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10/07/2013

Can Switching Antiretroviral Agents Reduce Hyperlipidemia in HIV? A Report from ID Week 2013


Hyperlipidemia is one of the most common metabolic disturbances occurring in HIV-infected individuals on antiretroviral (ARV) therapy. It may result from direct effects of certain ARVs or what has been termed “return to health”. In reality, control of HIV infection with ARV therapy often returns the patient to same unhealthy lipid levels that would likely have been present in the absence of HIV infection, based on diet, lifestyle and genetics. Management of hyperlipidemia in HIV generally follows the same principles used in the general population, except drug-drug interactions between ARVs and lipid-lowering agents may limit efficacy, increase toxicity and reduce treatment options. Another difference is that patients receiving ARVs known to cause hyperlipidemia may sometimes be managed by switching to alternate ARVs.

The SPIRIT study enrolled 476 participants with stable virologic control on an ART regimen anchored by a ritonavir-boosted protease inhibitor (PI) and randomized them to switch to the fixed-dose combination (FDC) of tenofovir DF/emtricitabine and rilpivirine (TDF/FTC/RIL), or remain on the baseline regimen. The primary outcome, reported previously, showed that switching was virologically non-inferior to continuing the PI-containing regimen at 24 weeks. At ID Week 2013, Tebas et al. presented the effects of switching on lipid profiles. At baseline, 41% of participants were on lopinavir or fosamprenavir, older PIs that have been associated with significant hyperlipidemia. Most of the rest were on atazanavir or darunavir, thought to cause less hyperlipidemia. Most were already taking tenofovir at baseline, although 13% were on abacavir, which causes somewhat more hyperlipidemia than tenofovir. After 24 weeks, the mean changes from baseline (mg/dL) in total cholesterol (TC), LDL, HDL and triglycerides (TG) for the switch and PI arms were were -25 and -1, -16 and 0, -4 and -1 and -54 and +3, respectively. With these changes, the proportion of participants in the switch group achieving a TC <200 increased from 59% to 84%, an LDL <100 from 29% to 45% and TG <150 from 59% to 84%, while the PI group had little change. After week 24, participants in the PI arm were switched to the rilpivirine-based FDC. Similar reductions were seen at study week 48 in the delayed switch group while the changes seen in the group originally randomized to switch to the FDC were sustained. No data on the distribution of baseline regimens in the two treatment arms or on use of lipid lowering agents was presented, although Dr. Tebas commented during Q & A that use was low and probably could not explain much of the observed changes. This study suggests patients switching from boosted PI regimens to the TDF/FTC/RIL FDC can gain moderate benefit to plasma lipids, potentially avoiding addition of lipid-lowering agents or allowing use of lower doses which may limit cost or potential for toxicity. Because the regimens used at baseline had varying potential to cause hyperlipidemia, a subgroup analysis according to baseline PI-use would help validate the findings.

Reference:
Tebas P, Palella F, Ruane P et al. SPIRIT: Simplification to Rilpivirine/Emtricitabine/Tenofovir DF Single-Tablet Regimen from Boosted Protease Inhibitor Maintains HIV-1 Suppression and Improves Fasting Lipids at Week 48. ID Week 2013, San Francisco, CA, October 2-6, 2013, abstract 672.


Source: Reporting from San Francisco for PRN News: David H Shepp, MD