for the adequate targeted therapy selecting.

Intra-tumour molecular heterogeneity of clear cell renal cell carcinoma reveals the diversity of the response to targeted therapies using patient-derived xenograft models

Inter- and intra-tumour molecular heterogeneity is increasingly recognized in clear cell renal cell carcinoma (ccRCC). It may partially explain the diversity of responses to targeted therapies and the various clinical outcomes. In this study, a 56-year-old male ccRCC patient with multiple metastases received radical nephrectomy and resection of the metastatic tumour in chest wall. The surgical specimens were implanted into nude mice to establish patient-derived xenograft (PDX) models with KI2367 model derived from the primary tumour and KI2368 model from the metastastic tumour. The two modles were treated with Sorafenib, Sunitinib, Axitinib, combined Sorafenib/Sunitinib, or alternating therapy of Sorafenib and Sunitinib. Significant anti-tumour activity was found in KI2367 treated with Sorafenib/Sunitinib monotherapy, combined Sorafenib/Sunitinib, and alternating therapy of Sorafenib/Sunitinib (P<0.05) but not in that treated with Axitinib monotherapy. In contrast, KI2368 was significantly responsive to Sunitinib monotherapy, combined Sorafenib/Sunitinib therapy and alternating therapy of Sorafenib/Sunitinib but not responsive to Sorafenib and Axitinib monotherapy (P<0.05). RNAseq of the two models demonstrated that the expression levels of 1,725 genes including the drug targeted genes of PDGFA, PDGFB and PDGFRA were >5-fold higher in KI2367 than in KI2368 and the expression levels of 994 genes were > 5-fold higher in KI2368 than in KI2367. These results suggest the presence of intra-tumour molecular heterogeneity in this patient. This heterogeneity may influence the response to targeted therapies. Multiple biopsy, liquid biopsy and genomic analysis of intra- tumour molecular heterogeneity may help guide a more precise and effective plan in selecting targeted therapies for ccRCC patients.

Sodium butyrate enhances the growth inhibitory effect of sunitinib in human renal cell carcinoma cells

Sunitinib (SU) is a small molecule that inhibits the receptor tyrosine kinase (RTK) signaling pathway, and has been clinically used to treat advanced renal cell carcinoma (RCC). However, SU is not always effective as RCC is a highly chemoresistant type of cancer. One of the factors that confer chemoresistance to RCC is a hypoxic condition. Lack of oxygen activates hypoxia-inducible factor (HIF) protein, which is followed by the upregulation of growth factors, including vascular endothelial growth factor and activation of the RTK signaling pathway. In this context, histone deacetylase inhibitors (HDACIs) are considered prominent combined agents for SU as they downregulate the expression of HIFs. Therefore, the present study aimed to investigate the effectiveness of combined treatment with SU and sodium butyrate (NaBu), an HDACI. Long-term exposure to these agents exerted a stronger growth inhibitory effect in RCC cell lines compared with single treatment groups. Furthermore, combined treatment suppressed HIF-2α protein, which was induced under hypoxic conditions. In addition, this combination sustained the activity of the RTK signaling pathway to the level of intact cells, although a single treatment with SU or NaBu was demonstrated to increase this activity. Overall, it is suggested that the combination of SU and NaBu is effective for overcoming drug resistance in RCC.

Pharmacokinetics, pharmacodynamics and clinical efficacy of nivolumab in the treatment of metastatic renal cell carcinoma

INTRODUCTION

Nivolumab is a recombinant, humanized monoclonal antibody that binds PD-1. The binding of PD-1 with PD-L1, expressed on antigen-presenting cells and tumor cells, suppresses the ability of T-lymphocytes to recognize and destroy tumor cells. Nivolumab reverts this inhibitory signal and has led to a significant prolongation of overall survival in patients with metastatic renal cell carcinoma (RCC).

AREAS COVERED

The rationale for immunotherapy in metastatic RCC, key immune checkpoint pathways, nivolumab pharmacodynamics, results from the main clinical trials, and predictors of response are discussed.

