Lloyd Mayer

Maintenance infliximab for Crohn's disease: the ACCENT I randomised trial

BACKGROUND We did a randomised controlled trial to assess the benefit of maintenance infliximab therapy in patients with active Crohns disease who respond to a single infusion of infliximab. METHODS 573 patients with a score of at least 220 on the Crohns disease activity index (CDAI) received a 5 mg/kg intravenous infusion of infliximab at week 0. After assessment of response at week 2, patients were randomly assigned repeat infusions of placebo at weeks 2 and 6 and then every 8 weeks thereafter until week 46 (group I), repeat infusions of 5 mg/kg infliximab at the same timepoints (group II), or 5 mg/kg infliximab at weeks 2 and 6 followed by 10 mg/kg (group III). The prespecified co-primary endpoints were the proportion of patients who responded at week 2 and were in remission (CDAI <150) at week 30 and the time to loss of response up to week 54 in patients who responded. Analyses of the co-primary endpoints were by intention to treat. FINDINGS 335 (58%) patients responded to a single infusion of infliximab within 2 weeks. At week 30, 23 of 110 (21%) group I patients were in remission, compared with 44 of 113 (39%) group II (p=0.003) and 50 of 112 (45%) group III (p=0.0002) patients. Thus, patients in groups II and III combined were more likely to sustain clinical remission than patients in group I (odds ratio 2.7, 95% CI 1.6-4.6). Throughout the 54-week trial, the median time to loss of response was 38 weeks (IQR 15 to >54) and more than 54 weeks (21 to >54) for groups II and III, respectively, compared with 19 weeks (10-45) for group I (p=0.002 and p=0.0002, respectively). Infliximab safety was consistent with that seen in other trials of infliximab in Crohns disease and rheumatoid arthritis. In particular, the incidence of serious infections was similar across treatment groups. INTERPRETATION Patients with Crohns disease who respond to an initial dose of infliximab are more likely to be in remission at weeks 30 and 54, to discontinue corticosteroids, and to maintain their response for a longer period of time, if infliximab treatment is maintained every 8 weeks.

A Short-Term Study of Chimeric Monoclonal Antibody cA2 to Tumor Necrosis Factor α for Crohn's Disease

Background Studies in animals and an open-label trial have suggested a role for antibodies to tumor necrosis factor α, specifically chimeric monoclonal antibody cA2, in the treatment of Crohns disease. Methods We conducted a 12-week multicenter, double-blind, placebo-controlled trial of cA2 in 108 patients with moderate-to-severe Crohns disease that was resistant to treatment. All had scores on the Crohns Disease Activity Index between 220 and 400 (scores can range from 0 to about 600, with higher scores indicating more severe illness). Patients were randomly assigned to receive a single two-hour intravenous infusion of either placebo or cA2 in a dose of 5 mg per kilogram of body weight, 10 mg per kilogram, or 20 mg per kilogram. Clinical response, the primary end point, was defined as a reduction of 70 or more points in the score on the Crohns Disease Activity Index at four weeks that was not accompanied by a change in any concomitant medications. Results At four weeks, 81 percent of the patients giv...

Incidence and importance of antibody responses to infliximab after maintenance or episodic treatment in Crohn’s disease

BACKGROUND & AIMS The effect of different treatment regimens on antibody responses to infliximab and their clinical significance was examined by using data from ACCENT I. METHODS Patients with Crohns disease (n = 573) received 5 mg/kg infliximab (week 0) and then were randomly assigned to blinded infusions at weeks 2 and 6 and every 8 weeks until week 46 of placebo (group I), 5 mg/kg infliximab (group II), or 5 mg/kg infliximab at weeks 2 and 6, followed by 10 mg/kg thereafter (group III). At week 14 or later, patients losing response could cross over to episodic infliximab treatment increased by 5 mg/kg. Samples for antibody determination were collected before the first infusion and at weeks 14, 22, 54, 62, 72, and, if applicable, before and after crossover. RESULTS Through week 72, antibodies to infliximab were detected in 30%, 10%, and 7% of groups I, II, and III, respectively (P < 0.0001). Patients receiving immunomodulators had a lower incidence of antibodies compared with patients receiving infliximab alone (10% and 18%, respectively; P = 0.02). Antibodies were associated with a 12% absolute increase in infusion reactions but no increase in serious infusion reactions or serum sickness-like reactions. In the overall population, similar proportions of antibody-positive and antibody-negative patients achieved clinical response (64% and 62%, respectively; P = NS) or clinical remission (41% and 39%, respectively; P = NS) at week 54. Notably, 86% of patients responded to retreatment, and 63% were in clinical response at week 54; however, fewer antibody-positive group I patients attained clinical remission (31%) compared with those who were antibody negative (37%) or antibody inconclusive (54%) (P = NS). CONCLUSIONS Reduced antibody formation and greater clinical benefit were observed with an induction regimen followed by maintenance treatment compared with a single dose followed by episodic retreatment in Crohns disease patients treated with infliximab.

