October 27, 2001
Dr. Rosenberg discussed structured treatment interruptions (STIs) and presented the data from his study of STI after acute infection. Because he has presented this study before at other conferences, there was not a lot of new information.
In his study, 14 subjects with acute HIV infection (captured even before full seroconversion) underwent repeated cycles of therapy interruption. Patients had full suppression of viremia for at least eight months, and stopped all antiretrovirals at the same time. Treatment was restarted in patients whose plasma viral load level was greater than 5,000 copies/mL for three weeks or was greater than 50,000 copies/mL on any occasion. Of the 14 subjects, persistent control of viremia was seen in seven subjects, with control achieved in four people after a single treatment cessation, two after a second treatment interruption, and one person after a third interruption. The time to restart therapy increased progressively in most patients but all patients experienced some return of viremia. They had an increase in the cytotoxic T-lymphocyte (CTL) response as measured by several assays.
This was a very important study because it proves the concept that treatment during acute infection can control viral replication in a significant proportion of patients when it is discontinued, and it can justify, to a certain degree, the current recommendation for treating (in a clinical trial) all these patients.
Unfortunately, the same cannot be said for chronic infections. Dr. Rosenberg presented the data from the Swiss-Spanish Intermittent Treatment Trial (SSITT). In this study, 128 subjects who were on HAART and had an undetectable viral load underwent four interruptions, each comprising two weeks off and eight weeks on therapy. At 40 weeks, medications were discontinued until viral load rose above 5,000 copies/mL. Only one in every five patients was able to maintain this low viral load. So, in chronic infection, repeated treatment interruptions do not seem to substantially help.
The talk was a summary of these two well-known studies, and we were all expecting more new information. I guess we will have to wait until the conferences in the Spring.
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