EXPERT OPINION

Nivolumab demonstrated a statistically significant advantage over everolimus in overall survival in metastatic RCC patients after first-line antiangiogenic therapy. Nevertheless, a number of issues remain to be resolved regarding the use of this drug in RCC. It is now imperative to identify which patients can benefit most from immunotherapy and studies are ongoing to define its role in other settings and/or in combinations with antiCTLA4 or antiangiogenic drugs.

Treatment patterns and clinical outcomes in patients with renal cell carcinoma in the UK: insights from the RECCORD registry

BACKGROUND

The aim of the RECCORD registry was to gather real-world UK data on the use of targeted therapies in renal cell carcinoma (RCC) and assess clinical outcomes. Here, demographic and outcome data are presented with the treatment patterns and demographic profile of patients on the registry.

PATIENTS AND METHODS

Patients were retrospectively identified at seven UK hospitals with large cancer centres in England (5), Scotland (1) and Wales (1). Anonymised data were collected through an online registry covering demographics, treatments and outcomes. Five hundred and fourteen UK adult patients with metastatic RCC were included in the study for analysis. Patients were included if they were treated for metastatic RCC at one of the seven centres, and started systemic anti-cancer treatment from March 2009 to November 2012 inclusive. In addition to demographic factors, the principal outcome measures were overall survival (OS), time to disease progression and toxicity.

RESULTS

The majority of first-line treatment was with sunitinib; first-line use of pazopanib increased as the study progressed. 15.8% of patients received second-line treatment, half of whom were prescribed everolimus. Median OS (from initiation of first-line treatment) was 23.9 months (95% confidence interval [CI] 18.6-29.1 months), similar to that reported for clinical trials of targeted RCC therapies [Ljungberg B, Campbell SC, Choi HY et al. The epidemiology of renal cell carcinoma. Eur Urol 2011; 60: 615-621; Abe H, Kamai T. Recent advances in the treatment of metastatic renal cell carcinoma. Int J Urol 2013; 20: 944-955; Motzer RJ, Hutson TE, Tomczak P et al. Overall survival and updated results for sunitinib compared with interferon alfa in patients with metastatic renal cell carcinoma. J Clin Oncol 2009; 27: 3584-3590]. OS was significantly longer for those who received second-line treatment after disease progression (33.0 months; 95% CI 30.8-35.2 months) than those who did not (20.9 months; 95% CI 16.4-25.3 months; P = 0.008).

CONCLUSIONS

RECCORD is a large 'real-world' database assessing metastatic RCC treatment patterns and outcomes. Treatment patterns changed over time as targeted therapies were approved and became widely available; survival data in RECCORD are consistent with those reported for systemic treatments in clinical trials. Kaplan-Meier analysis of results demonstrated that receiving second-line therapy was a major prognostic factor for longer OS.

Molecular analysis of sunitinib resistant renal cell carcinoma cells after sequential treatment with RAD001 (everolimus) or sorafenib

Sequential application of target drugs is standard procedure after renal cell carcinoma (RCC) patients develop resistance. To optimize the sequence, antitumour effects of the mTOR inhibitor RAD001 or the tyrosine kinase inhibitor (TKI) sorafenib on RCC cells with acquired resistance to the TKI sunitinib was evaluated. RCC cells were exposed to 1 μM sunitinib for 24 hrs (as control) and for 8 weeks (to induce resistance) and then switched to RAD001 (5 nM) or sorafenib (5 μM) for a further 8 weeks. Tumour cell growth, cell cycle progression, cell cycle regulating proteins and intracellular signalling were then investigated. Short-term application of sunitinib (24 hrs) induced cell growth blockade with accumulation in the G2/M phase. RCC cells became resistant to sunitinib after 8 weeks, demonstrated by accelerated cell growth along with enhanced cdk1, cdk2, loss of p27, activation of Akt, Rictor and Raptor. Switching to sorafenib only slightly reduced growth of the sunitinib resistant RCC cells and molecular analysis indicated distinct cross-resistance. In contrast, full response was achieved when the cancer cells were treated with RAD001. p19 and p27 strongly increased, phosphorylated Akt, Rictor and Raptor decreased and the tumour cells accumulated in G0/G1. It is concluded that an mTOR-inhibitor for second-line therapy could be the strategy of choice after first-line sunitinib failure.

