Quantification of G250 mRNA expression in renal epithelial neoplasms by real-time reverse transcription-PCR of dissected tissue from paraffin sections

Diagnostic Challenges of Kidney Cancer: A Systematic Review of the Role of Positron Emission Tomography-Computerized Tomography

PURPOSE

Positron emission tomography-computerized tomography is a leading imaging modality for many types of solid tumors. The ability to characterize molecular processes noninvasively during a relatively fast whole-body scan is the major advantage of this technology. We reviewed the literature in an attempt to clarify the usefulness of positron emission tomography-computerized tomography in patients with a renal mass.

MATERIALS AND METHODS

We searched PubMed® for articles published from 2004 through September 2015 using the keywords "renal," "kidney," "mass," "tumor," "cancer," and "PET/CT."

RESULTS

A total of 158 relevant articles were included in the review. Most diagnostic studies used (18)F-fluorodeoxyglucose, a marker of glucose metabolism, as the radiotracer. The results were substandard, with sensitivity rates in the range of 31.5% to 77% for diagnosis of renal cell carcinomas. There were higher success rates for diagnosis of clear cell carcinomas. Carbonic anhydrase IX is an enzyme expressed in 95% of clear cell carcinomas but not in normal renal tissue or in benign or nonclear cell malignancies. A chimeric mouse-human antibody to carbonic anhydrase IX labeled with (124)I-girentuximab was demonstrated to diagnose clear cell tumors with sensitivity of 86.2% and specificity of 85.9%. For diagnosis of metastases positron emission tomography-computerized tomography with (18)F-fluorodeoxyglucose was observed to be more accurate than computerized tomography alone (94% vs 89%). Studies with other tracers also reveal encouraging results. Positron emission tomography-computerized tomography holds great promise in predicting prognosis and response to tyrosine kinase inhibitors. Current tyrosine kinase inhibitor treatments usually induce only mild lesion shrinkage. Thus, assessment of response based on changes in size of metastases is insufficient. Low (18)F-fluorodeoxyglucose uptake before treatment and decreased uptake after 2 cycles of treatment are associated with better survival. Using labeled medications as radiotracers before actual treatment may assist in selection of the most effective medication for a specific patient.

CONCLUSIONS

Positron emission tomography-computerized tomography with (18)F-fluorodeoxyglucose currently has lower sensitivity compared to enhanced computerized tomography for diagnosis of primary renal masses but better sensitivity for diagnosis of metastases. Predicting and monitoring response to targeted therapy could direct the clinician toward drug selection or modification during therapy. The possibility of treating patients with advanced renal cell carcinoma with (124)I-girentuximab attached to (177)Lu, a strong β-emitter, is investigated.

Circulating Carbonic Anhydrase IX and Antiangiogenic Therapy in Breast Cancer

INTRODUCTION

Carbonic anhydrase IX (CAIX) is a hypoxia regulated metalloenzyme integral to maintaining cellular pH. Increased CAIX expression is associated with poor prognosis in breast cancer. To explore CAIX as a biomarker for breast cancer therapies, we measured plasma CAIX levels in healthy control subjects and in breast cancer patients.

METHODS

In control subjects we evaluated plasma CAIX stability via commercially available ELISA. We then similarly quantified plasma CAIX levels in (1) locally advanced breast cancer (LABC) patients treated with neoadjuvant paclitaxel + sunitinib (T + S) followed by doxorubicin and cyclophosphamide (AC); (2) metastatic breast cancer (MBC) patients treated with systemic chemotherapy.

RESULTS

Plasma CAIX levels were stable at room temperature for at least 48 hours in control subjects. Mean baseline plasma CAIX levels were lower in controls compared to patients with LABC or MBC. In LABC, CAIX levels rose significantly in response to administration of antiangiogenic therapy (T + S) (p = 0.02) but not AC (p = 0.37). In patients with MBC treated without an antiangiogenic agent CAIX levels did not change with therapy.

CONCLUSIONS

Our results suggest that CAIX may be an easily obtained, stable measure of tumor associated hypoxia as well as a useful pharmacodynamic biomarker for antiangiogenic therapy.

Next revolution in molecular theranostics: personalized medicine for urologic cancers

Extensive lists of molecular biomarkers are currently evaluated as potential targets for directed cancer therapies. We reviewed three potential candidate biomarkers to play a role in the near future as molecular theranostics for urologic malignancies. Carbonic anhydrase type IX is a surrogate marker of hypoxia highly expressed in cancer cells. Their expression and clinical significance in kidney and urothelial bladder cancer are discussed as well as the main therapeutic approaches that are currently under evaluation. For prostate cancer, available evidence on the use of prostate-specific membrane antigen and neuropeptide receptors radiolabeled analog and the undergoing clinical studies are also analyzed and discussed at different stages of prostate cancer.

