SAN FRANCISCO, Sept. 14 /PRNewswire-FirstCall/ -- Schering-Plough Corporation (NYSE: SGP) today reported long-term data with vicriviroc, its investigational CCR5 receptor antagonist, from an ongoing, open-label extension of the Phase II VICTOR-E1 study in treatment-experienced HIV-infected patients. The results showed that vicriviroc plus optimized background therapy achieved durable virologic suppression and increased CD4 cell counts, and was generally well tolerated over two years of therapy. These 96-week results were presented at the 49th Annual Interscience Conference on Antimicrobial Agents and Chemotherapy (ICAAC).(1)
The study involved 85 treatment-experienced HIV-infected patients who received 48 weeks of open-label vicriviroc (30 mg once daily) plus an optimized antiretroviral regimen containing a ritonavir-boosted protease inhibitor after completion of 48 weeks of treatment in the double-blind phase of the VICTOR-E1 study (total of 96 weeks). More than half of these patients began open-label treatment with undetectable virus, i.e. an HIV-1 RNA level of less than 50 copies/mL, and about two-thirds had less than 400 copies/mL. Seventy patients remained on therapy at the time of the 96-week analysis. The virologic effect seen during the double-blind phase of the study was sustained in these patients during open-label vicriviroc treatment, with the percentage of patients achieving undetectable virus increasing over the course of therapy. Importantly, further improvements in CD4 counts were observed with longer vicriviroc therapy, with a mean increase of 50 cells/mm3 from week 48 of the double-blind study to the end of the 96-week period.
The data also showed that vicriviroc was generally well tolerated in this highly treatment-experienced population. Adverse events occurring in 5 percent or more of patients were sinusitis, cough and insomnia, consistent with findings in the double-blind phase of the VICTOR-E1 study. One patient discontinued therapy upon simultaneous diagnosis of Hodgkin's lymphoma and Kaposi's sarcoma, which were not considered treatment-related. Another patient discontinued therapy due to pregnancy. Nineteen patients experienced an adverse event of interest during the open-label portion of the study: 11 (13 percent) upper respiratory track infection, 6 (7 percent) dyslipidemia, 3 (4 percent) malignancy, 2 cardiovascular (2 percent), 1 premalignancy (1 percent) and 1 herpes simplex virus infection (1 percent). There were no treatment-emergent deaths, seizures or liver-related adverse events. Resistance to vicriviroc was infrequent and developed slowly, generally after prolonged treatment. Treatment failure occurred in 11 patients, eight of whom had one or fewer active drugs in their optimized background therapy.
"These long-term results with vicriviroc added to optimized background therapy are encouraging and show potential for 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 generally well tolerated, with most patients continuing on treatment for as long as two years."
Vicriviroc, currently in Phase III development, is an extracellular inhibitor of HIV infection. Unlike other classes of HIV drugs that work to inhibit viral replication within human CD4 cells, most of which are part of the immune system, vicriviroc is a member of the CCR5 receptor antagonist class, and is designed to prevent the virus from infecting healthy CD4 cells by blocking its predominant entry route, the CCR5 co-receptor. Approximately 50-60 percent of treatment-experienced patients have virus that uses the CCR5 co-receptor.(2)
About the Study
This ongoing, open-label extension of the VICTOR-E1 Phase II study was designed to provide continued therapy with vicriviroc and to collect safety data. Evidence for sustained viral suppression and CD4 cell count improvement was monitored. After completing 48 weeks of treatment in the double-blind phase of the VICTOR-E1 study, patients (including patients in the placebo arm) were offered open-label vicriviroc 30 mg once daily plus an optimized antiretroviral regimen containing a ritonavir-boosted protease inhibitor. The mean duration of vicriviroc treatment in the open-label phase was 13 months.
