Dig Dis Sci (2008) 53:175–180 DOI 10.1007/s10620-007-9840-2
ORIGINAL PAPER
Bowman-Birk Inhibitor Concentrate: A Novel Therapeutic Agent for Patients with Active Ulcerative Colitis Gary R. Lichtenstein Æ Julius J. Deren Æ Seymour Katz Æ James D. Lewis Æ Ann R. Kennedy Æ Jeffrey H. Ware
Received: 20 December 2006 / Accepted: 5 April 2007 / Published online: 6 June 2007 Springer Science+Business Media, LLC 2007
Abstract Bowman-Birk inhibitor concentrate (BBIC), a soy extract with high protease inhibitor activity, is efficacious in the treatment of colitis in mice and has been used in numerous clinical trials. A randomized, double blind, placebo-controlled trial was performed to investigate the safety and possible benefits of BBIC in patients with active ulcerative colitis. The Sutherland Disease Activity Index (SDAI) was used to assess disease activity, response (Index decrease ‡ 3), and remission (Index £ 1 with no rectal bleeding) in patients receiving 12 weeks of therapy. The Index scores of patients receiving BBIC decreased more than those of the patients receiving placebo (P = 0.067). Beneficial trends were observed in the rates of remission (P = 0.082) and clinical response (P = 0.22). No severe adverse events were observed. This trial suggests a potential benefit over placebo for both achieving clinical response and induction of remission in patients with active ulcerative colitis without apparent toxicity. Keywords Colitis Protease inhibitor Inflammatory bowel disease Toxicity Safety
G. R. Lichtenstein J. J. Deren S. Katz J. D. Lewis A. R. Kennedy J. H. Ware Department of Medicine, Division of Gastroenterology, University of Pennsylvania School of Medicine, 3rd Floor Ravdin Building, 3400 Spruce Street, Philadelphia, PA 19104-4283, USA J. H. Ware (&) Department of Radiation Oncology, University of Pennsylvania School of Medicine, 183 John Morgan Building, 3620 Hamilton Walk, Philadelphia, PA 19104-6072, USA e-mail:
[email protected]
Introduction The incidence of ulcerative colitis (UC) in the United States is approximately 11 per 100,000 [1]. Although the etiology remains unclear, the epidemiology of the disease is well characterized. The prevalence of UC is highest in the US and Europe and in developed countries generally. Epidemiological studies indicate that a diet high in soybeans and other legumes may contribute to an attenuated incidence of UC [2, 3]. Given the inadequacy of our current therapies for patients with UC there is a constant search for new classes of medications. The Bowman-Birk inhibitor (BBI) is a soybean-derived protease inhibitor. Inhibitors of the BBI family are present in all legumes. BBI concentrate (BBIC) is a soy extract enriched in BBI. In three completed clinical trials evaluating BBIC, no serious adverse events have been attributed to BBIC and adverse event rates in patients receiving BBIC therapy have been similar to those in patients receiving placebo [4–7]. A potent anti-inflammatory effect has been associated with BBI ingestion in several animal studies [8–10]. Analysis of tissue from rat colitis lesions indicated that activated tissue proteases are potently inhibited by BBI [11]. BBI has been shown to be an effective inhibitor of several human proteases associated with inflammation-mediating cells, including elastase [12, 13], cathepsin G [13, 14], and mast cell chymase [15]. Given the lack of toxicity and the potent anti-inflammatory effect of BBIC in animals when assessed in an acute injury/colitis model [10], the potential for BBIC to benefit patients with active UC was investigated. Materials and methods A randomized, double blind, placebo-controlled trial in patients with active ulcerative colitis was performed. The
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safety and efficacy of BBIC on symptoms and endoscopic findings were investigated. The protocol was approved by the Institution Review Board and all participants provided written informed consent. Inclusion criteria were a previous established diagnosis of ulcerative colitis and a Sutherland Disease Activity Index (SDAI; see below) score of 4–10 [16]. Patients with recent use of antibiotics or previous or current use of immunosuppressants were excluded. Use of 5-ASA drugs and corticosteroids ( 0.05) when analyzed using the Wilcoxon matched pairs test
Number of Patients
4
(p=0.082)
45%
