MGBG: teaching an old drug new tricks.

Methylglyoxalbisguanylhydrazone or MGBG is an agent with a unique mechanism of action (polyamine biosynthesis inhibition). MGBG was discarded in the 1960s because of severe mucositis and other toxicities. New clinical trials in the late 1970s and early 1980s utilized weekly administration and indicated MGBG had significant activity in patients with chemotherapy-refractory Hodgkin's and non-Hodgkin's lymphoma. In addition, some activity was noted in patients with head and neck, prostate, esophageal, and endometrial cancer. The toxicities on the weekly schedule were minimal and no myelosuppression was noted. Based on MGBG's spectrum of antitumor activity and its activity in severely debilitated patients, we hypothesize that MGBG may have greater antitumor activity in patients who are malnourished (possibly based on polyamine depletion). MGBG is a good candidate for treatment of AIDS-associated NHL because it has proven activity in patients with NHL which is not associated with AIDS, crosses the blood brain barrier, is non-myelosuppressive, and appears to work in patients with inanition (no polyamines available to reverse MGBG's antitumor effects). Clinical trials are ongoing to determine the activity of MGBG in AIDS-associated NHL and other diseases. Based on encouraging initial results, it appears MGBG may become part of our therapeutic armamentarium.