Toll-Like Receptors on Tumor Cells Facilitate Evasion of Immune Surveillance

The signal pathways that trigger tumor cell escape from immune surveillance are incompletely understood. Toll-like receptors (TLRs), which activate innate and adaptive immune responses, are thought to be restricted to immune cells. We show here that TLRs, including TLR4, are expressed on tumor cells from a wide variety of tissues, suggesting that TLR activation may be an important event in tumor cell immune evasion. Activation of TLR4 signaling in tumor cells by lipopolysaccharide induces the synthesis of various soluble factors and proteins including interleukin-6, inducible nitric oxide synthase, interleukin-12, B7-H1, and B7-H2, and results in resistance of tumor cells to CTL attack. In addition, lipopolysaccharide-stimulated tumor cell supernatants inhibit both T cell proliferation and natural killer cell activity. Blockade of the TLR4 pathway by either TLR4 short interfering RNA or a cell-permeable TLR4 inhibitory peptide reverses tumor-mediated suppression of T cell proliferation and natural killer cell activity in vitro, and in vivo, delays tumor growth and thus prolongs the survival of tumor-bearing mice. These findings indicate that TLR signaling results in a cascade leading to tumor evasion from immune surveillance. These novel functions of TLRs in tumor biology suggest a new class of therapeutic targets for cancer therapy.

The incidence and management of infusion reactions to infliximab: a large center experience.

OBJECTIVE:To assess the incidence and management of infusion reactions to infliximab, a chimeric monoclonal antibody that targets human tumor necrosis factor-α, in patients with Crohns disease treated at a large infusion center.METHODS:A total of 165 consecutive patients who received 479 infliximab infusions in the Division of Clinical Immunology Infusion Center at Mount Sinai Medical Center from July, 1998 to January, 2001 were evaluated. Specific treatment protocols for initial and subsequent acute infusion reactions were followed and the outcomes documented.RESULTS:The overall incidence of infusion reactions to infliximab was 6.1% (29 of 479) of infusions, affecting 9.7% (16 of 165) of patients. Mild, moderate, or severe acute reactions occurred in 3.1% (15 of 479), 1.2% (six of 479), and 1.0% (five of 479) of infliximab infusions, respectively. Use of treatment protocols resulted in rapid resolution of all acute reactions to infliximab. With the prophylaxis protocol, all patients who experienced an initial mild or moderate acute reaction were able to receive additional infusions. Four patients experienced a total of five severe acute reactions. Three patients were retreated: two patients had no further problems, whereas one patient had a second severe acute reaction that rapidly resolved with treatment. Suggesting that acute infusion reactions are not type I hypersensitivity reactions, in 11 patients who experienced 14 acute infusion reactions, serum tryptase levels were normal. Delayed infusion reactions occurred in 0.6% (three of 479) of infusions.CONCLUSIONS:Infliximab infusions were accompanied by acute reactions in approximately 5% of infusions. These reactions did not seem to be true IgE-mediated type I hypersensitivity events. Using appropriate treatment protocols, these reactions were effectively treated and prevented upon retreatment in nearly all patients. Delayed reactions were rare, occurring in <1% of infusions.

Infliximab in the treatment of severe, steroid-refractory ulcerative colitis: A pilot study

We report the experience of 11 patients (of 60 planned patients) enrolled in a double-blind, placebo-controlled clinical trial of infliximab in patients with severe, active steroid-refractory ulcerative colitis. The study was terminated prematurely because of slow enrollment. Patients having active disease for at least 2 weeks and receiving at least 5 days of intravenous corticosteroids were eligible to receive a single intravenous infusion of infliximab at 5, 10, or 20 mg/kg body weight. The primary endpoint used in this study was treatment failure at 2 weeks after infusion. Treatment failure was defined as 1) unachieved clinical response as defined by a modified Truelove and Witts severity score, 2) increase in corticosteroid dosage, 3) addition of immunosuppressants, 4) colectomy, or 5) death. Safety evaluations included physical examination, clinical chemistry and hematology laboratory tests, and occurrence of adverse experiences. Four of 8 patients (50%) who received infliximab were considered treatment successes at 2 weeks, compared with none of 3 patients who received placebo. Improvement in erythrocyte sedimentation rates and serum concentrations of C-reactive protein and interleukin-6 correlated with the clinical response observed in patients receiving infliximab. Infusion with infliximab produced no significant adverse events. Infliximab was well tolerated and may provide clinical benefit for some patients with steroid-refractory ulcerative colitis.

Tacrolimus for the treatment of fistulas in patients with Crohn's disease: a randomized, placebo-controlled trial.