4 3 2 8.3%
1 0
BBIC
Placebo
Fig. 3 Induction of remission (intention-to-treat analysis) in ulcerative colitis patients receiving BBIC or placebo. Patients who did not complete the trial (3 receiving BBIC and 2 receiving placebo) were counted as not achieving remission
Response to treatment Response to treatment was defined as a 3-point decrease in SDAI, as previously utilized in other studies [18, 21]. Seven patients receiving BBIC responded to treatment (i.e., achieved a 3-point decrease in SDAI score) as did 4 patients receiving placebo (Fig. 2; P = 0.22, Fisher’s exact test). If patients who dropped out of the trial are included as nonresponders, then 7 out of 14 patients (50%) receiving BBIC responded to treatment, as did 4 out of 14 patients (29%) receiving placebo. This achieved a P value of 0.22 using the Fisher’s exact test. Induction of remission Remission was defined as achieving an SDAI score of 0 or 1 with no rectal bleeding upon evaluation at drug discontinuation. This was achieved by 5 out of 14 patients (36%) receiving BBIC and 1 of the 12 patients (7.1%) taking placebo (Fig. 3; P = 0.082, Fisher’s exact test).
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SDAI components The SDAI comprises four components: stool frequency, rectal bleeding, mucosal appearance, and physician rating of disease activity. The scores for each component were analyzed for differences between the BBIC and placebo groups. The change in component score was calculated (final score minus initial score), and each treatment group further divided into those who improved (negative score change) and those who did not improve (zero or positive score change.) The data are summarized in Table 2. The scores from the BBIC patients were compared with the scores from the patients receiving placebo using the Wilcoxon signed rank test. In the subgroup of patients with elevated markers of inflammation (i. e., elevated CRP or ESR levels), no correlation was observed between treatment with active medication and achievement of either response or remission.
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Table 2 Sutherland Disease Activity Index componentsa Stool frequency (%) P value
Rectal bleeding (%)
Mucosal appearance (%)
Physician’s rating (%)
0.063
0.37
0.087
0.17
BBIC (improved/treated)
7/14 (50)
5/14 (36)
7/14 (50)
7/14 (50)
Placebo (improved/treated)
5/14 (41)
3/14 (21)
5/14 (36)
4/14 (29)
a
Presented are the number of patients with improved (final score – initial score > 0) and unimproved (final score – initial score £ 0). Patients who did not complete the trial had no final scores and were counted as being unimproved. Statistical analysis considered the initial and final scores, so only patients with final scores were included
Discussion The results presented here suggest that BBIC might have beneficial effects in UC patients. The anti-inflammatory activity of BBIC in UC is presumably due to the ability of BBI to inhibit the activity of proteases involved in inflammation, such as human elastase [13], human cathepsin G [13], and human mast cell chymase [15]. These proteases, which are released from activated immunocytes, can quickly cause severe proteolytic damage to the extracellular matrix. Serum contains inhibitors of these serine proteases to keep their potentially dangerous activities in check. BBI then, can augment the endogenous protease inhibitor activities in serum. In addition to the direct inhibition of the catalytic activity of certain proteases, BBI can also inhibit the activation of numerous other proteases present in serum and tissues as inactive zymogens [8]. This activity of BBI may explain its ability to almost abolish the activity of proteases present in UC lesions [11]. Soy BBI is an 8-kDa protein. Fourteen of its 71 amino acid residues are cysteines, which form seven intramolecular disulfide bonds. It is thought that this tightly disulfidebonded structure contributes to the high stability of BBI, which can withstand boiling temperatures without losing activity and can survive transit through the digestive tract [22, 23]. Studies performed with radiolabeled BBI indicate that approximately one half of the BBI administered orally is eliminated in the feces in an unaltered form, while the rest enters intestinal epithelial cells [24] or crosses the intestinal epithelium via a paracellular