MRI features indicative of permanent colon damage in ulcerative colitis: an exploratory study.

BACKGROUND AND AIMS: It is uncertain whether ulcerative colitis leads to accumulated bowel damage on cross sectional image. We aimed to characterize bowel damage in patients with ulcerative colitis using magnetic resonance imaging and determine its relation with duration of disease and the impact on patients' quality of life. METHODS: In this prospective study, subjects with ulcerative colitis in endoscopic remission underwent MRI without bowel cleansing and completed quality-of-life questionnaires. Subjects' magnetic resonance findings were analyzed considering normal values and thresholds determined in controls with no history of inflammatory bowel disease (n=40) and in patients with Crohn's disease with no history of colonic involvement (n=12). Subjects with UC were stratified according to disease duration (<7 years vs. 7‒14 years vs. >14 years). RESULTS: We analyzed 41 subjects with ulcerative colitis [20 women; Mayo endoscopic subscore 0 in 38 (92.7%) and 1 in 3 (7.3%)]. Paired segment-by-segment comparison of magnetic resonance findings in colonic segments documented of being affected by ulcerative colitis versus controls showed subjects with ulcerative colitis had decreased cross-sectional area (p≤0.0034) and perimeter (p≤0.0005), and increased wall thickness (p=0.026) in all segments. Colon damage, defined as wall thickness ≥3 mm, was seen in 22 (53.7%) subjects. Colon damage was not associated with disease duration or quality of life. CONCLUSIONS: Morphologic abnormalities in the colon were highly prevalent in patients with ulcerative colitis in the absence of inflammation. Structural bowel damage was not associated with disease duration or quality of life.

Clinical and treatment outcomes of a second subcutaneous or intravenous anti-TNF in patients with ulcerative colitis treated with two consecutive anti-TNF agents: data from the ENEIDA registry.

Background: Infliximab seems to be the most efficacious of the three available anti-TNF agents for ulcerative colitis (UC) but little is known when it is used as the second anti-TNF. Objectives: To compare the clinical and treatment outcomes of a second subcutaneous or intravenous anti-TNF in UC patients. Design: Retrospective observational study. Methods: Patients from the ENEIDA registry treated consecutively with infliximab and a subcutaneous anti-TNF (or vice versa), naïve to other biological agents, were identified and grouped according to the administration route of the first anti-TNF into IVi (intravenous initially) or SCi (subcutaneous initially). Results: Overall, 473 UC patients were included (330 IVi and 143 SCi). Clinical response at week 14 was 42.7% and 48.3% in the IVi and SCi groups (non-statistically significant), respectively. Clinical remission rates at week 52 were 32.8% and 31.4% in the IVi and SCi groups (nonsignificant differences), respectively. A propensity-matched score analysis showed a higher clinical response rate at week 14 in the SCi group and higher treatment persistence in the IVi group. Regarding long-term outcomes, dose escalation and discontinuation due to the primary failure of the first anti-TNF and more severe disease activity at the beginning of the second anti-TNF were inversely associated with clinical remission. Conclusion: The use of a second anti-TNF for UC seems to be reasonable in terms of efficacy, although it is particularly reduced in the case of the primary failure of the first anti-TNF. Whether the second anti-TNF is infliximab or subcutaneous does not seem to affect efficacy.

OBJECTIVES: To compare the clinical and treatment outcomes of a second subcutaneous or intravenous anti-TNF in UC patients. DESIGN: Retrospective observational study. METHODS: Patients from the ENEIDA registry treated consecutively with infliximab and a subcutaneous anti-TNF (or vice versa), naïve to other biological agents, were identified and grouped according to the administration route of the first anti-TNF into IVi (intravenous initially) or SCi (subcutaneous initially). RESULTS: Overall, 473 UC patients were included (330 IVi, 143 SCi). Clinical response at week 14 was 42.7% and 48.3% in the IVi and SCi groups (non-statistically significant), respectively. Clinical remission rates at week 52 were 32.8% and 31.4%, in the IVi and SCi groups (nonsignificant differences), respectively. A propensity-matched score analysis showed a higher clinical response rate at week 14 in the SCi group and higher treatment persistence in the IVi group. Regarding long-term outcomes, dose escalation and discontinuation due to the primary failure of the first anti-TNF and more severe disease activity at the beginning of the second anti-TNF were inversely associated with clinical remission. CONCLUSION: The use of a second anti-TNF for UC seems to be reasonable in terms of efficacy, although it is particularly reduced in the case of the primary failure of the first anti-TNF. Whether the second anti-TNF is infliximab or subcutaneous does not seem to affect efficacy.

