Comparison of two pancreatic enzyme products for exocrine insufficiency in patients with cystic fibrosis.

BACKGROUND: Zenpep (APT-1008) is a pancreatic enzyme product for the treatment of exocrine pancreatic insufficiency (EPI) associated with cystic fibrosis (CF). METHODS: Zenpep and Kreon, both containing 25,000 lipase units, were compared in a randomised, double-blind, crossover, non-inferiority study for CF-associated EPI in patients aged ≥12years. Patients on a standardised diet and stabilised treatment were randomised to two treatment sequences: Zenpep/Kreon or Kreon/Zenpep. The primary efficacy endpoint was the coefficient of fat absorption over 72h (CFA-72h). RESULTS: 96 patients (mean age 19.2years, 60.4% males) were randomised with 83 completers of both sequences comprising the efficacy population. Zenpep demonstrated non-inferiority and equivalence to Kreon in fat absorption (LS mean CFA-72h: Zenpep, 84.1% [SE 1.1] vs. Kreon, 85.3% [SE 1.1]; p=0.297). Safety and tolerability were similar. CONCLUSIONS: Zenpep is comparable with Kreon in efficacy and safety for the treatment of adolescents and adults with CF-associated EPI. NCT01641393.

The impact of abdominal pain on global measures in patients with chronic idiopathic constipation, before and after treatment with linaclotide: a pooled analysis of two randomised, double-blind, placebo-controlled, phase 3 trials.

BACKGROUND: Few clinical trials in chronic idiopathic constipation (CIC) patients have evaluated abdominal symptom severity and whether CIC patients with abdominal symptoms respond similarly to patients with limited abdominal symptoms. AIMS: To examine abdominal symptom severity and relationships between symptoms and global measures at baseline; compare linaclotide's effect on symptoms in subpopulations with more or less abdominal pain; and assess relationships between symptom improvement and global measures in these two subpopulations. METHODS: In two phase 3 trials, patients meeting modified Rome II CIC criteria were assigned to linaclotide 145 µg, 290 µg, or placebo once daily. Patients rated abdominal and bowel symptoms daily during 2-week pre-treatment and 12-week treatment periods. Linaclotide's effect on symptoms and global measures [constipation severity, health-related quality of life (HRQOL), treatment satisfaction] and their inter-relationships were assessed in post hoc analyses of abdominal pain subpopulations. RESULTS: Of 1271 CIC patients, 23%, 32%, and 43% reported moderate-to-severe abdominal pain, discomfort, and bloating, respectively, during baseline. In more-severe abdominal pain patients, abdominal symptoms were more strongly correlated than bowel symptoms with global measures, but in less-severe abdominal pain patients, abdominal and bowel symptoms were similarly correlated with global measures, at baseline and post-treatment. Linaclotide significantly improved all symptoms and global measures in both subpopulations. CONCLUSIONS: When abdominal pain is present in CIC, abdominal and not bowel symptoms may drive patient assessments of constipation severity, HRQOL, and treatment satisfaction. Linaclotide (145 µg and 290 µg) is an effective treatment for both abdominal and bowel symptoms, even in CIC patients with more severe abdominal pain at baseline. (Clinicaltrials.gov: NCT00765882, NCT00730015).

Responders vs clinical response: a critical analysis of data from linaclotide phase 3 clinical trials in IBS-C.