Vicriviroc Phase III Studies in Treatment-Experienced Patients
Patient enrollment has been completed in two large Phase III registration studies, known as VICTOR-E3 and VICTOR-E4 (Vicriviroc in Combination Treatment with an Optimized Antiretroviral Therapy Regimen in HIV-Infected Treatment-Experienced Subjects), evaluating vicriviroc 30 mg once daily in combination with an optimized background antiretroviral regimen containing a ritonavir-boosted protease inhibitor compared to a control group receiving new optimized background therapy alone. The optimized background therapy must include at least two drugs to which the patient's HIV is susceptible. Patients coinfected with hepatitis B or C may be included in these studies and there are few exclusions of commonly prescribed drugs or need for dose adjustments based on the known vicriviroc drug-drug interaction profile. The two studies involve a total of more than 850 patients at more than 160 sites in North America, Latin America, Europe and South Africa.
Vicriviroc Phase II Studies in Treatment-Naive Patients
Patient enrollment also has been completed in an ongoing Phase II study of vicriviroc in a novel nucleoside-sparing regimen for first-line therapy of adult treatment-naive HIV-infected patients with R5-tropic virus only. Approximately 80-90 percent of treatment-naive patients have virus that uses the CCR5 co-receptor.(3) The study evaluates vicriviroc 30 mg once-daily in combination with ritonavir-boosted atazanavir,(4) compared to a control group receiving Truvada (emtricitabine and tenofovir disoproxil fumarate)(5) plus ritonavir-boosted atazanavir, which is a currently recommended option for first-line therapy. This novel nucleoside-sparing vicriviroc regimen is designed to provide additional options for treatment-naive patients in a once daily regimen, while preserving other drug classes for subsequent lines of treatment. The study involves 200 patients at more than 35 sites in North America, Central America, Europe and South Africa. The study is sponsored by Schering-Plough with support from Bristol-Myers Squibb.
For more information about vicriviroc clinical studies, please visit www.clinicaltrials.gov, search term: vicriviroc.
Schering-Plough is an innovation-driven, science-centered global health care company. Through its own biopharmaceutical research and collaborations with partners, Schering-Plough creates therapies that help save and improve lives around the world. The company applies its research-and-development platform to human prescription and consumer products as well as to animal health products. Schering-Plough's vision is to "Earn Trust, Every Day" with the doctors, patients, customers and other stakeholders served by its colleagues around the world. The company is based in Kenilworth, N.J., USA, and its Web site is www.schering-plough.com.
SCHERING-PLOUGH DISCLOSURE NOTICE: The information in this press release includes certain "forward-looking statements" within the meaning of the Private Securities Litigation Reform Act of 1995, including statements relating to the company's clinical development plans and the potential for vicriviroc. Forward-looking statements relate to expectations or forecasts of future events. Schering-Plough does not assume the obligation to update any forward-looking statement. Many factors could cause actual results to differ materially from Schering-Plough's forward-looking statements, including uncertainties in the regulatory process, among other uncertainties. For further details about these and other factors that may impact the forward-looking statements, see Schering-Plough's Securities and Exchange Commission filings, including Part II, Item 1A. "Risk Factors" in the Company's second quarter 2009 10-Q, filed July 24, 2009.
(1) McCarthy M, Suleiman J, Diaz R, et al. Vicriviroc Long-Term Safety and Efficacy: 96-Week Results from the VICTOR-E1 Study. 49th Annual Interscience Conference on Antimicrobial Agents and Chemotherapy (ICAAC); Sept. 12-15, 2009; San Francisco, CA, USA; No. H-923.
(2) Coakley E, et al. Second International Workshop Targeting HIV Entry. Oct. 20-21, 2006; Boston, MA, USA; No. 8.
(3) Hoffmann C (2007) The epidemiology of HIV coreceptor tropism. Eur J Med Res (2007) 12: 385-390.
(4) Atazanavir sulfate is a Bristol-Myers Squibb Company prescription medicine. Please see the atazanavir product insert for information on this product.
(5) Truvada is a registered trademark of Gilead Sciences, Inc. Please see the Truvada product insert for information on this product.
SOURCE Schering-Plough Corporation