Targeted therapy of kidney cancer: keeping the art around the algorithms

BACKGROUND

Therapy for metastatic kidney cancer is actively evolving, particularly in the results of registration drug trials that have led to the approval of vascular endothelial growth factor pathway drugs such as sorafenib, sunitinib, pazopanib, bevacizumab, and axitinib, with focus on patients with good- or intermediate-risk criteria and clear cell histology. Mammalian target of rapamycin (mTOR) drugs such as everolimus and temsirolimus pivotal trials emphasize experiences in the setting of prior treatment or high-risk features. Interferon and interleukin 2 also are part of the treatment algorithms.

METHODS

The results of pivotal trials and the underlying context for the development of a cogent, cohesive treatment plan for an individual are reviewed, touching on decision points such as nephrectomy, metastasectomy, and medical initiation and discontinuation time points.

RESULTS

To the extent that these drug therapies are essential for achieving best outcomes for patients, these pivotal trial results and associated guidelines exist within a multidimensional, multidisciplinary context of many other disease features, comorbid features, and non-drug treatment decisions. Other dimensions include investigational targeted therapies, patient selection strategies, surgical strategies, and immunotherapies, some of which are in active development.

CONCLUSIONS

Clinicians should work toward the best use of drug sequencing and selection strategies based on core data derived from prospective randomized trials. To address individual patient needs, they should also recognize and emphasize individualized goals, to the extent that these are different from issues that were directly addressed in the trials.

Natural history of malignant bone disease in renal cancer: final results of an Italian bone metastasis survey

Background

Bone metastasis represents an increasing clinical problem in advanced renal cell carcinoma (RCC) as disease-related survival improves. There are few data on the natural history of bone disease in RCC.

Patients and methods

Data on clinicopathology, survival, skeletal-related events (SREs), and bone-directed therapies for 398 deceased RCC patients (286 male, 112 female) with evidence of bone metastasis were statistically analyzed.

Results

Median time to bone metastasis was 25 months for patients without bone metastasis at diagnosis. Median time to diagnosis of bone metastasis by MSKCC risk was 24 months for good, 5 months for intermediate, and 0 months for poor risk. Median number of SREs/patient was one, and 71% of patients experienced at least one SRE. Median times to first, second, and third SRE were 2, 5, and 12 months, respectively. Median survival was 12 months after bone metastasis diagnosis and 10 months after first SRE. Among 181 patients who received zoledronic acid (ZOL), median time to first SRE was significantly prolonged versus control (n = 186) (3 months vs 1 month for control; P<0.05).

Conclusions

RCC patients with bone metastasis are at continuous risk of SREs, and in this survey ZOL effectively reduced this risk.

Real-world outcomes in metastatic renal cell carcinoma: insights from a Joint Community-Academic Registry

INTRODUCTION

As new therapeutics for metastatic renal cell carcinoma (mRCC) are quickly introduced to market, comparative randomized trial evidence guiding treatment decisions is lacking, especially in the second treatment exposure and beyond. As a demonstration case, we studied mRCC in real-world clinical settings by creating a joint community-academic retrospective mRCC registry to assess outcomes.

MATERIALS AND METHODS

For this overall survival (OS) analysis, the analytic cohort included all patients in the registry diagnosed between January 1, 2007, to May 31, 2011 (N = 384). Patients were grouped by up to three treatment exposures according to each drug's mechanism of action: vascular endothelial growth factor tyrosine kinase inhibitor (VEGFR TKI), mammalian target of rapamycin inhibitor (mTOR), or no systemic treatment (NSTx, which could include radiation or surgery). OS by exposure sequence was evaluated using Kaplan-Meier, pairwise comparison, and Cox regression analyses.

