The therapy of kidney cancer with biomolecular drugs

Lupeol alters viability of SK-RC-45 (Renal cell carcinoma cell line) by modulating its mitochondrial dynamics

Renal cell carcinoma (RCC) is the most common kidney cancer leading to 140,000 deaths per year. Among all RCCs 80% evolve from the epithelial proximal tubular cells within the kidney. There is a high tendency of developing chemoresistance and resistance to radiation therapy in most RCC patients. Therefore, kidney resection is considered as the most effective treatments for patients having localized RCC. There is a high tendency of post-operative recurrence among 20-40% of the patients and this recurrence is not curable. It is also clear that modern medicine has no curative treatment options against metastatic RCC. Lupeol [lup-20(29)-en-3β-ol] is a pentacyclic triterpenoid compound naturally found in various edible fruits and in many traditionally used medicinal plants, and has been demonstrated as effective against highly metastatic melanoma and prostate cancers. The present study was designed to evaluate the effect of lupeol to RCC with molecular details. Treatment with lupeol on SK-RC-45 (a RCC cell line) with the LC₅₀ dose of 40μM (for 48 h) induces mitochondrial hyper fission which eventually leads to apoptosis while SK-RC-45 counteracts by enhancing autophagy-mediated selective removal of fragmented mitochondria. This is the first study which concurrently reports the effects of lupeol on RCC and its effect on the mitochondrial dynamics of a cell. Herein, we conclude that lupeol has potential to be an effective agent against RCC with the modulation of mitochondrial dynamics.

Isoquercetin as an Adjunct Therapy in Patients With Kidney Cancer Receiving First-Line Sunitinib (QUASAR): Results of a Phase I Trial

Sunitinib is the most commonly prescribed drug for advanced renal cell carcinoma in the first-line setting and has been associated with multiple adverse events related to its on–and off–target effects, including hand and foot syndrome and fatigue. It was hypothesized that sunitinib-induced fatigue may be related to off target inhibition of the AMPK enzyme, which results in impairment of energy-producing processes at a systemic level. Quercetin is a naturally occurring flavonol with established AMPK-stimulating activity. While clinical use of quercetin is limited by its poor bio-availability, quercetin-3-O-β-d-glucopyranoside, that is isoquercetin, has an improved pharmacokinetic profile. On the grounds of the in vitro stimulatory activity with respect to AMPk, we hypothesized that oral isoquercetin could improve fatigue in kidney cancer patients receiving sunitinib. Given the lack of data on the safety of isoquercetin given concomitantly with sunitinib, we conducted a phase I trial to assess the safety of GMP manufactured isoquercetin given at two dose levels (450 and 900 mg a day). In the 12-patient study cohort included in this study, isoquercetin was administered concomitantly with 50 mg sunitinib for a median 81 days (IQR, 75.5, 86.5). None of the 12 patients required isoquercetin suspension or isoquercetin dose reduction because of adverse events. No abnormalities in ECG, heart or lower limbs doppler ultrasound were detected. A statistically significant improvement was reported for the FACIT fatigue score (6.8 points; 95% CI: 2.8–10.8; p = 0.002) and for the FACIT Adverse Events score (18.9 points; 95% CI: 9.1–28.8; p < 0.001) after isoquercetin consumption vs. baseline. In this phase I trial, isoquercetin was remarkably safe, with a preliminary signal of activity in terms of improvement of sunitinib adverse events.

Orellanine specifically targets renal clear cell carcinoma

Renal cell carcinoma (RCC), arising from the proximal tubule in the kidney, accounts for approximately 85% of kidney cancers and causes over 140,000 annual deaths worldwide. In the last decade, several new therapies have been identified for treatment of metastatic RCC. Although these therapies increase survival time compared to standard care, none of them has curative properties. The nephrotoxin orellanine specifically targets proximal tubular epithelial cells, leaving other organs unaffected. We therefore hypothesized that the selective toxicity of orellanine extends to clear cell RCC (ccRCC) cells since they emanate from proximal tubular cells. Orellanine would thus target both primary and metastatic ccRCC in vitro and in vivo. We found that orellanine induces dose-dependent cell death in proximal tubular cells and in all ccRCC cells tested, both primary and cell lines, with no toxicity detected in control cells. The toxic action of orellanine involve decreased protein synthesis, disrupted cell metabolism and induction of apoptosis. In nude rats carrying human ccRCC xenografts, brief orellanine treatment eliminated more than 90% of viable tumor mass compared to control rats. This identifies orellanine as a potential treatment concept for ccRCC patients on dialysis, due to its unique selective toxicity towards ccRCC.

