Faculty Bibliography

Administration of cis-dichlorodiammineplatinum(II) may be associated with a number of serious side effects, including nephrotoxicity, gastroeintestinal side effects (nausea, vomiting, and diarrhea), myelosuppression, and occasional transient elevations in liver function tests. In addition, ototoxicity (tinnitus and hearing loss), anaphylactic reactions, peripheral neuropathies, and hypomagnesemia with resulting tetany may also be encountered. The toxic potential of this new agent necessitates careful clinical monitoring during treatment.

The chemotherapeutic effects of 6-diazo-5-oxo-L-norleucine (DON) and N-[N-gamma-glutamyl-6-diazo-5-oxo-norleucinyl]6-diazo-5-oxo-norleucine (azotomycin) were evaluated in a spectrum of transplantable experimental tumor systems including xenografts of human tumors in athymic mice. Both drugs displayed remarkable activity against the murine leukemia L1210 and P388, the Colon Tumors C26 and C38 and the CD8F1 mammary tumor. No significant activity was observed against Lewis lung carcinoma, B16 carcinoma, B16 melanoma, and intracranial ependymoblastoma. DON and azotomycin also exhibited striking inhibitory effects on the growth of s.c. human tumor (MX-1 mammary, LX-1 lung and CX-1 and CX-2 colon) xenografts in athymic mice. With the exception of one colon xenograft (CX-1), all tumor lines were markedly responsive to both drugs. Tumor regressions below the initial tumor sizes of 100 to 300 mg, albeit temporary, were brought about by one course of treatment every 4 days for 3 doses (at optimal dose) with either drug. Although these drugs have been tested previously in the clinic and have shown only limited therapeutic effectiveness, they seem to worthy of a second and closer look in light of the recent laboratory results.

Immune reactivity of patients with early or advanced breast cancer, compared with healthy controls, has been measured using in vivo and in vitro tests. The results of our study show that impairment of cellular responsiveness occurred in women with advanced disease.

Previous retrospective analyses have suggested a very positive correlation in toxic doses of antineoplastic agents between mice and humans. Additional toxicological information has now been accumulated and reveals a noticeable variability in the existing data base. Nevertheless, it is likely that mouse toxicological studies will become a principal determinant for estimating initial doses to be used in humans. Recognition of the factors responsible for differences in determinations of toxic dose levels in mice will enhance the proper utilization of this approach.

A review of the clinical data on azaserine, DON, and azotomycin reveals that these agents have limited but definite antitumor activity. All three drugs are analogs of L-glutamine and contain a diazo group. They have been studied as single agents in a wide variety of human malignancies and have also been included in trials using combination chemotherapy. Most of these studies were performed early in the history of clinical trials and, therefore, the method of reporting results and the evaluation criteria were quite different from those in use today. A renewed interest in these agents has been triggered by the remarkable activity of DON and azotomycin against human tumor lines implanted into nude mice. On the basis of this activity and the clinical data we have compiled, we feel that new clinical trials with these agents are warranted.