Clinical

Lexiva less likely than nelfinavir to induce resistance mutations in HIV

Last Updated: 2003-10-31 14:45:04 -0400 (Reuters Health)

By Karla Gale

NEW YORK (Reuters Health) - Phase III study findings for GlaxoSmithKline's new HIV protease inhibitor Lexiva (fosamprenavir calcium) indicate that it resembles nelfinavir in efficacy, according to investigators. Advantages over the older agent include once-daily dosing without fluid or diet restrictions, and the development of fewer drug resistance mutations over time.

"We also saw a lower proportion of patients that experienced virologic failure" while taking Lexiva, lead investigator Dr. Thomas Stark, from GSK in London, told Reuters Health. SOLO study 48-week findings were presented this week at a meeting of the European AIDS council in Warsaw.

The trial involved 649 HIV-infected subjects being treated with antiretroviral therapy for the first time: 322 patients were treated with Lexiva 1,400 mg daily along with 200 mg ritonavir, and 327 subjects took nelfinavir 1250 mg b.id. Subjects in both arms of the trial were also treated with abacavir sulfate and lamivudine b.i.d.

Approximately two-thirds of patients in both arms achieved undetectable viral loads, regardless of viral load at baseline. "We saw no clinically relevant differences in the safety profile in patients co-infected with hepatitis B and/or C," Dr. Stark commented.

Both drugs were associated with increased fasting HDL cholesterol levels, averaging 46 mg/dL after 48 weeks. HDL cholesterol had risen to above 40 mg/dL in 76% of those on Lexiva and 69% in the nelfinavir arm. The increased HDL levels offset increases in total cholesterol concentrations.

In contrast to nelfinavir-treated subjects, those in the Lexiva arm developed no primary resistance mutations to protease inhibitors and significantly fewer nucleoside reverse transcriptase mutations, Dr. Stark said.

He and his colleagues are now compiling 96-week results. "Trends remained good after 48 weeks," the investigator added.