Knowledge about how anticancer drugs work has stimulated the search for drugs that counteract toxicities (protectors) or enhance their effectiveness (potentiators).
• Protectors include the thiol amifostine, other thiols including glutathione, dexrazoxane and the
colony-stimulating factors.
• Potentiators—also named modulators—include buthionine sulfoximine (BSO), L-leucovorin, dipyridamole and
drugs such as cyclosporin and its derivatives that reverse multi-drug resistance .
Amifostine (Ethyol, WR2721) is under study by US Bioscience as a protector against the bone marrow toxicity of cisplatin and cyclophosphamide and possibly as a protector against some other toxic effects of cisplatin, such as those on the nerves and kidney. Antitumor effects appear to be unchanged. Vomiting and low blood pressure are its principal side effects.
Dexrazoxane (ICRF-187, ADR 529) protects against the toxic effects on the heart of anthracyclines such as doxorubicin . The FDA withheld approval, however, because of doubts about the slight protection of antitumor effects as well. The drug may play a role in preventing cardiotoxicity in children, the effects of which show up later in adolescence. Its use also has to be considered in adjuvant programs that include doxorubicin where a long life expectancy might be affected by cardiac events.
