Efficacy of sorafenib in advanced renal cell carcinoma independent of prior treatment, histology or prognostic group

AIM

To assess the response rate and safety of sorafenib in different subpopulations of patients with advanced renal cell carcinoma (RCC).

METHODS

Single-arm open access trial. Key eligibility: advanced RCC with either clear-cell or non-clear-cell histopathology; progression on prior systemic chemotherapy or treatment naïve. Sorafenib was commenced at 400 mg twice daily continuously.

RESULTS

A total 47 participants with metastatic RCC were treated with sorafenib. Overall, 1 participant experienced complete response, 6 (13%) had documented partial response (PR) and 29 (62%) had stable disease (SD) as the best response. Eight (17%) had non-clear-cell histopathology and five (10%) had sarcomatoid features. In the non-clear-cell histopathology cohort, five participants (62.5%) had SD. Twenty-three (49%) participants were treatment naïve; of these, 1/23 showed CR, 5/23 experienced PR and 13/23 had SD (clinical benefit: 83%). Overall, 14 (30%) and 22 (47%) participants had high-risk status according to MSKCC (Memorial Sloan-Kettering Cancer Center) and Heng prognostic scores, respectively. In the MSKCC poor prognostic group (14 participants), one participant had CR, two participants showed PR and eight participants had SD (clinical benefit: 79%). In Heng poor prognostic group (22 participants), 1 participant experienced CR, 2 participants showed PR and 13 had SD (clinical benefit: 73%). Hand-foot syndrome (53%), rash (47%), fatigue (42%), nausea (40%), anorexia (34%) and diarrhea (32%) were the most common adverse events.

CONCLUSIONS

This study confirms the efficacy and tolerability of sorafenib in a different spectrum of advanced RCC patients including non-clear-cell histology, poor prognostic status and as first-line treatment.

High dose intermittent sorafenib shows improved efficacy over conventional continuous dose in renal cell carcinoma

BACKGROUND

Renal cell carcinoma (RCC) responds to agents that inhibit vascular endothelial growth factor (VEGF) pathway. Sorafenib, a multikinase inhibitor of VEGF receptor, is effective at producing tumor responses and delaying median progression free survival in patients with cytokine refractory RCC. However, resistance to therapy develops at a median of 5 months. In an effort to increase efficacy, we studied the effects of increased sorafenib dose and intermittent scheduling in a murine RCC xenograft model.

METHODS

Mice bearing xenografts derived from the 786-O RCC cell line were treated with sorafenib according to multiple doses and schedules: 1) Conventional dose (CD) continuous therapy; 2) high dose (HD) intermittent therapy, 3) CD intermittent therapy and 4) HD continuous therapy. Tumor diameter was measured daily. Microvessel density was assessed after 3 days to determine the early effects of therapy, and tumor perfusion was assessed serially by arterial spin labeled (ASL) MRI at day 0, 3, 7 and 10.

RESULTS

Tumors that were treated with HD sorafenib exhibited slowed tumor growth as compared to CD using either schedule. HD intermittent therapy was superior to CD continous therapy, even though the total dose of sorafenib was essentially equivalent, and not significantly different than HD continuous therapy. The tumors exposed to HD sorafenib had lower microvessel density than the untreated or the CD groups. ASL MRI showed that tumor perfusion was reduced to a greater extent with the HD sorafenib at day 3 and at all time points thereafter relative to CD therapy. Further the intermittent schedule appeared to maintain RCC sensitivity to sorafenib as determined by changes in tumor perfusion.

CONCLUSIONS

A modification of the sorafenib dosing schedule involving higher dose intermittent treatment appeared to improve its efficacy in this xenograft model relative to conventional dosing. MRI perfusion imaging and histologic analysis suggest that this benefit is related to enhanced and protracted antiangiogenic activity. Thus, better understanding of dosing and schedule issues may lead to improved therapeutic effectiveness of VEGF directed therapy in RCC and possibly other tumors.