Clinical and treatment outcomes of a second subcutaneous or intravenous anti-TNF in patients with ulcerative colitis treated with two consecutive anti-TNF agents. Data from the ENEIDA registry Background: Infliximab seems to be the most efficacious of the three available anti-TNF agents for ulcerative colitis (UC), but little is known when it is used as the second anti-TNF.

Real-World Evidence of Tofacinitib in Ulcerative Colitis: Short-Term and Long-Term Effectiveness and Safety.

INTRODUCTION: The objective of this study was to assess the durability, short-term and long-term effectiveness, and safety of tofacitinib in ulcerative colitis (UC) in clinical practice. METHODS: This is a retrospective multicenter study including patients with UC who had received the first tofacitinib dose at least 8 weeks before the inclusion. Clinical effectiveness was based on partial Mayo score. RESULTS: A total of 408 patients were included. Of them, 184 (45%) withdrew tofacitinib during follow-up (mean = 18 months). The probability of maintaining tofacitinib was 67% at 6 m, 58% at 12 m, and 49% at 24 m. The main reason for tofacitinib withdrawal was primary nonresponse (44%). Older age at the start of tofacitinib and a higher severity of clinical activity were associated with tofacitinib withdrawal. The proportion of patients in remission was 38% at week 4, 45% at week 8, and 47% at week 16. Having moderate-to-severe vs mild disease activity at baseline and older age at tofacitinib start were associated with a lower and higher likelihood of remission at week 8, respectively. Of 171 patients in remission at week 8, 83 (49%) relapsed. The probability of maintaining response was 66% at 6 m and 54% at 12 m. There were 93 adverse events related to tofacitinib treatment (including 2 pulmonary thromboembolisms [in patients with risk factors] and 2 peripheral vascular thrombosis), and 29 led to tofacitinib discontinuation. DISCUSSION: Tofacitinib is effective in both short-term and long-term in patients with UC. The safety profile is similar to that previously reported.

Predictors of bowel damage in the long-term progression of Crohn's disease.

BACKGROUND: Crohn's disease (CD) is a chronic inflammatory bowel disorder that progresses to bowel damage (BD) over time. An image-based index, the Lémann index (LI), has been developed to measure cumulative BD. AIM: To characterize the long-term progression of BD in CD based on changes in the LI and to determine risk factors for long-term progression. METHODS: This was a single-center longitudinal cohort study. Patients who had participated in prospective studies on the accuracy of magnetic resonance imaging using endoscopy as a gold standard and who had a follow-up of at least 5 years were re-evaluated after 5-12 years. RESULTS: Seventy-two patients were included. LI increased in 38 patients (52.8%), remained unchanged in 9 patients (12.5%), and decreased in 25 patients (34.7%). The small bowel score and surgery subscale significantly increased (P = 0.002 and P = 0.001, respectively), whereas the fistulizing subscale significantly decreased (P = 0.001). Baseline parameters associated with BD progression were ileal location (P = 0.026), CD phenotype [stricturing, fistulizing, or both (P = 0.007, P = 0.006, and P = 0.035, respectively)], disease duration > 10 years (P = 0.019), and baseline LI stricturing score (P = 0.049). No correlation was observed between BD progression and baseline clinical activity, biological markers, or severity of endoscopic lesions. CONCLUSION: BD, as assessed by the LI, progressed in half of the patients with CD over a period of 5-12 years. The main determinants of BD progression were ileal location, stricturing/fistulizing phenotype, and disease duration.

Impact of Biological Agents on Postsurgical Complications in Inflammatory Bowel Disease: A Multicentre Study of Geteccu.

BACKGROUND: The impact of biologics on the risk of postoperative complications (PC) in inflammatory bowel disease (IBD) is still an ongoing debate. This lack of evidence is more relevant for ustekinumab and vedolizumab. AIMS: To evaluate the impact of biologics on the risk of PC. METHODS: A retrospective study was performed in 37 centres. Patients treated with biologics within 12 weeks before surgery were considered "exposed". The impact of the exposure on the risk of 30-day PC and the risk of infections was assessed by logistic regression and propensity score-matched analysis. RESULTS: A total of 1535 surgeries were performed on 1370 patients. Of them, 711 surgeries were conducted in the exposed cohort (584 anti-TNF, 58 vedolizumab and 69 ustekinumab). In the multivariate analysis, male gender (OR: 1.5; 95% CI: 1.2-2.0), urgent surgery (OR: 1.6; 95% CI: 1.2-2.2), laparotomy approach (OR: 1.5; 95% CI: 1.1-1.9) and severe anaemia (OR: 1.8; 95% CI: 1.3-2.6) had higher risk of PC, while academic hospitals had significantly lower risk. Exposure to biologics (either anti-TNF, vedolizumab or ustekinumab) did not increase the risk of PC (OR: 1.2; 95% CI: 0.97-1.58), although it could be a risk factor for postoperative infections (OR 1.5; 95% CI: 1.03-2.27). CONCLUSIONS: Preoperative administration of biologics does not seem to be a risk factor for overall PC, although it may be so for postoperative infections.

