The von Hippel-Lindau tumor suppressor protein regulates gene expression and tumor growth through histone demethylase JARID1C

In clear-cell renal cell carcinoma (ccRCC), inactivation of the tumor suppressor von Hippel-Lindau (VHL) occurs in the majority of the tumors and is causal for the pathogenesis of ccRCC. Recently, a large-scale genomic sequencing study of ccRCC tumors revealed that enzymes that regulate histone H3 lysine 4 trimethylation (H3K4Me3), such as JARID1C/KDM5C/SMCX and MLL2, were mutated in ccRCC tumors, suggesting that H3K4Me3 might have an important role in regulating gene expression and tumorigenesis. In this study we report that in VHL-deficient ccRCC cells, the overall H3K4Me3 levels were significantly lower than that of VHL+/+ counterparts. Furthermore, this was hypoxia-inducible factor (HIF) dependent, as depletion of HIF subunits by small hairpin RNA in VHL-deficient ccRCC cells restored H3K4Me3 levels. In addition, we demonstrated that only loss of JARID1C, not JARID1A or JARID1B, abolished the difference of H3K4Me3 levels between VHL-/- and VHL+/+ cells, and JARID1C displayed HIF-dependent expression pattern. JARID1C in VHL-/- cells was responsible for the suppression of HIF-responsive genes insulin-like growth factor-binding protein 3 (IGFBP3), DNAJC12, COL6A1, growth and differentiation factor 15 (GDF15) and density-enhanced phosphatase 1. Consistent with these findings, the H3K4Me3 levels at the promoters of IGFBP3, DNAJC12, COL6A1 and GDF15 were lower in VHL-/- cells than in VHL+/+ cells, and the differences disappeared after JARID1C depletion. Although HIF2α is an oncogene in ccRCC, some of its targets might have tumor suppressive activity. Consistent with this, knockdown of JARID1C in 786-O VHL-/- ccRCC cells significantly enhanced tumor growth in a xenograft model, suggesting that JARID1C is tumor suppressive and its mutations are tumor promoting in ccRCC. Thus, VHL inactivation decreases H3K4Me3 levels through JARID1C, which alters gene expression and suppresses tumor growth.

ICUD-EAU International Consultation on Kidney Cancer 2010: treatment of metastatic disease

CONTEXT

Until the development of novel targeted agents directed against angiogenesis and tumour growth, few treatment options have been available for the treatment of metastatic renal-cell carcinoma (mRCC).

OBJECTIVE

This review discusses current targeted therapies for mRCC and provides consensus statements regarding treatment algorithms.

EVIDENCE ACQUISITION

Medical literature was retrieved from PubMed up to April 2011. Additional relevant articles and abstract reviews were included from the bibliographies of the retrieved literature.

EVIDENCE SYNTHESIS

Targeted treatment for mRCC can be categorized for the following patient groups: previously untreated patients, those refractory to immunotherapy, and those refractory to vascular endothelial growth factor (VEGF)-targeted therapy. Sunitinib and bevacizumab combined with interferon alpha are generally considered first-line treatment options in patients with favourable or intermediate prognoses. Temsirolimus is considered a first-line treatment option for poor-risk patients. Either sorafenib or sunitinib may be valid second-line treatments for patients who have failed prior cytokine-based therapies. For patients refractory to treatment with VEGF-targeted therapy, everolimus is now recommended. Pazopanib is a new treatment option in the first- and second-line setting (after cytokine failure). Sequential and combination approaches, and the roles of nephrectomy and tumour metastasectomy will also be discussed.

CONCLUSIONS

Increasing clinical evidence is clarifying appropriate first- and second-line treatments with targeted agents for patients with mRCC. Based on phase 2 and 3 trials, a sequential approach is most promising, while combination therapy is still investigational. The role of nephrectomy in mRCC is being evaluated in ongoing phase 3 clinical trials.