Enhancing the clinical activity of sorafenib through dose escalation: rationale and current experience

Sorafenib is an oral multitargeted tyrosine and serine/threonine kinase inhibitor approved for the treatment of advanced renal cell and hepatocellular carcinoma. An understanding of its dose-toxicity relationship has paved the way for trials seeking to enhance its clinical activity through the exploration of alternative dosing strategies. In this article, we review the dose-toxicity relationship of sorafenib observed during its phase I and early phase II testing, explore its toxicity profile at the recommended dose and schedule, discuss the evidence for dose escalation to higher levels, and examine the preliminary evidence for clinical activity of this strategy. Owing to a temporal relationship between toxicity and dose, it may be possible in select patients to escalate sorafenib to doses beyond those currently employed. However, because of the potential for increased toxicity, sorafenib dose escalation should currently be performed only in the context of a clinical trial.

Feasibility study of intra-patient sorafenib dose-escalation or re-escalation in patients with previously treated advanced solid tumors

PURPOSE

To determine if intra-patient dose escalation of the multi-targeted kinase inhibitor sorafenib is feasible in patients with advanced pretreated solid malignancies.

METHODS

An intra-patient dose escalation scheme starting at 400 mg BID was employed in this prospective trial. Doses were escalated to 600 mg BID for the second cycle and to 800 mg BID for the third cycle in the absence of grade 3+ adverse events. In the event of grade 3+ adverse events during cycle 1, doses were reduced to 400 mg daily through cycle 2. Dose re-escalation for cycle 3 was allowed in the absence of grade 3+ adverse events during cycle 2. Further dose escalation was prohibited. The primary endpoint was the overall percentage of patients tolerating dose escalation to 600 mg BID through cycle 2 or tolerating re-escalation to 400 mg BID through cycle 3.

RESULTS

Fifty eligible patients with various solid tumors and a median of 3 prior therapies were enrolled. Eleven patients (22%) tolerated primary dose escalation or re-escalation. Only 14 patients (28%) completed cycle 1 without dose modification or discontinuing treatment. Seven of 13 patients tolerated primary dose escalation through cycle 2. Four of 5 patients tolerated dose re-escalation through cycle 3. Reasons for escalation failure included tumor progression (42%) and adverse events (26%). Common grade 3+ adverse events included hand-foot skin reaction, hypertension, and hypophosphatemia.

CONCLUSIONS

Intra-patient dose escalation and/or re-escalation of sorafenib were not feasible in pretreated solid tumor patients. Sorafenib dose escalation remains an investigational approach.

Future directions in renal cell carcinoma: 2011 and beyond

Emerging from a largely cytokine-based era, the last several years have witnessed a dramatic change in the therapeutic landscape of renal cancer. Molecularly targeted and antiangiogenic agents now form the backbone of most therapeutic strategies for patients with advanced renal cell carcinoma (RCC). Although the next few years may not see such broad paradigm shifts, there remains significant room for improvement in the care of patients with RCC. This review discusses challenges that face physicians and researchers as well as innovations that may contribute to improving the therapeutic outcomes for patients with RCC.

Long-term safety of sorafenib in advanced renal cell carcinoma: follow-up of patients from phase III TARGET

BACKGROUND

The phase III Treatment Approaches in Renal cancer Global Evaluation Trial (TARGET) indicated that sorafenib is effective and well tolerated in advanced renal cell carcinoma patients. However, few data have been published on the safety of long-term sorafenib treatment. A retrospective subgroup analysis was performed to evaluate the efficacy and safety of sorafenib in patients in TARGET who received treatment for >1 year.

METHODS

The present subgroup analysis (based on the September 2006 database with updated safety analysis) evaluated the efficacy and safety of sorafenib in all patients in the sorafenib arm of TARGET who were treated for >1 year. The assessments included the overall survival, progression-free survival (PFS), disease control rate (DCR), and safety. The patients remained on therapy post-progression at the discretion of the investigator.

RESULTS

In TARGET, 169 patients received treatment with sorafenib for >1 year. The median PFS of patients in this subpopulation was 10.9 months from the date of randomisation, with a DCR of 92%. The most commonly reported treatment-related adverse events of any grade were diarrhoea (74%), rash/desquamation (51%), hand-foot skin reaction (49%), alopecia (39%), and fatigue (38%). Adverse events were mild to moderate, and presented early in the course of the treatment; there were no unexpected toxicities associated with the long-term administration of sorafenib.