Clinical outcome after anti-tumour necrosis factor therapy discontinuation in 1000 patients with inflammatory bowel disease: the EVODIS long-term study.

BACKGROUND: The long-term outcome of patients after antitumour necrosis factor alpha (anti-TNF) discontinuation is not well known. AIMS: To assess the risk of relapse in the long-term after anti-TNF discontinuation. METHODS: This was an extension of the evolution after anti-TNF discontinuation in patients with inflammatory bowel disease (EVODIS) study (Crohn's disease or ulcerative colitis patients treated with anti-TNFs in whom these drugs were withdrawn after achieving clinical remission) based in the same cohort of patients whose outcome was updated. Clinical remission was defined as a Harvey-Bradshaw index ≤4 points in Crohn's disease, a partial Mayo score ≤2 in ulcerative colitis and the absence of fistula drainage despite gentle finger compression in perianal disease. RESULTS: This was an observational, retrospective, multicenter study. A total of 1055 patients were included. The median follow-up time was 34 months. The incidence rate of relapse was 12% per patient-year (95% confidence interval [CI] = 11-14). The cumulative incidence of relapse was 50% (95% CI = 47-53): 19% at one year, 31% at 2 years, 38% at 3 years, 44% at 4 years and 48% at 5 years of follow-up. Of the 60% patients retreated with the same anti-TNF after relapse, 73% regained remission. Of the 75 patients who did not respond, 48% achieved remission with other therapies. Of the 190 patients who started other therapies after relapse, 62% achieved remission with the new treatment. CONCLUSIONS: A significant proportion of patients who discontinued the anti-TNF remained in remission. In case of relapse, retreatment with the same anti-TNF was usually effective. Approximately half of the patients who did not respond after retreatment achieved remission with other therapies.

Effectiveness and safety of methotrexate monotherapy in patients with Crohn's disease refractory to anti-TNF-α: results from the ENEIDA registry.

BACKGROUND: Methotrexate can be used to maintain remission in Crohn's disease patients who are intolerant to thiopurines. Data on its use as monotherapy in other scenarios are limited. AIM: To assess the effectiveness of methotrexate monotherapy in Crohn's disease patients after previous failure to anti-tumour necrosis factor (anti-TNFα) drugs. METHODS: A retrospective, observational multicentre study of data from the Spanish ENEIDA registry. Participants were patients with active Crohn's disease and previous failure to anti-TNFα started on methotrexate monotherapy. Short-term effectiveness was assessed at 12-16 weeks based on Harvey-Bradshaw index (HBI): clinical remission as HBI ≤ 3 points and clinical response as HBI drop of ≥ 3 points over baseline. Long-term effectiveness was defined as steroid-free methotrexate persistence from 12 to 16 weeks until maximum follow up. Adverse events were recorded. RESULTS: Data were compiled for 110 patients treated with methotrexate after a failed response to one (39%) or two (55.6%) anti-TNFα agents. Short-term clinical response and remission rates were 60% and 30.9% respectively. Of 74 patients who continued after week 16, long-term effectiveness was achieved in 82% and 74% at 12 and 24 months respectively. In the multivariate analysis, non-remission at short term (vs remission) was associated with long-term failure (HR 2.58, 95%CI 1.95-3.68, P = 0.028). Adverse events (evaluated in 100 patients) were recorded in 44%, and in 30.4% of these patients, they led to methotrexate discontinuation. CONCLUSIONS: The benefits observed suggest methotrexate monotherapy could be a valid option in Crohn's disease patients with previous failure to anti-TNFα.

Early treatment with anti-tumor necrosis factor agents improves long-term effectiveness in symptomatic stricturing Crohn's disease.