Germline and somatic DNA methylation and epigenetic regulation of KILLIN in renal cell carcinoma

We recently identified germline methylation of KILLIN, a novel p53-regulated tumor suppressor proximal to PTEN, in >1/3 Cowden or Cowden syndrome-like (CS/CSL) individuals who are PTEN mutation negative. Individuals with germline KILLIN methylation had increased risks of renal cell carcinoma (RCC) over those with PTEN mutations. Therefore, we tested the hypothesis that KILLIN may be a RCC susceptibility gene, silenced by germline methylation. We found germline hypermethylation by combined bisulfite restriction analysis in at least one of the four CpG-rich regions in 23/41 (56%) RCC patients compared to 0/50 controls (P < 0.0001). Of the 23, 11 (48%) demonstrated methylation in the -598 to -890 bp region in respect to the KILLIN transcription start site. Furthermore, 19 of 20 advanced RCC showed somatic hypermethylation upstream of KILLIN, with the majority hypermethylated at more than one CpG island (13/19 vs. 3/23 with germline methylation, P < 0.0001). qRT-PCR revealed that methylation significantly downregulates KILLIN expression (P = 0.05), and demethylation treatment by 5-aza-2'deoxycytidine significantly increased KILLIN expression in all RCC cell lines while only increasing PTEN expression in one line. Furthermore, targeted in vitro methylation revealed a significant decrease in KILLIN promoter activity only. These data reveal differential epigenetic regulation by DNA promoter methylation of this bidirectional promoter. In summary, we have identified KILLIN as a potential novel cancer predisposition gene for nonsyndromic clear-cell RCC, and the epigenetic mechanism of KILLIN inactivation in both the germline and somatic setting suggests the potential for treatment with demethylating agents.

Baseline patient-reported kidney cancer-specific symptoms as an indicator for median survival in sorafenib-refractory metastatic renal cell carcinoma

INTRODUCTION

The goal of the study was to determine the relationship of baseline Functional Assessment of Cancer Therapy-Kidney Cancer Symptom Index (FKSI) scores with median progression-free survival (mPFS) and median overall survival (mOS) after treatment with axitinib in patients with sorafenib-refractory metastatic renal cell carcinoma.

METHODS

As part of a multicenter, open-label, phase II study, patients (N = 62) reported symptoms at baseline using the FKSI, with higher scores indicating less severe symptoms. A Weibull (fully parametric) model was fit to time-to-event data to establish the relationship of baseline FKSI score with mPFS and mOS. Kaplan-Meier curves were obtained as sensitivity analyses.

RESULTS

Longer progression-free and overall survivals were associated with higher (more favorable) baseline FKSI-15 and FKSI disease-related symptoms (FKSI-DRS) subscale specific to kidney cancer scores. For example, for FKSI-15 scores of 0 (most symptoms), 30, and 60 (no symptoms), the mPFS were 0.72, 3.83, and 20.43 months, respectively, and the mOS were 1.05, 6.27, and 37.53 months. Similar patterns and interpretations were observed for the FKSI-DRS scores. The results from the Kaplan-Meier analyses supported the parametric model.

DISCUSSIONS/CONCLUSIONS

Baseline patient-reported kidney cancer symptoms are linked to mPFS and mOS in a clear and interpretable way. These results support the evaluation of patient-reported symptoms at baseline in clinical trials and in clinical practice to measure symptom severity and potentially predict progression-free and overall survival outcomes.

IMPLICATIONS FOR CANCER SURVIVORS

The results provide a heightened opportunity to use patient data not only to assist in medical treatment planning but also to prepare patients, who have advanced disease and an already reduced expected lifespan, with an opportunity to deal with the psychosocial aspects of the dying process.

Pazopanib for the treatment of renal cancer

INTRODUCTION

Dramatic advances in the care of patients with advanced renal cell carcinoma (RCC) have occurred over the last 10 years. Insights into the molecular pathogenesis of this disease have elucidated the importance of signaling cascades related to angiogenesis in the management of RCC. Pazopanib is a novel, small-molecule tyrosine kinase inhibitor that targets vascular endothelial growth factor receptors (VEGFR)-1, -2, and -3; platelet-derived growth factor receptors (PDGFR)-α and -β; and c-kit tyrosine kinases. Pazopanib exhibits distinct pharmacokinetic and toxicity profiles compared with other agents in the class of VEGF signaling pathway inhibitors.

