Temsirolimus in VEGF-refractory metastatic renal cell carcinoma

Treatment of Refractory Metastatic Renal Cell Carcinoma

First-line treatment for metastatic renal cell carcinoma (mRCC) rapidly shifted in recent years with the advent of combination therapies, including immune checkpoint inhibitor (ICI) doublets and combinations of an ICI with a vascular endothelial growth factor receptor (VEGFR) targeted tyrosine kinase inhibitor (TKI). Despite improvements in overall survival and many durable responses, there exists a significant number of patients who fail to respond to these agents, and many patients eventually progress. Given the rapid changes in the front-line setting, it is essential to understand treatment options in refractory mRCC. Here, we review the evidence behind current options for later-line therapies, often involving additional VEGFR-TKIs alone or in combination with mammalian target of rapamycin (mTOR) targeted agents, as well as situations where consideration of immunotherapy rechallenge may be appropriate. Additionally, we describe ongoing clinical trials examining concurrent ICI and TKI in the refractory setting, as well as those studying novel agents, such as targeted drug-antibody conjugates and hypoxia inducible factor 2α (HIF-2α) inhibitors. Finally, we review considerations for non-clear cell histologies in the refractory setting and mechanisms of resistance in mRCC.

Everolimus Versus Temsirolimus in Metastatic Renal Cell Carcinoma After Progression With Previous Systemic Therapies

BACKGROUND

Everolimus is an approved agent for use after disease progression with vascular endothelial growth factor receptor-tyrosine kinase inhibitors (VEGFR-TKIs) in patients with metastatic renal cell carcinoma. With recently published trials showing efficacy of nivolumab and cabozantinib in the second-line therapy setting, the use of everolimus will likely move to the third- or fourth-line therapy setting. Temsirolimus has occasionally been used instead of everolimus for many reasons, including financial considerations, assurance of patient compliance given its intravenous administration, its toxicity profile, patient performance status, and patient or physician preference. However, efficacy of everolimus and temsirolimus in this setting have not been compared in a randomized trial. The results from retrospective studies have been inconsistent.

MATERIALS AND METHODS

We identified patients treated with a first-line VEGFR-TKI for metastatic renal cell carcinoma and then treated with either everolimus or temsirolimus on progression from the databases of 2 large academic cancer centers. Progression-free survival (PFS) and overall survival (OS) were assessed from the initiation of second-line treatment using the Kaplan-Meier method.

RESULTS

A total of 90 patients received either everolimus (n = 59; 66%) or temsirolimus (n = 31; 34%) after progression during first-line VEGFR-TKI therapy. The patient and disease characteristics were similar in both groups. The median PFS was not different, but OS was superior with everolimus compared with temsirolimus (24.2 months vs. 12.1 months; hazard ratio, 0.58; P = .047).

CONCLUSION

Our results bolster existing guidelines supporting everolimus over temsirolimus as salvage therapy after previous systemic therapies.

Prognostic factors in second-line targeted therapy for metastatic clear-cell renal cell carcinoma after progression on an anti-vascular endothelial growth factor receptor tyrosine kinase inhibitor

BACKGROUND

About 40% of metastatic clear-cell renal cell carcinoma (m-ccRCC) patients receive a second-line targeted therapy after failure of anti-vascular endothelial growth factor receptor tyrosine kinase inhibitors (anti-VEGFR-TKI). Efficacy of second-line therapy is usually limited and prognostic and predictive factors at the start of second-line therapy are lacking. To identify the subgroup of patients that will benefit from such treatment remains a challenge.

METHODS

We performed a multi-institutional, retrospective study of patients who received a second-line therapy after progression on an anti-VEGFR-TKI. Univariate and multivariate analyses were performed in order to identify prognostic factors for progressive disease (PD) as best response, progression-free survival (PFS) and overall survival (OS) on second-line therapy.