RESULTS

Median OS was 17.2 months. OS (months) for one exposure was: mTOR 5.4, TKI 18.2, NSTx 18.4; for two exposures: mTOR/TKI 9.3, TKI/mTOR 13.9, TKI/TKI 35.2; and for three exposures: TKI/mTOR/TKI 20.9, TKI/TKI/mTOR 33.1. By pairwise comparison, OS for TKI, mTOR/TKI, TKI/mTOR, TKI/TKI, TKI/mTOR/TKI and TKI/TKI/mTOR sequences was greater than mTOR (all P < .04); demographics confirmed that individuals treated with early mTOR inhibition more commonly had adverse prognostic features. In Cox regression analysis, compared with the referent (TKI), TKI/TKI (hazard ratio = 0.53; P = .03) had a lower risk of death, and mTOR (hazard ratio = 2.16; P = .002) had a higher risk of death.

CONCLUSIONS

mRCC survival outcomes are different by pattern, with general findings consistent with trial-based expectations in similar patient populations. Real-world data can provide context around patterns of care and impact when experimental trial data are lacking.

The prospects of pazopanib in advanced renal cell carcinoma

The landscape of treatment for advanced/metastatic renal cell carcinoma (mRCC) has advanced significantly in the last decade and continues to evolve with the approval of new drugs targeting the vascular endothelial growth factor (VEGF) and its receptors and mammalian target of rapamycin (mTOR). Currently available oral VEGF tyrosine kinase inhibitors (TKIs) approved for treatment of mRCC include sorafenib, sunitinib, pazopanib, and axitinib. This review focuses on pazopanib, a multikinase VEGF TKI indicated for patients with treatment-naïve and cytokine-refractory mRCC. This article describes the preclinical and clinical evolution of pazopanib, with an emphasis on its development and role in mRCC. Pivotal trials are discussed that demonstrate the efficacy and safety of pazopanib and its important role in the treatment of patients with mRCC in comparison to other available treatment options. The clinical path of pazopanib continues to develop further, with several ongoing studies exploring its role in neoadjuvant and adjuvant RCC. Furthermore, its potential role in sequential and combination studies with other VEGFR and non-VEGFR targeted agents is discussed. Overall, pazopanib is a unique VEGF TKI, with a different and more favorable safety profile compared with other members of the VEGF TKI family and represents an attractive alternative for patients with mRCC.

Oral naftopidil suppresses human renal-cell carcinoma by inducing G(1) cell-cycle arrest in tumor and vascular endothelial cells

Renal cell carcinoma (RCC) is an angiogenesis-dependent and hypoxia-driven malignancy. As a result, several targeting agents are being investigated. However, the efficacy of current regimens is generally insufficient for their toxicity and poor overall response rates. We have recently reported that naftopidil exerts growth-inhibitory effects on human prostate cancer cells. In this study, we investigated the biochemical mechanisms by which naftopidil produces growth-inhibitory and antiangiogenic effects on RCC. We first tested the effects of naftopidil on the proliferation of ACHN and Caki-2 RCC cells. Next, we set up a model simulating the tumor microenvironment, in which ACHN cells were grafted onto the renal capsule of mice. We then tested the effects of naftopidil on human umbilical vein endothelial cells' cell proliferation and Matrigel plug vascularization. Finally, to establish the antitumor activity of naftopidil on RCC, we tested the antitumor effects of naftopidil on excised tumor specimens from 20 patients with RCC that were grafted beneath the renal capsule of mice. Naftopidil showed similar in vitro growth-inhibitory effects on all cell lines. Fluorescence-activated cell sorting analysis revealed an increase in G1 cell-cycle arrest in all naftopidil-treated cell lines. In vivo tumorigenic studies showed a significant reduction of ACHN tumor weight, Ki-67 index, and microvessel density (MVD) in naftopidil-treated mice. Naftopidil attenuated neovascularization in an in vivo Matrigel plug assay. Studies in mouse xenograft models also showed a significant MVD reduction in naftopidil-treated excised human RCC. The growth-inhibitory effects of naftopidil suggest it may be a novel anticancer agent and a potential preventive option for RCC.