Biological toxicities as surrogate markers of efficacy in patients treated with mTOR inhibitors for metastatic renal cell carcinoma

Background

Metabolic toxicities of mTOR inhibitors (mTORi) are well characterized. The purpose of the study was to investigate the relationship between these metabolic toxicities and mTORi efficacy.

Methods

From 2007 to 2011, metabolic toxicities were retrospectively collected in patients treated with an mTORi (everolimus, temsirolimus) for a metastatic renal cell carcinoma (mRCC) in a single institution. Patients were eligible if they have received an mTORi for at least 28 days. Changes in the following parameters were analyzed: lymphocytes, serum creatinine, glycemia, serum phosphate, liver transaminases, cholesterol, and triglycerides. The efficacy was assessed by progression-free survival (PFS) and tumor response.

Results

Data were collected from seventy-five patients (everolimus = 44 patients; temsirolimus = 31 patients). Six patients exhibited a partial response, 42 a stable disease and 15 had a progressive disease (12 missing). After a median follow-up of 12.8 months, the median PFS was 6.7 months (95% confidence interval: 4.0-9.1 months). Patients with CB had a statistically more severe absolute increase of glycemia and absolute decrease in phosphatemia (p = 0.002 and p = 0.02 respectively). The Progression Free Survival was significantly higher with the onset rate of hypophosphatemia (p = 0.03) and hyperglycemia (p = 0.001) and lower with the onset rate of lymphopenia (p = 0.004).

Conclusions

Hyperglycemia, hypophosphatemia and lymphopenia, were significantly associated with tumor response and/or PFS. Those events, as well as their onset rate, should be prospectively monitored as predictors of response to mTORi.

Targeting Strategies for Renal Cell Carcinoma: From Renal Cancer Cells to Renal Cancer Stem Cells

Renal cell carcinoma (RCC) is a common form of urologic tumor that originates from the highly heterogeneous epithelium of renal tubules. Over the last decade, targeting therapies to renal cancer cells have transformed clinical care for RCC. Recently, it was proposed that renal cancer stem cells (CSCs) isolated from renal carcinomas were responsible for driving tumor growth and resistance to conventional chemotherapy and radiotherapy, according to the theory of CSCs; this has provided the rationale for therapies targeting this aggressive cell population. Precise identification of renal CSC populations and the complete cell hierarchy will accurately inform characterization of disease subtypes. This will ultimately contribute to more personalized and targeted therapies. Here, we summarize potential targeting strategies for renal cancer cells and renal CSCs, including tyrosine kinase inhibitors, mammalian target of rapamycin inhibitors (mTOR), interleukins, CSC marker inhibitors, bone morphogenetic protein-2, antibody drug conjugates, and nanomedicine. In conclusion, targeting therapies for RCC represent new directions for exploration and clinical investigation and they plant a seed of hope for advanced clinical care.

Prevention of Hepatitis B Virus Reactivation With Lamivudine in a Patient With Advanced Renal Cell Carcinoma Treated With Everolimus

Anticancer agents may trigger reactivation of hepatitis B virus infection ensuing in asymptomatic to severe liver damage. Preemptive administration of antiviral agents such as lamivudine to patients receiving cytotoxic chemotherapy has been shown to inhibit viral replication and prevent such events. No data are available so far concerning the coadministration of antiviral agents and everolimus, an oral mammalian target of rapamycin inhibitor recently approved for the treatment of advanced renal cell carcinoma. We present in this study the first case to our knowledge of a hepatitis B surface antigen-positive patient with metastatic renal cell carcinoma who has been successfully treated with prophylactic lamivudine and everolimus. Long-term depletion of viral replication was obtained along with stabilization of lung and bone metastases. Hepatitis B surface antigen positivity may be found in up to 10% of cancer patients but should not be considered a contraindication to treatment with everolimus.