RESULTS

For the whole cohort of 108 patients, mOS from the start of second-line therapy was 8.9 months while mPFS on second-line therapy was 2.8 months. A total of 49/105 (47%) patients had PD, 50/105 (48%) stable disease (SD) and 6/105 (6%) a partial response (PR). On multivariate analysis, the following markers were associated with improved outcome on second-line therapy: a PFS on first-line therapy ≥12 months (HR for PFS: 1.961; p = 0.008) (HR for OS: 1.724; p = 0.037) and Fuhrman grade 1-2 tumors (HR for OS: 2.198; p = 0.007). Markers associated with poorer outcome on second-line therapy were: elevated serum lactate dehydrogenase (LDH) levels (HR for PFS: 0.511; p = 0.04) (HR for OS: 0.392; p = 0.017), low albumin (HR for OS: 0.392; p = 0.01) and elevated corrected calcium levels (HR for OS: 0.416; p = 0.01). The impact on OS of the Memorial Sloan Kettering Cancer Centre (MSKCC) and International Renal Cell Carcinoma Database Consortium (IMDC) prognostic scores as calculated at start of second-line therapy was validated in our patient series.

CONCLUSIONS

Duration of first-line PFS, Fuhrman grade, serum LDH levels, albumin levels, corrected calcium levels and the MSKCC and IMDC scores calculated at start of second-line therapy are prognostic factors for m-ccRCC patients treated with second-line targeted therapy.

Clinical experience with everolimus in the second-line treatment of advanced renal cell carcinoma

Everolimus is an oral inhibitor of mammalian target of rapamycin (mTOR-I) and is currently approved for the treatment of metastatic renal cell carcinoma (mRCC) after failure of first-line vascular endothelial growth factor receptor tyrosine kinase inhibitor (TKI). In this narrative review, we aim to report the available evidence about the use of everolimus as second-line therapy for mRCC. A literature search was performed using PubMed/MEDLINE and abstracts from major conferences on clinical oncology as sources. We report data from prospective as well as retrospective and real world data studies and we analyze the safety and efficacy profile of everolimus as second-line therapy for mRCC. Although different drugs are currently available for the second-line treatment of mRCC, everolimus represents a feasible and safe option in this setting, especially for patients who have experienced high-grade toxicity or are still carrying TKI-related toxicities from first-line treatment.

Management of metastatic renal cell carcinoma progressed after sunitinib or another antiangiogenic treatment

Prognosis of metastatic renal cell carcinoma (mRCC) has markedly improved in the recent years. Several factors such as precocious diagnosis, better supportive care, and an increased number of targeted therapies are responsible for this progress. From 2006 to date, 7 drugs have been approved for treatment of mRCC, and among these only 2 are recommended for the second line of therapy with grade 1 evidence. Tyrosine kinase inhibitors (TKIs) and mammalian target of rapamycin (mTOR) inhibitors are the strategies with more evidence, but no comparative studies are available and what is the best second line remains an open issue. Herein, we review the available evidence on the second-line treatment focusing mainly on prospective studies. We identify a special population of patients in whom more evidence is available, and we propose a possible strategy for the management of progressed mRCC and for primary resistant lesions as well as for patients who need a rapid response in lesions. In the majority of patients, several factors should be considered: toxicity reported during first-line therapy, performance status, the absence of correlation between the length of first-line therapy and the probability to respond to second-line therapy, and the lack of comparative trials between mTOR inhibitors and TKI. When an mTOR inhibitor is selected, everolimus must be preferred, although in the RECORD1 trial only the increase in progression-free survival has been reported and the increase in terms of overall survival has not been reached. When another TKI is the choice, there are no strong pieces of evidence that favor the use of a defined molecule. In every case, we recommend to start the selected targeted agents at standard dosage and to pursue therapy as long as possible because the control of disease should be the primary endpoint for the management of mRCC.

Temsirolimus for patients with metastatic renal cell carcinoma: outcomes in patients receiving temsirolimus within a compassionate use program in a tertiary referral center

Aim

Temsirolimus has shown efficacy as first-line treatment of patients with metastatic renal cell carcinoma and poor prognostic features. The efficacy of temsirolimus in other clinical settings, such as second-line therapy, is unclear. The aim of this study was to investigate the outcomes of an unselected group of patients with renal cancer treated with temsirolimus in a compassionate use program.

Patients and methods

This retrospective analysis included all patients receiving temsirolimus at a tertiary referral center between November 2007 and October 2008. Information was obtained through review of patient notes, electronic records, and pharmacy records. Baseline characteristics, prognostic features, and previous treatments were recorded for all patients. Outcome measures were response rate, progression-free survival (PFS), overall survival (OS), and toxicities.

