Predictive genomic biomarkers of therapeutic effects in renal cell carcinoma

BACKGROUND

In recent years, there have been great improvements in the therapy of renal cell carcinoma. Nevertheless, the therapeutic effect varies significantly from person to person. To discern the effective treatment for different populations, predictive molecular biomarkers in response to target, immunological, and combined therapies are widely studied.

CONCLUSION

This review summarized those studies from three perspectives (SNPs, mutation, and expression level) and listed the relationship between biomarkers and therapeutic effect, highlighting the great potential of predictive molecular biomarkers in metastatic RCC therapy. However, due to a series of reasons, most of these findings require further validation.

Prognostic outcome in patients treated with tyrosine kinase inhibitors as first-line molecular-targeted therapy for metastatic renal cell carcinoma: Experience in real-world clinical practice in Japan

The aim of this study was to evaluate the oncological efficacy of tyrosine kinase inhibitors (TKIs) as first-line molecular-targeted therapy for Japanese patients with metastatic renal cell carcinoma (mRCC) in a routine clinical setting. This study included a total of 271 consecutive Japanese patients with TKI-naive mRCC, including 172 patients who received sorafenib and 99 who received sunitinib for ≥2 months as a first-line molecular-targeted agent. The prognostic outcomes of these patients were retrospectively assessed. During the observation period (median, 19 months), 126 patients (46.5%) succumbed to the disease and the median overall survival (OS) for the entire cohort was 33.1 months. The univariate analysis identified the Memorial Sloan-Kettering Cancer Center (MSKCC) classification, C-reactive protein (CRP) level, lymph node metastasis, bone metastasis, liver metastasis, histological subtype and sarcomatoid characteristics as significant predictors of OS. Of these factors, only the MSKCC classification, CRP level and liver metastasis were found to be independently associated with OS in the multivariate analysis. Furthermore, there were significant differences in OS according to the positivity for these 3 independent risk factors (i.e., negative for all factors vs. positive for a single factor vs. positive for 2 or 3 factors). These findings suggest that the introduction of TKIs as first-line molecular-targeted agents resulted in favorable cancer control outcomes in Japanese mRCC patients and that the prognosis of these patients may be stratified by 3 potential parameters, including the MSKCC classification, CRP level and liver metastasis.

Primary results of ROSE/TRIO-12, a randomized placebo-controlled phase III trial evaluating the addition of ramucirumab to first-line docetaxel chemotherapy in metastatic breast cancer

PURPOSE

Currently, antiangiogenic strategies in metastatic breast cancer have demonstrated modest improvements in progression-free survival (PFS) but not improved quality or duration of survival, warranting evaluation of new agents in a placebo-controlled setting. Ramucirumab is a human immunoglobulin G1 antibody that binds vascular endothelial growth factor receptor-2 and blocks ligand-stimulated activation. The ROSE/TRIO-012 trial evaluated ramucirumab with docetaxel in unresectable, locally recurrent, or metastatic breast cancer.

PATIENTS AND METHODS

In this double-blind, placebo-controlled, randomized, multinational phase III trial, 1,144 patients with human epidermal growth factor receptor 2 (HER2) -negative breast cancer who had not received cytotoxic chemotherapy in the advanced setting were randomly assigned at a two-to-one ratio to receive docetaxel 75 mg/m(2) plus ramucirumab 10 mg/kg or docetaxel 75 mg/m(2) plus placebo once every 3 weeks. Treatment continued until disease progression, unacceptable toxicity, or other withdrawal criteria. Patients were stratified by previous taxane therapy, visceral metastasis, hormone receptor status, and geographic region. An independent data monitoring committee oversaw the trial. The primary end point was investigator-assessed PFS.