miR-17 inhibition enhances the formation of kidney cancer spheres with stem cell/ tumor initiating cell properties

Renal cell carcinoma (RCC) is an aggressive disease, with 35% chance of metastasis. The 'cancer stem cell' hypothesis suggests that a subset of cancer cells possess stem cell properties and is crucial in tumor initiation, metastasis and treatment resistance. We isolated RCC spheres and showed that they exhibit cancer stem cell/ tumor initiating cell-like properties including the formation of self-renewing spheres, high tumorigenicity and the ability to differentiate to cell types of the original tumor. Spheres showed increased expression of stem cell-related transcription factors and mesenchymal markers. miRNAs were differentially expressed between RCC spheres and their parental cells. Inhibition of miR-17 accelerated the formation of RCC spheres which shared molecular characteristics with the spontaneous RCC spheres. Target prediction pointed out TGFβ pathway activation as a possible mechanism to drive RCC sphere formation. We demonstrate that miR-17 overexpression interferes with the TGFβ-EMT axis and hinders RCC sphere formation; and validated TGFBR2 as a direct and biologically relevant target during this process. Thus, a single miRNA may have an impact on the formation of highly tumorigenic cancer spheres of kidney cancer.

How can we improve prognostic models in renal cell carcinoma?

The therapeutic improvements in renal cell carcinoma brought about by the transition from the 'cytokine era' to the 'targeted agents era', have not affected the peculiar prognostic heterogeneity of the disease, nor have they diminished the importance of risk group classification based on easily assessable and commonly available laboratory and clinical variables. In the landmark study conducted by Motzer et al. before biological agents were available, the median survival of patients in the good prognosis group was 20 months, while the patients in the poor-risk group had a median survival time of only 4 months. With the introduction of anti-VEGF agents, overall survival has approximately doubled in all risk classes. In a population-based analysis of 670 patients treated with anti-VEGF agents, either in the first-line setting or in the second-line setting after cytokines, stratification according to the Database Consortium model showed that patients in the favorable risk group had a median overall survival of 43.2 months, while patients in the poor-risk group had a median overall survival of 7.8 months.

A photo-responsive peptide- and asparagine-glycine-arginine (NGR) peptide-mediated liposomal delivery system

The conjugation of tunable peptides or materials with nanocarriers represents a promising approach for drug delivery to tumor cells. In this study, we report the development of a novel liposomal carrier system that exploits the cell surface binding synergism between photo-sensitive peptides (PSPs) and targeting ligands. The positive charges of the lysine residues on the cell-penetrating peptides (CPPs) were temporarily caged by the photolabile-protective groups (PG), thereby forming a PSP. Furthermore, this PSP enhances specific uptake into cancer cells after rapidly uncaging the PG via near-infrared (NIR) light illumination. In the circulatory system, the cell penetrability of PSP was hindered. In contrast, the asparagine-glycine-arginine (NGR) peptide moieties, selectively bind to CD13-positive tumors, were attached to the nanocarrier to facilitate the active accumulation of this liposomal carrier in tumor tissue. The dual-modified liposomes (PSP/NGR-L) were prepared by emulsification method, and the concentrations of DSPE-PEG₂₀₀₀-psCPP and DSPE-PEG₅₀₀₀-NGR in the liposomes were chosen to be 4% and 1% (molar ratio), respectively. The mean particle size of the PSP/NGR-L was about 95 nm, and the drug entrapment efficiency was more than 90%. Cellular uptake results demonstrated that the proposed PSP/NGR-L had an enhancement of cancer cell recognition and specific uptake. Furthermore, the PSP/NGR-L demonstrated a stronger antitumor efficacy in the HT-1080 tumor model in nude mice with the aid of NIR illumination.