Results

Thirty-eight patients were included in the analysis, with median age of 62 years, among whom 37% were untreated and 63% had received one or more previous treatments. Thirty-four percent of the patients had three or more poor prognostic factors. Four patients (11%) achieved a partial response (PR); in all four of these patients, the PR was confirmed by two subsequent computed tomography (CT) scans, and in one patient, the PR lasted for more than 18 months. A total of 34% achieved stable disease, and 50% had disease progression. Median OS was 7.6 months (95% confidence interval [CI] 4.8–10.5), and median PFS was 3.2 months (95% CI 1.0–5.5). Patients with two or fewer poor prognostic factors had a survival of 10.12 months compared with 5.03 months of those with three or more. Median survival was 14.9 months for untreated patients and 6.4 months for previously treated patients.

Conclusion

Our results indicate some efficacy of temsirolimus in untreated patients with renal tumors and poor-intermediate prognosis, although the limitations of small sample size and retrospective nature must be taken into account. The role of temsirolimus in previously treated patients remains controversial given the recently published results of the INTORSECT trial and the discrepancies between the few published series.

Clinical outcomes in patients with metastatic renal cell carcinoma receiving everolimus or temsirolimus after sunitinib

INTRODUCTION

There are little data on the clinical activity of temsirolimus (TM) and everolimus (EV) when used as second-line therapy after sunitinib (SU) in patients with metastatic renal cell carcinoma (mRCC).

METHODS

Patients with mRCC treated with EV or TM after SU were included in this retrospective analysis. Progression-free survival (PFS), time to sequence failure (TTSF) from the start of SU to disease progression with EV/TM and overall survival (OS) were estimated using Kaplan-Meier method and compared across groups using the log-rank test. Cox proportional hazards models were applied to investigate predictors of TTSF and OS.

RESULTS

In total, 89 patients (median age 60.0 years) were included. At baseline 43% were classified as MSKCC good-risk, 43% as intermediate-risk and 14% as poor-risk. Median OS was 36.3 months and median TTSF was 17.2 months. Sixty-five patients received SU-EV and 24 patients SU-TM. Median PFS after the second-line treatment was 4.3 months in the EV group and 3.5 months in the TM group (p = 0.63). Median TTSF was 17.0 and 18.9 months (p = 0.32) and the OS was 35.8 and 38.3 months (p = 0.73) with SU-EV and SU-TM, respectively. The prognostic role of initial MSKCC was confirmed by multivariable analysis (hazard ratio 1.76, 95% confidence interval 1.08-2.85. p = 0.023).

CONCLUSIONS

This study did not show significant differences in terms of disease control and OS between EV and TM in the second-line setting. EV remains the preferred mTOR inhibitor for the treatment of mRCC patients resistant to prior tyrosine kinase inhibitor treatment.

Temsirolimus for advanced renal cell carcinoma

Renal cell carcinomas (RCCs) represent one of the ten leading cancer entities with an increasing incidence especially in the western world. Unfortunately, about 25% of the patients develop metastatic RCC (mRCC) associated with a most unfavorable prognosis. In the recent years, various new agents targeting VEGF or VEGF receptor (VEGFR) or the mTOR pathway have been approved for the treatment of mRCC with significant prolongation of progression-free survival and, in part, of overall survival (OS). Targeting the mTOR kinase is an interesting option for mRCC. Temsirolimus, one of the available mTOR inhibitors, has been approved as a single agent in poor-risk mRCC patients based on the pivotal Phase III trial showing a significant superiority in OS versus IFN-α or temsirolimus + IFN-α, which has been verified by a pivotal Phase III trial. The benefit has been shown for clear cell carcinoma and papillary RCC as well. For poor prognosis patients, temsirolimus improves median survival by 3.6 months. In second-line treatment compared with sorafenib following first-line treatment with sunitinib temsirolimus showed a relative progression-free survival benefit for patients with nonclear cell RCC with temsirolimus. The median OS for the temsirolimus group was 12.27 and 16.64 months for the sorafenib group. In 2007, the US FDA granted approval for temsirolimus for the treatment of advanced RCC.

