Interleukin-2 Based Therapy for Kidney Cancer

Maintenance biotherapy with interleukin-2 and interferon for metastatic renal cell cancer

The term maintenance immunotherapy comprises at least two different therapeutic approaches: the continuation of immunotherapy beyond disease progression and the use of chronic immunotherapy after the achievement of an initial response (or disease stabilization) with more intensive treatment modalities, such as chemotherapy. The former therapeutic approach was proposed in renal cell carcinoma some years ago relying on several immunological considerations. Some years later, we have learned that it is feasible and endowed with a favorable therapeutic index; furthermore, its immunologic effects are well described and reproducible, and it has antitumor activity. However, due to the lack of adequate randomized Phase III studies, the actual impact of this treatment strategy on patient survival has not yet been proved. The rationale of this treatment, its immunological and clinical results, as well as its pitfalls and perspectives, will be presented and discussed in this review.

Aldesleukin in advanced renal cell carcinoma

Renal cell carcinoma accounts for 2-3% of all malignancies. The most common subtype [85%] is the clear cell variant. A total of 30% of patients present with metastatic disease at diagnosis and another 30-40% will develop metastases during the course of the disease. Conventional cancer treatment is not effective, but cytokines including recombinant interleukin-2 (aldesleukin) have demonstrated clinical activity of various degrees. This drug profile provides a review of the literature on studies using aldesleukin in patients with metastatic renal cell carcinoma. Aldesleukin has been used in different dose schedules applying various administration routes, as either monotherapy or in combination with other cytokines, chemotherapy, endocrine treatment and adoptive cellular immunotherapy. Although a large number of randomized trials have been performed with different treatment strategies, it still remains uncertain whether the dose or combination of aldesleukin with other agents substantially influence treatment outcome. It appears that factors other than those that are treatment related are responsible for the course of the disease.

Differential gene expression identifies subgroups of renal cell carcinoma

Clear cell carcinoma of the kidney, the most common subtype of renal cell cancer, displays different biological behavior in different patients. This heterogeneity cannot be recognized by light microscopy. In this study, gene expression in 16 clear cell renal cell carcinoma samples and 17 non-malignant tissue types comprising 539 samples was determined using oligonucleotide microarrays representing approximately 40,000 known genes and ESTs. Differences in gene expression were quantified as the fold change in gene expression between the various sets of samples. A set of genes was identified that was overexpressed in the renal cell carcinoma samples compared with the normal kidney samples. Principle component analysis of the set of renal cell carcinomas using this set of genes overexpressed in renal cell cancer revealed the existence of 2 major subgroups among the renal carcinomas. A series of principle component analyses of the set of renal cell carcinomas using different gene sets composed of genes involved in different metabolic pathways also revealed the same 2 major subgroups of the renal cell cancers. Eisen clustering using the same genes also revealed the same 2 major renal cell cancer subsets. Review of the pathology suggested that these 2 subgroups differed in pathologic grade. Genes differentially expressed between the 2 renal cell cancer subsets were identified. Examination of gene expression in each renal cell cancer subset and the pool of renal cell carcinoma samples compared with that in 17 different normal tissues revealed genes specifically overexpressed in renal cell cancer compared with these normal tissues. The authors conclude that gene expression patterns may be useful in helping to further classify subtypes of renal cell carcinoma that may have clinical significance. In addition, the genes identified as overexpressed in each set of clear cell renal cell carcinomas compared with normal tissues may represent useful targets for therapy.

Lymphocyte therapy of renal cell carcinoma

During the past 20 years, there has been considerable interest in lymphocyte therapy as a treatment for renal cell carcinoma. There is no therapeutic role for B-lymphocyte therapy, but their products, monoclonal antibodies, now have widespread clinical applications. The major types of autologous lymphocyte therapy that have been explored in clinical trials are cytotoxic lymphokine-activated killer cells, which are natural killer cells and T-cells that have been stimulated in vitro by interleukin-2 or other similar cytokines; cytotoxic and noncytotoxic tumor infiltrating lymphocytes, which are T-cells derived from tumor tissue; other tumor antigen-stimulated T-lymphocytes derived from regional lymph nodes or peripheral blood; and noncytotoxic lymphocytes of the memory/helper phenotype. More recently, allogeneic immune therapy using nonmyeloablative hematopoietic stem cell transplant and/or donor lymphocyte therapy has also shown promise.

Targeted therapy in renal cell carcinoma

Hypoxia-regulated genes such as vascular endothelial growth factor (VEGF) and epidermal growth factor (EGF) are both important for tumour progression in renal cell carcinoma (RCC). Drugs that block these and other pathways have been examined in Phase I and II clinical trials in patients with advanced or metastatic RCC. Results from a randomised study of an anti-VEGF antibody demonstrate a delay in the time to disease progression, suggesting a biological effect and change in the natural history of the disease. Results using small-molecule inhibitors of VEGF, FLT3, KIT and platelet-derived growth factor receptor tyrosine kinases, such as sunitinib, show a 40% objective response rate. Results from a Phase III clinical trial with sorafenib, an inhibitor of multiple tyrosine kinases, show only a 2% response rate; however, a statistically significant improvement in progression-free survival was observed. Objective responses have also been noted using an inhibitor of the mammalian target of rapamycin. Conversely, EGF receptor inhibitors, proteosome inhibitors, microtubule stabilising agents, cell-cycle inhibitors and imatinib were also examined with few objective responses. Ultimately, identifying the predictive factors for responsiveness to these targeted therapies may improve the clinical benefit; for example, RCC with biallelic mutations in the von Hippel-Lindau gene would have higher levels of hypoxia-inducible factor-1alpha, and may be more responsive to inhibitors of angiogenesis. Phase III studies comparing the combinations of targeted therapy could lead to a new standard of care for RCC.

Tyrosine kinase inhibitors in renal cell carcinoma

Current standard treatments for patients with metastatic (stage IV) renal cell carcinoma involve both surgical removal of tumors and treatment with biological agents such as interleukin 2 and/or IFN-alpha. Unfortunately, such approaches are inadequate for most patients with stage IV disease; the result is a median time to progression of 2 to 4 months and an overall survival of 6 to 17 months. Standard chemotherapy has been uniformly disappointing in this disorder. It is clear that new therapies are needed to approach these patients. Recently, a greater understanding of cancer genetics has led to the successful development of novel therapeutics directed against targets linked to specific types of cancer. During the past decade, researchers have identified the von Hippel-Lindau (VHL) gene as an important tumor suppressor in clear cell carcinoma of the kidney. Elucidation of the VHL gene product (pVHL) and its regulation of hypoxia-inducible factor signaling have created a potential genetic basis for growth factor-targeted strategies in this disease. This review will focus on the potential growth factor targets in clear cell carcinoma, their relation to VHL and hypoxia-inducible factor, and the clinical challenges that face their development.