AREAS COVERED

This review discusses the scientific rationale for the development of pazopanib, as well as the preclinical and clinical trials that led to the approval of pazopanib for patients with advanced RCC. The most recent information, including data from the 2010 meeting of the American Society of Clinical Oncology and the design of ongoing Phase III trials, is discussed. Finally, an algorithm utilizing level I evidence for the treatment of patients with this disease is proposed.

EXPERT OPINION

The treatment of metastatic RCC has changed dramatically over the last 5 years. Six novel agents - sunitinib, sorafenib, temsirolimus, everolimus, bevacizumab (used in combination with interferon), and pazopanib (Votrient) - have been approved for the treatment of metastatic RCC. The clinical data to date clearly place pazopanib among the most active of the targeted therapies.

MDSC as a mechanism of tumor escape from sunitinib mediated anti-angiogenic therapy

Sunitinib is a receptor tyrosine kinase inhibitor (TKI) that is front-line therapy for metastatic renal cell carcinoma (mRCC). Its antitumor activity is related to its ability to block tumor cell and tumor vasculature cell signaling via several TKI receptors (i.e. vascular endothelial growth factor receptors VEGFRs, platelet-derived growth factors (PDGFs), and stem cell factors). Sunitinib also targets myeloid derived suppressor cells (MDSCs) significantly reducing their accumulation in the peripheral blood and reversing T cell (IFNγ) suppression in both mRCC patients and in murine tumor models. This reduction in immune suppression provides a rationale for combining sunitinib with immunotherapy for the treatment of certain tumor types. Despite these encouraging findings, however, we have observed that sunitinib has variable impact at reducing MDSCs and restoring T cell function within the tumor microenvironment. Given the immunosuppressive and proangiogenic activities of MDSC, it seems plausible that their persistence may contribute to the resistance that develops in sunitinib-treated patients. While sunitinib reduced tumor infiltrating MDSCs in Renca and CT26-bearing mice, coinciding with strong to modest decreases in tumor size respectively, it was ineffective at reducing MDSCs (<35% reduction in Gr1+CD11b+) or tumor burden in 4T1-bearing mice. Persistence of intratumor MDSCs was paralleled by depressed intratumor T cell IFNγ response and increased GM-CSF expression. Additionally, in vitro and in vivo experiments showed that GM-CSF prolongs survival of MDSCs, thus protecting them from the effects of sunitinib via a pSTAT5-dependent pathway. Although preliminary, there is evidence of intratumor MDSC resistance in some mRCC patients following sunitinib treatment. Intratumor MDSC persistence and T cell IFNγ response post nephrectomy in patients receiving sunitinib in a neoadjuvant setting are being compared to RCC patients undergoing nephrectomy without prior sunitinib treatment. Tumors from untreated patients showed suppressed T cell IFNγ response along with substantial expression of MDSCs (5% of total digested cells). Thus far, tumors from 5/8 neoadjuvant patients showed persistence of intratumor MDSCs and low T cell IFNγ production post sunitinib treatment, findings that parallel results from untreated tumors. In the remaining 3 neoadjuvant patients, intratumor MDSCs were detected at low levels which coincided with a T cell IFNγ response similar to that observed with normal donor peripheral T cells. GM-CSF's role in promoting MDSC survival in patient tumors is supported by the observation that GM-CSF is produced in short-term RCC cultures at levels capable of protecting MDSCs from sunitinib-induced cell death. Additionally, persistence of MDSC also may be associated with increased expression of proangiogenic proteins, such as MMP9, MMP8, and IL-8 produced by tumor stromal cells or infiltrating MDSCs. Indeed our findings suggest that the most dominate MDSC subset in RCC patients is the neutrophilic population that produces proangiogenic proteins. We propose that the development of sunitinib resistance is partly mediated by the survival of MDSCs intratumorally, thereby providing sustained immune suppression and angiogenesis.

