MONTREAL, Canada--Tomudex (ZD1694), a new direct and specific thymidylate synthase (TS) inhibitor, has been shown to be especially promising for the treatment of patients with advanced colorectal cancer, David Cunningham, MD, said at the 19th International Congress of Chemotherapy.
The new TS inhibitor has antitumor activity at least as effective as the best standard therapy with the prototypic TS inhibitor fluorouracil(Drug information on fluorouracil) in combination with leucovorin, while having significantly fewer life-threatening side effects and producing better palliative results, said Dr. Cunningham, consultant oncologist, Institute for Cancer Research and the Royal Marsden Hospital, Sutton, UK.
These conclusions were reached from a comparative phase III clinical trial in which 439 patients with previously untreated colorectal cancer were randomized to Tomudex, 3.0 mg/m² IV as a single dose once every 3 weeks (222 patients), or fluorouracil, 425 mg/m², and leuco-vorin, 20 mg/m², as an IV bolus daily for 5 days every 4 or 5 weeks.
Five randomized patients did not receive therapy, but all individuals who received trial treatments, whether or not they were eligible or evaluable, were included in the analysis.
With a median follow-up of 5.3 months, the overall response rate was 20% in the Tomudex-treated patients (2% complete response and 18% partial response) vs 13% for patients receiving fluorouracil and leucovorin (2% complete response and 11% partial response), Dr. Cunningham noted.
In addition, 21 patients in the Tomu-dex group and six on fluorouracil and leucovorin had 40% to 50% reductions in measurable lesion size, strongly suggesting that with a longer follow-up, the results would be even more favorable with regard to Tomudex treatment, he said.