Piperlongumine and its analogs down-regulate expression of c-Met in renal cell carcinoma

The c-Met protein, a transmembrane receptor tyrosine kinase, is the product of a proto-oncogene. Its only known ligand, hepatocyte growth factor (HGF), regulates cell growth, motility, migration, invasion, proliferation, and angiogenesis. The aberrant expression of c-Met is often associated with poor prognosis in multiple cancers, including renal cell carcinoma (RCC). Silencing or inactivation of c-Met leads to decreased viability of cancer cells, thereby making ablation of c-Met signaling an attractive concept for developing novel strategies for the treatment of renal tumors. Naturally-occurring products or substances are the most consistent source of drug development. As such, we investigated the functional impact of piperlongumine (PL), a naturally occurring alkaloid present in the Long pepper (Piper longum) on c-Met expression in RCC cells and demonstrated that PL and its analogs rapidly reduce c-Met protein and RNA levels in RCC cells via ROS-dependent mechanism. PL-mediated c-Met depletion coincided with the inhibition of downstream c-Met signaling; namely Erk/MAPK, STAT3, NF-κB and Akt/mTOR. As such, PL and PL analogs hold promise as potential therapeutic agents for the treatment of metastatic RCC and the prevention of postoperative RCC recurrence.

Histologic variations and immunohistochemical features of metastatic clear cell renal cell carcinoma

BACKGROUND

Due to advancements in treatment of metastatic and advanced renal cell carcinoma (RCC), it has become increasingly important to diagnose metastatic RCC and the specific subtype. In this study, we investigated the diverse histologic features of metastatic clear cell renal cell carcinoma (CCRCC) cases in comparison with corresponding primary lesions.

METHODS

We identified 119 metastatic CCRCC cases from 81 corresponding primary lesions diagnosed between 1995 and 2010 and evaluated the diverse histologic and immunohistochemical features of these lesions.

RESULTS

A total of 44 primary lesions (54.3%) had a non-clear cell component in addition to a typical clear cell component. Of the 119 metastatic lesions, 63 lesions (52.9%) contained a non-clear cell component, and 29 metastatic lesions were composed of a non-clear cell component only. Rhabdoid features were the most frequent non-clear cell histology among the metastatic lesions. Metastatic CCRCCs mainly showed positive CD10 and epithelial membrane antigen staining and negative cytokeratin 7 staining.

CONCLUSIONS

Metastatic CCRCC commonly showed a variety of histologic features. If there is a difficulty to diagnose metastatic CCRCC due to a variety of histologic features or small biopsy specimen, histologic review of the primary lesion and immunohistochemical analysis can help determine the correct diagnosis.

The effect of liposomal size on the targeted delivery of doxorubicin to Integrin αvβ3-expressing tumor endothelial cells

Size of the liposomes (LPs) specially governs its biodistribution. In this study, LPs were developed with controlled sizes, where variation in LP size dictates the ligand-receptor interaction, cellular internalization and its distribution within the tumor microenvironment. The therapeutic efficacies of doxorubicin (DOX)-loaded RGD modified small size (~100 nm in diameter, dnm) and large size (~300 dnm) PEGylated LPs (RGD-PEG-LPs) were compared to that of Doxil (a clinically used DOX-loaded PEG-LP, ~100 dnm) in DOX resistant OSRC-2 (Renal cell carcinoma, RCC) tumor xenografts. Doxil, which accumulated in tumor tissue via the enhanced permeability and retention (EPR) effect, failed to suppress tumor growth. Small size RGD-PEG-LP, that targets the tumor endothelial cells (TECs) and extravasates to tumor cells, failed to provide anti-tumor effect. Large size RGD-PEG-LP preferentially targets the TECs via minimization of the EPR effect, and significantly reduced the tumor growth, which was exerted through its strong anti-angiogenic activity on the tumor vasculature rather than having a direct effect on DOX resistant RCC. The prepared large size RGD-PEG-LP that targets the TECs via interacting with Integrin αvβ3, is a potentially effective and alternate therapeutic strategy for the treatment of DOX resistant tumor cells by utilizing DOX, in cases where Doxil is ineffective.

Polypharmacology of sulfonamides: pazopanib, a multitargeted receptor tyrosine kinase inhibitor in clinical use, potently inhibits several mammalian carbonic anhydrases

Pazopanib, a new, multi-targeted tyrosine kinase inhibitor (TKI) used clinically for the treatment of several types of tumors, incorporates a primary sulfonamide moiety normally associated with the inhibition of the metallo enzyme carbonic anhydrase (CA, EC 4.2.1.1). Here we show that pazopanib and related sulfonamides such as indisulam, acetazolamide or ureido-substituted peptidomimetic benzenesulfonamides are low nanomolar inhibitors of many of the fifteen human isoforms hCA I-XIV. These data indicate that in addition to the TK inhibitory action, pazopanib may exert antitumor/antimetastatic effects also due to the potent inhibition of the tumor-associated, hypoxia-inducible enzymes CA IX and XII.