Noncytotoxic differentiation treatment of renal cell cancer

Current drug therapy for metastatic renal cell cancer (RCC) results in temporary disease control but not cure, necessitating continued investigation into alternative mechanistic approaches. Drugs that inhibit chromatin-modifying enzymes involved in transcription repression (chromatin-relaxing drugs) could have a role, by inducing apoptosis and/or through differentiation pathways. At low doses, the cytosine analogue decitabine (DAC) can be used to deplete DNA methyl-transferase 1 (DNMT1), modify chromatin, and alter differentiation without causing apoptosis (cytotoxicity). Noncytotoxic regimens of DAC were evaluated for in vitro and in vivo efficacy against RCC cell lines, including a p53-mutated RCC cell line developed from a patient with treatment-refractory metastatic RCC. The cell division-permissive mechanism of action-absence of early apoptosis or DNA damage, increase in expression of HNF4α (hepatocyte nuclear factor 4α), a key driver associated with the mesenchymal to epithelial transition, decrease in mesenchymal marker expression, increase in epithelial marker expression, and late increase in cyclin-dependent kinase inhibitor CDKN1B (p27) protein-was consistent with differentiation-mediated cell-cycle exit. In vivo blood counts and animal weights were consistent with minimal toxicity of therapy. The distinctive mechanism of action of a dose and schedule of DAC designed for noncytotoxic depletion of DNMT1 suggests a potential role in treating RCC.

Direct and differential suppression of myeloid-derived suppressor cell subsets by sunitinib is compartmentally constrained

The antiangiogenic drug sunitinib is a receptor tyrosine kinase inhibitor with significant, yet not curative, therapeutic effects in metastatic renal cell carcinoma (RCC). Sunitinib is also an immunomodulator, potently reversing myeloid-derived suppressor cell (MDSC) accumulation and T-cell inhibition in the blood even of nonresponder RCC patients. We observed that sunitinib similarly prevented MDSC accumulation and restored normal T-cell function to the spleens of tumor-bearing mice, independent of the capacity of sunitinib to inhibit tumor progression (RENCA>CT26>4T1). Both monocytic and neutrophilic splenic MDSC were highly repressible by sunitinib. In contrast, MDSC within the microenvironment of 4T1 tumors or human RCC tumors proved highly resistant to sunitinib and ambient T-cell function remained suppressed. Proteomic analyses comparing tumor to peripheral compartments showed that granulocyte macrophage colony-stimulating factor (GM-CSF) predicted sunitinib resistance and recombinant GM-CSF conferred sunitinib resistance to MDSC in vivo and in vitro. MDSC conditioning with GM-CSF uniquely inhibited signal transducers and activators of transcription (STAT3) and promoted STAT5 activation. STAT5ab(null/null) MDSC were rendered sensitive to sunitinib in the presence of GM-CSF in vitro. We conclude that compartment-dependent GM-CSF exposure in resistant tumors may account for the regionalized effect of sunitinib upon host MDSC modulation and hypothesize that ancillary strategies to decrease such regionalized escape will enhance the potency of sunitinib as an immunomodulator and a cancer therapy.

Abstract 630: Interleukin-8 as a potential mediator for renal cell carcinoma resistance to antiangiogenic sunitinib therapy