Application of monoclonal antibody G250 recognizing carbonic anhydrase IX in renal cell carcinoma

Monoclonal antibody G250 (mAbG250) recognizes a determinant on carbonic anhydrase IX (CAIX). CAIX is expressed by virtually all renal cell carcinomas of the clear cell type (ccRCC), but expression in normal tissues is restricted. The homogeneous CAIX expression in ccRCC and excellent targeting capability of mAbG250 in animal models led to the initiation of the clinical evaluation of mAbG250 in (metastatic) RCC (mRCC) patients. Clinical studies confirmed the outstanding targeting ability of mAbG250 and cG250 PET imaging, as diagnostic modality holds great promise for the future, both in detecting localized and advanced disease. Confirmation of the results obtained in the non-randomized clinical trials with unmodified cG250 is needed to substantiate the value of cG250 treatment in mRCC. cG250-Based radio immuno-therapy (RIT) holds promise for treatment of patients with small-volume disease, and adjuvant treatment with unmodified cG250 may be of value in selected cases. In the upcoming years, ongoing clinical trials should provide evidence for these assumptions. Lastly, whether cG250-based RIT can be combined with tyrosine kinase inhibitors, which constitutes the current standard treatment for mRCC, needs to be established.

Multimodal imaging and detection strategy with 124 I-labeled chimeric monoclonal antibody cG250 for accurate localization and confirmation of extent of disease during laparoscopic and open surgical resection of clear cell renal cell carcinoma

Renal cell carcinoma (RCC) accounts for approximately 85% to 90% of all primary kidney malignancies, with clear cell RCC (ccRCC) constituting approximately 70% to 85% of all RCCs. This study describes an innovative multimodal imaging and detection strategy that uses ¹²⁴I-labeled chimeric monoclonal antibody G250 (¹²⁴I-cG250) for accurate preoperative and intraoperative localization and confirmation of extent of disease for both laparoscopic and open surgical resection of ccRCC. Two cases presented herein highlight how this technology can potentially guide complete surgical resection and confirm complete removal of all diseased tissues. This innovative ¹²⁴I-cG250 (ie, ¹²⁴I-girentuximab) multimodal imaging and detection approach, which would be clinically very useful to urologic surgeons, urologic medical oncologists, nuclear medicine physicians, radiologists, and pathologists who are involved in the care of ccRCC patients, holds great potential for improving the diagnostic accuracy, operative planning and approach, verification of disease resection, and monitoring for evidence of disease recurrence in ccRCC patients.

Is serous cystadenoma of the pancreas a model of clear-cell-associated angiogenesis and tumorigenesis?

BACKGROUND

Similar to the other von Hippel-Lindau (VHL)-related tumors such as renal cell carcinomas and capillary hemangioblastomas, serous cystadenomas (SCAs) of the pancreas are also characterized by clear cells. Over the years, we have also noticed that the tumor epithelium shows a prominent capillary network.

METHODS

Eighteen cases of SCA were reviewed histologically, and immunohistochemical analysis was performed for CD31 and vascular endothelial growth factor (VEGF) as well as the molecules implicated in clear-cell tumorigenesis: GLUT-1, hypoxia-inducible factor-1 (HIF-1alpha), and carbonic anhydrase IX (CA IX).

RESULTS

There was an extensively rich capillary network that appears almost intraepithelially in all cases of SCA, which was confirmed by CD31 stain that showed, on average, 26 capillaries per every 100 epithelial cells. VEGF expression was identified in 10/18 cases. Among the clear-cell tumorigenesis markers, CA IX was detected in all cases, GLUT-1 and HIF-1alpha in most cases.

CONCLUSION

As in other VHL-related clear-cell tumors, there is a prominent capillary network immediately adjacent to the epithelium of SCA, confirming that the clear-cell- angiogenesis association is also valid for this tumor type. Molecules implicated in clear-cell tumorigenesis are also consistently expressed in SCA. This may have biologic and therapeutic implications, especially considering the rapidly evolving drugs against these pathways. More importantly, SCA may also serve as a model of clear-cell-associated angiogenesis and tumorigenesis, and the information gained from this tumor type may also be applicable to other clear-cell tumors.