CONCLUSIONS

Results of this subgroup analysis of patients enrolled in TARGET who received treatment for >1 year indicate that long-term treatment with sorafenib is associated with continued efficacy and a well-tolerated safety profile.

Frequent dose interruptions are required for patients receiving oral kinase inhibitor therapy for advanced renal cell carcinoma

OBJECTIVE

Recent advances for patients with advanced or metastatic renal cell carcinoma (RCC) have been shown to improve progression-free survival with both response rates and disease stabilizing activity. Sorafenib, a multikinase inhibitor, and sunitinib, an inhibitor of vascular endothelial growth factor-r and platelet-derived growth factor-r, have been approved by the Food and Drug Administration since 2005/2006. This retrospective analysis of patients treated with both aforementioned kinase inhibitors for advanced RCC presents data related to their antitumor effects as well as safety profile with particular attention to dose interruption and modification requirements.

METHODS

This was a retrospective review of patients diagnosed with RCC either with advanced disease at initial presentation or after first-line therapy, who received either continuous sorafenib 400 mg bid or sunitinib 50 mg Qday for 4 weeks on and 2 weeks off until disease progression or untoward drug reaction. Tumor response was evaluated by response evaluation criteria in solid tumors criteria, and adverse events were graded by National Cancer Institute-Common Toxicity Criteria.

RESULTS

From December 2005 to May 2008, 34 patients were followed. Twenty-two patients received sorafenib first line, 10 received sunitinib first line, and 2 patients received sorafenib as third-line therapy. Twenty-nine were evaluable for response rates. There were 10 patients (34%) who had stabilization of disease, 8 patients (28%) who had a partial response, and 11 patients (38%) who had progression of disease. The progression-free survival median was 8 months. Of the 34 patients evaluable for toxicities, grade 3 or 4 adverse event occurred in 19 patients (56%). These patients required either dose modifications and/or treatment interruptions within an average of the first 2 weeks of treatment. Eight patients (24%) required drug discontinuation. Eleven patients (32%) required dose reductions, but were able to resume the targeted dose after slow dose escalation. Three patients (9%) remain dose reduced for greater than 12 weeks.

CONCLUSIONS

Sorafenib and sunitinib have extended patients' disease-free survival by several months; however, the initial grade 3 or 4 adverse event presented in the literature appear to have been under-reported. Our experience suggests that the first 4 weeks of treatment is the most likely timeframe within which drug reactions occur. Therefore, careful monitoring and possibly additional clinical visits are warranted during this time period. Although a significant percentage of patients require dose modification, many can be restarted and titrated up to the targeted dose.

Systemic therapy for metastatic renal cell carcinoma

Renal cell cancer (RCC) is the most common form of cancer of the kidney and accounts for approximately 44,000 cases per year in the United States. Historically, only immunotherapy showed activity in metastatic RCC. The improved survival and quality of life for patients with metastatic RCC over the last several years are direct results of advances made in understanding the development of RCC. Three targeted therapies-sunitinib, sorafenib, and temsirolimus-have been approved for use in the United States recently. Current research is aimed at developing new drugs and combining available drugs to improve upon the responses and survival seen with approved single agents.

Randomized phase II trial of first-line treatment with sorafenib versus interferon Alfa-2a in patients with metastatic renal cell carcinoma

PURPOSE

An open-label, phase II study to evaluate progression-free survival (PFS), overall best response, adverse events (AEs), and patient-reported outcomes with sorafenib versus interferon alfa-2a (IFN-alpha-2a) in patients with untreated, advanced renal cancer.

PATIENTS AND METHODS

A total of 189 patients were randomly assigned to oral sorafenib 400 mg twice daily or to subcutaneous IFN-alpha-2a 9 million U three times weekly (period 1). Sorafenib patients who progressed were dose-escalated to 600 mg twice daily; IFN-alpha-2a patients who progressed were switched to sorafenib 400 mg twice daily (period 2).