Sunitinib is considered the first line therapy for advanced clear cell renal cell carcinoma (ccRCC), a deadly form of kidney cancer. Unfortunately, most patients exhibit progressive disease after about one year of treatment. The mechanisms of progression are poorly understood. The aim of this study was to evaluate the mechanism of resistance to sunitinib and to identify potential targets to overcome sunitinib resistance. We generated xenograft models that mimicked clinical resistance to sunitinib. Higher microvessel density was found in sunitinib-resistant tumors, which indicated that an escape from anti-angiogenesis occurred in these tumors. This escape coincided with increased tumor secretion of interleukin-8 (IL-8) into the plasma. Co-administration of an IL-8 neutralizing antibody resensitized these tumors to sunitinib treatment, demonstrating the functional contribution of IL-8 to sunitinib resistance. Immunohistochemical staining showed that IL-8 expression was elevated in ccRCC tumors from patients who were refractory to sunitinib treatment, indicating IL-8 levels may predict clinical response to sunitinib. In conclusion, our results demonstrate that IL-8 is an important contributor, among others, to sunitinib resistance in ccRCC. IL-8 may serve as a therapeutic target for treatment of sunitinib resistant ccRCC, as well as a biomarker for both acquired and intrinsic sunitinib resistance.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 630.

Sunitinib and sorafenib in metastatic renal cell carcinoma patients with renal insufficiency

BACKGROUND

Although clinical trials with sunitinib and sorafenib in metastatic renal cell carcinoma (mRCC) have included patients with moderate renal insufficiency (RI), the incidence of renal toxicity induced by their administration as well as the safety of these agents in patients with more severe renal insufficiency has not been extensively reported.

PATIENTS AND METHODS

Patients with mRCC treated with vascular endothelial growth factor-targeted therapy with either RI at time of treatment initiation or who developed RI during therapy were identified. RI was defined as serum creatinine (Cr) > or = 1.9 mg/dl or a creatinine clearance (CrCl) < 60 ml/min/1.73 m(2) for >3 months before treatment. Objective outcomes and toxic effects of treatment were also measured.

RESULTS

A total of 39 patients were identified: 21 patients who initiated therapy with preexisting RI and 18 patients who developed RI during treatment. In patients with RI at the start of therapy, Cr increased in 57%, and 48% of patients required dose reduction. The median time to maximum RI was 6.6 months (range 0.4-19.6 months). In patients who developed RI while receiving therapy, median serum Cr and CrCl at the start of therapy were 1.5 mg/dl (range 1.1-1.8) and 61 ml/min (range 43-105), respectively. Patients experienced a median increase in serum Cr of 0.8 mg/dl (range 0.3-2.8) and a median decrease in CrCl of 25 ml/min (range 8.54-64.76). Overall, 5 patients (24%) achieved a partial response (PR), 13 (62%) had stable disease (SD) and 3 (14%) had progressive disease (PD). Estimated progression-free survival (PFS) was 8.4 months. The most common toxic effects (all grades) were fatigue (81%), hand-foot syndrome (HFS) (52%) and diarrhea (48%). Six patients experienced grade III toxicity (29%), primarily HFS.

CONCLUSIONS

Sunitinib and sorafenib can be safely given to patients with renal insufficiency, provided adequate monitoring of renal function. For those patients developing an increase in Cr, dose modifications may be required to allow continuation of therapy. The clinical outcome of patients with baseline renal dysfunction and patients who develop renal dysfunction does not appear to be compromised.

Elevated levels of select gangliosides in T cells from renal cell carcinoma patients is associated with T cell dysfunction

Increased expression of gangliosides by different tumor types including renal cell carcinoma (RCC) is thought to contribute to the immune suppression observed in cancer patients. In this study, we report an increase in apoptotic T cells from RCC patients compared with T cells from normal donors that coincided with the detection of T cells staining positive for GM2 and that the apoptosis was predominantly observed in the GM2(+) but not the GM2(-) T cell population. Ganglioside shedding from tumor rather than endogenous production accounts for GM2(+) T cells since there was no detectable level of mRNA for GM2 synthase in RCC patient T cells and in T cells from normal healthy donors after incubation with either purified GM2 or supernatant from RCC cell lines despite their staining positive for GM2. Moreover, reactive oxygen species as well as activated caspase 3, 8, and 9 were predominantly elevated in GM2(+) but not GM2(-) T cells. Similarly, increased staining for GD2 and GD3 but not GD1a was detected with patient T cells with elevated levels of apoptosis in the GD2(+) and GD3(+) cells. These findings suggest that GM2, GD2, and GD3 play a significant role in immune dysfunction observed in RCC patient T cells.

