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Schering CCR5 Drug Vicriviroc Study Continues
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Schering-Plough presents data on HIV drug
note from Jules Levin: the presentation by Wayne Greaves from Schering in an oral session at the 13th CROI in Denver feb 8, 2006 was actually heartening, because in his explanation as to why the study was stopped highlighted reasons why the drug could be studied in new trials. There were several key reasons appearing as to why there was a higher patient viral failure rate. the primary reason appears to be the viral load reduction was low, -1.34 log, and this appears to be cause the dose used was too low. Higher dosing of the drug can be explored of 100 to 125 mg and perhaps ritonavir boosting can be explored. There was a 2-week monotherapy period at the start of the study that was stopped and perhaps this caused drug resistance to emerge, but a higher & more potent dosing regimen could address this concern. Although valuable time was lost with this poorly designed study, restudy of the drug at improved dosing appears feasible particularly because there have not been safety issues emerging from study of the drug
By Toni Clarke
BOSTON, Feb 10 (Reuters) - Schering-Plough Corp. said on Friday data from a discontinued trial of its experimental HIV treatment helps shed light on a newly-evolving class of drugs that drugmakers hope will be the next big wave in HIV therapy.
Schering-Plough last year terminated a study of its experimental drug vicriviroc in combination with a standard treatment after patients who had not received previous treatment experienced sharp spikes in the amount of the HIV virus in their blood, while the control group did not.
Vicriviroc is part of the class of drugs known as CCR5 receptor antagonists, which target a strain of the virus called R5 and are designed to block a key receptor needed by the virus to enter and infect the cell. Current treatments work by preventing the virus from replicating once it is inside the cell.
Joy Schmitt, a spokeswoman for Schering-Plough, said researchers had been concerned that the spike in viral load in the discontinued trial was caused by a shift and change in the makeup of the R5 strain of the virus, which would cause the drug to fail or make for resistance.
"We were heartened to learn that this did not appear to be the case," she said.
Schering-Plough said it plans to conduct new trials of the drug in patients who have not previously received treatment. It is currently conducting a mid-stage trial of the drug, in combination with other therapies, in patients who have already received treatment.
Schering-Plough is one of several companies aiming to develop a CCR5 drug, including Pfizer Inc. and Sangamo BioSciences Inc. But controversy surrounds the class, as some trials have shown the drugs can cause liver toxicity. GlaxoSmithKline Plc terminated a CCR5 program because of safety issues. Schmitt said Schering-Plough's drug did not show liver toxicity.
"There has been disappointment in this class but there is still tremendous hope," said Schmitt.
Schering's vicriviroc safe in phase 2
KENILWORTH, N.J., Feb. 10 (UPI) -- Schering-Plough said Friday results of a phase 2 trial of vicriviroc show the HIV drug safe despite issues with efficacy.
The company terminated the trial last October when patients who were taking vicriviroc together with GlaxoSmithKline's Combivir showed virologic breakthrough, or increased levels of HIV.
Schering-Plough said it plans to continue the development of vicriviroc and is considering whether to combine it with protease inhibitors.
"These results have proven instructive to the further development of vicriviroc and will inform our plans for designing additional studies," said Wayne Greaves, Schering's senior director of global clinical development.
"While the optimal dose of vicriviroc and its role in antiretroviral regimens require further evaluation, vicriviroc was shown to be well tolerated by patients in this trial with no marked safety concerns - specifically, no liver toxicity," Greaves said. "Further, separate drug interaction studies with commonly used protease inhibitors showed no need for dose adjustment for vicriviroc, which bodes well for studying vicriviroc in various protease inhibitor containing treatment regimens in our future trials."
Vicriviroc is currently in an ongoing phase 2 study involving treatment-experienced HIV patients.
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