RESULTS

Median PFS in patients treated with ramucirumab plus docetaxel was 9.5 months, compared with 8.2 months in patients who received placebo plus docetaxel (hazard ratio [HR], 0.88; P = .077). Median overall survival was 27.3 months in patients who received ramucirumab plus docetaxel, compared with 27.2 months in patients who received placebo plus docetaxel (HR, 1.01; P = .915). Toxicities seen at significantly higher rates in patients receiving ramucirumab included fatigue, hypertension, febrile neutropenia, palmar-plantar erythrodysesthesia syndrome, and stomatitis.

CONCLUSION

Addition of ramucirumab to docetaxel in HER2-negative advanced breast cancer did not meaningfully improve important clinical outcomes.

Sunitinib resistance in renal cell carcinoma

Of the many targeted therapies introduced since 2006, sunitinib has carved its way to become the most commonly used first-line therapy for the treatment of metastatic renal cell carcinoma (RCC). Despite significant improvements in progression-free survival, 30% of the patients are intrinsically resistant to sunitinib and the remaining 70% who respond initially will eventually become resistant in 6-15 months. While the molecular mechanisms of acquired resistance to sunitinib have been unravelling at a rapid rate, the mechanisms of intrinsic resistance remain elusive. Combination therapy, sunitinib rechallenge and sequential therapy have been investigated as means to overcome resistance to sunitinib. Of these, sequential therapy appears to be the most promising strategy. This mini review summarises our emerging understanding of the molecular mechanisms, and the strategies employed to overcome sunitinib resistance.

Association of VEGF and VEGFR2 single nucleotide polymorphisms with hypertension and clinical outcome in metastatic clear cell renal cell carcinoma patients treated with sunitinib

PURPOSE

Biomarkers that predict response or toxicity to antiangiogenic therapy are sought to favorably inform the risk/benefit ratio. This study evaluated the association of vascular endothelial growth factor (VEGF) and VEGF receptor 2 (VEGFR2) genetic polymorphisms with the development of hypertension (HTN) and clinical outcome in metastatic clear cell renal cell carcinoma (MCCRCC) patients treated with sunitinib.

PATIENT AND METHODS

Sixty-three MCCRCC patients receiving sunitinib (50 mg 4/2) with available blood pressure (BP) data and germline DNA were retrospectively identified. A panel of candidate VEGF and VEGFR2 single nucleotide polymorphisms (SNPs) were evaluated for associations with the development of hypertension and clinical outcome.

RESULTS

VEGF SNP -634 genotype was associated with the prevalence and duration of sunitinib-induced hypertension (as defined by systolic pressure ≥150 mmHg and/or diastolic pressure ≥90 mmHg) in both univariable analysis (P = .03 and .01, respectively) and multivariable analysis, which adjusted for baseline BP and use of antihypertension medication (P = .05 and .02, respectively). Patients with the GG genotype were estimated to have a greater likelihood of being hypertensive during treatment compared with patients with the CC genotype (odds ratio of 13.62, 95% confidence interval [CI] 3.71-50.04). No single VEGF or VEGFR SNPs were found to correlate with clinical outcome. However, the combination of VEGF SNP 936 and VEGFR2 SNP 889 were associated with overall survival after adjustment for prognostic risk group (P = .03).

CONCLUSIONS

In MCCRCC patients treated with sunitinib, VEGF SNP -634 is associated with hypertension and a combination of VEGF SNP 936 and VEGFR2 SNP 889 genotypes is associated with overall survival.

Does axitinib (AG-01376) have a future role in metastatic renal cell carcinoma and other malignancies?

Axitinib (Pfizer Inc., UK) is an oral small-molecule receptor tyrosine kinase inhibitor that targets angiogenesis. Axitinib has greater affinity and is a more selective inhibitor of VEGF receptor 1, -2 and -3, PDGFR and c-KIT than both sunitinib and sorafenib. It has encouraging efficacy and safety data in Phase II trials for metastatic renal cell carcinoma and advanced thyroid cancer patients. It is now being investigated in two Phase III trials in metastatic renal cell carcinoma and in Phase II trials in a range of tumor types. These trials will determine whether axitinib is an effective and safe antiangiogenic therapy.