Management of side effects associated with sunitinib therapy for patients with renal cell carcinoma

Advances in the understanding of the biology of renal cell carcinoma have led to recent approval of several new agents including drugs that target vascular endothelial growth factor. Sunitinib is an oral tyrosine kinase inhibitor which interferes with multiple intracellular tumorogenic pathways, and has demonstrated impressive antitumor activity in phase II and subsequently improvement in progression free survival in phase III renal cancer trials. We review the unique side effects of sunitinib therapy with emphasis on establishing effective patient education for anticipation and early management of therapy-related side effects.

Sunitinib reverses type-1 immune suppression and decreases T-regulatory cells in renal cell carcinoma patients

PURPOSE

Immune dysfunction is well documented in renal cell carcinoma (RCC) patients and likely contributes to tumor evasion. This dysfunction includes a shift from a type-1 to a type-2 T-cell cytokine response and enhanced T-regulatory (Treg) cell expression. Given the antitumor activity of select tyrosine kinase inhibitors such as sunitinib in metastatic RCC (mRCC) patients, it is relevant to assess their effect on the immune system.

EXPERIMENTAL DESIGN

Type-1 (IFNgamma) and type-2 (interleukin-4) responses were assessed in T cells at baseline and day 28 of treatment with sunitinib (50 mg/d) by measuring intracellular cytokines after in vitro stimulation with anti-CD3/anti-CD28 antibodies.

RESULTS

After one cycle of treatment, there was a significant increase in the percentage of IFNgamma-producing T cells (CD3(+), P < 0.001; CD3(+)CD4(+), P = 0.001), a reduction in interleukin-4 production (CD3(+) cells, P = 0.05), and a diminished type-2 bias (P = 0.005). The increase in type-1 response may be partly related to modulation of Treg cells. The increased percentage of Treg cells noted in mRCC patients over healthy donors (P = 0.001) was reduced after treatment, although not reaching statistical significance. There was, however, an inverse correlation between the increase in type-1 response after two cycles of treatment and a decrease in the percentage of Treg cells (r = -0.64, P = 0.01). In vitro studies suggest that the effects of sunitinib on Treg cells are indirect.

CONCLUSIONS

The demonstration that sunitinib improved type-1 T-cell cytokine response in mRCC patients while reducing Treg function provides a basis for the rational combination of sunitinib and immunotherapy in mRCC.

Abstract 2539: CTLA-4 blockade for hormone refractory prostate cancer: Dose-dependent induction of CD8+ T cell activation and clinical responses

CTLA-4 is a costimulatory molecule expressed on activated T cells that delivers an inhibitory signal to these T cells. CTLA4 blockade with antibody treatment has been shown to augment T cell responses and anti-tumor immunity in animal models and is being developed as an immunotherapy for cancer patients. We performed a phase I trial in patients with metastatic, hormone refractory prostate cancer (HRPC) where sequential cohorts of 3-6 patients were treated with escalating doses (0.5, 1.5 or 3 mg/kg) of ipilimumab, a fully human anti-CTLA-4 antibody (Medarex/BMS), given IV on day 1 of each 28-day cycle x 4 cycles. Patients also received GM-CSF (sargramostim, Berlex) 250 mg/m2/d SC on days 1-14 of the 28-day cycles. Patients were monitored for toxicity as well as for T cell activation. PSA and radiographic tests were performed at baseline and through therapy to evaluate for clinical response. 24 patients have been treated in the initial phase of this study. Of 6 patients treated on the highest dose level (3.0 mg/kg x 4), 3 (50%) had confirmed PSA declines of &gt;50%, and one of these patients had a partial response in hepatic metastases. Immune-related adverse events associated with ipilimumab treatment were also seen more frequently at higher doses of treatment. Expansion of CD25+CD69+ CD8 T cells was also seem primarily at the highest dose level. The treatment also induced an antibody and CD8 T cell immune response to NY-ESO-1. These results demonstrate that CTLA-4 blockade induces not only the expansion of activated effector CD8 T cells in vivo in cancer patients, but also can induce from the endogenous T cell repertoire of these patients T cells that are specific for tumor-associated antigens. CD8 T cell activation, toxicity, and clinical responses also appear to be dose-dependent. Supported by NIH P50 CA89520.