RESULTS

In period 1 PFS was similar for sorafenib-treated (n = 97; 5.7 months) and IFN-alpha-2a-treated patients (n = 92; 5.6 months); more sorafenib-treated patients had tumor shrinkage (68.2% v 39.0%). Common drug-related AEs (Grades > or = 3) for sorafenib were hand-foot skin reaction (11.3%), diarrhea (6.2%), and rash/desquamation (6.2%); for IFN-alpha-2a, these were fatigue (10.0%), nausea (3.3%), flu-like syndrome (2.2%), and anorexia (2.2%). Sorafenib-treated patients reported fewer symptoms, better quality of life (QOL), and greater treatment satisfaction. In period 2, 41.9% of patients who received sorafenib 600 mg twice daily (n = 43) experienced tumor reduction (median PFS, 3.6 months). After the switch to sorafenib 400 mg twice daily, tumors were reduced in 76.2% of 50 patients (median PFS, 5.3 months). AEs were mostly grade 1 to 2; no increase in AEs of grades > or = 3 occurred after sorafenib dose escalation.

CONCLUSION

In this study, sorafenib resulted in similar PFS as IFN-alpha-2a in patients with untreated RCC. However, sorafenib-treated patients experienced greater rates of tumor size reduction, better QOL, and improved tolerability. Both dose escalation of sorafenib after progression and a switch to sorafenib after progression on IFN-alpha-2a resulted in clinical benefit.

Cytoreductive nephrectomy in metastatic clear-cell renal cell carcinoma: perspectives in the tyrosine kinase inhibitor era

Cytoreductive nephrectomy in combination with adjuvant immunotherapy is an established treatment option for selected patients with metastatic clear-cell renal cell carcinoma (mCC-RCC). Multitargeted antiangiogenic and mammalian target of rapamycin tyrosine kinase inhibitors (TKIs) are now established treatment paradigms in patients with mCC-RCC. Given that all the recent seminal TKI trials in mCC-RCC provide no evidence base for the use of cytoreductive nephrectomy in the TKI era, it is not presently clear where such a surgical approach fits into the treatment paradigm. This review summarizes the evidence for the management of mCC-RCC and outlines novel approaches to be tested within future trials if the initial proposed phase III trials in this setting, using sunitinib, are successful. Overall, two principal questions need addressing. First, is cytoreductive nephrectomy necessary in the TKI era? Second, if so, what is the most appropriate scheduling of TKI therapy with cytoreductive nephrectomy?

Recent advances in the treatment of renal cell carcinoma and the role of targeted therapies

Immunotherapy confers a small but significant overall survival advantage in metastatic renal cell carcinoma (RCC) but only for the minority of patients, i.e. the 20% with good prognostic features. Recent developments in the molecular biology of renal cell carcinoma have identified multiple pathways associated with the development of this cancer. Several strategies have been investigated targeting these pathways, with significant clinical benefits shown in early studies. New agents including the small molecule targeted inhibitors sunitinib, sorafenib and temsirolimus, and the monoclonal antibody bevacizumab have shown anti-tumour activity in randomised clinical trials and have become the standard of care for most patients. Sunitinib and temsirolimus have shown significant improvements in progression-free survival (sunitinib) and overall survival (temsirolimus) in separate phase III studies in the first-line setting when compared with interferon-alpha. Sorafenib has demonstrated prolonged progression-free survival in a phase III study in comparison with placebo in the second-line setting. More recently two phase III studies have compared bevacizumab and interferon-alpha with interferon-alpha alone. Both studies showed a statistically significant improvement in progression-free survival for the combination arm. Additional studies are needed to optimise the use of these agents by identifying those patients who most benefit and elucidating the best way of delivering them, either in combination or as sequential single agents.

Improving outcomes in patients with advanced renal cell carcinoma

The emergence of targeted therapies for advanced renal cell carcinoma has been a dramatic turning point in improving outcomes for the majority of patients with this disease. In study populations comprising primarily good- and intermediate-risk patients with clear cell renal cell carcinoma and prior nephrectomy, prolonged progression-free survival was demonstrated for three angiogenesis-targeted agents: sunitinib (compared with interferon [IFN]), bevacizumab plus IFN (vs IFN alone) and sorafenib (vs placebo in cytokine-refractory patients). As a first-line treatment for patients with multiple poor-risk factors, temsirolimus, which inhibits mTOR, has improved not only progression-free survival compared with IFN but, more importantly, overall survival. Further studies are needed to determine whether combinations and/or sequencing of these targeted agents can further improve outcomes.