BACKGROUND: US Food and Drug Administration (FDA) set a rigorous standard for defining patient responders in irritable bowel syndrome-C (IBS-C; i.e., FDA's Responder Endpoint) for regulatory approval. However, this endpoint's utility for health-care practitioners to assess clinical response has not been determined. We analyzed pooled IBS-C linaclotide trial data to evaluate clinically significant responses in linaclotide-treated patients who did not meet the FDA responder definition. METHODS: Percentages of FDA non-responders reporting improvement in abdominal pain, bowel function and/or global relief measures were determined using pooled data from two linaclotide Phase 3 IBS-C trials. KEY RESULTS: 1602 IBS-C patients enrolled; 34% of linaclotide-treated and 17% of placebo-treated patients met the FDA Responder Endpoint (p < 0.0001). Among FDA non-responders at week 12, 63% of linaclotide-treated patients reported their abdominal pain was at least somewhat relieved, compared with 48% of placebo-treated patients. For stool frequency, 62% of linaclotide-treated patients reported that they were at least somewhat improved at week 12, compared with 46% of placebo-treated patients. For global IBS symptoms, 65% of linaclotide-treated patients reported at least some IBS-symptom relief, 43% reported adequate relief of IBS symptoms, and 57% reported being satisfied with linaclotide treatment, vs placebo rates of 48%, 34%, and 41% respectively. CONCLUSIONS & INFERENCES: Most linaclotide-treated IBS-C patients who were FDA non-responders reported some improvement in abdominal pain and stool frequency, and global relief/satisfaction. In addition to the FDA Responder Endpoint, differing response thresholds and symptom-specific change from baseline should be considered by clinicians for a complete understanding of clinical response to linaclotide and other IBS-C therapies.

An evaluation of the FDA responder endpoint for IBS-C clinical trials: analysis of data from linaclotide Phase 3 clinical trials.

BACKGROUND: Our objective was to evaluate the performance of the Food and Drug Administration (FDA) Responder Endpoint for clinical trials in IBS-C, using data from two large Phase 3 clinical trials of linaclotide. The FDA interim endpoint requires that, for 50% of trial weeks, patients report ≥30% decrease in Abdominal Pain at its worst and (in the same week) an increase in Complete Spontaneous Bowel Movements (CSBMs) of ≥1 from baseline. METHODS: Anchor-based methodology was used to estimate thresholds of clinically meaningful change using symptom-specific patient rating of change questions (PRCQs) and symptom severity questions. The diagnostic accuracy of the FDA Responder Endpoint was assessed using sensitivity/specificity-based methods. KEY RESULTS: Using anchor-based methods, the estimates of the clinically meaningful improvement thresholds for Abdominal Pain ranged from 25.9% to 32.4% and thresholds for increase in weekly CSBM rate ranged from 1.4 to 1.6 CSBMs per week. Compared with the symptom-specific PRCQs for patient rating of relief, the FDA Responder Endpoint has a sensitivity of 60.7%, a specificity of 93.5%, and an accuracy of 82.0%. Changing the number of weeks required to be a responder or the percentage improvement in the Abdominal Pain criteria did not result in notable improvement in the accuracy of the FDA Responder Endpoint. CONCLUSIONS & INFERENCES: The FDA Responder Endpoint for IBS-C clinical trials represents clinically meaningful improvements in IBS-C symptoms for patients with excellent specificity and reasonable sensitivity.

Randomised clinical trials: linaclotide phase 3 studies in IBS-C - a prespecified further analysis based on European Medicines Agency-specified endpoints.

BACKGROUND: Treatment options that improve overall symptoms of irritable bowel syndrome with constipation (IBS-C) are lacking. AIM: A prespecified further analysis to evaluate the efficacy and safety of linaclotide, a guanylate cyclase C agonist, in patients with IBS-C, based on efficacy parameters prespecified for European Medicines Agency (EMA) submission. METHODS: Two randomised, double-blind, multicentre Phase 3 trials investigated once-daily linaclotide (290 µg) for 12 weeks (Trial 31) or 26 weeks (Trial 302) in patients with IBS-C. Prespecified primary endpoints were the EMA-recommended co-primary endpoints: (i) 12-week abdominal pain/discomfort responders [≥30% reduction in mean abdominal pain and/or discomfort score (11-point scales), with neither worsening from baseline, for ≥6 weeks] and (ii) 12-week IBS degree-of-relief responders (symptoms 'considerably' or 'completely' relieved for ≥6 weeks). RESULTS: Overall, 803 (Trial 31) and 805 patients (Trial 302) were randomised. A significantly greater proportion of linaclotide-treated vs. placebo-treated patients were 12-week abdominal pain/discomfort responders (Trial 31: 54.8% vs. 41.8%; Trial 302: 54.1% vs. 38.5%; P < 0.001) and IBS degree-of-relief responders (Trial 31: 37.0% vs. 18.5%; Trial 302: 39.4% vs. 16.6%; P < 0.0001). Similarly, significantly more linaclotide- vs. placebo-treated patients were responders for ≥13 weeks in Trial 302 (abdominal pain/discomfort: 53.6% vs. 36.0%; IBS degree-of-relief: 37.2% vs. 16.9%; P < 0.0001). The proportion of sustained responders (co-primary endpoint responders plus responders for ≥2 of the last 4 weeks of treatment) was also significantly greater with linaclotide vs. placebo in both trials (P < 0.001). CONCLUSION: Linaclotide treatment significantly improved abdominal pain/discomfort and degree-of-relief of IBS-C symptoms compared with placebo over 12 and 26 weeks. TRIAL REGISTRATION: ClinicalTrials.gov (identifiers: NCT00948818 and NCT00938717).