Differential expression of caveolin-1 in renal neoplasms

BACKGROUND

Caveolin-1 is a major component of membrane caveolae, which are specialized lipid raft microdomains on cell membrane that are implicated in molecular transport, cell adhesion, and signal transduction. The overexpression of caveolin-1 recently was associated with a poor outcome in patients with clear-cell renal cell carcinoma (CCRCC) and was proposed as a useful diagnostic marker. In the current study, the authors used immunohistochemistry to investigate the membranous and cytoplasmic expression of caveolin-1 and its correlation with other pathologic parameters in different subtypes of renal neoplasms.

METHODS

A tissue microarray (TMA) was constructed from 60 normal kidneys, 22 CCRCCs, 20 papillary renal cell carcinomas (PRCCs), 16 chromophobe renal cell carcinomas (ChRCCs), and 19 oncocytomas (ONCs). The TMA was immunostained for caveolin-1 protein. Both membranous and cytoplasmic caveolin-1 expression levels were measured and were correlated with tumor size, Fuhrman nuclear grade, and pathologic stage.

RESULTS

Caveolin-1 was expressed normally in distal convoluted tubules, collecting ducts, parietal cells of Bowman capsule, smooth muscle, and vascular endothelial cells. Membranous caveolin-1 expression was detected in 19 of 22 CCRCCs (86.4%), which was significantly higher than the membranous caveolin-1 expression detected in PRCCs (1 of 20 tumors; 5%), ChRCCs (0 of 16 tumors; 0%), and ONCs (1 of 19 tumors; 5.3%). Cytoplasmic caveolin-1 expression was detected in 16 of 22 CCRCCs (72.7%), in 13 of 20 PRCCs (65%), in 8 of 16 ChRCCs, (50%), and in 13 of 19 ONCs (68.4%). The percentage of tumors that expressed cytoplasmic caveolin-1 did not differ significantly among the different types of renal tumors (P = .1). Only membranous caveolin-1 expression was correlated with tumor size (Pearson correlation = 0.266; P = .043). There was no correlation between membranous or cytoplasmic caveolin-1 expression and other pathologic parameters, including Fuhrman nuclear grade and staging according to the American Joint Committee on Cancer tumor, lymph node, metastasis classification system.

CONCLUSIONS

Caveolin-1 expression has 2 distinctive patterns in renal neoplasms: membranous and cytoplasmic. In the current study, membranous caveolin-1 expression was detected predominantly in CCRCCs and only rarely in other subtypes of renal neoplasms. Thus, the current results indicated that caveolin-1 expression may have potential both as a diagnostic marker in the differential diagnosis of renal tumors and as a therapeutic target, especially for CCRCC.

Thyroid function test (TFT) abnormalities in patients (pts) with metastatic renal cell carcinoma (RCC) treated with sorafenib

