08/07/08

Switching from Enfuvirtide to Raltegravir: Pros and Cons Reported at IAC

At the 17th International AIDS Conference in Mexico City Tuesday, Towner et al, Talbot et al, and Khanlou et al presented posters that addressed the issue of switching patients from enfuvirtide (ENF) to raltegravir (RAL) for quality of life issues.

Towner, et. al (TUPE0115) prospectively evaluated this strategy in 51 patients who were virologically controlled for at least six months on an ENF containing regimen. At twelve weeks after switch, all were virologically suppressed, though one subject had an increase in viral load at week four, but resuppressed with no change in regimen. CD4⁺ counts increased 25 cells/mm3, and satisfaction surveys showed greater satisfaction with RAL compared to ENF. There were no serious adverse events or significant lab abnormalities seen.

Talbot, et al (TUPE0112) reported on a retrospective look at 18 patients who were virologically suppressed on an ENF regimen, and also found no virologic failures and no adverse events, though no CD4⁺ cell count increase was reported.

Khanlou, et al (TUPE0087) described three cases of hepatic cytolysis in patients who were switched to RAL from ENF, and who were also treated with tipranavir/ritonavir. Liver function tests increased up to 10X nl for AST and up to 40X nl for ALT, 2 to 4 weeks after switch to RAL. All three cases had been on stable tipranavir/ritonavir, had negative repeat viral hepatitis studies, and were not on hepatotoxic drugs.

TPV trough levels were available for one patient pre- and post-switch: 46 ng/mL prior to switch and increased to 108 ng/mL after switch to RAL (therapeutic range 10-39 ng/mL). The authors cautioned that there may be a TPV-RAL interaction, and that the combination should be used with caution until further PK studies are available.


References:

Towner W, et. al. TUPE0115: pilot study of switching enfuvirtide to raltegravir in HIV-1 positive patients well controlled on an enfuvirtide based regimen. Presented at: 17th International AIDS Conference; August 3-8, 2008; Mexico City, Mexico. Abstract TUPE0115.

Talbot, et al. TUPE0112: retrospective analysis of a switch from enfuvirtide to raltegravir in patients with undetectable viral load: efficacy and safety at 12 weeks in a Montreal cohort. Presented at: 17th International AIDS Conference; August 3-8, 2008; Mexico City, Mexico. Abstract TUPE0112.

Khanlou, et al. TUPE0087: development of hepatic cytolysis after switching from enfuvirtide to raltegravir in virologically suppressed patients treated with tipranavir/ritonavir Presented at: 17th International AIDS Conference; August 3-8, 2008; Mexico City, Mexico. Abstract TUPE0087.

Source: Reporting from Mexico City for PRN News: Anita Radix, MD, MPH and Rona Vail, MD