Eniluracil plus 5-fluorouracil and leucovorin: treatment for metastatic breast cancer patients in whom capecitabine treatment rapidly failed.

Background: As part of a comparative phase II study of eniluracil/5-FU/Lv vs. capecitabine (Xeloda), an oral 5-FU prodrug for MBC, patients with rapid PD during capecitabine therapy crossed over to take eniluracil/5-FU/Lv.

Patients And Methods: Ten evaluable patients with radiologically documented PD within 70 days of capecitabine treatment were treated with a modified oral weekly eniluracil/5-FU/Lv regimen.

Phase I clinical trial to evaluate the safety, tolerability, and pharmacokinetics of high-dose intravenous ascorbic acid in patients with advanced cancer.

Purpose: This phase I clinical trial evaluated the safety, tolerability, and pharmacokinetics of high-dose intravenous (i.v.) ascorbic acid as a monotherapy in patients with advanced solid tumors refractory to standard therapy.

A possible cause and remedy for the clinical failure of 5-fluorouracil plus eniluracil.

Background: Eniluracil is a potent inactivator of dihydropyrimidine dehydrogenase (uracil reductase), the enzyme that rapidly catabolizes 5-fluorouracil (5-FU). Although eniluracil in combination with 5-FU was promising in phase I and II studies, in 2 multicenter phase III colorectal cancer studies, eniluracil dosed in a 10-to-1 ratio to 5-FU produced less antitumor benefit than the standard regimen of 5-FU/leucovorin without eniluracil. The current study tested whether the high eniluracil doses caused the clinical failure.

Superoxide radical production by allopurinol and xanthine oxidase.

Oxypurinol, an inhibitor of xanthine oxidase (XO), is being studied to block XO-catalyzed superoxide radical formation and thereby treat and protect failing heart tissue. Allopurinol, a prodrug that is converted to oxypurinol by xanthine oxidase, is also being studied for similar purposes. Because allopurinol, itself, may be generating superoxide radicals, we currently studied the reaction of allopurinol with xanthine oxidase and confirmed that allopurinol does produce superoxide radicals during its conversion to oxypurinol.