Sulindac inhibits neointimal formation after arterial injury in wild-type and apolipoprotein E-deficient mice.

Neointimal hyperplasia is a critical component of restenosis, a major complication of angioplasty and related therapeutic procedures. We studied the effects of hyperlipidemia and the nonsteroidal anti-inflammatory drugs, aspirin (acetyl-salicylic acid; ASA), and sulindac, on neointimal formation in a mouse femoral arterial injury model. At 2 months of age, normolipidemic, wild-type (WT), and hyperlipidemic, apolipoprotein E-deficient (apoE-/-) mice were divided into three treatment groups: Western-type diet (WD), WD + ASA (200 mg/kg food), and WD + sulindac (300 mg/kg food). After 1 week, mice underwent arterial injury and treatments were maintained for 4 weeks. Histomorphometry of the injured arteries showed striking effects of plasma cholesterol levels and drug treatment on neointimal hyperplasia. In the WD or WD + ASA groups, apoE-/- mice had twice the neointimal area than WT mice ( approximately 30,000 vs. 13,000 microm(2) per section; P < 0.0001). Compared with ASA or WD alone, sulindac treatment resulted in approximately 70% (P = 0.0001) and 50% (P = 0.01) reductions in the neointimal area in apoE-/- and WT mice, respectively. ASA, at a dose sufficient to inhibit platelet aggregation, did not affect neointimal formation in mice of either genotype. Evidence of macrophages was noted in the lesions of apoE-/- mice in the WD and WD + ASA groups, but remarkably, none was detectable with sulindac treatment, despite hyperlipidemia, suggesting early steps in the response to injury were abrogated. These results demonstrate sulindac reduces neointimal formation in both normolipidemic and hyperlipidemic settings and raise the possibility that similar benefits may be obtained in patients undergoing angioplasty and related procedures.

Is inhibition of cyclooxygenase required for the chemopreventive effect of NSAIDs in colon cancer? A model reconciling the current contradiction.

NSAIDs are powerful chemopreventive agents for colon cancer, but their mechanism of action remains unknown. Their best recognized pharmacological property is inhibition of the enzyme cyclooxygenase (COX), which catalyzes the synthesis of prostaglandins; however, additional effects are well documented. Current studies on the mechanism of the chemopreventive effect of NSAIDs lead to two contradictory conclusions: NSAIDs prevent colon cancer either by inhibiting the activity of COX, or through mechanisms that do not require COX inhibition. To resolve this apparent conflict, after examining several alternatives, we propose a model, which assumes that both mechanisms are correct but that they exert their effect either on different steps of the multistep process of colon carcinogenesis or on different control mechanisms. This postulated dual action of NSAIDs may explain their remarkable effectiveness in colon cancer prevention. Unraveling these mechanistic details can be very rewarding for the design of more refined approaches to cancer chemoprevention and for a deeper understanding of colorectal carcinogenesis.

The effect of lithocholic acid on proliferation and apoptosis during the early stages of colon carcinogenesis: differential effect on apoptosis in the presence of a colon carcinogen.

