Stopping treatment when you have a low but detectable level of HIV may result in less serious viral rebound than stopping when you have undetectable viral load, according to the latest study from structured treatment interruption pioneer Franco Lori. His findings may also offer further evidence of a key role for hydroxyurea in managing structured treatment interruptions.
Reporting at the Seventh Conference on Retroviruses on Monday, Dr Lori presented results of a study which matched eight individuals on HAART with eight individuals taking ddI and hydroxyurea only. Whilst 6/8 of the HAART group had viral load below 50 copies at baseline, the average viral load in the hydroxyurea group was just above 500 copies, with some individuals above 1500 copies.
When the two groups stopped treatment, 5/8 HAART patients experienced viral load rebound of greater than 2 log to above 10,000 copies, but the hydroxyurea group only experienced a slight increase in viral load (to a an average level of 4,000 copies). Viral load then began to decline back towards baseline after four weeks off treatment, and none of the hydroxyurea group resumed treatment before the eight week interruption period was over.
There was also a marked difference in CD4 responses during the off-treatment period. Whilst the HAART group experienced an average CD4 decline of nearly 200 cells during the eight week break, the average CD4 count of the hydroxyurea group remained stable.
When treatment was resumed, viral load fell in both groups, but remained detectable in the hydroxyurea group.
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Reference
Lori F et al. Control of viremia after structured treatment interruptions. Abstract 352, Seventh Conference on Retroviruses, San Francisco, 2000.