Renal cell carcinoma

PURPOSE OF REVIEW

The recent contributions to renal cell carcinoma in the fields of molecular biology and the expanded use of molecularly targeted agents will be reviewed. This study is intended to update prognostic and therapeutic decision-making data and provide perspective on advances in understanding the molecular biology of this disease.

RECENT FINDINGS

Updates to the currently used prognostic algorithms for renal cell carcinoma are needed, and recently verified prognostic nomograms will be discussed. This comes in the wake of numerous advances in the use of molecularly targeted drugs, which will be reviewed. Finally, advancements in understanding the biology of renal cell carcinoma include the discovery of von Hippel-Lindau associated mechanisms involved in renal cyst formation and renewed appreciation for the influence of this pathway on the tumor cell glucose utilization profile.

SUMMARY

Renal cell carcinoma continues to evolve swiftly with the approval of new agents and the maturation of clinical trials to provide relevant structure to treatment decisions. This study will give an overview of the latest concepts in the epidemiology and biology of renal cell carcinoma and provide current surgical and systemic updates for managing renal cell carcinoma.

Update on the medical treatment of metastatic renal cell carcinoma

CONTEXT

Metastatic renal cell carcinoma (mRCC) has long been treated only by immunotherapy with good results only in a small population of patients. In recent years, major improvements in treatment possibilities have occurred with the advent of anti-angiogenic drugs. In the past 2 yr, pivotal phase III trials have confirmed this major breakthrough by increasing the progression-free survival rates and/or overall survival rates provided by sunitinib, sorafenib, and bevacizumab, and more recently by the mTOR (mammalian target of rapamycin) inhibitors temsirolimus and everolimus.

OBJECTIVE

To update the previous review on smart drugs published in the European Journal in 2006 (Patard JJ, et al. Understanding the importance of smart drugs in renal cell carcinoma. Eur Urol 2006; 49:633-43).

EVIDENCE ACQUISITION

Critical review of published literature 2006-2008 (Pubmed website search words: renal cell carcinoma and/or targeted therapy and prospective trials) and more recent meeting abstracts (American Society of Clinical Oncology 2007). Quality assessment included prospective phase I-III trials and critical evaluations with low numbers of patients, retrospective analyses, and slide presentations of meeting abstracts.

EVIDENCE SYNTHESIS

This review presents the current situation and provides more recent data on sequential treatment, the association of targeted drugs, and the treatment of non-clear-cell histologies.

CONCLUSIONS

Treatment of mRCC with targeted therapy centers on at least two major pathways: angiogenesis and mTOR involving inhibiting drugs that may be used alone, in combination, or sequentially.

Targeted therapy for advanced renal cell carcinoma

BACKGROUND

Advanced renal cell carcinoma has been resistant to drug therapy of different types and new types of drug therapy are needed. Targeted agents inhibit known molecular pathways involved in cellular proliferation and neoangiogenesis, the induction by the tumour of host microvascular networks. Angiogenesis is of special interest in the clear cell histologic subtype of renal cancer because of its vascularity and constitutively activated hypoxia-inducible path in the majority of tumours.

OBJECTIVES

1) To provide a systematic review of studies testing targeted agents.2) To identify the type and degree of clinical benefit, if any, of targeted agents over the prior standard of care, particularly any impact on overall survival.

SEARCH STRATEGY

1) Electronic search of CENTRAL, MEDLINE and EMBASE databases.2) Hand search of international cancer meeting abstract and other sources specified in the protocol.

SELECTION CRITERIA

Randomized controlled studies of targeted agents in patients with advanced renal cell cancer reporting major remission rate or overall survival by allocation. Progression-free survival (PFS) was adopted as an additional outcome because PFS was a commonly chosen primary outcome, and because several pivotal studies allowed crossover from the control to the investigational arm after closure to accrual thereby making overall survival a problematic endpoint.

DATA COLLECTION AND ANALYSIS

Nineteen fully eligible studies tested ten different targeted agents (Table 04). One additional study was excluded because no outcome data by allocation have been reported (Hutson 2007). For purposes of comparison, the studies were divided into three groups: Group 1 studies compared different doses of the same agents; Group 2 studies examined the impact of targeted agents in patients who had received prior cytokine or other systemic therapy; and Group 3 studies tested targeted agents in systemically naive patients, either against standard interferon-alfa or against another control therapy. Meta-analysis was not utilized because there were very few situations where the same agents had been tested in the same group in more than one study.

