Current and future systemic treatments for renal cell carcinoma

Systemic treatment of renal cell carcinoma has changed dramatically since 2007, with the development and approval of six new agents, which target complex molecular pathways regulating tumour angiogenesis and cell proliferation and survival. These treatments have significantly improved survival times in metastatic renal cell carcinoma, but remain palliative. A number of newer agents are in clinical development, which offer theoretical advantages over existing treatments, and research methodologies are adapting with the aim of defining an individualised approach to therapy which exploits the underlying tumour biology. This review will provide an overview of current and emerging systemic treatments and how they might be integrated with surgical therapy, with a particular focus on advanced, clear cell metastatic renal cell carcinoma.

New targeted therapies for renal cell carcinoma

INTRODUCTION

The aim of treatment in metastatic renal cell carcinoma is palliation. In the last 5 years, multiple targeted agents have been developed which have resulted in prolongation of patients' lives, but complete responses remain rare. New therapies and approaches are required to further improve the prognosis for patients with this disease.

AREAS COVERED

This review discusses the molecular targets in renal cell carcinoma relevant to the development of new treatments and describes the progress of novel therapies. The evidence is compiled from the PubMed database and proceedings of scientific meetings, searched up to December 2010.

EXPERT OPINION

A multitude of experimental agents are in clinical development and offer theoretical advantages over those currently in use. It is hoped that these treatments will result in better long-term control of metastatic renal cell carcinoma, with improved side effect profiles, but curative treatment in this disease remains elusive until the mechanisms underlying response and resistance to therapy are elucidated. Progress in the field has been limited by inadequate tissue collection within clinical trials; current and future clinical trial design will incorporate a larger translational component in an attempt to establish predictive biomarkers.

Targeted therapy for metastatic renal cell carcinoma: current treatment and future directions

An understanding of vascular endothelial growth factor (VEGF) and mammalian target of rapamycin (mTOR) pathways has greatly changed the way metastatic renal cell carcinoma (RCC) is treated. Based on available phase III randomized trials, anti-VEGF agents such as sunitinib, sorafenib, bevacizumab-based therapy, and mTOR-targeted agents such as temsirolimus and everolimus have been used in the treatment armamentarium for this disease. Now that agents directed against these pathways have largely replaced immunotherapy as the standard of care, new questions have emerged and are the subject of ongoing clinical trials. The development of new targeted therapies including axitinib, pazopanib, cediranib, volociximab, tivozanib (AV-951), BAY 73-4506, and c-met inhibitors such as GSK1363089 and ARQ197 may potentially expand the list of treatment options. Sequential and combination targeted therapies are currently under investigation in advanced disease as are adjuvant and neo-adjuvant approaches around nephrectomy.

The vascular endothelial growth factor receptor-2 tyrosine kinase inhibitor cediranib (Recentin; AZD2171) inhibits endothelial cell function and growth of human renal tumor xenografts

PURPOSE

The goal of this study was to examine the therapeutic potential of the vascular endothelial growth factor (VEGF) signaling inhibitor cediranib in a human model of renal cell carcinoma (Caki-1).

METHODS AND MATERIALS

The effects of cediranib treatment on in vitro endothelial cell function (proliferation, migration, and tube formation), as well as in vivo angiogenesis and tumor growth, were determined.

RESULTS

In vitro, cediranib significantly impaired the proliferation and migration of endothelial cells and their ability to form tubes, but had no effect on the proliferation of Caki-1 tumor cells. In vivo, cediranib significantly reduced Caki-1 tumor cell-induced angiogenesis, reduced tumor perfusion, and inhibited the growth of Caki-1 tumor xenografts.

CONCLUSIONS

The present results are consistent with the notion that inhibition of VEGF signaling leads to an indirect (i.e., antiangiogenic) antitumor effect, rather than a direct effect on tumor cells. These results further suggest that inhibition of VEGF signaling with cediranib may impair the growth of renal cell carcinoma.

Phase I and Pharmacokinetic Study of Daily Oral AZD2171, an Inhibitor of Vascular Endothelial Growth Factor Tyrosine Kinases, in Combination With Carboplatin and Paclitaxel in Patients With Advanced Non–Small-Cell Lung Cancer: The National Cancer Institute of Canada Clinical Trials Group

Purpose

AZD2171 is a potent inhibitor of vascular endothelial growth factor receptors that showed broad antitumor activity in preclinical models. Doses of up to 45 mg/d of AZD2171 are tolerable when administered alone. This study evaluated escalating doses of AZD2171 in combination with standard chemotherapy in patients with advanced non–small-cell lung cancer.

Patients and Methods

Eligible patients received carboplatin targeted to an area under the concentration time curve of 6 mg · min/mL and paclitaxel 200 mg/m2, both on day 1 of a 3-week cycle; daily oral AZD2171 at either 30 mg or 45 mg commenced day 2 of cycle 1. Pharmacokinetics of all drugs were performed, and tumor response was assessed by Response Evaluation Criteria in Solid Tumors (RECIST).

Results

Twenty patients were enrolled. No dose-limiting toxicities were observed during cycle 1 at either dose. Fatigue, diarrhea, anorexia, and granulocytopenia were common; hypertension was manageable with a treatment algorithm designed for this protocol. No clinically significant drug-related bleeding was observed. At 45 mg/d, fatigue and diarrhea were increased, and headache and hoarseness were observed. Paclitaxel clearance decreased during cycle 2, but no other significant pharmacokinetic interactions were observed. After radiology review, confirmed responses were observed in nine patients (response rate, 45%; 95% CI, 23% to 68%); all but one enrolled patient showed evidence of tumor shrinkage, some with cavitation.

Conclusion

AZD2171 can be combined with standard doses of carboplatin/paclitaxel with encouraging antitumor activity. Toxicity is increased, but predictable and manageable.

Using Molecular Biology to Develop Drugs for Renal Cell Carcinoma

BACKGROUND: Renal cell carcinoma is a disease marked by a unique biology which has governed it's long history of poor response to conventional cancer treatments. The discovery of the signaling pathway activated as a result of inappropriate constitutive activation of the hypoxia inducible factors (HIF), transcription factors physiologically and transiently stabilized in response to low oxygen, has provided a primary opportunity to devise treatment strategies to target this oncogenic pathway. OBJECTIVE: A review of the molecular pathogenesis of renal cell cancer as well as molecularly targeted therapies, both those currently available and those in development, will be provided. In addition, trials involving combination or sequential targeted therapy are discussed. METHODS: A detailed review of the literature describing the molecular biology of renal cell cancer and novel therapies was performed and summarized. RESULTS/CONCLUSION: Therapeutics targeting angiogenesis have provided the first class of agents which provide clinical benefit in a large majority of patients and heralded renal cell carcinoma as a solid tumor paradigm for the development of novel therapeutics. Multiple strategies targeting this pathway and now other identified pathways in renal cell carcinoma provide numerous potential opportunities to make major improvements in treating this historically devastating cancer.