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Elvitegravir Is As Effective As Isentress In Previously Treated People With HIV (IAS 2011)

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Published: Jul 21, 2011 1:47 pm
Elvitegravir Is As Effective As Isentress In Previously Treated People With HIV (IAS 2011)

Results from an ongoing Phase 3 clinical trial show that the the investigational drug elvitegravir, given once daily, is as effective as twice daily Isentress in treatment-experienced adults with HIV.

“Elvitegravir represents a new suitable option for treatment-experienced patients,” said Dr. Jean-Michel Molina from the Hopital Saint Louis in Paris, who presented the results yesterday at the 6th International AIDS Society Conference on HIV Pathogenesis, Treatment, and Prevention (IAS 2011).

“Elvitegravir was overall pretty well tolerated, with a safety profile that was comparable to that of [Isentress],” he added. He noted that the drug is also being investigated in previously untreated patients as a component of the proposed “Quad” (cobicistat/elvitegravir/emtricitabine/tenofovir) combination pill.

Based on the results, Gilead stated in a press release that it plans to apply for U.S. Food and Drug Administration and European Medicines Agency approval of elvitegravir and the “Quad” combination pill in 2012. If approved, the “Quad” pill would be a once daily all-in-one antiretroviral regimen.

Elvitegravir is a potential new integrase inhibitor that is being developed by Gilead Sciences. Currently the only approved integrase inhibitor is Isentress (raltegravir), marketed by U.S. pharmaceutical company Merck. Isentress is approved both as a first-line treatment for HIV and for people who are treatment experienced.

In this Phase 3 study, investigators are comparing the efficacy of elvitegravir and Isentress in HIV-positive adults who had previously taken antiretrovirals from at least two different drug classes. The study includes 702 participants, a majority of whom (63 percent) were resistant to two or more classes of antiretrovirals at the start of the trial.

Half of the participants were randomly assigned to receive elvitegravir once daily and the other half Isentress twice daily. All participants are also taking a boosted protease inhibitor plus a third antiretroviral as part of their combination therapy.

The most common background regimen is Norvir (ritonavir)-boosted Prezista (darunavir) plus Viread (tenofovir). Participants taking Reyataz (atazanavir) or Kaletra (lopinavir/ritonavir) receive a lower dose of elvitegravir, 85 mg daily instead of 150 mg.

Results showed that after 48 weeks, 59 percent of participants taking elvitegravir successfully achieved and maintained undetectable viral loads (amount of HIV in the blood), compared to 58 percent of participants taking Isentress.

Improvements in CD4 (white blood cell) counts were also similar between the two groups: an average increase of 138 cells per microliter in participants taking elvitegravir versus 147 cells per microliter in participants taking Isentress.

Results also showed that 27 percent of participants who failed treatment with elvitegravir developed resistance to integrase inhibitors, versus 21 percent of participants who failed treatment with Isentress. The difference was not large enough to be considered significant.

The most common moderate to severe side effects in both groups were diarrhea, upper respiratory tract infections and bronchitis, back pain, and depression. Discontinuation rates due to side effects were also similar between the two groups: 3 percent of participants in the elvitegravir group and 4 percent in the Isentress group, respectively.

Although the trial was originally scheduled to run for 48 weeks, Gilead announced earlier this year that it would extend the trial to 96 weeks to obtain additional long-term safety and efficacy data on elvitegravir (see related AIDS Beacon news). The study is currently ongoing and is expected to be completed by the end of the year.

For more information, please see the study presentation or the abstract at the IAS 2011 conference website, or the Gilead Sciences press release.

Photo by Lee Nachtigal on Flickr – some rights reserved.
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