A case of melphalan sustained accumulation in an 80-year old patient

Considering renal risk while managing cancer

Renal function is an important consideration in the management of patients with advanced cancer. There is a reciprocal relationship between cancer and the kidney: chronic kidney disease can increase the risk of developing cancer, and patients with cancer often experience renal impairment owing to age, disease-related factors and nephrotoxic treatments. As therapies for cancer continue to improve, patients are living longer with their disease, potentially extending the period over which they are susceptible to long-term complications. Furthermore, secondary symptoms, such as bone metastases or infections, may arise that will require treatment. Certain treatments, including chemotherapy, antibiotics and some bone-targeted agents, are nephrotoxic and may require dose modifications or interruptions to prevent renal injury. Nephrologists should play a key role in the identification and management of renal impairment in patients with cancer. Furthermore, they may be able to provide advice on protecting the kidneys in instances where nephrotoxic agents require dose reductions or interruptions, and when novel therapies or combinations are used. Collaboration between oncologists and nephrologists is important to optimal patient management. This article reviews the relationship between cancer and kidney disease and examines the treatments that may impact kidney function. Considerations for monitoring renal function are also discussed.

Development of an assay for cellular efflux of pharmaceutically active agents and its relevance to understanding drug interactions

Drug interactions may dictate the failure or success of a treatment. Patients undergoing hematopoietic stem cell transplantation (HSCT) are exposed to various types of drugs, and understanding how these drugs interact is of the utmost importance. The pharmacokinetics of busulfan, melphalan, and cyclophosphamide, drugs commonly used for HSCT, are known to be affected by a variety of other drugs with differing molecular structures. We hypothesized that these structurally unrelated drugs affect the transport of DNA-alkylating agents. To test this hypothesis, we developed a flow cytometry assay that used 5-carboxyfluorescein diacetate acetoxymethyl ester, which is cleaved by nonspecific intracellular esterases to 5-carboxyfluorescein (5-CF), a fluorescent ligand for the drug transporter MRP1. A decreased 5-CF efflux in the presence of a test compound suggests competitive inhibition. We demonstrated that chlorambucil, 4-hydroperoxycyclophosphamide, ketoconazole, ethacrynic acid, everolimus, and sirolimus strongly inhibited 5-CF efflux in lymphoma and leukemia cell lines. The efflux of these drugs partially depends on the glutathione (GSH) level, and their cytotoxicity is synergistic with inhibited GSH synthesis. This is consistent with the hypothesis that their GSH-conjugated products are ligands of a common cellular drug transporter. Our results may explain clinical observations on the effects of various drugs on the pharmacokinetics and pharmacodynamics of alkylating agents, and the assay may be used to deduce interaction mechanisms of drugs transported by a common system.