Lithocholic acid (LCA) is implicated in human and experimental animal carcinogenesis. Its effect on apoptosis and proliferation of the colonic epithelium was studied in a 1,2-dimethylhydrazine (DMH)-induced murine carcinogenesis model. Four groups of mice, control, LCA, DMH and DMH+LCA, were studied for 4 weeks, a period corresponding to early stages of carcinogenesis. Apoptosis (AI) and proliferation (PI) indices in the colon were determined by immunohistochemistry. LCA stimulated apoptosis [AI = 1.2 +/- 0.3% (all values are the mean +/- SEM) versus control 0.5 +/- 0.1%, P < 0. 05], as did DMH (4.3 +/- 0.8%, P < 0.02). DMH increased apoptosis at the base of the crypt nearly 50-fold, with no effect at the lumenal third. In mice receiving DMH, LCA suppressed apoptosis almost completely (0.1 +/- 0.03%); this suppression was complete at the lower two-thirds of the crypt (AI = 0) and 60% at the lumenal third. LCA increased proliferation (PI = 22.2 +/- 4.6% versus 15.4 +/- 1% in controls), but this did not reach statistical significance. DMH increased proliferation (PI = 34.6 +/- 2.3%, P < 0.01). In mice receiving DMH, proliferation (41 +/- 2.9%) was about two-thirds of the additive effect. LCA affected proliferation, mainly in the middle third of the crypt; DMH's effect was similar in distribution, but more pronounced. In mice receiving DMH, LCA shifts proliferation upward, extending it to the lumenal third of the crypt. LCA's main cell kinetic effect in the colon is on apoptosis; this effect differs in normal (stimulation) and pre-malignant colon (nearly complete suppression). LCA does not significantly stimulate proliferation in either normal or pre-malignant colon. The differential effect of LCA on apoptosis in the presence of a carcinogen partially explains its effect as a promoter on colon carcinogenesis in animal models, and may have important implications for human carcinogenesis.

Altered gastric epithelial cell kinetics in Helicobacter pylori-associated intestinal metaplasia: implications for gastric carcinogenesis.

We have compared apoptosis and proliferation in antral epithelium from individuals not infected with H. pylori (Hp), those with Hp-induced gastritis and those with Hp-induced gastritis containing areas of gastric intestinal metaplasia, the precursor lesion to gastric adenocarcinoma. Antral biopsies from 42 patients were assessed for evidence of Hp infection, severity of gastritis and intestinal metaplasia. Apoptosis was evaluated by the TUNEL assay and proliferation by Ki-67 immunohistochemistry and were expressed as apoptotic (AI) and proliferation (PI) indices. In the 31 Hp-positive (Hp(+)) patients, apoptosis and proliferation were increased compared with the 11 Hp-negative (Hp(-)) patients (AI = 1. 22 +/- 0.13% vs. 0.15 +/- 0.03%, p < 0.0001; PI = 24 +/- 1% vs. 13 +/- 2%, p < 0.0001). Increases were proportional to the severity of the inflammation. Within foci of intestinal metaplasia, in 9 of the Hp(+) patients, apoptosis was significantly reduced compared with surrounding gastritis (AI = 0.20 +/- 0.06% vs. 1.34 +/- 0.23%, p = 0. 0014), whereas proliferation was not altered (PI = 25.4 +/- 4% vs. 24.7 +/- 2%, p = 0.87), resulting in a lower AI/PI ratio in intestinal metaplasia than in surrounding gastritis (0.008 +/- 0.005 vs. 0.054 +/- 0.009, p < 0.02). Hp-induced gastritis is thus associated with increased epithelial apoptosis and proliferation compared with uninfected controls. In intestinal metaplasia, proliferation remains increased but apoptosis reverts to normal levels, and this perhaps contributes to Hp-associated gastric carcinogenesis.

Role of diet and NSAIDs in the chemoprevention of colorectal cancer.

Colorectal cancer is a major public health problem. It is also one of the most preventable cancers. Although the colorectal cancer incidence and mortality in whites have been declining over the past 2 decades, these statistics are rising in nearly all ethnic minority groups. The development of colorectal cancer is influenced by exogenous factors, such as dietary constituents and drugs. While reputable data on the chemopreventive effects of diet and drugs, such as nonsteroidal anti-inflammatory drugs (NSAIDs), in specific minority groups are limited, evidence suggests that dietary factors may affect colorectal carcinogenesis in various ethnic minority groups. Clearly, more studies are necessary to resolve these questions. Because the risk of colorectal cancer is increasing in minority patients, they cannot wait for the results of such studies. Therefore, until definitive data are available, it is prudent for physicians to recommend that all individuals be screened for colorectal cancer according to accepted guidelines and to educate them regarding healthful eating habits that will prevent the development of colorectal cancer. Physicians should be particularly vigilant in recommending these approaches to minority patients. Patients should be advised to consume a well-balanced, low-fat, high-fiber diet that is rich in fruits and vegetables.