Randomized phase III trial of temsirolimus versus sorafenib as second-line therapy after sunitinib in patients with metastatic renal cell carcinoma

PURPOSE

This international phase III trial (Investigating Torisel As Second-Line Therapy [INTORSECT]) compared the efficacy of temsirolimus (mammalian target of rapamycin inhibitor) and sorafenib (vascular endothelial growth factor receptor [VEGFR] tyrosine kinase inhibitor) as second-line therapy in patients with metastatic renal cell carcinoma (mRCC) after disease progression on sunitinib.

PATIENTS AND METHODS

In total, 512 patients were randomly assigned 1:1 to receive intravenous temsirolimus 25 mg once weekly (n = 259) or oral sorafenib 400 mg twice per day (n = 253), with stratification according to duration of prior sunitinib therapy (≤ or > 180 days), prognostic risk, histology (clear cell or non-clear cell), and nephrectomy status. The primary end point was progression-free survival (PFS) by independent review committee assessment. Safety, objective response rate (ORR), and overall survival (OS) were secondary end points.

RESULTS

Primary analysis revealed no significant difference between treatment arms for PFS (stratified hazard ratio [HR], 0.87; 95% CI, 0.71 to 1.07; two-sided P = .19) or ORR. Median PFS in the temsirolimus and sorafenib arms were 4.3 and 3.9 months, respectively. There was a significant OS difference in favor of sorafenib (stratified HR, 1.31; 95% CI, 1.05 to 1.63; two-sided P = .01). Median OS in the temsirolimus and sorafenib arms was 12.3 and 16.6 months, respectively. Safety profiles of both agents were consistent with previous studies.

CONCLUSION

In patients with mRCC and progression on sunitinib, second-line temsirolimus did not demonstrate a PFS advantage compared with sorafenib. The longer OS observed with sorafenib suggests sequenced VEGFR inhibition may benefit patients with mRCC.

Sequencing therapy in metastatic renal cell cancer

The sequencing of targeted therapy is well established in metastatic renal cancer. Switching between different vascular endothelial growth factor (VEGF)-targeted therapies or VEGF-targeted therapies and mammalian target of rapamycin (mTOR) inhibitors are both of proven benefit. The optimal sequence remains unclear. Unfortunately, there is a lack of biomarkers to drive decision making. In this article we review the current data and describe the treatment options for patients.

An evidence-based guide to the selection of sequential therapies in metastatic renal cell carcinoma

Targeted therapies have introduced a paradigm shift in the management of metastatic renal cell carcinoma. Currently, four molecules (sunitinib, pazopanib, bevacizumab plus interferon, temsirolimus) are considered in first-line therapy, and three other molecules for second, or subsequent lines of therapy (everolimus, axitinib, sorafenib). In addition, other molecules and sequencing schemes are being tested in ongoing phase II/III studies. We conducted a systematic review using PubMed and several other databases up to December 2011 of prospective and retrospective studies on treatment management of metastatic renal cell carcinoma using targeted therapies, with a special focus on use of sequential treatment. Based on phase III data, the optimal sequencing scheme for patients with clear cell or even non-clear cell histological subtype appears to consist of sunitinib, followed by axitinib, followed by everolimus. Subsequent treatment options rely on lower evidence studies and could consist of fourth-line sorafenib or sunitinib rechallenge. Such therapies would qualify as last recourse options. In another context, temsirolimus may be used in patients who fulfill the Memorial Sloan-Kettering Cancer Center poor risk criteria or who have poor performance status. We conclude that in the current setting, sequential therapy represents the cornerstone of effective management of metastatic renal cell carcinoma.

Temsirolimus in overtreated metastatic renal cancer with subsequent use of sunitinib: A case report

During the last decade, we have been developing new therapeutic strategies for the treatment of renal cancer, based on knowledge derived from molecular biology. We report a case of long-term renal metastatic cancer progression despite therapy with sunitinib and interleukin, which are the most active drugs in renal cancer. Disease stabilization for 58 weeks was achieved upon sequential use of temsirolimus, following the occurrence of disease progression during angiogenic therapy. The patient demonstrated excellent tolerance without marked symptoms for 10 months. Hypothyroidism and mumps-related adverse events were present. The survival time from diagnosis to lung metastasis was 8 years. Thus, this case demonstrates promising therapeutic effects of the sequential use of tyrosine kinase inhibitors (TKIs) and mammalian target of rapamycin (mTOR) inhibitors during different stages of the disease.