MAIN RESULTS

In systemically untreated patients in studies using subcutaneous interferon-alfa as control therapy, the major findings were: 1) An improvement in overall survival has been demonstrated only with the use of weekly intravenous temsirolimus in patients with unselected renal cancer histology and adverse prognostic features (median survival 10.9 months versus 7.3 months for temsirolimus or interferon-alfa respectively, HR 0.73, P = 0.008 log rank, Hudes 2007). However, the chance of major remission was low and not improved with temsirolimus. 2) In patients with mostly good or intermediate prognostic risk with clear cell renal cancer, oral sunitinib improves the chance of major remission, the probability of symptomatic improvement, and freedom from disease progression (Motzer 2007); in a similar setting, the addition of biweekly intravenous bevacizumab to interferon-alfa also improved the chance of major remission and prolonged progression-free survival (Escudier 2007b); overall survival had not changed at the time of interim reporting of either study. In patients with clear cell renal cancers who had failed prior cytokine therapy, oral sorafenib gives a better quality of life than placebo as well as improved chance of being free of disease progression; overall survival may have improved but is hard to evaluate because of crossover of placebo-assigned patients after the study closed to accrual (Escudier 2007a).

AUTHORS' CONCLUSIONS

Based on less than a decade of experience, some targeted agents with specified molecular targets have demonstrated clinically useful benefits over the previous standard of care for patients with advanced renal cancer. Much more research is required to fully establish the role of targeted agents in this condition.

Sorafenib inhibits activation of human peripheral blood T cells by targeting LCK phosphorylation

Sorafenib, a novel drug for metastatic renal cancer, has broad-spectrum activity against multiple tyrosine kinases, including Raf-1, vascular endothelial growth factor receptor and platelet-derived growth factor receptor. However, little is known about its effects on the immune system. In this report, we examine the effects of sorafenib on the proliferation and activation of human peripheral blood T cells, as well as its effects on T-cell-mediated immune response in mice. At concentrations similar to those used in patients, sorafenib inhibited the proliferation of primary human T cells in vitro. At more than 10 microM, sorafenib caused an irrecoverable inhibition of proliferation, even after drug withdrawal. In addition, sorafenib induced T-cell apoptosis at concentrations higher than 10 muM. sorafenib also caused G(0)/G(1) phase arrest, inhibition of CD25 and CD69 expression, interleukin-2 production and LCK phosphorylation in the T cells; all of these effects exhibited dose and time dependence. When tested against contact dermatitis in mice, sorafenib significantly reduced the ear swelling induced by picryl chloride. These findings suggest that sorafenib may cause the loss of T-cell immune response by inducing apoptosis and targeting LCK. This could potentially lead to immunosuppression in patients with cancer.

Is cell death a critical end point for anticancer therapies or is cytostasis sufficient?

Since the discovery of conventional chemotherapy and the development of new target-based agents, the importance of cytostasis in anticancer activity has been debated. This review examines the relative importance of both cytostasis and cytotoxicity based on both preclinical data and clinical reports. Several limitations of our basic and clinical methods to evaluate cytostasis and cytotoxicity will be highlighted. Molecular mechanisms of cytostasis will be analyzed, including interference with the cell cycle as well as putative links with necrosis and autophagy. Finally, we will cite evidence that most older and newer compounds are both cytostatic and cytotoxic. The relative role of cytostasis and cytotoxicity on future drug screening and clinical development will be explored.

