Clinical utility of routine proteinuria evaluation in treatment decisions of patients receiving bevacizumab for metastatic solid tumors

BACKGROUND

Bevacizumab is an anti-vascular endothelial growth factor monoclonal antibody approved for use in treatment of patients with metastatic breast, colorectal, and non-small cell lung cancer. In the pivotal Phase 3 clinical trials, grades 3-4 proteinuria occurred in <5% of patients. The manufacturer recommends monitoring for the development of proteinuria but does not provide specific recommendations, except to discontinue treatment if the patient develops nephrotic syndrome.

OBJECTIVE

To determine the incidence and severity of elevated proteinuria and the frequency of changes in bevacizumab administration due to elevated proteinuria; secondary objectives included analysis of the cost of routine proteinuria monitoring and the relationship of proteinuria with other patient comorbidities such as diabetes, hypertension, chronic kidney disease, and viral hepatitis.

METHODS

A retrospective chart review was performed at the University of Washington Medical Center, a large academic teaching hospital, and its affiliated ambulatory clinics at the Seattle Cancer Care Alliance. Patients treated with bevacizumab and seen in the breast, lung, and gastrointestinal cancer clinics from June 1, 2005, to November 30, 2007, were included in the study.

RESULTS

A total of 243 patients were included in the analysis. Only 1.6% of these patients developed grades 3-4 proteinuria. All 4 of these patients had a history of hypertension, 2 of these patients had prior chronic kidney disease, and 3 patients had prior viral hepatitis. Elevated proteinuria affected treatment decisions in 2% of patients. Over $130,000 was charged to patients for monitoring of proteinuria.

CONCLUSIONS

These results demonstrate that the development of grades 3-4 proteinuria with bevacizumab is rare and affects treatment decisions in few patients with metastatic solid tumor. Furthermore, routine proteinuria monitoring is associated with high cost and may not be required before each administration.

Imaging angiogenesis of genitourinary tumors

Angiogenesis is a key process in the growth and metastasis of cancer, and genitourinary tumors are no exception. The evolution of angiogenesis as an important target for novel anticancer therapeutics has brought with it new challenges for in vivo imaging. Most imaging techniques quantify physiological parameters, such as blood volume and capillary endothelial permeability. Although CT, PET and ultrasonography have shown promise, MRI is the most common method used to evaluate angiogenesis in clinical trials of genitourinary tumors. Pilot studies of MRI, CT and ultrasonography in patients with renal cancer have produced promising results; reductions in vascular permeability and blood flow have been correlated with progression-free survival. The vascular characteristics of prostate cancer have been evaluated by MRI, and this has been suggested as a means of assessing tumor response to hormone deprivation therapy. Current evidence highlights the potential of angiogenesis imaging in the diagnosis, staging and possibly response monitoring of bladder cancer. In the future, assessment of the angiogenic process at the structural, functional and molecular levels, before, during and after antiangiogenic therapy will undoubtedly be integrated into wider clinical practice.

The role of docetaxel based therapy for prostate cancer in the era of targeted medicine

Docetaxel based chemotherapy has been shown to modestly extend life, relieve pain and improve the quality of life in patients with metastatic castration-resistant prostate cancer. Current trials are attempting to build on the backbone of docetaxel by combining it with novel biological agents. Trials are also investigating the role of docetaxel for earlier stages of prostate cancer. No standard second-line systemic therapy exists and such patients are candidates for clinical trials. The increased understanding of the mechanisms of progressive castration-resistant prostate cancer is being translated into an increasing pipeline of novel therapies.

Emerging therapies in castrate-resistant prostate cancer

PURPOSE OF REVIEW

Prostate cancer continues to represent a major health problem. It represents the most common cancer in US men, with an estimated 186 320 new cases diagnosed in 2008. It is the second leading cause of cancer death in men in the United States. Despite several attempts, the median survival for men with metastatic castrate-resistant prostate cancer is 1-2 years, with improvements in survival seen primarily with docetaxel-based therapies. Treatment options are limited, and there is a clear need for therapies that improve outcome. The purpose of this article is to discuss recent developments in the field of metastatic hormone-refractory prostate cancer, including new cytotoxic agents, antiproliferative agents, immune-based therapies, circulating tumor markers and antiangiogenic agents.

RECENT FINDINGS

During this last year, several promising approaches yielded disappointing results in the phase III setting (GVAX, satraplatin, DN-101); nonetheless, expectations for other agents (abiraterone, zibotentan, Provenge) still remain high.

SUMMARY

These new agents will need to demonstrate survival benefit for approval. Circulating tumor cells have been shown to provide important prognostic information and are anticipated to be incorporated in future clinical decision-making.

Anti-angiogenesis approach to genitourinary cancer treatment

Angiogenesis plays a crucial role in the survival, proliferation, and metastatic potential of several tumors, including genitourinary (GU) cancers. Over the last decade, increasing basic science and clinical research have led to the approval of several angiogenesis inhibitors. GU tumors are unique in its pathogenesis whereby specific pathways, such as involvement of the Von Hippel-Lindau gene in clear cell renal cell cancer and aberrant overexpression of vascular endothelial growth factor in prostatic cancers and transitional cell bladder cancers, allow for potential targeting using angiogenesis inhibitors. This review discusses the biologic pathways as well as the rationale for using angiogenesis inhibitors in renal cell, prostate, and transitional cell bladder cancers. This review also focuses on pivotal trials and emerging data on the use of these inhibitors.