354   Short-Cycle Intermittent HAART: A Pilot Study.

M. Dybul*¹, T. W. Chun¹, C. Yoder¹, M. Belson¹, B. Hidalgo¹, K. Hertogs², B. Larder², C. Fox³, J. Orenstein⁴, J. Metcalf¹, R. Davey¹, C. Hallahan¹, R. Dewar⁵, M. Baseler⁵, and A. S. Fauci¹.
¹NIAID/NIH, Bethesda, MD;²VIRCO, Belgium and UK;³Molecular Histology Lab., Rockville, MD;⁴George Washington Univ., Washington, DC; and⁵SAIC, Frederick, MD.

Background:Continuous HAART, although effective in many patients, can be toxic and prohibitive in cost, and adherence is difficult. By decreasing the time during which patients receive medications, intermittent HAART could reduce cost and toxicity while potentially enhancing adherence.

Methods:Twelve HIV-infected individuals with plasma HIV RNA levels of <500 copies/ml for >6 months and <50 copies/ml × 2 at screening and a CD4⁺T cell count >300 cell/mm³(mean 940, range 428-1331) were assigned to receive cycles of d4T, 3TC and IND/RIT for 7 days followed by 7 days off drugs for 24 months or until failure. Failure was defined as plasma HIV RNA >500 copies/ml or a CD4⁺T cell count decline >25% of baseline × 2 as determined after the off-drug periods.

Results:At 24 weeks, 3 of 3 patients continue with plasma HIV RNA <50 copies/ml. 2 of 3 patients had infrequent values of <300 copies/ml during the first 8 weeks. There has been no significant change in CD4⁺or CD8⁺T cell counts or in CD8⁺CD38⁺T cell percent. One patient had plasma HIV RNA<50 copies/ml at 12 weeks. A 5th patient did not adhere to the study regimen. He resumed continuous HAART on week 12 after plasma HIV RNA reached a level of 20,142 copies/ml after 3 weeks off HAART. Data will be available for presentation from an additional 4 months follow-up as well as on lymph node and CD4⁺T cell reservoirs and genotype and phenotype drug susceptibility testing. Data on an additional 7 patients recently entered into the study will also be presented.

Conclusions:These data suggest that following reduction of plasma HIV RNA to <50 copies/ml, 50% less HAART administered in short, intermittent cycles may maintain CD4⁺T cell counts and suppression of plasma HIV RNA. Intermittent HAART may be an important therapeutic option when it is not possible to sustain continuous therapy.