Source: Jpn J Clin Hematol  |  Posted 6 years ago

By Ed Susman

DENVER, CO -- February 9, 2006 -- In a phase 1/2, 10-day monotherapy trial, the integrase inhibitor GS9317 was able to lower HIV viral loads by as much as 2 logs -- 99%.

Researchers used 5 different GS9317 dosing regimens in the trial -- 200 mg twice a day, 400 mg twice a day, 800 mg twice a day, 800 mg once a day, or 50 mg boosted by 100 mg ritonavir once a day.

"In all cases, GS9137 outperformed the placebo arm of the trial," said Andrew Cheng, MD, vice president for clinical research, Gilead Sciences, Forster City, California. Dr. Cheng presented the study findings here on February 8[^]th[] at the 13[^]th[] Conference on Retroviruses and Opportunistic Infections (CROI).

He noted, however, that ritonavir allows GS9137 to remain in the bloodstream up to 9 hours.

The study evaluated the antiviral activity, safety, and pharmacokinetic properties for the integrase inhibitor, Dr. Cheng said.

Future studies of GS9137 will include ritonavir boosting, he said. Those trials will test 20 mg, 50 mg, and 125 mg, all of which will be boosted by ritonavir, Dr. Cheng said. The goal is to seek once-daily dosing of the drug, he added.

In the 10-day monotherapy trials, Dr. Cheng said that GS9137 reduced circulating HIV in the blood by as much as 2log[_]10[]. He tested 30 patients with the various dosages and compared them with 10 patients who were on placebo. The difference reached statistical significance at the P < .0001 level, he said.

"The drug was also very well tolerated," Dr. Chang said. "All adverse events related to the study drug were grade 1 or grade 3 in severity, resolved on treatment, and were not associated with GS9137."

He said that none of the patients in the study were forced to discontinue the study drug. There were no serious adverse events in the treatment arm, he said.

[Presentation title: The HIV Integrase Inhibitor GS-9137 (JTK-303) Exhibits Potent Antiviral Activity in Treatment-Na?ve and Experienced Patients. Abstract 160LB]