Radiolabeled antibodies in renal cell carcinoma

Renal cell carcinoma (RCC) is a radio- and chemotherapy resistant tumor, which has a very high morbidity and mortality when metastasized. The current treatment options demonstrate limited efficacy and severe side-effects. Therefore, there is a need for new therapeutic strategies for RCC. As for other malignancies, monoclonal antibodies (mAbs) targeting tumor-associated antigens have been developed for RCC. One of these, mAb G250, targets the MN/CAIX/G250 antigen, which is ubiquitously expressed in clear cell RCC (ccRCC). ccRCC is the most common form of RCC with a prevalence of 80%. Expression of G250 in normal tissue is restricted to the gastrointestinal mucosa and related structures, thereby making it a suitable candidate for targeting ccRCC. In several clinical studies the efficient accumulation of mAb G250 in ccRCC has been demonstrated, resulting in high contrast images. G250-imaging could prove to be a valuable tool in diagnosing metastases in patients with a G250-antigen positive primary tumor and/or in the differential diagnosis of suspect kidney lesions. Furthermore, the therapeutic efficacy of radiolabeled G250 has been investigated in a series of studies. Thus far, most efforts have been devoted to G250 labeled with high doses of ¹³¹I. Other radionuclides which may enhance the therapeutic index of this radiolabeled mAb are currently under investigation. In our institution, an activity dose escalation study is currently ongoing to investigate the therapeutic potential of ¹⁷⁷Lu-labeled G250 in metastatic ccRCC patients. In this review, the current status of the diagnostic and therapeutic properties of radiolabeled antibodies in RCC is described.

Relative quantification and detection of different types of infectious bursal disease virus in bursa of Fabricius and cloacal swabs using real time RT-PCR SYBR green technology

In present study, different types of infectious bursal disease virus (IBDV), virulent strain DK01, classic strain F52/70 and vaccine strain D78 were quantified and detected in infected bursa of Fabricius (BF) and cloacal swabs using quantitative real time RT-PCR with SYBR green dye. For selection of a suitable internal control gene, real time PCR parameters were evaluated for three candidate genes, glyceraldehyde-3-phosphate dehydrogenase (GAPDH), 28S rRNA and beta-actin to IBDVs. Based on this beta-actin was selected as an internal control for quantification of IBDVs in BF. All BF samples with D78, DK01 or F52/70 inoculation were detected as virus positive at day 1 post inoculation (p.i.). The D78 viral load peaked at day 4 and day 8 p.i., while the DK01 and F52/70 viral load showed relatively high levels at day 2 p.i. In cloacal swabs, viruses detectable were at day 2 p.i. for DK01 and F52/70, day 8 p.i. for D78. Importantly, the primers set were specific as the D78 primer set gave no amplification of F52/70 and DK01 and the DK01 primer set gave no amplification of D78, thus DK01 and D78 could be quantified simultaneously in dually infected chickens by use of these two set of primers. The method described here is robust and may sever as a useful tool with high capacity for diagnostics as well as in viral pathogenesis studies.

Different vascular endothelial growth factor (VEGF), VEGF-receptor 1 and -2 mRNA expression profiles between clear cell and papillary renal cell carcinoma

OBJECTIVES

To examine vascular endothelial growth factor (VEGF), VEGF-receptor-(R)1, and R2 mRNA levels in renal cell carcinoma (RCC), a tumour generally refractory to most medical therapy, but for which a potentially useful therapeutic alternative is inhibition of angiogenesis.

PATIENTS AND METHODS

VEGF, VEGF-R1 and -R2 mRNA levels were analysed using the quantitative reverse transcription-polymerase chain reaction. RNA was extracted from 84 conventional (clear cell) RCCs (cRCC), 20 papillary (pRCC), six chromophobe (chRCC), and 27 corresponding kidney cortex tissues, obtained from 110 patients in whom high-quality RNA was available from the tumours (53 women and 57 men, mean age 64.7 years, range 25-85).

RESULTS

The VEGF, VEGF-R1, and -R2 mRNA levels were higher in tumour than in kidney cortex tissues. Among the RCC types, cRCC had higher VEGF levels than pRCC. In cRCC, VEGF-R2 levels were higher in stage I-II than in more advanced stages. In pRCC, VEGF and VEGF-R2 levels were higher in stage III than in stage I-II tumours. In cRCC, patients with VEGF levels below the median had a significantly shorter survival time than those with higher levels. By contrast, in pRCC, VEGF, VEGF-R1 and -R2 RNA levels above the median were related to adverse survival. Using multivariate analysis in cRCCs, VEGF-R1 mRNA level was the last factor to be omitted after stepwise elimination analysis.