"Real world" treatment of metastatic renal cell carcinoma in a joint community-academic cohort: progression-free survival over three lines of therapy

BACKGROUND

New targeted therapeutics approved for metastatic renal cell carcinoma (mRCC) offer multiple options in each line of therapy; however, there are few prospective data beyond the first-line settings, and overall comparative effectiveness data are limited. In the targeted therapy era, progression-free survival (PFS) has been the most common regulatory end point for demonstrating the benefit of new therapies.

PATIENTS AND METHODS

Drawing on a joint community-academic retrospective mRCC registry, we analyzed all patients who had undergone at least 1 line of systemic therapy (N = 325) for PFS. Patients were grouped according to treatment choice (sorafenib, sunitinib, temsirolimus, everolimus, and "other") for up to 3 lines of therapy. PFS by treatment choice and line of therapy was evaluated using Kaplan-Meier and Cox regression analyses.

RESULTS

PFS was longest in patients treated with sunitinib in the first and second lines of therapy. First-line PFS for sorafenib, sunitinib, temsirolimus, everolimus, and "other" was 6.9, 8.9, 4.2, not analyzed (too few patients), and 10.8 months, respectively. Second-line PFS was 4.6, 7.0, 3.2, 3.8, and 4.1 months, respectively. Third-line PFS was 4.5, 4.6, 9.9, 4.2, and 2.9, months, respectively. The risk of progression in patients treated with temsirolimus was about twice that of patients treated with sunitinib in the first and second lines of therapy.

CONCLUSION

Patients treated with sunitinib had the longest PFS in the first and second lines of therapy. PFS from practice-based data appear consistent with trial-based expectations; however, practice variation was still evident.

Tivozanib in the treatment of renal cell carcinoma

Renal cell carcinoma (RCC) is an aggressive malignancy compared to other urological malignancies and has been associated with poor responses to conventional cytotoxic chemotherapy. Interferon-α and interleukin-2 were previously utilized in a limited number of patients with good performance status due to toxicity and safety issues. Over the last decade, through advances in the understanding of the biology and pathology of RCC, the important role of vascular endothelial growth factor (VEGF) in RCC has been identified. Data from randomized trials have led to the approval of first-generation tyrosine kinase inhibitors (TKIs) sorafenib, sunitinib, and pazopanib; however, these agents inhibit a wide variety of kinase targets and are associated with a range of adverse effects. More recently, a new generation TKI, axitinib, has been approved by the US Food and Drug Administration. Tivozanib is a novel TKI, which is a potent inhibitor of VEGF-1, VEGF-2, VEGF-3, c-kit, and PDGR kinases, with a more restricted target spectrum. Phase II and III studies have demonstrated significant activity and a favorable safety profile as an initial targeted treatment for advanced RCC. This review examines the emerging data with tivozanib for the treatment of advanced RCC. Preclinical investigations as well as Phase I, II, and III data are examined; data on the comparative benefits of tivozanib are reviewed. Finally, we discuss the future potential of tivozanib in combination, biomarkers associated with tivozanib response, and acquisition of resistance and nonkidney cancer indications.

Phase Ib study of tivozanib (AV-951) in combination with temsirolimus in patients with renal cell carcinoma

BACKGROUND

Tivozanib is a potent and selective tyrosine kinase inhibitor of vascular endothelial growth factor receptors (VEGFR)-1, -2 and -3, with a long half-life. Tivozanib has demonstrated clinical activity and acceptable tolerability in renal cell carcinoma (RCC). This phase Ib study determined the recommended phase II dose (RP2D) and evaluated the safety and clinical activity of tivozanib plus temsirolimus, a mammalian target of rapamycin inhibitor.

PATIENTS AND METHODS

Patients with advanced RCC were administered open-label tivozanib 0.5, 1.0 or 1.5mg/d orally (3 weeks on/1 week off) and temsirolimus 15 or 25 mg/week intravenously in a 3+3 dose-escalation design and subsequent expansion cohort.

