Improving outcomes in metastatic clear cell renal cell carcinoma by sequencing therapy

Targeted agents have substantially improved outcomes in metastatic clear cell renal cell carcinoma. However, due to multiple mechanisms of evasive resistance, almost all patients progress at some point and may require subsequent therapies. Various agents have been explored after failure of first-line treatment in randomized clinical trials. However, so far few questions about the optimal sequence have been answered. Both everolimus and axitinib have been considered standard of care after failure of first-line VEGF-TKI; sorafenib has been proposed as an additional option. In clinical practice, several factors may influence the choice of subsequent treatment: these include considerations on appropriate drug exposure in first-line, gained insights on prognostic and predictive factors as well as mechanisms of resistance. Once the decision in second-line has been made and treatment has been initiated, treating physicians may already be challenged by the question of what to offer in third- and later lines. Treatment beyond second-line treatment isn't supported by strong evidence, and at this stage of disease, retrospective reports on rechallenge may help to guide decisions. In addition, local treatment approaches including metastasectomy and stereotactic radiosurgery may help to optimize outcomes in all treatment lines.

Optimal management of metastatic renal cell carcinoma: current status

The armamentarium for the systemic therapy of advanced renal cell carcinoma (RCC) has undergone dramatic changes over the past 6 years. While high-dose interleukin (IL)-2 remains an option for highly selected good and intermediate risk patients with clear-cell histology because of durable complete responses in a small fraction of patients, cytokine-based therapy including interferon (IFN) has been supplanted by vascular-endothelial growth factor (VEGF) and mammalian target of rapamycin (mTOR) inhibitors. Treatment decision is initially based on prognostication of the disease. As metastatic RCC (mRCC) is commonly an indolent disease, a period of observation should always been considered. For good and intermediate risk disease, pazopanib, sunitinib or the combination of bevacizumab plus IFN are considered. Notably, recent data suggest non-inferiority for the efficacy of pazopanib compared to sunitinib coupled with a better toxicity profile. A novel VEGF receptor inhibitor, tivozanib, is expected to be approved based on improvement in PFS when compared to sorafenib in the first-line setting. The use of temsirolimus for poor risk disease is supported by a phase III trial dedicated to this group of patients. The role of cytoreductive nephrectomy in the context of VEGF and mTOR inhibitors is being studied in randomized trials. Selected patients with solitary or oligometastatic disease may be eligible for metastatectomy. Following first-line VEGF inhibitors, second-line therapy with everolimus and axitinib have demonstrated benefits in progression-free survival (PFS). One phase III trial comparing sorafenib and temsirolimus in the post-sunitinib setting showed no difference in PFS, the primary endpoint, but did show a superior overall survival for sorafenib. Sorafenib, pazopanib and axitinib have all demonstrated clinical benefit following cytokines. Therapy following first-line mTOR inhibitors remains undefined, although VEGF inhibitors have demonstrated activity in this setting. Optimal sequencing of agents and individualized therapy based on biomarkers is undergoing investigation. Today, the choice of therapy is based on patient and physician decision, which is a function of comorbidities, toxicity profiles and costs. Clinical trials evaluating novel agents and combinations should be preferred when available since agents in the current therapeutic arsenal have not yielded cures despite extending median survival to greater than 2 years. One noteworthy new class of agents that has yielded durable responses is programmed death (PD)-1 inhibitors, which target a T-lymphocyte checkpoint and are heralding a resurgence of immunotherapy. Finally, optimal therapy for non-clear cell RCC remains to be delineated, although sunitinib, everolimus and other VEGFR-TKI or mTOR inhibitors have all demonstrated modest benefit.

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.

Treatment selection in metastatic renal cell carcinoma: expert consensus

In metastatic renal cell carcinoma (mRCC), many factors influence clinical decisions, including histology, tumour burden, prognostic factors, comorbidities, and the ability of the patient to tolerate treatment. Progression-free survival (PFS) durations reported from randomized trials of targeted therapies vary considerably, in part because of differences in patient characteristics. For first-line therapy, an estimate of PFS with sunitinib, bevacizumab plus interferon, or sorafenib in a 'general' population is 8-9 months, but each regimen is suitable for different patient categories. For example, sunitinib is suitable for all-prognosis groups, particularly younger, fitter patients; pazopanib for patients with a good or intermediate prognosis; bevacizumab plus interferon for good-prognosis patients or those with indolent disease; and sorafenib for patients at all prognostic risk levels, particularly the elderly and those with comorbidities. Sequential therapy with targeted agents provides significant benefit, and should be considered in all patients who can tolerate such treatment. Level 1 evidence supports sequential use of tyrosine kinase inhibitors, as well as these agents followed by everolimus. We consider how patient characteristics have influenced the results of studies of first-line therapy, and we provide expert opinion on the most appropriate treatment choices for particular patient groups receiving first-line and second-line therapy.

Progression free survival of first line vascular endothelial growth factor-targeted therapy is an important prognostic parameter in patients with metastatic renal cell carcinoma

PURPOSE

Intrinsic resistance in metastatic renal cell carcinoma (mRCC) was recently associated with poor overall survival (OS), suggesting that VEGF inhibitor sensitivity may represent a valuable prognostic marker. We explored the duration of progression free survival (PFS) in first-line treatment and other variables as prognostic markers in mRCC.

METHODS

Medical records from 119 mRCC patients receiving first line treatment with tyrosine kinase inhibitors (TKI) were retrieved retrospectively. Kaplan-Meier and log-rank analyses were employed on PFS and OS and multivariate Cox proportional hazard model analysed clinical parameters for their prognostic relevance.

RESULTS

The median PFS of first line treatment was 8.4 months (95% confidence interval 5.8-11) associated with a median OS of 28.2 months (95% CI 20.9-35.4). Second line therapy with another TKI or mTOR-inhibitor was applied to 81 patients (68%). PFS of any second line therapy was 5.1 and 3.7 months in first line treatment responders and non-responders (p = 0.3), respectively. Univariate analyses revealed bone metastases, prior cytokine treatment, Memorial Sloan Kettering cancer centre (MSKCC) score, objective response rate, Eastern Cooperative Oncology Group (ECOG) performance status, first line PFS with 6 months taken as cut-off parameter and second line treatment as prognostic variables. Multivariate analyses proved first line PFS above 6 months (95% CI 0.154-0.641; HR 0.314), second line treatment (95% CI 0.162-0.657; HR 0.326), MSKCC score (95% CI 1.07-3.392; HR 1.905) and objective response rate (95% CI 0.358-0.989; HR 0.595) to be independent prognostic markers.

CONCLUSIONS

The duration of first line PFS is an independent prognostic variable but not predictive for subsequent therapy.