BACKGROUND & AIMS This study determined the effectiveness of tacrolimus for the treatment of Crohns disease fistulas. METHODS The study was a randomized, double-blind, placebo-controlled, multicenter clinical trial. Forty-eight patients with Crohns disease and draining perianal or enterocutaneous fistulas were randomized to treatment with oral tacrolimus 0.2 mg. kg(-1). day(-1) or placebo for 10 weeks. The primary outcome measure was fistula improvement as defined by closure of >/=50% of particular fistulas that were draining at baseline and maintenance of that closure for at least 4 weeks. A secondary outcome measure was fistula remission as defined by closure of all fistulas and maintenance of that closure for at least 4 weeks. RESULTS Forty-three percent of tacrolimus-treated patients had fistula improvement compared with 8% of placebo-treated patients (P = 0.004). Ten percent of tacrolimus-treated patients had fistula remission compared with 8% of placebo-treated patients (P = 0.86). Adverse events significantly associated with tacrolimus, including headache, increased serum creatinine level, insomnia, leg cramps, paresthesias, and tremor, were managed with dose reduction. CONCLUSIONS Oral tacrolimus 0.2 mg. kg(-1). day(-1) is effective for fistula improvement, but not fistula remission, in patients with perianal Crohns disease. Adverse events associated with tacrolimus can be managed by dose reduction. Lower doses of tacrolimus should be evaluated.

Antigen processing and presentation by intestinal epithelial cells – polarity and complexity

The mechanisms by which gut-associated lymphoid tissue (GALT) maintains a balance between oral tolerance and active immune response in the face of exposure to high antigen concentrations remains a central question in mucosal immunity. Here, Robert Hershberg and colleagues discuss the evidence that human intestinal epithelial cells function as antigen-presenting cells (APCs) capable of regulating T-cell responses in the intestinal mucosa

Mucus Enhances Gut Homeostasis and Oral Tolerance by Delivering Immunoregulatory Signals

Guardian of the Gut The intestine is able to tolerate continual exposure to large amounts of commensal bacteria and foreign food antigens without triggering an inappropriate inflammatory immune response. In the large intestine, this immunological tolerance is thought to occur via a physical separation between environment and host imposed by a continuous mucous layer built up from the secreted mucin protein, MUC2. However, in the small intestine, this mucous layer is porous, necessitating an additional layer of immune control. Shan et al. (p. 447, published online 26 September; see the Perspective by Belkaid and Grainger) now report that in the small intestine, MUC2 plays an active role in immunological tolerance by activating a transcription factor in resident dendritic cells, thereby selectively blocking their ability to launch an inflammatory response. This work identifies MUC2 as a central mediator of immune tolerance to maintain homeostasis in the gut and possibly at other mucosal surfaces in the body. Mucus not only forms a physical barrier in the intestine but also promotes immunological tolerance of bacteria and foods. [Also see Perspective by Belkaid and Grainger] A dense mucus layer in the large intestine prevents inflammation by shielding the underlying epithelium from luminal bacteria and food antigens. This mucus barrier is organized around the hyperglycosylated mucin MUC2. Here we show that the small intestine has a porous mucus layer, which permitted the uptake of MUC2 by antigen-sampling dendritic cells (DCs). Glycans associated with MUC2 imprinted DCs with anti-inflammatory properties by assembling a galectin-3–Dectin-1–FcγRIIB receptor complex that activated β-catenin. This transcription factor interfered with DC expression of inflammatory but not tolerogenic cytokines by inhibiting gene transcription through nuclear factor κB. MUC2 induced additional conditioning signals in intestinal epithelial cells. Thus, mucus does not merely form a nonspecific physical barrier, but also constrains the immunogenicity of gut antigens by delivering tolerogenic signals.

Expression of class II molecules on intestinal epithelial cells in humans: Differences between normal and inflammatory bowel disease

Expression of class II antigens on human intestinal epithelial cells was assessed using a sensitive avidinbiotin-peroxidase technique. HLA-DR was present predominantly in the normal small bowel with diminished but evident expression in the colon. HLA-DP staining was less prominent, and HLA-DQ was absent. In inflammatory bowel disease the expression of both HLA-DR and HLA-DP was increased, but that for HLA-DQ remained absent, suggesting an inherent defect in the ability of intestinal epithelial cells to express HLA-DQ. In related experiments, an interferon gamma-treated malignant epithelial cell line T84 also failed to stain for HLA-DQ and HLA-DP despite the presence of HLA-DR. Isolated RNAs for all three subclasses of HLA-D were detectable by slot-blot analysis, suggesting that the lack of HLA-DQ expression relates to posttranscriptional defects in intestinal epithelium. These and other differences with conventional class II antigen-positive accessory cells (macrophages/B cells) may help to explain the unique properties of intestinal epithelial cells as antigen-presenting cells.