Immune checkpoint inhibitors in renal cell carcinoma

The immune system has long been known to play a critical role in the body's defence against cancer, and there have been multiple attempts to harness it for therapeutic gain. Renal cancer was, historically, one of a small number of tumour types where immune manipulation had been shown to be effective. The current generation of immune checkpoint inhibitors are rapidly entering into routine clinical practice in the management of a number of tumour types, including renal cancer, where one drug, nivolumab, an anti-programmed death-1 (PD-1) monoclonal antibody (mAb), is licensed for patients who have progressed on prior systemic treatment. Ongoing trials aim to maximize the benefits that can be gained from this new class of drug by exploring optimal timing in the natural course of the disease as well as combinations with other checkpoint inhibitors and drugs from different classes.

Significance of gene expression analysis of renal cell carcinoma

Renal cell carcinoma (RCC) describes a family of epithelial tumors arising from within the kidney. Each subtype of RCC presents a unique clinical picture with varied tumor biology, patient prognosis and response to treatment. Gene expression profiling offers the ability to analyze thousands of candidate genes in high-throughput arrays and has led to a greater knowledge of the molecular genetics of RCC. This powerful technology can identify RCC subtypes, recapitulating and refining the current histological classifications. Gene expression data also promise to advance current staging systems and improve prognostic information for patients and clinicians. Understanding the genetic signature of RCC tumors will allow for sophisticated application of systemic and targeted therapies, improving patient response and minimizing unnecessary exposure of patients to treatment toxicities. This article reviews the significance of gene expression analysis in the understanding of tumor biology and RCC treatment.

Biomarkers for anti-angiogenic therapy in cancer

Angiogenesis, the development of new vessels from existing vasculature, plays a central role in tumor growth, survival, and progression. On the molecular level it is controlled by a number of pro- and anti-angiogenic cytokines, among which the vascular endothelial growth factors (VEGFs), together with their related VEGF-receptors, have an exceptional position. Therefore, the blockade of VEGF signaling in order to inhibit angiogenesis was deemed an attractive approach for cancer therapy and drugs interfering with the VEGF-ligands, the VEGF receptors, and the intracellular VEGF-mediated signal transduction were developed. Although promising in pre-clinical trials, VEGF-inhibition proved to be problematic in the clinical context. One major drawback was the generally high variability in patient response to anti-angiogenic drugs and the rapid development of therapy resistance, so that, in total, only moderate effects on progression-free and overall survival were observed. Biomarkers predicting the response to VEGF-inhibition might attenuate this problem and help to further individualize drug and dosage determination. Although up to now no definitive biomarker has been identified for this purpose, several candidates are currently under investigation. This review aims to give an overview of the recent developments in this field, focusing on the most prevalent tumor species.

Targeted therapy in renal cell carcinoma: moving from molecular agents to specific immunotherapy

Non-specific immunotherapy has been for a long time a standard treatment option for patients with metastatic renal cell carcinoma but was redeemed by specific targeted molecular therapies, namely the VEGF and mTOR inhibitors. After moving treatment for mRCC to specific molecular agents with a well-defined mode of action, immunotherapy still needs this further development to increase its accuracy. Nowadays, an evolution from a rather non-specific cytokine treatment to sophisticated targeted approaches in specific immunotherapy led to a re-launch of immunotherapy in clinical studies. Recent steps in the development of immunotherapy strategies are discussed in this review with a special focus on peptide vaccination which aims at a tumor targeting by specific T lymphocytes. In addition, different combinatory strategies with immunomodulating agents like cyclophosphamide or sunitinib are outlined, and the effects of immune checkpoint modulators as anti-CTLA-4 or PD-1 antibodies are discussed.

Treatment selection for patients with metastatic renal cell carcinoma: identification of features favoring upfront IL-2-based immunotherapy

The availability of approved agents with distinct mechanisms of action (immunotherapy, vascular endothelial growth factor pathway, and mTOR inhibitors) has complicated treatment decisions for patients with advanced kidney cancer. High-dose IL-2 therapy is the only treatment that can produce durable complete responses; however, it has significant side effects and the vast majority of patients do not benefit. Thus, identifying the optimal patients to receive first-line IL-2 therapy is a priority. Past studies have identified some clinical features that might be associated with benefit from IL-2-based immunotherapy. Subsequent investigations of tumors from patients treated with IL-2 suggested that response was unlikely in patients with tumors with papillary features or low carbonic anhydrase IX (CAIX) expression. A model combining histologic features and CAIX expression separated patients into two groups of roughly equal size, with 96% of long-term responding patients being in the favorable prognostic group. This model is currently undergoing prospective validation. More recent studies involving gene expression profiling and array CGH have begun to identify additional features that might predict response to IL-2 therapy. Taken together, these data offer the possibility to limit the use of this toxic therapy to those most likely to benefit.

Update on the application of interleukin-2 in the treatment of renal cell carcinoma

High-dose bolus interleukin 2 (IL-2) was granted Food and Drug Administration approval based on its ability to produce durable complete responses in a small number of patients with metastatic renal cell carcinoma. Results from randomized phase 3 trials suggest that regimens involving lower doses of IL-2, either alone or in combination with IFN, produce fewer tumor regressions of less overall quality. Given the toxicity, expense, and limited efficacy of this treatment, recent studies have focused on identifying predictors of response (or resistance) to IL-2 therapy. This year, investigators launched a clinical trial designed to prospectively determine if patients who are more likely to respond to high-dose IL-2 can be identified before starting therapy. As the list of effective therapies for metastatic renal cell carcinoma grows, improvements in patient selection will be necessary to ensure that patients who might attain a durable remission with IL-2 will not miss this opportunity.