CONCLUSION

VEGF and its receptors were associated with tumour stage and survival, but were not independent prognostic factors. Different RCC types had different expression patterns of VEGF and receptor mRNA levels. We conclude that different pathways might be involved in regulating angiogenesis in the specific RCC types. Detailed knowledge of angiogenesis in RCC is essential when designing new treatment trials where angiogenesis inhibition is used.

Expression analysis of mRNA in formalin-fixed, paraffin-embedded archival tissues by mRNA in situ hybridization

Gene expression in diseased tissues can indicate the contribution to a disease process and potentially guide therapeutic decision-making. Archival tissues with associated clinical outcome may be useful to discover or validate the role of a candidate gene in a disease process or the response to therapy. Such archival tissues are commonly formalin-fixed and paraffin-embedded, restricting the methods available for gene expression analysis. Obviously, the detection of proteins in tissues requires adaptation for each protein and the detection of secreted proteins can prove difficult or of reduced value since the protein detected may not reflect the total amount produced. Thus, we describe here a reliable method for the detection of mRNA in archival tissues. The method for mRNA in situ hybridization (ISH) was adapted by us for >15 different genes and applied to several hundred tissue microarrays (TMAs) and full sections generating >10,000 expression data points. We also discuss the utility of TMAs to simultaneously analyze several hundred tissue samples on one slide to minimize variability and preserve valuable tissue samples. Experimental protocols are provided that can be implemented without major hurdles in a typical molecular pathology laboratory and we discuss quantitative analysis as well as advantages and limitations of ISH with a special focus on secreted proteins. We conclude that ISH is a reliable and cost effective approach to gene expression analysis in archival tissues that is amenable to screening of series of tissues or of genes of interest.

Emerging drugs for renal cell carcinoma

Renal cell carcinoma (RCC) still represents a therapeutic challenge when patients have advanced or metastatic disease. Treatment using IL-2 and IFN-alpha continues to be the standard of care in patients who are able to tolerate such regimens. Targeted therapy may become the first-line treatment for patients resistant or intolerant to cytokines as new emerging drugs continue to be investigated. Understanding the genetic abnormalities related to the development of RCC (e.g., VHL gene abnormalities) and identifying molecular targets (e.g., epidermal growth factor, vascular endothelial growth factor and carbonic anhydrase IX) are playing a major role in the emergence of these novel agents for the treatment of this malignancy. Overall, these drugs are better tolerated and more acceptable to use by patients than the traditional cytokine-based regimens. The use of oral drugs to treat various malignancies including RCC seems to be the new paradigm of the future. Further understanding of their mechanisms of action and confirmation of their benefits on the clinical outcome is needed.

Messenger RNA Expression Ratios among Four Genes Predict Subtypes of Renal Cell Carcinoma and Distinguish Oncocytoma from Carcinoma

PURPOSE

Morphologic distinction among clear cell, papillary, and chromophobe types of renal cell carcinoma (RCC) can be difficult, as is the differential diagnosis between oncocytoma and RCC. Whether these renal tumors can be distinguished by their mRNA expression profile of a few selected genes was examined.

EXPERIMENTAL DESIGN

The expression of four genes in renal tumor was evaluated by quantitative reverse transcription-PCR: carbonic anhydrase IX (CA9), methylacyl-CoA racemase (AMACR), parvalbumin (PVALB), and chloride channel kb (CLCNKB). Thirty-one fresh-frozen and 63 formalin-fixed, paraffin-embedded tumor specimens were analyzed.

RESULTS

CA9 expression was highest in clear cell carcinoma and lowest in chromophobe RCC and in oncocytoma. AMACR expression was highest in papillary RCC, and CLCNKB was highest in chromophobe RCC/oncocytoma. PVALB was highest in chromophobe RCC, variable in oncocytoma, and low in clear cell and papillary types. Similar findings were observed in fresh-frozen and formalin-fixed specimens. The mRNA expression ratios among these genes (i.e., CA9/AMACR and AMACR/CLCNKB ratios) further accentuate the gene expression differences among these tumors, and a molecular diagnostic algorithm was established. This algorithm accurately classified the 31 fresh-frozen tumors into 14 clear cell, 5 papillary, 6 chromophobe, and 6 oncocytomas. In the formalin-fixed group, the molecular criteria accurately classified the cases into 15 clear cell, 16 papillary, and 32 in the chromophobe/oncocytoma group but could only separate some, but not all, oncocytomas from chromophobe RCC.

CONCLUSIONS

RNA expression ratios based on the four-gene panel can accurately classify subtypes of RCC as well as help distinguish some oncocytomas from chromophobe RCC.