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.

Vascular endothelial growth factors and receptors: anti-angiogenic therapy in the treatment of cancer

Vascular endothelial growth factors (VEGFs) are critical regulators of vascular and lymphatic function during development, in health and in disease. There are five mammalian VEGF ligands and three VEGF receptor tyrosine kinases. In addition, several VEGF co-receptors that lack intrinsic catalytic activity, but that indirectly modulate the responsiveness to VEGF contribute to the final biological effect. This review describes the molecular features of VEGFs, VEGFRs and co-receptors with focus on their role in the treatment of cancer.

Characteristics of human Ewing/PNET sarcoma models

Ewing/PNET (peripheral neuroepithelioma) tumors are rare aggressive bone sarcomas occurring in young people. Rare-disease clinical trials can require global collaborations and many years. In vivo models that as accurately as possible reflect the clinical disease are helpful in selecting therapeutics with the most promise of positive clinical impact. Human Ewing/PNET sarcoma cell lines developed over the past 45 years are described. Several of these have undergone genetic analysis and have been confirmed to be those of Ewing/PNET sarcoma. The A673 Ewing sarcoma line has proven to be particularly useful in understanding the biology of this disease in the mouse. The chromosomal translocation producing the EWS/FLI1 fusion transcript characterizes clinical Ewing sarcoma. Cell lines that express this genetic profile are confirmed to be those of Ewing sarcoma. The A673 Ewing sarcoma line grows in culture and as a xenograft in immunodeficient mice. The A673 model has been used to study Ewing sarcoma angiogenesis and response to antiangiogenic agents. Many Ewing sarcoma clinical specimens express the cell surface protein endosialin. Several Ewing sarcoma cell lines, including the A673 line, also express cell surface endosialin when grown as subcutaneous tumor nodules and as disseminated disease; thus the A673 is a useful model for the study of endosialin biology and endosialin-directed therapies. With the advent of tools that allow characterization of clinical disease to facilitate optimal treatment, it becomes imperative, especially for rare tumors, to develop preclinical models reflecting disease subsets. Ewing PNET sarcomas are a rare disease where models are available.

An enzyme-linked immunosorbent assay to study bevacizumab pharmacokinetics

INTRODUCTION

Bevacizumab is an antivascular endothelial growth factor humanized monoclonal antibody used to inhibit angiogenesis in cancer. It displays an important interindividual pharmacokinetic variability, which could explain part of the interindividual differences in clinical response. Therefore, an assay to measure bevacizumab serum concentrations is needed.

METHODS

An enzyme-linked immunosorbent assay was developed using microtiter plates sensitised with vascular endothelial growth factor 165, a recombinant form of vascular endothelial growth factor. Lower and upper limits of quantitation as well as limit of detection were determined. Eight calibrators and three quality controls, with concentrations of 5 mg/L, 30 mg/L, and 75 mg/L, were tested on five occasions initially and on five subsequent occasions. Trough and peak serum concentrations of bevacizumab were measured in patients with metastatic colorectal cancer. Bevacizumab concentrations were described using a two-compartment population pharmacokinetic model with first-order constants.

RESULTS

Imprecision and accuracy of calibrators and quality controls were 20% or less, except for the zero calibrator. The limit of detection was 0.033 mg/L. Lower and upper limits of quantitation were 5 and 75 mg/L, respectively. A total of 175 blood samples was available for analysis from 16 patients. Median (range) trough and peak concentrations during the treatment were 47.2 (9.6-106.9) mg/L and 159.3 (33.0-327.3) mg/L, respectively.

CONCLUSION

This method is rapid, accurate, reproducible, and may be useful for pharmacokinetic and pharmacokinetic-pharmacodynamic studies as well as in therapeutic drug monitoring of bevacizumab.