Mechanisms of resistance to anti-angiogenesis therapies

Angiogenesis, the formation of new blood vessels from preexisting ones, provides oxygen and nutrients to actively proliferating tumor cells. Hence, it represents a critical aspect of tumor progression and metastasis. Because inhibition of angiogenesis represents a major approach to cancer treatment, the development of inhibitors of angiogenesis is a major challenge. The first FDA approved anti-angiogenic drug bevacizumab, a humanized monoclonal antibody directed against the Vascular Endothelial Growth Factor (VEGF), has been approved for the treatment of metastatic colorectal, lung, breast, and kidney cancers. The encouraging results have lead to the development, in the past few years, of other agents targeting angiogenic pathways as potent anti-cancer drugs and a number of them have been approved for metastatic breast, lung, kidney, and central nervous system cancers. Despite a statistically significant increase in progression free survival, which has accelerated FDA approval, no major benefit to overall survival was described and patients inevitably relapsed due to acquired resistance. However, while progression free survival was increased by only a few months for the majority of the patients, some clearly benefited from the treatment with a real increase in life span. The objective of this review is to present an overview of the different treatments targeting angiogenesis, their efficacy and the mechanisms of resistance that have been identified in different cancer types. It is essential to understand how resistance (primary or acquired over time) develops and how it may be overcome.

A contemporary update on rates and management of toxicities of targeted therapies for metastatic renal cell carcinoma

BACKGROUND

To provide an updated review of adverse events associated with sunitinib, pazopanib, bevacizumab, temsirolimus, axitinib, everolimus and sorafenib and their management.

MATERIALS AND METHODS

We performed a PubMed and Cochrane-based review of side effects associated with the seven agents including product monographs to provide an outline of treatment measures aiming to reduce their toxicities. Subject and outcome of interest, design type, sample size, pertinence and quality, and detail of reporting were the indicators of manuscript quality.

RESULTS

All targeted therapies cause adverse events. Most adverse events may be prevented or tested before they escalate to severe levels.

CONCLUSION

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

Temsirolimus: a safety and efficacy review

INTRODUCTION

The vascular endothelial growth factor (VEGF) pathway and the mammalian Target of Rapamycin (mTOR) represent the most frequently exploited targets in renal cell carcinoma (RCC). Temsirolimus is an inhibitor of mTOR, and is a unique ester derivative of sirolimus, a macrocyclic lactone, with improved pharmaceutical properties, including stability and solubility. Temsirolimus binds to the cytoplasmic protein FKBP-12, and the complex binds and inhibits mTOR.

AREAS COVERED

This review summarizes the clinical findings and safety of temsirolimus in RCC patients.

EXPERT OPINION

A Phase III clinical trial has demonstrated that temsirolimus has statistically significant advantages over treatment with IFN-α in RCC patients with poor prognosis, in terms of OS (overall survival), PFS (progression-free survival), and tumor response. Median OS was improved 49% compared to IFN-α, and median PFS was approximately doubled. It is now considered the standard for RCC patients with poor prognostic features. The possibility that this agent is useful in metastatic non-clear cell carcinoma patients has also been suggested by a subset analysis of the pivotal Phase III trial. Studies in untreated favorable and intermediate risk clear cell and refractory mRCC patients are required.

Axitinib for the treatment of patients with advanced metastatic renal cell carcinoma (mRCC) after failure of prior systemic treatment

The landscape of renal cell carcinoma (RCC) treatment has changed dramatically during recent years. Bevacizumab/interferon, sunitinib, sorafenib, temsirolimus, everolimus, and pazopanib have been proven effective in metastatic RCC. Axitinib is a novel tyrosine kinase inhibitor, which inhibits the vascular endothelial growth factor receptor (VEGFR) at subnanomolar level. Based on this extraordinary VEGFR inhibition, axitinib is considered a next-generation agent. The recent AXIS trial reported on axitinib's efficacy in second line treatment of RCC, which led to its recent approval in the USA. This review focuses on the clinical efficacy of axitinib in RCC patients.

