A risk-benefit assessment of amifostine in cytoprotection

Recent advances in chemotherapy have focused on the benefit of high dose regimens, increasing the dose intensity of conventional chemotherapy and using intensified chemotherapy with or without autologous bone marrow rescue. Dose intensity usually increases objective response rates of antineoplastic drugs and might, in some circumstances, improves survival. However, unacceptable acute and/or cumulative toxicity often impairs the proper management of patients, leading to dose reduction or treatment delay, thus reducing the efficacy and potentially the quality of life of patients. Therefore, considerable efforts have been made to manage, to prevent, and to delay many acute and cumulative treatment-related toxicities. Amifostine (WR-2721 ) is a multiorgan cytoprotector which has demonstrated cytoprotective effects, in vitro and in vivo, against the most common cytotoxic drug-related toxicities and against radiation-induced adverse effects in healthy tissues. In vitro and in vivo, cytoprotection was observed in several organs including kidney, haematopoietic stem cells, myocardial cells, neural cells, and mucosa, without detectable protection of malignant cells. In addition, in preclinical studies, amifostine appeared to be able to reduce the risk of radiation-induced secondary neoplasms. Phase I studies showed that nausea/vomiting and hypotension are the dose-limiting toxicities of amifostine and these may be controlled by reducing the duration of injection of amifostine. Phase II and randomised studies have confirmed the efficacy of amifostine in protecting against radiotherapy-induced mucositis, cisplatin-induced nephrotoxicity, cyclophosphamide-induced neutropenia and carboplatin-induced thrombocytopenia. Importantly, the cytoprotection of healthy tissues occurred without any significant deleterious effect on response rate, time to progression, and survival of patients receiving amifostine. However, in addition to the potential quality of life benefit, the most important question of whether the use of a cytoprotective agent might translate into the possibility of maintaining the dose intensity of anticancer therapies has still to be answered. The real benefit of amifostine in the overall management of patients with cancer requires additional studies to determine whether this chemoprotective approach can be of benefit to patients by increasing response rate, time to progression, and long term survival in patients receiving the more recent combination therapies involving new drugs such as the taxanes and oxaliplatin.