RESULTS

Of 27 patients treated, 20 patients had received ≥ 1 prior VEGF-targeted therapy. No dose-limiting toxicities occurred; the RP2D was determined to be tivozanib 1.5mg/d plus temsirolimus 25mg/week. Combination of tivozanib plus temsirolimus demonstrated acceptable tolerability and suggested no synergistic toxicity. The most common grade ≤ 3 adverse events were fatigue and thrombocytopenia (15% each). One patient each required dose reduction of tivozanib or temsirolimus due to an adverse event. Confirmed partial responses and stable disease were achieved at 23% and 68%, respectively. Pharmacokinetic analyses may suggest lack of an interaction between tivozanib and temsirolimus.

CONCLUSIONS

In this small phase Ib study, tivozanib and temsirolimus were safely combined at the fully recommended dose and schedule of both agents. The observed clinical activity and manageable toxicity profile of this combination warrant further exploration in patients with RCC.

A comprehensive overview of targeted therapy in metastatic renal cell carcinoma

Chemotherapy and immunotherapy failed to deliver decisive results in the systemic treatment of metastatic renal cell carcinoma. Agents representing the current standards operate on members of the RAS signal transduction pathway. Sunitinib (targeting vascular endothelial growth factor), temsirolimus (an inhibitor of the mammalian target of rapamycin - mTOR) and pazopanib (a multi-targeted receptor tyrosine kinase inhibitor) are used in the first line of recurrent disease. A combination of bevacizumab (inhibition of angiogenesis) plus interferon α is also first-line therapy. Second line options include everolimus (another mTOR inhibitor) as well as tyrosine kinase inhibitors for patients who previously received cytokine. We review the results of clinical investigations focusing on survival benefit for these agents. Additionally, trials focusing on new agents, including the kinase inhibitors axitinib, tivozanib, dovitinib and cediranib and monoclonal antibodies including velociximab are also discussed. In addition to published outcomes we also include follow-up and interim results of ongoing clinical trials. In summary, we give a comprehensive overview of current advances in the systemic treatment of metastatic renal cell carcinoma.

Immunoexpression status and prognostic value of mammalian target of rapamycin and hypoxia-induced pathway members in papillary cell renal cell carcinomas

Dysregulation of the mammalian target of rapamycin and hypoxia-induced pathways has been consistently identified in clear cell renal cell carcinomas. However, experience with non-clear cell renal cell carcinoma subtypes is scant. In this study, we evaluated the immunohistochemical expression of upstream (PTEN and phosphorylated AKT) and downstream (phosphorylated S6 and 4EBP1) effectors of the mammalian target of rapamycin pathway, as well as related cell-cycle proteins (p27 and c-MYC), and a member of the hypoxia-induced pathway (HIF-1α) in 54 patients with papillary renal cell carcinoma treated by nephrectomy. PTEN was lower in tumor than in normal kidney, and loss of PTEN expression was found in 48% of the patients. In tumor tissues, phosphorylated S6, 4EBP1, and HIF-1α were higher than in normal kidney. Conversely, scores of p27 were lower in tumor than in normal kidney. Finally, scores of c-MYC and phosphorylated AKT were similar in tumor and in normal kidney. Overall mortality and cancer-specific mortality were 24% and 11%, respectively. Tumor progression was observed in 17% of the patients. None of the tested biomarkers predicted cancer-specific mortality or tumor progression. As expected, patients with high T-stage tumors had higher hazard ratios for cancer-specific mortality (hazard ratio, 6.9) and tumor progression (hazard ratio, 6.7). Patients with higher Fuhrman grades also had higher risks for cancer-specific mortality (hazard ratio, 11.4) and tumor progression (hazard ratio, 4.5). In summary, our study provides evidence of dysregulation of the mammalian target of rapamycin and hypoxia-induced pathways in papillary renal cell carcinoma. Immunohistochemistry for members of the mammalian target of rapamycin pathway and for HIF-1α lacked prognostic significance in our cohort.

