A review of the use of chemoprotectants in cancer chemotherapy.

Dose-limiting toxicity secondary to antineoplastic chemotherapy is principally due to the inability of the drugs to differentiate between normal and malignant cells. This results in normal tissue damage, as well as the desired antitumour effect. Toxicity may be acute, as in cisplatin-induced nephrotoxicity or alkylating agent myelotoxicity and haemorrhagic cystitis, or cumulative, as in anthracycline-related cardiac toxicity or cisplatin neurotoxicity. The consequences of this often include serious adverse effects and the inability to deliver adequate dose-intensive therapy against the cancer. Chemoprotective agents have been developed to provide site-specific protection against normal tissue toxicity, without compromising antitumour activity. Several chemoprotective compounds have recently been developed, including dexrazoxane (ICRF-187), amifostine (ethiofos: WR-2721), mesna and ORG-2766. Initial results confirm their promise as selective protective agents, although further randomised trials are required to identify their optimal role when used alone or in combination with other toxicity modifiers, including haematopoietic growth factors, with the ultimate aim being adequate dose escalation of chemotherapy to overcome tumour resistance.