Tyrosine kinase inhibitors and anti-angiogenic therapies in kidney cancer

Renal cell carcinoma (RCC) is a heterogeneous disease as reflected in its presentation and clinical course, pathological subtypes, nuclear grades and molecular biology. Emerging data indicate that renal tumors express a variety of molecular tumor markers and unique patterns of gene expression. Clinically the disease behaves quite heterogeneously, with courses ranging from indolent to highly aggressive. Surgical monotherapy or as part of a multimodal approach remains the standard of care for most cases of RCC. Radical or partial nephrectomy is associated with a 5-year cancer specific survival (CSS) of 85-97% for pT1 tumors. Unfortunately, 20% of patients have either locally advanced or node positive (N+) RCC while another 22% have metastatic RCC (mRCC) at presentation. Unlike the outcomes in early localized disease, survival rates for N+ patients are poor and patients with mRCC are rarely cured despite aggressive multimodal therapy. Classic cytotoxic chemotherapy has repeatedly been shown to have little effect and only 5-20% of patients with mRCC respond to immunologic agents such as interferon and/or interleukin. Cytoreductive nephrectomy with systemic immunotherapy is associated with few cures with median survivals of 12-24 months. Recent advances in our understanding of the molecular origins and pathways of RCC have led to the development of more effective targeted therapies. Here we review the molecular pathways that define the pertinent therapeutic targets in RCC and the clinical data for these new and promising agents.

Renal cell carcinoma: new developments in molecular biology and potential for targeted therapies

Renal cell carcinoma (RCC) affects 38,000 individuals in the U.S. yearly. Seventy-five percent of cases are clear-cell carcinomas, and a majority is driven by dysfunction of the von Hippel-Lindau (VHL) gene. VHL loss of function and other non-VHL pathways leading to RCC share aberrant activation of the hypoxic response, such as upregulation of vascular endothelial growth factor (VEGF) and consequent neoangiogenesis. Metastatic RCC has been notoriously resistant to therapy. For decades, its treatment has been based on nephrectomy and limited use of toxic and often inefficient immunotherapy with interleukin-2 or interferon-alpha. However, new biologic agents are beginning to break the resistance barrier. Small-molecule multikinase inhibitors that target VEGF receptors (sunitinib and sorafenib) have a favorable toxicity profile and can prolong time to progression and preserve quality of life when used in newly diagnosed or previously treated patients. The anti-VEGF antibody bevacizumab enhances the response rate and prolongs disease control when added to interferon-alpha. Temsirolimus, a mammalian target of rapamycin inhibitor, prolongs the survival duration of patients with poor-risk disease. Despite three new drugs being approved for RCC in the past 2 years, responses are mostly partial and of limited duration. Multiple new drugs and drug combinations are undergoing clinical trials and will likely impact the treatment of RCC in future years. Compounds found to be active in the metastatic setting are now being tried in earlier stage disease in an attempt to improve curability. However, no method has yet been validated to predict patient response to these newer treatments.

Renal cell cancer

Metastatic renal cell cancer has traditionally been treated with interferon and interleukin-2. An improved understanding of the biology of renal cancer has engendered novel targeted therapeutic agents that have altered the natural history of this disease. The vascular endothelial growth factor and its related receptor and the mammalian target of rapamycin signal transduction pathway in particular have been utilized as therapeutic targets. Sunitinib malate, sorafenib tosylate, temsirolimus, and bevacizumab/interferon alfa have improved clinical outcomes in randomized trials. Other antiangiogenic agents have also demonstrated activity in early studies. Given the availability of multiple treatment options, several questions emerge as to how to integrate these new therapies into the management of metastatic renal cell cancer. Recently reported and planned clinical trials will help clarify the role of these agents. The future of therapy for renal cancer appears promising owing to the efficacy of these novel agents.

Toxicities associated with the administration of sorafenib, sunitinib, and temsirolimus and their management in patients with metastatic renal cell carcinoma

OBJECTIVE

To provide a systematic review of the side effects associated with sorafenib, sunitinib, and temsirolimus and to provide an outline of possible preventive or therapeutic measures.

METHODS

We performed a PubMed-based systematic review of side effects associated with the three agents and relied on product monographs and prescribing information to provide an outline of treatments aimed at reducing these toxicities.

RESULTS

Side effects range from <1% to 72%. Grade 3/4 side effects are less common and range from <1% to 13% for sorafenib, <1% to 16% for sunitinib, and 1% to 20% for temsirolimus. Overall, sunitinib causes the most grade 3/4 side effects and sorafenib causes the fewest grade 3/4 side effects, although head-to-head trials are required to compare safety profiles of all three kinase inhibitors. Virtually all side effects can be managed effectively.

CONCLUSION

Prevention, recognition, and prompt management of side effects are of key importance and avoid unnecessary dose reductions, which may undermine treatment efficacy.