Combination therapy using polyamine synthesis inhibitor alpha-difluoromethylornithine and adriamycin in treatment of rats carrying the Dunning R3327 MAT-LyLu prostatic adenocarcinoma.

Prostate cells of human and rat origin produce polyamines in high content, whose apparent functions relate to cellular proliferation and secretory activities. Formation is dependent on the enzyme ornithine decarboxylase (ODC) which is irreversibly inhibited by alpha-difluoromethylornithine (DFMO). It has been postulated that pretreatment with DFMO may render cells more susceptible to subsequent chemotherapy. Copenhagen X Fischer F1 rats bearing the Dunning R3327 MAT-LyLu prostatic adenocarcinoma were given DFMO or adriamycin (ADR), alone or in combination. Those receiving DFMO were continuously provided the drug ad libitum, in water (2.5%), for the duration of the experiment, beginning 2 days prior to ADR administration. At intervals, tumor sizes were measured, animal survivals noted and comparisons made to nontreated, tumor-bearing controls. The results indicate that ADR alone or in combination with DFMO significantly reduced tumor progression, but that only combination therapy significantly prolonged survivals. Decreased tumor progression produced by DFMO alone was not statistically significant. Differences produced with combined use were additive and suggest that DFMO may augment ADR chemotherapy.