Pazopanib for the treatment of patients with advanced renal cell carcinoma

Dramatic advances in the care of patients with advanced renal cell carcinoma have occurred over the last ten years, including insights into the molecular pathogenesis of this disease, that have now been translated into paradigm-changing therapeutic strategies. Elucidating the importance of signaling cascades related to angiogenesis is notable among these achievements. Pazopanib is a novel small molecule tyrosine kinase inhibitor that targets VEGFR-1, -2, and -3; PDGFR-α, PDGFR-β; and c-kit tyrosine kinases. This agent exhibits a distinct pharmacokinetic profile as well as toxicity profile compared to other agents in the class of VEGF signaling pathway inhibitors. This review will discuss the scientific rationale for the development of pazopanib, as well as preclinical and clinical trials that led to approval of pazopanib for patients with advanced renal cell carcinoma. The most recent information, including data from 2010 national meeting of the American Society of Clinical Oncology, and the design of ongoing Phase III trials, will be discussed. Finally, an algorithm utilizing Level I evidence for the treatment of patients with this disease will be proposed.

Perspectives in drug development for metastatic renal cell cancer

Patients with renal cell carcinoma (RCC) exhibit a spectrum of clinical outcomes, with some patients following an indolent clinical course and others displaying rapidly advancing disease. As evidence points to RCC being largely refractory to traditional chemotherapy and radiotherapy strategies, immunotherapeutic approaches played a dominant role in the management of metastatic RCC for a quarter of a century. Management of this challenging tumor has been revolutionized by the incorporation of molecularly targeted therapies such as inhibitors of pathways involving tyrosine kinase signaling and the mammalian target of rapamycin (mTOR). The improvements in disease stabilization and survival seen with these agents has meant that molecularly targeted therapy now forms the foundation for treating RCC and has resulted in a multitude of studies investigating similar compounds for efficacy in RCC. Despite this, the rationale for using immunomodulatory regimens remains strong and its ongoing place in this era of targeted treatments continues to pose interesting clinical questions. The challenge of maintaining durable responses from our current therapies persists and this review highlights the plethora of options now available in RCC treatment and the directions in which modern management are heading.

Vascular endothelial growth factor receptors VEGFR-2 and VEGFR-3 are localized primarily to the vasculature in human primary solid cancers

PURPOSE

Vascular endothelial growth factor (VEGF) signaling is key to tumor angiogenesis and is an important target in the development of anticancer drugs. However, VEGF receptor (VEGFR) expression in human cancers, particularly the relative expression of VEGFR-2 and VEGFR-3 in tumor vasculature versus tumor cells, is poorly defined.

EXPERIMENTAL DESIGN

VEGFR-2- and VEGFR-3-specific antibodies were identified and used in the immunohistochemical analysis of human primary cancers and normal tissue. The relative vascular localization of both receptors in colorectal and breast cancers was determined by coimmunofluorescence with vascular markers.

RESULTS

VEGFR-2 and VEGFR-3 were expressed on vascular endothelium but not on malignant cells in 13 common human solid tumor types (n > 400, bladder, breast, colorectal, head and neck, liver, lung, skin, ovarian, pancreatic, prostate, renal, stomach, and thyroid). The signal intensity of both receptors was significantly greater in vessels associated with malignant colorectal, lung, and breast than adjacent nontumor tissue. In colorectal cancers, VEGFR-2 was expressed on both intratumoral blood and lymphatic vessels, whereas VEGFR-3 was found predominantly on lymphatic vessels. In breast cancers, both receptors were localized to and upregulated on blood vessels.

CONCLUSIONS

VEGFR-2 and VEGFR-3 are primarily localized to, and significantly upregulated on, tumor vasculature (blood and/or lymphatic) supporting the majority of solid cancers. The primary clinical mechanism of action of VEGF signaling inhibitors is likely to be through the targeting of tumor vessels rather than tumor cells. The upregulation of VEGFR-3 on tumor blood vessels indicates a potential additional antiangiogenic effect for dual VEGFR-2/VEGFR-3-targeted therapy.