The FINANCIAL — Data Analysis of Up to Four Years of Treatment Presented at ICAAC/IDSA 2008 Annual Meeting Schering-Plough Corporation (NYSE: SGP) on October 26 reported a data analysis showing that vicriviroc, its investigational CCR5 receptor antagonist, demonstrated sustained viral suppression and increased CD4 cell counts and was well tolerated through up to four years of therapy in treatment-experienced HIV-infected patients. Vicriviroc was administered once-daily as a single tablet in combination with an optimized antiretroviral regimen containing a ritonavir-boosted protease inhibitor. These results represent the longest treatment duration and clinical experience reported to date for a CCR5 receptor antagonist.
Vicriviroc, currently in Phase III development, is an extracellular inhibitor of HIV infection designed to prevent the virus from infecting the immune system's CD4 cells by blocking the CCR5 co-receptor. Approximately 50-60 percent of treatment-experienced patients have virus that uses the CCR5 co-receptor.(1)
Researchers presented the data at the joint Interscience Conference on Antimicrobial Agents and Chemotherapy (ICAAC) and Infectious Diseases Society of America (IDSA) annual meeting.(2)
The pooled data analysis involved 205 treatment-experienced HIV-infected patients from two vicriviroc Phase II studies who continued on vicriviroc at the completion of 48 weeks of treatment in an open-label extension for each study. Patients received vicriviroc for up to 216 weeks of total treatment duration as part of an optimized antiretroviral regimen.
This analysis showed that vicriviroc was well tolerated overall, with patients developing few complications of HIV disease. Adverse events observed were consistent with expectations for the treatment-experienced HIV-infected population. Importantly, the incidence of malignancy seen across the vicriviroc clinical program has not increased over time even as the cumulative exposure to vicriviroc has increased by numbers of patients and duration of treatment.
"These long-term results demonstrate that vicriviroc added to an optimized background therapy may provide durable viral suppression and sustained elevated CD4 counts in treatment-experienced HIV-infected patients," said Jihad Slim, M.D., division of infectious diseases, Saint Michael's Medical Center, Newark, N.J., and an investigator for the vicriviroc clinical program. "Importantly, vicriviroc was well tolerated, with some patients continuing on treatment for up to four years, and it was not associated with increased liver, CNS or cardiovascular adverse events or with an increased incidence of malignancy in this patient population."