Progress and contrasts of the development of tivozanib for therapy of kidney cancer

INTRODUCTION

Targets for drug development for the treatment of kidney cancer (renal cell carcinoma; RCC) include vascular endothelial growth factor (VEGF) and its receptors and mammalian target of rapamycin. Currently available oral multitargeted VEGF tyrosine kinase inhibitors (TKIs) that have been approved by the US Food and Drug Administration for advanced RCC, include sunitinib, sorafenib and pazopanib. Off-target TKI inhibition can potentially preclude full-dose combination with other targeted and chemotherapeutic agents. There is a need to develop more potent and selective targeted agents for RCC therapy, which are more effective and have minimal off-target effects.

AREAS COVERED

This drug evaluation review addresses the ongoing development for the treatment of RCC with tivozanib: a potent, selective and long-half-life VEGF TKI. The testing for clinical efficacy alone or in combination with other therapies for RCC and for other tumor types, and the clinical and market relevance of introducing another RCC therapy are discussed.

EXPERT OPINION

Tivozanib is distinguished by its high potency, selectivity, long-half-life and its potential to be effectively combined with other agents in RCC. This may offer more effective, yet well-tolerated treatment options. The relative clinical and market relevance remain to be seen, both for RCC therapy and other tumor types.

Mammalian target of rapamycin expression and laryngeal squamous cell carcinoma prognosis: novel preliminary evidence

AIMS

The mammalian target of rapamycin (mTOR) has a key role in regulating cancer cell proliferation, apoptosis, cell migration, and angiogenesis. The aim of this study was to assess the relationships between mTOR and clinicopathological and prognostic parameters in laryngeal squamous cell carcinoma (SCC).

METHODS AND RESULTS

Mammalian target of rapamycin expression was determined in 103 consecutive operable laryngeal SCCs. Among the mTOR-positive cases, the locoregional recurrence rate was higher (P=0.048) and the disease-free survival (DFS) rate was shorter (P=0.031) in patients with mTOR expression >50.7%. In the N(0) subgroup, the disease recurrence rate was higher (P=0.034) and the DFS was shorter (P=0.009) in patients with mTOR expression >50.7%. In mTOR-positive patients, multivariate analysis showed that N stage (P=0.0001) and mTOR status (P=0.042) were independent indicators of a poor prognosis.

CONCLUSIONS

mTOR appeared to be a significant predictor of DFS in univariate and multivariate models. mTOR expression in laryngeal SCC may be useful for the detection of patients at higher risk for recurrence, and N(0) patients at higher risk for early locoregional recurrence who might benefit from more aggressive therapy. The role of mTOR inhibitors in multimodality or multitarget strategies against laryngeal SCC warrants investigation.

Temporal aspects of the action of ASA404 (vadimezan; DMXAA)

IMPORTANCE OF THE FIELD

Tumor vascular disrupting agents (tumor VDAs) act by selective induction of tumor vascular failure. While their action is distinct from that of antiangiogenic agents, their clinical potential is likely to reside in improving the efficacy of combination therapy.

AREAS COVERED IN THIS REVIEW

This review describes the preclinical development, clinical trial and mode of action of ASA404, a flavonoid class tumor VDA. This class has a unique dual action, simultaneously disrupting vascular endothelial function and stimulating innate tumor immunity. This review covers the early development of ASA404, through to Phase III trial.

WHAT THE READER WILL GAIN

The reader will gain insight into the sequence of ASA404-induced changes in tumor tissue. Early events include increased vascular permeability, increased endothelial apoptosis and decreased blood flow, while later effects include the induction of serotonin, tumor necrosis factor, other cytokines and chemokines, and nitric oxide. This cascade of events induces sustained reduction of tumor blood flow, induction of tumor hypoxia and increased inflammatory responses. The reader will also gain an appreciation of how the potentiation of radiation and chemotherapeutic effects by ASA404 in murine tumors shaped the development of combination clinical trials.

