13th International AIDS Conference Durban, South Africa - July 9-July 14, 2000

Int Conf AIDS 2000 Jul 9-14; 13:19 (abstract no.. LbOr12)

Dybul M, Yoder C, Belson M, Hallahan C, Hertogs K, Larder B, Metcalf J, Davey R, Chun TW, Polis M, Dimitrov D, Fauci A
Laboratory of Immunoregulation, NIAID, NIH, Bethesda, MD 20892. Fax: 301-402-0070, E-mail: mdybul@nih.gov.

BACKGROUND: Continuous highly active anti-retroviral therapy (HAART), although effective in many patients, can be toxic and prohibitive in cost for many countries and adherence is difficult. By decreasing the time patients receive medications, intermittent HAART could reduce cost and toxicity while enhancing adherence.

METHODS: 7 HIV-infected individuals with plasma HIV RNA <500 copies/ml > 6 months and <50 copies/ml x 3 prior to enrollment, and CD4+ T-cell counts > 300 cells/mm³ (mean 997, range 428-1331) were randomized to receive d4T, 3TC and RIT/IND for 7 days followed by 7 days off therapy (4 patients) or for 2 days followed by 5 days off therapy (3 patients) for 6 months. Failure was defined as plasma HIV RNA >500 copies/ml or a CD4+ T-cell count decline >25% x 2 after the off-drug periods.

RESULTS: At 6-10 weeks 4/4 patients receiving HAART 7/14 days and 2/3 patients receiving HAART 2/7 days maintained plasma HIV levels < 500 copies/ml when measured after the off-drug period. The patient who failed had plasma HIV RNA levels of 1074 and 1235 copies/ml at weeks 5 and 6 but returned to < 50 copies/ml 2 weeks after resuming continuous therapy. No individuals experienced a significant change in CD4+ or CD8+ T-cell counts or percent of cells CD8+CD38+ when measured after the off drug period. Genotype and phenotype drug susceptibility assays and 4 additional weeks of data will be available for presentation.

CONCLUSION: 6/7 patients who received 50% (7/14 days) or 30 % (2/7 days) of the medication required for continuous HAART suppress plasma HIV RNA <500 copies/ml and maintain CD4+ T-cell counts for 6-10 weeks when determinations are made after the off drug period. These data suggest that following reduction of plasma HIV RNA to < 50 copies/ml, short cycle intermittent HAART may maintain suppression of HIV plasma viremia and CD4+ T-cell counts. Intermittent HAART may be an important treatment option in countries where continuous HAART is financially untenable.

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