DDC/AZT ALTERNATING REGIMEN STUDY: PRELIMINARY RESULTS

DDC/AZT ALTERNATING REGIMEN STUDY: PRELIMINARY RESULTS show that alternating therapy with AZT (zidovudine) and DDC (dideoxycytidine) may be more effective and less toxic than therapy with either of the nucleoside analogs alone, Brown University researcher Gail Skowron, MD, reported at the Sixth International Conference on AIDS. Skowron described preliminary results from an ongoing Phase II study evaluating alternating weekly and monthly regimens of AZT against intermittent use of either drug alone and continuous use of AZT. Early results from the 100-plus patient study, which is being conducted at 12 AIDS Clinical Trial Units, show that both weekly and monthly alternating regimens "resulted in a reduction in AZT and DDC-related side effects," Skowron said. The predominant side effect of AZT is bone marrow suppression, while the central side effect of DDC is peripheral neuropathy. The "alternating regimens of DDC and AZT also enhanced CD4 cell count...and suppressed p24 antigen levels," Skowron said. The preliminary data indicates that "alternating regimens that contain the higher dose of DDC [.03 mg/kg every four hours] may show greater ability to sustain rises in CD4 cell counts and suppress p24 antigen," she reported. The "high dose DDC alternating monthly regimens with AZT may be better tolerated" than the weekly alternating regimens, Skowron added. Skowron cautioned, however, that results from the trial are preliminary and that the number of patients (approximately 16 in each of the seven treatment arms) are small. "This is a small study; we are sharing our data to show you what the trends are, but not to show statistical difference," she said. "I would not try to say [from these data] that any of these regimens are better than continuous AZT...I believe that this study is going to help us to design larger studies that should involve a greater number of patients comparing what looks to be a good combination of drugs." As expected, the AIDS conference has not been a forum for news of any "breakthrough" developments in AIDS therapy. For the near term, many of the researchers appear to be placing hope for improved therapy on combinations of existing agents, such as AZT and DDC. In addition to enhanced safety and efficacy, Wellcome Research Laboratory researcher Brendan Larder, MD, suggested in his presentation to the conference that a "cocktail approach" may also improve resistance problems currently being seen with AZT. Among AZT data presented at the conference, Margaret Fischl, MD, University of Miami Medical School, showed an analysis of two major AZT trials, ACTG 019 and 016, indicating that therapy with the agent may be most useful if done very early in HIV-infected individuals. Fischl's analysis also showed that there may be particular subgroups of HIV-infected patients that will benefit most from early therapy. Updated results on a previously reported trial of AZT 300 mg combined with acyclovir were also presented at the meeting. University of Washington researcher Robert Coombs, MD, said the updated results show comparable efficacy of AZT 300 mg daily and 600 mg daily, which was not enhanced with the addition of acyclovir. Based on the results, Coombs said that further clinicals on low dose AZT "are clearly warranted."