Advances in Treating CMV
Long-awaited results from a study of treating CMV (cytomegalovirus) retinitis show that a new formulation of oral (by mouth) ganciclovir, known as valganciclovir, is as effective as the intravenous (IV, injection into the vein) version of the drug. This is the first time that an oral drug for treating CMV has been shown to be as effective as the IV version.
The use of valganciclovir results in similar drug levels in blood as those produced by the IV form. This is a major improvement over the currently approved oral form of ganciclovir (Cytovene), which is hampered by poor absorption into the bloodstream and consequently weak control of CMV. The standard version of oral ganciclovir is only approved for maintenance therapy (to prevent CMV from recurring in people who have already been treated for the disease) and for preventing initial CMV disease (though the data for prevention use are weak and conflicting). It is not approved for treating the active disease.
Study ResultsThe study included 160 people with active CMV disease and CD4+ cell counts averaging around 25. About 25% of the volunteers were not on highly active anti-HIV therapy when they started. Participants received either 900mg of valganciclovir twice a day for three weeks followed by one week of 900mg daily or 5mg/kg of IV ganciclovir twice a day for three weeks followed by one week of 5mg/kg daily.
There was no difference in rates of CMV disease progression between the two groups at the end of four weeks. About 10% in each group continued to have progressive CMV disease, and about 65% in each group responded well in controlling the virus. There are no data yet to show whether valganciclovir is equivalent to the IV formulation in the time to relapse (when CMV recurs).
Future StudyA large study is planned to look at the effectiveness of preventive CMV treatment with valganciclovir. It will study the drug's use in people without CMV disease who have measurable CMV levels in their blood (called CMV PCR-positive). Several studies have shown that CMV PCR-positive people are more likely to develop CMV disease than CMV PCR-negative people.
If this strategy works, it will mean that only people at risk for developing CMV disease would need to use preventive therapy. This is unlike the current standard in which people consider CMV prevention therapy based solely on their CD4+ cell counts. This will reduce the cost of HIV care as well as spare people the risks of side effects of potentially unnecessary therapy.
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