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Pilot study of switching enfuvirtide to raltegravir in HIV-1 positive patients well controlled on an enfuvirtide based regimen
W. Towner1, D. Klein2, S. Follansbee3, K. Yu4, H.L. Kerrigan1, M. Horberg5
1Kaiser Permanente, Los Angeles, United States, 2Kaiser Permanente, Hayward, United States, 3Kaiser Permanente, San Francisco, United States, 4Kaiser Permanente, West Los Angeles, United States, 5Kaiser Permanente, Internal Medicine, Santa Clara, United States
Background: Enfuvirtide (ENF) is a highly effective therapy against HIV-1, but is administered subcutaneously and associated with painful injection site reactions. Raltegravir (RAL), an oral integrase inhibitor, represents another treatment option in a novel drug class. The primary objective of this study was to assess the virologic effect of switching ENF to RAL in HIV-1 patients with HIV-1 RNA below the level of quantification (BLQ; defined as < 75 copies/ml by bDNA assay, or < 50 copies/ml by Ultrasensitive PCR) on their current antiretroviral regimen. The secondary objective was to assess quality of life changes after regimen simplification.
Methods: Patients were recruited from Kaiser Permanente, California, USA with plasma HIV-1 RNA BLQ for ³ 6 months on an ENF-containing regimen. ENF was replaced with RAL 400mg orally twice daily, with the antiretroviral background regimen remaining unchanged.
Results: Forty-seven male and four female patients (mean age of 52 years) were enrolled with a mean baseline CD4+ count of 376 cells/mm3, mean number of 14 previous antiretrovirals taken, and mean time on ENF prior to switch of 997 days (264-2457). On the last genotypic analysis prior to ENF, subjects had a mean of 4 NRTI, 1 NNRTI, and 3 primary PI mutations. After 12 weeks of RAL therapy, 50/51 patients remained consistently BLQ. One patient had detectable viremia 4 weeks after starting RAL, but re-suppressed to BLQ without changes in the antiretroviral regimen. At 12 weeks of RAL therapy, the mean CD4+ cell increase was 25 cells/mm3. Standardized patient treatment satisfaction surveys administered at Baseline and Week 12 showed greater satisfaction with RAL compared to ENF. No serious adverse events or significant laboratory abnormalities were noted during RAL therapy.
Conclusions: Among heavily treatment-experienced patients, substituting ENF for RAL in a virologically suppressive regimen was safe and effective at 12 weeks, with improvement in overall patient satisfaction.
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