A review of tumour lysis syndrome with targeted therapies and the role of rasburicase

WHAT IS KNOWN AND OBJECTIVE

Tumour lysis syndrome (TLS) is an oncologic emergency with potentially devastating consequences classically associated with cytotoxic chemotherapy. In recent years, molecularly targeted drugs have assumed an increasingly important role in cancer therapeutics. The possibility of TLS is often overlooked in this setting. Rasburicase, a recombinant urate oxidase, is remarkably effective in treating hyperuricemia, thought to be central to the pathogenesis of renal injury in TLS. Our objective is to review the literature on TLS especially as it pertains to targeted therapies and summarize current knowledge and provide future directions regarding the role of rasburicase in the management of TLS.

METHODS

A MEDLINE search was conducted using PubMed and the keyphrase 'tumor lysis syndrome' to identify articles describing TLS with a broad range of novel anti-cancer agents. Meeting abstracts were also reviewed. Additionally, the biomedical literature was searched using the keyword 'rasburicase'.

RESULTS AND DISCUSSION

Tumour lysis syndrome has been described with nearly every class of 'targeted therapy'. This is not surprising as any drug causing death of cancer cells by any mechanism may lead to TLS in the appropriate setting. Although there is a wealth of evidence suggesting that rasburicase is extremely effective in correcting hyperuricemia, prospective trials showing that it improves hard outcomes such as acute renal failure, need for dialysis and mortality are lacking. Furthermore, much lower doses and durations of therapy than approved appear to be effective in controlling hyperuricemia, potentially leading to enormous cost savings.

WHAT IS NEW AND CONCLUSION

Any effective cancer therapy can lead to TLS. Physicians should consider the risk of TLS on a case-by-case basis and determine appropriate prophylaxis. The role of rasburicase continues to evolve. Randomized controlled trials evaluating clinically relevant outcomes are needed.

Perfusion MRI in the early clinical development of antivascular drugs: decorations or decision making tools?

INTRODUCTION

Classically, the first step in the clinical development of drugs in oncology involves assessments of dose limiting toxicity (DLT) and maximum tolerated dose (MTD). New paradigms are needed for antiangiogenic drugs and vascular disrupting agents (VDAs) as they are active at doses well below the MTD and as single agents their use might not translate into anti-tumour efficacy. MRI is able to assess the antivascular effects of antivascular drugs via changes in functional kinetic parameters; however, the usefulness of MRI in decision making has been questioned by many.

OBJECTIVES

Our aim is to review the experience of using dynamic contrast-enhanced MRI (DCE-MRI) in early clinical development of vascular directed anticancer therapies over the last decade. Thirty-nine phase I and II studies including data on more than 700 patients have been published as abstracts and/or papers, documenting DCE-MRI changes after the administration of antiangiogenic drugs and VDAs.

DISCUSSION

Perfusion MRI is helpful in assessing whether mechanistic goals are achieved, in assisting dose selection for phase II studies, in selecting subpopulations enriched for response and in predicting patient benefit. Imaging tools are increasingly available. Future challenges for imaging include correlation with clinical measures of efficacy and determining relationships with blood and serum biomarkers.