Current status of targeted therapy for advanced renal cell carcinoma

The treatment of metastatic renal cell carcinoma (mRCC) has recently evolved from being predominantly cytokine-based treatment to the use of targeted agents, which include sorafenib, sunitinib, bevacizumab (plus interferon alpha [IFN-α]), temsirolimus, everolimus, pazopanib, and most recently, axitinib. Improved understanding of the molecular pathways implicated in the pathogenesis of RCC has led to the development of specific targeted therapies for treating the disease. In Korea, it has been 5 years since targeted therapy became available for mRCC. Thus, we now have broader and better therapeutic options at hand, leading to a significantly improved prognosis for patients with mRCC. However, the treatment of mRCC remains a challenge and a major health problem. Many questions remain on the efficacy of combination treatments and on the best methods for achieving complete remission. Additional studies are needed to optimize the use of these agents by identifying those patients who would most benefit and by elucidating the best means of delivering these agents, either in combination or as sequential single agents. Furthermore, numerous ongoing research activities aim at improving the benefits of the new compounds in the metastatic situation or their application in the early phase of the disease. This review introduces what is currently known regarding the fundamental biology that underlies clear cell RCC, summarizes the clinical evidence supporting the benefits of targeted agents in mRCC treatment, discusses survival endpoints used in pivotal clinical trials, and outlines future research directions.

Mechanism-based therapeutics for autosomal dominant polycystic kidney disease: recent progress and future prospects

Autosomal dominant polycystic kidney disease (ADPKD) is the most common inherited kidney disease, accounting for up to 10% of patients on renal replacement therapy. There are presently no proven treatments for ADPKD and an effective disease-modifying drug would have significant implications for patients and their families. Since the identification of PKD1 and PKD2, there has been an explosion in knowledge identifying new disease mechanisms and testing new drugs. Currently, the three major treatment strategies are to: (1) reduce cAMP levels; (2) inhibit cell proliferation, and (3) reduce fluid secretion. Several compounds shown to be effective in preclinical models have already undergone clinical trials and more are planned. In addition, a whole raft of other compounds have been developed from preclinical studies. The purpose of this paper is to evaluate the results of recent published trials, review current trials and highlight the most promising compounds in the pipeline. There appears to be no shortage of potential candidates, but several key issues need to be addressed to facilitate clinical translation.

Randomized controlled study of natural interferon α as adjuvant treatment for stage II or III renal cell carcinoma

BACKGROUND

The prophylactic effect of postoperative interferon on recurrence and distant metastasis in stage II or III renal cell carcinoma is unclear. In most studies, interferon has been administered for 6 months or less. Therefore, we performed a clinical study of the efficacy of 1-year postoperative administration of natural interferon α, which is generally used in Japan.

METHODS

The subjects were patients diagnosed with stage II or III renal cell carcinoma who underwent radical nephrectomy. The subjects were randomly allocated to receive an intramuscular injection of natural interferon α (3 million to 6 million units) 3 times a week for 1 year or to receive follow-up observation until recurrence or metastasis occurred. Chest and abdominal CT were performed once yearly for all patients. The primary endpoint was progression-free survival.

RESULTS

From September 2001 to August 2006, a total of 107 patients were registered, but 7 subsequently withdrew from the study. Therefore, 100 patients were included in the analysis. The primary endpoint of progression-free survival did not differ significantly between the groups that received natural interferon α or follow-up observation (p = 0.456, log-rank test). However, peak hazards of progression in the interferon group were delayed for about 6-10 months compared with the observation group.

CONCLUSION

Progression-free survival showed no improvement after administration of natural interferon α to patients with stage II or III renal cell carcinoma for 1 year after radical nephrectomy. The peak hazards of progression might be delayed by about 6 months by interferon administration.