Importance of fibroblast growth factor receptor in neovascularization and tumor escape from antiangiogenic therapy

Therapeutic inhibition of pathways involved in angiogenesis has become the standard of care in renal cell carcinoma (RCC). Most currently available antiangiogenic agents inhibit the vascular endothelial growth factor (VEGF) pathway. Although these drugs have produced exciting benefits, some tumors do not respond to these agents. In addition most if not all tumors that initially respond will eventually develop resistance. Tumor escape from antiangiogenic therapy may include various signaling pathways that are involved in angiogenesis, including the fibroblast growth factor (FGF) signaling pathway. Emerging preclinical data suggest that FGF and VEGF act distinctly and synergistically to promote tumor vascularization. The current review discusses the role of FGF signaling in resistance to anti-VEGF therapies and outlines potential therapeutic implications.

Safety and efficacy of temsirolimus in heavily pretreated patients with metastatic renal cell carcinoma

BACKGROUND

First line treatment with temsirolimus is considered standard of care in poor risk patients with metastatic renal cell carcinoma. The role of temsirolimus in pretreated patients with any risk profile is unclear. The aim of this retrospective analysis was to investigate the impact of temsirolimus in patients who had progressed on various treatment lines.

MATERIAL AND METHODS

From April 2007 to July 2009, all patients who had progressed on receptor-tyrosine kinase-inhibitors, VEGF-antibodies and other agents were treated with temsirolimus (25 mg weekly). Physical examination, white blood cell count and chemistry were obtained weekly and tumor response was assessed every 12 weeks.

RESULTS

Thirty patients with a median age of 68 years range (44-81) received treatment with temsirolimus. Most patients were categorized intermediate risk (60%) and the majority had three or more metastatic sites (56.7%). Temsirolimus was median the fourth (range 2-5) systemic treatment line. Grade 3 and 4 toxicities were rare and consisted of anemia, thrombocytopenia and hyperglycemia. Objective remission and stable disease were achieved in 13.3% and 60% of the patients, respectively. The median progression free survival was 4.9 months (2.93-6.81 95% CI).

CONCLUSION

Temsirolimus appears feasible, safe and active in heavily pretreated patients.

mTOR inhibitors in advanced renal cell carcinoma

Better understanding of the molecular biology of renal cell carcinoma (RCC) has led to the development of several targeted anti-cancer agents, several of which have since received approval for treatment of advanced disease. Two of these, the intravenous agent temsirolimus and the oral everolimus, exhibit antitumor effects through inhibition of the mammalian target of rapamycin (mTOR) pathway. This article reviews their mechanisms of action in the context of the current understanding of RCC pathophysiology, the clinical data leading to their approval, class-specific toxicities, potential molecular mechanisms behind treatment resistance and novel treatment approaches for RCC that incorporate mTOR blockade.

Sequencing of agents for metastatic renal cell carcinoma: can we customize therapy?

CONTEXT

The expanding armamentarium of agents for the therapy of advanced clear cell renal cell carcinoma (RCC) warrants further investigation of optimal patient selection.

OBJECTIVE

To analyze the second and subsequent line of targeted therapies for advanced RCC while integrating clinical and molecular markers and imaging.

EVIDENCE ACQUISITION

Data were acquired from research published in peer-reviewed literature or presented at major conferences.

EVIDENCE SYNTHESIS

Following first-line vascular endothelial growth factor (VEGF) inhibitors, second-line therapy with everolimus, a mammalian target of rapamycin inhibitor, and axitinib, a VEGF receptor tyrosine kinase inhibitor, have demonstrated benefits in progression-free survival (PFS). Sorafenib, pazopanib, and axitinib have demonstrated extension of PFS following cytokines. Optimal patient selection based on biomarkers is undergoing investigation. Clinical trials evaluating novel agents and combinations should be preferred.

CONCLUSIONS

Currently, the sequence of therapy is based on patient and physician decision, which may be influenced by comorbidities and toxicity profiles.

