DIDEOXYCYTIDINE FOR AIDS IS IN PHASE I STUDY

DIDEOXYCYTIDINE FOR AIDS IS IN PHASE I STUDY at the National Institutes of Health (NIH) Clinical Center, Robert Yarchoan, a scientist with the National Cancer Institute's clinical oncology program, reported at a Nov. 21 NIH conference on progress in cancer treatment. Yarchoan said the Phase I clinical trial began in mid-November. It is expected to run for approximately six months. Dideoxycytidine, an NIH investigational compound, is similar to Burroughs Wellcome's AZT (azidothymidine), Yarchoan said. He explained that they both belong to a group of compounds believed to be inhibitors of reverse transcriptase, an enzyme crucial for the reproduction of the AIDS retrovirus. Yarchoan said that "at a very low dose. . . [Dideoxycytidine] completely blocks replication" of the virus. He maintained that the compound has "10 times" the potency of AZT in vitro. HHS announced in October that it is seeking an industry sponsor to collaborate in the development of dideoxycytidine for the treatment of AIDS ("The Pink Sheet" Oct. 20, In Brief). Eligibility criteria for the dideoxycytidine trial, according to Yarchoan, are similar to those followed in the Phase I AZT trial. "All the patients have to have less than 350 T4 cells, reasonably good bone marrow function, and [must] be basically, at least in the short term, in . . . good shape [with] good liver function [and] no active opportunistic infections," Yarchoan said. Patients with AIDS-related complex who have symptoms of oral candidiasis and significant weight loss are also being considered for the study, he said. Yarchoan indicated that placebos would not be used in Phase II NIH trials with dideoxycytidine because of "ethical" concerns. Burroughs Wellcome's Phase II placebo-controlled trial with AZT was halted in September when preliminary results indicated the drug was prolonging patients' lives ("The Pink Sheet" Sept. 22, p. 3). Updating the conference on AZT trials, Yarchoan said that a clinical trial exploring the effect of AZT in children with AIDS should begin "in a week or so." He noted that NCI is also planning to study the synergistic action of AZT and Burroughs Wellcome's anti-herpes drug Zovirax (acyclovir).