TAKE HOME MESSAGE

Although there are species differences in ASA404 activity, many features of its action in mice translate to human studies. The future of ASA404 as an effective clinical agent will rely on the development of an appreciation of its ability to optimize the complex interaction between tumor vasculature and tumor immunity during therapy.

Targeted therapies for the treatment of metastatic renal cell carcinoma: clinical evidence

Although systemic therapy for patients with metastatic renal cell carcinoma (mRCC) was once limited to the cytokines interleukin-2 and interferon (IFN)-α, in recent years several targeted therapies have become available for first- and second-line use. These include sorafenib, sunitinib, bevacizumab (plus IFN-α), temsirolimus, everolimus, and, most recently, pazopanib. This expanded list of treatment options arose from molecular biological research that revealed aberrant signal transduction activities in RCC, enabling the identification of specific molecular targets for therapy. Molecular-targeted therapies have better efficacy and tolerability than cytokine therapy, and many are administered orally. The superior outcomes achieved with molecular-targeted agents are prompting investigators to reconsider overall survival as a primary endpoint in clinical trials, given the inherent complications of a required long duration of follow-up, a required large population, and confounding caused by crossover trial designs or effects of subsequent therapy after progression on the agent of interest. In mRCC trials, progression-free survival has become a popular primary endpoint and has served as the basis of approval for several targeted therapies. In addition to the identification of new agents, current research is focused on the evaluation of combination therapy with targeted agents. As more information regarding mechanisms of disease and drug resistance becomes available, new targets, new targeted agents, and new combinations will be studied with the goal of providing maximal efficacy with minimal toxicity. This article reviews the clinical evidence supporting the benefits of targeted agents in mRCC treatment, discusses survival endpoints used in their pivotal clinical trials, and outlines future research directions.

Signaling pathways in renal cell carcinoma

Renal cell carcinoma (RCC), the most lethal type of genitourinary cancer, is generally resistant to chemotherapy and radiation therapy. Surgical excision of the tumor at a localized stage remains the mainstay for curative therapy. A number of drugs developed in recent years have shown limited to significant efficacy in treating RCC. These drugs act by blocking critical signaling pathways associated with RCC tumor growth and survival, and angiogenesis. Beyond well-validated signaling targets such as VHL, VEGFR and mTOR, additional pathways including HGF/c-MET and Wnt/β-catenin have emerged as important to RCC pathogenesis. Mutations in one or more components of these signaling networks may affect tumor response to therapy. This review summarizes the state of knowledge about signaling pathways in RCC and discusses the known genetic and epigenetic alterations that underlie dysregulation of these pathways.

Histopathologic subtype-specific genomic profiles of renal cell carcinomas identified by high-resolution whole-genome single nucleotide polymorphism array analysis

To elucidate the novel and common genetic changes in histopathologic subtype-specific profiles of renal cell carcinomas (RCCs), a newly developed high-resolution whole-genome array analysis was applied. Human CNV370-Duo DNA Analysis BeadChip (genotype 370K) was used in a panel of 22 primary clear cell RCCs (ccRCCs), seven papillary RCCs (PRCCs) (six type II and one type I) and eight chromophobe RCCs (ChRCCs). In ccRCC, a chromosome 3p loss was identified in 95% of the carcinomas, suggesting that 3p loss is the first stage in ccRCC carcinogenesis. Other frequent changes included losses of 1p (23%), 3q (46%) and 8p (32%), and gains of 5q (32%), 7p (27%), 7q (27%) and 1q (23%). The most frequent chromosomal losses in PRCC (43%) were noted in 3p and 3q, followed by 29% of losses of 1p, 1q, 11q, 18q, 22p and 22q, and gains of 20q (57%), 20p (43%), 8q (43%) and 12q (43%). Loss of the entire chromosomes 1, 2, 6, 8, 10, 13 or 17 was noted in patients with ChRCC. A high-density single nucleotide polymorphism array analysis confirmed that partial chromosomal changes rarely occur in ChRCC. Additionally, 32 microdeletions and 10 microamplifications of less than 1 Mb were detected, which may represent potential candidate tumor suppressor genes and oncogenes, respectively.