VEGF spliced variants: possible role of anti-angiogenesis therapy

Angiogenesis has been targeted in retinopathies, psoriasis, and a variety of cancers (colon, breast, lung, and kidney). Among these tumour types, clear cell renal cell carcinomas (RCCs) are the most vascularized tumours due to mutations of the von Hippel Lindau gene resulting in HIF-1 alpha stabilisation and overexpression of Vascular Endothelial Growth Factor (VEGF). Surgical nephrectomy remains the most efficient curative treatment for patients with noninvasive disease, while VEGF targeting has resulted in varying degrees of success for treating metastatic disease. VEGF pre-mRNA undergoes alternative splicing generating pro-angiogenic isoforms. However, the recent identification of novel splice variants of VEGF with anti-angiogenic properties has provided some insight for the lack of current treatment efficacy. Here we discuss an explanation for the relapse to anti-angiogenesis treatment as being due to either an initial or acquired resistance to the therapy. We also discuss targeting angiogenesis via SR (serine/arginine-rich) proteins implicated in VEGF splicing.

Maximising the duration of disease control in metastatic renal cell carcinoma with targeted agents: an expert agreement

With six targeted agents approved (sorafenib, sunitinib, temsirolimus, bevacizumab [+interferon], everolimus and pazopanib), many patients with metastatic renal cell carcinoma (mRCC) will receive multiple therapies. However, the optimum sequencing approach has not been defined. A group of European experts reviewed available data and shared their clinical experience to compile an expert agreement on the sequential use of targeted agents in mRCC. To date, there are few prospective studies of sequential therapy. The mammalian target of rapamycin (mTOR) inhibitor everolimus was approved for use in patients who failed treatment with inhibitors of vascular endothelial growth factor (VEGF) and VEGF receptors (VEGFR) based on the results from a Phase III placebo-controlled study; however, until then, the only licensed agents across the spectrum of mRCC were VEGF(R) inhibitors (sorafenib, sunitinib and bevacizumab + interferon), and as such, a large body of evidence has accumulated regarding their use in sequence. Data show that sequential use of VEGF(R) inhibitors may be an effective treatment strategy to achieve prolonged clinical benefit. The optimal place of each targeted agent in the treatment sequence is still unclear, and data from large prospective studies are needed. The Phase III AXIS study of second-line sorafenib vs. axitinib (including post-VEGF(R) inhibitors) has completed, but the data are not yet published; other ongoing studies include the Phase III SWITCH study of sorafenib-sunitinib vs. sunitinib-sorafenib (NCT00732914); the Phase III 404 study of temsirolimus vs. sorafenib post-sunitinib (NCT00474786) and the Phase II RECORD 3 study of sunitinib-everolimus vs. everolimus-sunitinib (NCT00903175). Until additional data are available, consideration of patient response and tolerability to treatment may facilitate current decision-making regarding when to switch and which treatment to switch to in real-life clinical practice.

Combination or sequencing strategies to improve the outcome of metastatic renal cell carcinoma patients: a critical review

The introduction of novel anti-angiogenic therapies has greatly improved the outcome of patients with metastatic renal cell carcinoma (mRCC). The use of these therapies in combination or sequentially is proposed to provide greater efficacy. We have reviewed completed and ongoing clinical trials in mRCC that have reported efficacy and/or safety data of novel therapies used in combination or sequentially. Bevacizumab appears to be a useful partner when combined with interferon (IFN), while controversial results have been reported when combined with temsirolimus and everolimus. Other combinations appear to have unacceptable tolerability or require dose or schedule optimization. Sequencing data provide a clear indication that multiple lines of treatment may extend survival. The 'ideal' sequence, however, is still unknown. In conclusion, novel therapies used in combination or sequentially have potential to provide optimised treatment and patient outcomes in mRCC. The results from ongoing/planned trials are expected to help shape future therapy.

Sequential mTOR inhibitor treatment with temsirolimus in metastatic renal cell carcinoma following failure of VEGF receptor tyrosine kinase inhibitors

PURPOSE

Agents targeting the mammalian target of rapamycin (mTOR) pathway, e. g. everolimus, can provide clinical benefit in pretreated patients with metastatic renal cell carcinoma (mRCC), but data from randomized trials on the sequential use of temsirolimus are lacking. We retrospectively studied the efficacy and safety of temsirolimus therapy following failure of rTKI therapy.