5048

Background: Sorafenib is an orally bioavailable VEGF receptor inhibitor with anti-tumor activity in metastatic RCC. Sunitinib, another VEGF receptor inhibitor, induces biochemical hypothyroidism in 85% of metastatic RCC pts, the majority of whom have signs or symptoms of hypothyroidism (Rini BI et al. JNCI 2007 99(1):81–83). Thus, the incidence of TFT abnormalities in pts with metastatic RCC receiving sorafenib was investigated. Methods: The medical records of pts with metastatic RCC receiving sorafenib in one of five clinical trials at the Cleveland Clinic Taussig Cancer Center were reviewed. TFTs (TSH, T4, FTI and T3), patient demographics and clinical outcomes were recorded. Results: Between February 2004 and November 2006, 71 pts (49 males, 22 females) were treated with sorafenib. Baseline pt characteristics included a median age of 62 years (range, 35–87), 87% of pts had clear cell histology and 97% had prior nephrectomy. Forty-two pts had TFTs measured while receiving sorafenib and 19/42 pts (45%; 95% CI: 30–61%) had abnormal TFTs. The TFT abnormalities were consistent with hypothyroidism (13 pts), euthyroid sick syndrome (2 pts) or hyperthyroidism (4 pts). The median values in pts with abnormal TFTs were: TSH-7 μU/ml, T3–79 ng/dl, T4–12.7 μg/dl, FTI- 5.4; these values are just outside the normal laboratory ranges. The majority of pts did not have clinical signs or symptoms that could be attributed solely to thyroid dysfunction; only one pt (2%) received thyroid hormone replacement. The estimated progression free survival for pts with normal TFTs is 7.5 months vs. 6.1 months for pts with abnormal TFTs (p=0.79). Conclusion: Mild biochemical TFTs abnormalities are common in pts with metastatic RCC treated with sorafenib. However, severe TFT abnormalities and/or clinical signs/symptoms of thyroid dysfunction are not seen, and thyroid replacement therapy is not often indicated. In contrast to sunitinib, where the high incidence and clinical relevance of thyroid dysfunction requires routine monitoring, pts with metastatic RCC receiving sorafenib should have TFTs monitored only if clinically indicated.

[Table: see text]

Phase I/II trial of GM-CSF and lenalidomide in patients with hormone refractory prostate cancer (HRPC)

15515

Background: Administration of GM-CSF in combination with thalidomide induces PSA responses in 20–25% of pts with HRPC. When administered in the neoadjuvant setting, this combination induces T cell and dendritic cell (DC) infiltration in prostate tumor tissue. Lenalidomide is an immunomodulatory analogue of thalidomide. In an effort to evaluate the clinical and immune activity of GM-CSF plus lenalidomide, we conducted a phase I/II trial in pts with HRPC. Methods: Pts had progressive asymptomatic HRPC by Consensus Criteria. Prior immunotherapy or chemotherapy was not permitted. A phase I safety phase followed by a phase II trial was undertaken. All pts received GM-CSF at 250 μg administered SC three times weekly along with lenalidomide 25 mg/day orally on days 1–21 of a 28-day cycle. Primary endpoints were safety and objective and PSA responses. Exploratory endpoints included activation of circulating DC, regulatory T cells (Treg) and cytokine production. Results: To date 19 of 34 planned pts are enrolled (13 with evidence of metastases; 6 with PSA-only disease). Seventeen pts are eligible for response (2 pts too early) Median age is 71 (49–80), median PSA is 19.1 (2.1–153.1). Median cycles of therapy is 4 (range: 1–14+). Overall, 13 of 17 pts (76%) experienced a reduction in PSA (<20% 2/17; 20–40% 7/17,>50% 4/17). Objective and PSA partial responses were observed in 2 and 4 of 17 pts respectively. Nine pts discontinued therapy (5 due to PD, 3 due to toxicity, and 1 withdrew consent). No pts on the phase I portion of the trial experienced a DLT. Grade (G) 1–2 toxicities for all 17 pts included neutropenia (20%), thrombocytopenia (13%), diarrhea (43%), dizziness, (25%), and fatigue (90%). Three pts developed G4 toxicities (PE, neutropenia, and emesis). The number of Treg cells decreased after 2 cycles of therapy. Similarly, Th1 cytokine and TNF-a production was increased after therapy. Although mean serum VEGF levels were decreased after therapy, changes in the mean serum levels of IL-8 and bFGF were not observed. Conclusions: The combination of GM-CSF and lenalidomide is relatively well tolerated with evidence of antitumor activity. Exploratory studies support the ability of this therapy to modulate immune cells. Accrual to this study is ongoing.

[Table: see text]