96-Week MERIT ES Analysis Shows Efficacy Of Pfizer’s HIV/AIDS Treatment Celsentri/Selzentry (Maraviroc) in Treatment-Naïve HIV Patients

Source Press Release
Company Pfizer 
Tags Trial Results, Phase III, Systemic Anti-Infectives
Date July 21, 2009

Results Consistent With 48-Week Analysis

New York, NY -- July 21, 2009 -- At 96-week follow up, data from the MERIT ES analysis show that treatment-naïve HIV patients taking Celsentri/Selzentry (maraviroc), in combination with Combivir® (zidovudine/lamivudine) experienced comparable virologic suppression to undetectable levels and significantly greater increases in CD4 T-cell count through 96-weeks, compared to patients taking efavirenz in combination with  zidovudinelamivudine. The data also show the favorable tolerability of Celsentri/Selzentry, which was associated with fewer discontinuations due to adverse events.(1)

The 96-week results from MERIT ES were presented today at the 5th International AIDS Society (IAS) Conference on HIV Pathogenesis, Treatment and Prevention in Cape Town, South Africa. MERIT ES is an analysis of the data from the MERIT (Maraviroc versus  Efavirenz Regimens as Initial Therapy) study following retesting of screening samples using the enhanced sensitivity Trofile™ assay - therefore representing a subset of the MERIT primary analysis population. This enhanced sensitivity test was not available at the time of the MERIT study and is the only version of Trofile currently available.  

Results from the MERIT ES population show that, at 96 weeks, a similar number of patients taking Celsentri/Selzentry achieved undetectable viral load compared to those taking  efavirenz (<50 copies/ml="58.5" percent and 62.4 percent, respectively). Comparable results were seen based on a Time to Loss of Virologic Response* (TLOVR) analysis (<50 copies/ml="60.5" percent on  Celsentri/Selzentry versus 60.7 percent on  efavirenz). Results also show that, at the end of almost two years, a similar number of patients taking Celsentri/Selzentry remained on therapy compared to those taking  efavirenz (66.9 percent and 66.0 percent, respectively).  

“Durable HIV treatments are critical as they better ensure that patients remain on therapy, which can delay disease progression and help patients live considerably longer lives,” said Dr. Michael Saag, professor of Medicine and director of the Center for AIDS Research at the University of Alabama at Birmingham, who presented the results. “These results further support maraviroc’s durability and safety profile and, therefore, offer the potential to enhance currently available treatment options for treatment-naïve HIV patients.” 

For patients from the MERIT ES population with higher viral loads at screening (>100,000 copies/mL), a similar number of patients taking Celsentri/Selzentry maintained undetectable viral load compared to those taking  efavirenz (56.0 percent and 56.7 percent, respectively, based on TLOVR analysis). Additionally, at Week 96 the increase in CD4 T-cell count was significantly greater with  Celsentri/Selzentry than with  efavirenz (median change from baseline was +212 cells/mm3 and +171 cells/mm3, respectively, a difference of 41 cells/mm3 [95 percent CI: 17, 65]).  

Safety results from the full MERIT population show that, among those patients who remained on therapy (total patient years of exposure of 506 years for Celsentri/Selzentry and 507.9 years for  efavirenz), less than half the number of malignancies were observed in patients taking Celsentri/Selzentry compared to those taking  efavirenz (1.1 percent and 2.8 percent, respectively). There were also fewer cases of tuberculosis with  Celsentri/Selzentry compared to  efavirenz (0.3 percent and 2.2 percent, respectively).  

At 96-weeks, similar to 48-weeks, the most common adverse events reported by patients taking Celsentri/Selzentry were nausea, headache, fatigue and dizziness. For patients taking  efavirenz, nausea, headache, diarrhea, dizziness, vomiting and abnormal dreams were the most commonly reported adverse events. 

Among those patients taking Celsentri/Selzentry in MERIT at 96-weeks, 1.5 percent had elevated LDL-cholesterol levels that exceeded established thresholds to consider lipid-lowering drug initiation (defined by the NCEP guidelines)(2), compared to 9.9 percent for patients taking  efavirenz

About MERIT and MERIT ES 

MERIT is an ongoing randomized, blinded, non-inferiority trial in treatment-naïve patients with CCR5-tropic HIV-1. The Phase 3 trial compares the safety and efficacy of Celsentri/Selzentry 300  mg twice daily versus  efavirenz 600  mg once daily, administered with the fixed-dose combination  Combivir (a standard of care at the time of trial enrollment). Results of MERIT at 48-weeks were presented in July 2007 at the IAS Conference on HIV  Pathogenesis, Treatment and Prevention in Sydney, Australia. 

Overall for the MERIT ES analysis, 106 patients (15 percent) originally classified as having CCR5-tropic virus were reclassified as having dual or mixed tropic virus. Results of MERIT ES at 48-weeks were presented in October 2008 at the 48th Annual Interscience Conference on Antimicrobial Agents and Chemotherapy (ICAAC®)/ 46th Annual Meeting of the Infectious Diseases Society of America (IDSA) in  Washington D.C., USA.  

* A patient classified as a TLOVR non-responder required two consecutive viral load measurements of >50 copies/mL. A patient classified as a primary efficacy non-responder required one viral load measurement of >50 copies/mL. 

About Celsentri/Selzentry

Celsentri/Selzentry is an oral medicine that blocks viral entry to human cells. Rather than fighting HIV inside white blood cells,  Celsentri/Selzentry prevents the virus from entering uninfected cells by blocking its predominant entry route, the CCR5 co-receptor.  

Celsentri/Selzentry has been approved for use in several markets around the world including the United States, Canada and European Union in combination with other  antiretroviral medicinal products, for the treatment of experienced adult patients with only CCR5-tropic  HIV-1 detectable.  

In South Africa, maraviroc is not available commercially and is currently under review by the Medicine Control Council.  Maraviroc is marketed under the trade name  Selzentry® in the United States and Celsentri® in all other countries in which it is approved.

1. Pfizer Abstract: The MERIT study of  maraviroc in  antiretroviral-naïve patients with R5 HIV-1: 96-week results.

2. Third Report of the National Cholesterol Education Program (NCEP) Expert Panel on Detection, Evaluation, and Treatment of High Blood Cholesterol in Adults (Adult Treatment Panel III) final report. Circulation. 2002;106:3143–3421.

Source: Evaluate™
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