November 7, 2009 (San Diego, California) — Natalizumab significantly reduces hospitalization rates during both induction and maintenance treatments for patients with moderate to severe Crohn's disease compared with placebo, according to a retrospective analysis of 3 studies presented here at the American College of Gastroenterology 2009 Annual Scientific Meeting.
In addition, the hospitalization rates were also reduced in a subset of patients previously treated with anti-tumor necrosis factor (TNF) therapy.
The data were pulled from the previously presented phase 3 Evaluation of Natalizumab as Continuous Therapy (ENACT) I and II and Efficacy of Natalizumab in Crohn's Disease Response and Remission (ENCORE) trials and from the open-label Evaluation of the Natalizumab Antibody for Long-term Efficacy (ENABLE) extension study.
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| Dr. Corey A. Siegel |
"Hospitalization accounts for a large proportion of the cost of Crohn's disease management," said lead investigator Corey A. Siegel, MD, assistant professor of medicine and director of the Inflammatory Bowel Disease (IBD) Center at Dartmouth-Hitchcock Medical Center in Lebanon, New Hampshire. He presented the results during an IBD Plenary Session.
"In addition, hospitalization increases morbidity," said Dr. Siegel. "This study was important because keeping Crohn's disease patients out of the hospital can lead to a huge cost savings, and it's just better for them."
Background
In the ENACT 1 and ENCORE trials, patients were randomly assigned to receive either intravenous natalizumab 300 mg or placebo during an 84-day induction phase. In ENACT 2, the natalizumab responders were then rerandomized and treated for an additional 48 weeks. Patients losing response were rolled over to the open-label ENABLE study, and data from ENABLE plus ENACT 2 made up the 336-day maintenance period evaluated. There were approximately 1500 total patients enrolled in the trials.
For this analysis, the investigators examined the effect of natalizumab on hospitalization rates during both the induction and maintenance phases.
"Hospitalizations were identified from adverse event reports from all trials, and the rates of all-cause hospitalization and Crohn's disease–related hospitalizations per 100 patients were evaluated," reported Dr. Siegel.
The researchers also performed further analyses in a subpopulation of patients receiving prior anti-TNF alpha therapy.
Hospitalization Rates Lower With Natalizumab
End-of-the-study results showed that all hospitalization rates were lower in the natalizumab-treated patients compared with those treated with placebo.
An overall total of 136 all-cause hospitalizations were found. In those treated with natalizumab, the rate of hospitalizations was reduced by 34% (P = .009) during the induction period and 44% (P = .044) during the maintenance period compared with placebo.
The total number of Crohn's disease–related hospitalizations was 109. In the patients receiving natalizumab, the rate was reduced by 31% (P < .001) during the induction period and 58% (P = .027) during the maintenance period.
In patients who received prior anti-TNF therapy, the benefit associated with natalizumab was even higher, with induction rate reductions of 56% (P = .031) for all-cause and 55% (P = 0.052) for Crohn's-related hospitalizations.
During the maintenance period for this subpopulation, natalizumab had reductions of 60% (P = .034) and 75% (P = .029) for all-cause and Crohn's-related hospitalizations, respectively.
"Our overall finding was that patients who received natalizumab basically had a lower rate of hospitalization vs those who received placebo," said Dr. Siegel.
"We were encouraged to see this, particularly in the more difficult-to-treat subset of patients previously treated with anti-TNF therapy," he added. "This is a tough-to-treat patient population, so we're happy to see any result that helps and benefits them in any way. And I feel that these results are fairly robust."
He reported that in the future, he would like to see some longer-term results. "It's nice that this drug keeps patients out of the hospital over the first year. But what happens over a longer period of time? Finding that out will be important."
A Nice Evaluation of Data
"This was a very nice evaluation of data that was collected prospectively but retrospectively reviewed in an effort to better define [whether] use...helped patients avoid hospitalizations. And it clearly did avoid hospitalizations based on the post hoc analysis," said session moderator Gary Lichtenstein, MD, professor of medicine at the University of Pennsylvania School of Medicine and director of the Center for Inflammatory Disease at the University of Pennsylvania Health System in Philadelphia. Dr. Lichtenstein was not involved with this study.
He noted that, "The duration of hospitalization was not commented upon during the presentation, which would have been interesting. Also, it would be of interest to see specific Crohn's-related hospitalizations related to active disease as opposed to potentially adhesive disease, because adhesions can simulate active disease directly and it's somewhat difficult to tease out.
"But this looks promising and good, especially for patients that are treated with natalizumab who have had a previous failure of anti-TNF therapy," Dr. Lichtenstein concluded.
This study was supported by Elan Pharmaceuticals, Inc, and Biogen Idec, Inc. Dr. Siegel has served as a consultant and an advisory committee/board member to Elan and Biogen Idec. Dr. Lichtenstein has consulted with Elan Pharmaceuticals within the past year, but not with any research related to this study.
American College of Gastroenterology 2009 Annual Scientific Meeting: Abstract 41. Presented October 27, 2009.
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