METHODS

Twenty-nine patients treated with temsirolimus (25 mg/week) following progression on rTKI therapy were studied at four institutions. All patients had failed at least one prior rTKI therapy (sunitinib, n = 6; sorafenib, n = 1; both, n = 22). Over 80% had two or more prior therapies. Data on efficacy (response assessment, progression-free survival [PFS], overall survival [OS]) and safety (NCI-CTC) were analyzed.

RESULTS

Adverse events occurred in 90% of patients with the majority being grade 1 (n = 4, 14%) or grade 2 (n = 12, 41%). Most grade 3/4 toxicities (n = 10, 34%) were manageable and included anemia (n = 4, 14%), leukopenia/neutropenia (n = 2, 7%), hyperglycemia (n = 1, 3%), acidosis/alkalosis (n = 2, 7%), and infection (n = 1, 3%). One patient discontinued temsirolimus for grade 3 pneumonitis. Median (range) PFS and OS were 5.1 months (1-10.4) and 18.0 months (12.6-23.3), respectively. Best response included partial response (n = 1) and stable disease (n = 15) for a disease control rate of 55%, and disease progression of 45% (n = 13).

CONCLUSIONS

Temsirolimus after rTKI failure appears to provide promising safety and efficacy comparable to other treatment options in pretreated patients with mRCC.

Third-line sorafenib after sequential therapy with sunitinib and mTOR inhibitors in metastatic renal cell carcinoma

BACKGROUND

Sunitinib and everolimus have been approved for first- and second-line treatment, respectively, in metastatic renal cell carcinoma (mRCC). The role of sorafenib, which is approved for second-line treatment after cytokines failure, is presently to be defined.

OBJECTIVE

To determine whether third-line sorafenib after sequential use of sunitinib and mammalian target of rapamycin inhibitors (everolimus or temsirolimus) is feasible and effective.

DESIGN, SETTING, AND PARTICIPANTS

One hundred fifty medical records of patients with mRCC treated with first-line sunitinib between January 2006 and January 2010 were reviewed at four participating centers. Data regarding patients treated with the sequence sunitinib-everolimus or temsirolimus-sorafenib were extracted. Central analysis of radiographic images was performed using RECIST criteria to determine progression-free survival (PFS) and overall response rate (oRR) to sorafenib treatment.

MEASUREMENTS

PFS and oRR to sorafenib were the primary end points. Secondary outcomes were safety and overall survival (OS).

RESULTS AND LIMITATIONS

Thirty-four patients were eligible for the study. A median PFS of 4 mo (range: 3-6 mo) and a median OS of 7 mo since sorafenib treatment (range: 6-10 mo) were reported. Of the patients, 23.5% showed response to sorafenib, with an overall disease control rate (complete responses plus partial responses plus stable disease) of 44%. Selection bias, data incompleteness, and absence of study design are inevitable limitations of the study, although central review can strengthen the quality of presented data.

CONCLUSIONS

Third-line sorafenib appears to be active and well tolerated in mRCC after first-line sunitinib and second-line everolimus or temsirolimus, with no patients interrupting sorafenib because of toxicity or lack of compliance. Prospective, placebo-controlled trials are completely lacking and are required in this setting.

Long-term response with everolimus for metastatic renal cell carcinoma refractory to sunitinib

A 70-year-old man with metastatic renal cell carcinoma developed progressive liver metastases after 8 weeks of treatment with the multitargeted tyrosine kinase inhibitor (TKI) sunitinib. He then participated in the phase III placebo-controlled clinical trial of the oral mammalian target of rapamycin (mTOR) inhibitor everolimus, initially randomized to placebo (but had disease progression after 3 months) and crossed over to everolimus at time of unblinding. The patient had stable disease after 8 weeks (two cycles) of everolimus that was maintained until 28 months of therapy, at which time the patient had achieved a partial response. This case illustrates the potential for patients with metastatic renal cell carcinoma, a malignancy with historically poor prognosis, to derive long-term benefit from everolimus when used in a manner consistent with its approved indication (after TKI therapy with sunitinib or sorafenib).