mechanism [22]. Three hours after oral administration, [125I]BBI is present in all major organs except the brain [22]. Rodent studies involving intravenous injection of [125I]BBI show that the most of the labeled inhibitor is cleared from the blood by 3 h, and that labeled inhibitor was undetectable by 24 h [25]. Some of the BBI excreted in the urine retains its protease inhibitory activity [22, 23]. Because extracting BBI to a high degree of purity has proven prohibitive in cost, BBIC was developed. BBIC is an extract of soybeans enriched in BBI, which has attenuated trypsin-inhibitory activity [17]. The potency of BBIC is measured by its ability to inhibit chymotrypsin, as
detailed in the methods section. BBIC was first developed as a cancer preventive agent, as BBI is a potent inhibitor of malignant transformation in vitro and a highly effective cancer-preventive agent in animals (for a review see [8]). Although this cancer prevention effect has not yet been demonstrated in a human clinical trial, it may be of benefit to UC patients; patients with UC have an associated risk of colon cancer that begins 8–10 years after diagnosis and increases by 0.5–1.0% per year thereafter. Bowman-Birk inhibitor concentrate has achieved Investigational New Drug (IND) status with the Food and Drug Administration. There are currently six INDs associated with clinical trials utilizing BBIC. To date, several human trials have been completed in patients with benign prostatic hyperplasia [7], oral leukoplakia [4–6], and the present study in patients with ulcerative colitis. Reduced prostate volume, reductions in serum levels of prostatespecific antigen and triglycerides, and increased sexual function were observed in benign prostatic hyperplasia patients given BBIC [7]. A decrease in total lesion area was observed in oral leukoplakia patients given BBIC [4]. In all the above-mentioned trials, no drug-related toxicity was observed. This trial represents the first use of a novel protease inhibitor, the Bowman-Birk inhibitor, as a treatment agent for inflammatory bowel disease. There is a report of another protease inhibitor, camostat mesilate, that was used to treat two patients with UC [3]. While the patients did experience some temporary relief of symptoms, the study was not blinded or placebo-controlled, and the use of camostat mesilate in UC patients has not been further investigated. Therefore, BBIC represents a novel class of therapeutic agents that may have potential benefit in the treatment of UC. The toxicity and adverse event profiles of ulcerative colitis patients taking BBIC were comparable to those of patients taking placebo. In addition, the advantages of using BBIC include that it is oral, safe, natural, and has a relatively rapid onset of efficacy. The results presented here suggest that there is benefit over placebo for achieving both a clinical response and induction of remission, although the results did not quite achieve statistical significance. The results were, however, sufficient to suggest that a larger multicenter,
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placebo-controlled trial should be undertaken to assess the efficacy and safety of BBIC for the induction and remission of disease in patients with UC. This trial is currently underway. The use of BBIC was associated with no serious AEs during the course of the study. The AEs that did occur were relatively minor and had no long-term consequences. These results have been paralleled in other studies evaluating BBIC, suggesting the short-term safety of BBIC. We observed no decrease in CRP or ESR in patients studied and observed no benefit of BBIC in patients with elevated CRP or ESR. We suspect this might be due to a lack of statistical power due to the relatively small sample size evaluated in this pilot study. In conclusion, the results presented here indicate that a soybean extract might be associated with the regression of disease in UC patients without apparent toxicity or adverse side effects. Acknowledgements This work was supported in part by NIH grant #R43 GM55469–02 to ProtoMed, Inc. Ann R. Kennedy has a financial interest (equity) in ProtoMed, Inc. Special thanks to Linda Hurd, R.N, M.S.N, and E. J. DeMissie, R. N. for excellent clinical and technical support.
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