Nonsteroidal anti-inflammatory drugs and the induction of apoptosis in colon cells: evidence for PHS-dependent and PHS-independent mechanisms.

NSAIDs are potent chemopreventive agents for colon cancer. Although their mechanism of action is unknown, it probably relates to their modulation of colon epithelial cell kinetics, i.e. apoptosis and/or cell proliferation. NSAIDs are pleiotropic in their biochemical activities; their best known effect is inhibition of prostaglandin H synthase (PHS), the enzyme catalyzing the biosynthesis of prostaglandins. Current data appear to lead to two conflicting conclusions. One body of data indicates that PHS is important in induction of apoptosis and colon carcinogenesis and that its inhibition by NSAIDs is required for induction of apoptosis and their overall chemopreventive effect. Another set of data indicates that NSAIDs may induce apoptosis and prevent colon cancer without inhibiting the activity of PHS. Both sides of this argument are presented and discussed. This apparent contradiction may be resolved if one accepts that both mechanisms are correct but that they act on different steps of this multistep process.

Sulindac sulfide alters the expression of cyclin proteins in HT-29 colon adenocarcinoma cells.

Sulindac sulfide (SS), the active metabolite of the colon cancer chemopreventive compound sulindac, inhibits the proliferation of HT-29 colon cancer cells mainly by inducing cell quiescence. We determined by bivariate flow-cytometric analysis both the DNA and cyclin protein content of individual cells. Thus, we assessed in detail the expression of several cyclins during the cell-cycle phases and demonstrated that SS (i) decreases the expression of cyclins B1 and E and (ii) increases the expression of cyclins D1, D2 and D3, particularly in the G1 phase of the cell cycle. SS-induced apoptotic cells expressed both E- and D-type cyclins but not cyclin B1. The changes in cyclin expression combined with reduced catalytic activity of cyclin-dependent kinases could explain in molecular terms the anti-proliferative effect of SS on HT-29 colon cancer cells. These changes may contribute to the chemopreventive effect of sulindac.

Effect of aspirin on induction of apoptosis in HT-29 human colon adenocarcinoma cells.

Aspirin (ASA) and other nonsteroidal anti-inflammatory drugs (NSAIDs) inhibit colorectal tumorigenesis. Apoptosis is a critical determinant of tissue mass homeostasis and may play a role in carcinogenesis. We studied the effect of ASA on the survival of a human colon cancer cell line using more sensitive methods than we had applied previously. ASA induced apoptosis in HT-29 colon adenocarcinoma cells at concentrations > or =1 mM as established by: (a) morphological changes consistent with apoptosis in cells examined by fluorescence microscopy and semi-thin cell sections, and (b) DNA strand breaks: 45% of the cells were TdT-mediated dUTP nick end labeling (TUNEL) positive at 3 mM at 72 hr, and 70% were positive by the comet assay. Electron microscopy also confirmed the induction of apoptosis by ASA. ASA-induced apoptosis was not associated with: (a) a ladder pattern on genomic DNA electrophoresis, or (b) a subdiploid peak on flow cytometry. Apoptotic bodies were virtually absent on standard morphological assessments and only a few were detected on semi-thin sections. For the above reasons, this apoptosis induced by ASA is "atypical," and the unusual features of ASA-induced apoptosis, besides their taxonomic value, may offer clues to the mechanisms that control the process of apoptosis or perhaps the cancer chemopreventive properties of this compound. These findings demonstrate that ASA induces apoptosis in human colon cancer cells, bolstering the hypothesis that apoptosis may be a mechanism by which NSAIDs inhibit colon carcinogenesis. These findings should be examined in animal and/or clinical research studies in vivo.