BACKGROUND: There is limited evidence on the effectiveness of biological therapy in stricturing complications in patients with Crohn's disease. AIM: The study aims to determine the effectiveness of anti-tumor necrosis factor (TNF) agents in Crohn's disease complicated with symptomatic strictures. METHODS: In this multicentric and retrospective study, we included adult patients with symptomatic stricturing Crohn's disease receiving their first anti-TNF therapy, with no previous history of biological, endoscopic or surgical therapy. The effectiveness of the anti-TNF agent was defined as a composite outcome combining steroid-free drug persistence with no use of new biologics or immunomodulators, hospital admission, surgery or endoscopic therapy during follow-up. RESULTS: Overall, 262 patients with Crohn's disease were included (53% male; median disease duration, 35 months, 15% active smokers), who received either infliximab (N = 141, 54%) or adalimumab (N = 121, 46%). The treatment was effective in 87% and 73% of patients after 6 and 12 months, respectively, and continued to be effective in 26% after a median follow-up of 40 months (IQR, 19-85). Nonetheless, 15% and 21% of individuals required surgery after 1 and 2 years, respectively, with an overall surgery rate of 32%. Postoperative complications were identified in 15% of patients, with surgical site infection as the most common. Starting anti-TNF therapy in the first 18 months after the diagnosis of Crohn's disease or the identification of stricturing complications was associated with a higher effectiveness (HR 1.62, 95% CI 1.18-2.22; and HR 1.55, 95% CI 1.1-2.23; respectively). Younger age, lower albumin levels, strictures located in the descending colon, concomitant aminosalicylates use or presence of lymphadenopathy were associated with lower effectiveness. CONCLUSIONS: Anti-TNF agents are effective in approximately a quarter of patients with Crohn's disease and symptomatic intestinal strictures, and 68% of patients are free of surgery after a median of 40 months of follow-up. Early treatment and some potential predictors of response were associated with treatment success in this setting.

Tacrolimus induces short-term but not long-term clinical response in inflammatory bowel disease.

BACKGROUND: Tacrolimus is a calcineurin inhibitor commonly used for prophylaxis of rejection in renal and liver transplantation. There are limited but favourable data regarding its possible use in patients with inflammatory bowel disease (IBD). AIMS: To evaluate the efficacy and safety of tacrolimus in patients with IBD in clinical practice. METHODS: We performed a retrospective, multicentre study in 22 centres in Spain. All adult patients who received oral tacrolimus for luminal or perianal IBD were included. Clinical response was assessed by Harvey-Bradshaw index and partial Mayo score after 3 months. Perianal disease was evaluated by fistula drainage assessment. RESULTS: One hundred and forty-three patients were included (mean age 38 years; 51% male; median disease duration 110 months). In ulcerative colitis (UC) (n = 58), the partial Mayo score decreased after 3 months from median 6 to 3 (P = 0.0001), whereas in Crohn's disease (CD) (n = 85), the Harvey-Bradshaw index decreased after 3 months from median 9 to 7 (P = 0.011). In CD patients, blood tacrolimus concentrations during induction (>10 ng/mL vs <10 ng/mL; odds ratio 0.23, 95% CI 0.05-0.87) and the concomitant use of thiopurines (odds ratio 0.18, 95% CI 0.04-0.81) were associated with lower clinical disease activity at 3 months. Of 62 patients with perianal disease, complete closure was observed in 8% (n = 5) of patients with perianal fistulas, with 34% (n = 21) showing partial response. Treatment was maintained for a median of 6 months (IQR, 2-16). After a median clinical follow-up of 24 months (IQR, 15-57), the rate of treatment-related adverse events was 34%, correlating with blood drug concentrations (P = 0.021). Finally, 120 patients (84%) discontinued tacrolimus, usually due to absence or loss of response. Three patients (2%) were subsequently diagnosed with cancer. The overall rate of surgery was 39%, with a 33% colectomy rate in UC. CONCLUSIONS: Tacrolimus shows a clinical benefit in both CD and UC after 3 months of treatment, but its long-term effectiveness and frequent adverse events remain relevant issues in clinical practice.

Validation of the Simplified Magnetic Resonance Index of Activity [sMARIA] Without Gadolinium-enhanced Sequences for Crohn's Disease.

BACKGROUND: Gadolinium-enhanced sequences are not included in the simplified Magnetic Resonance Index of Activity [sMARIA], but in the derivation of this index readers had access to these sequences. The current study aimed to validate the sMARIA without gadolinium-enhanced sequences for assessing disease activity, severity, and response to treatment in patients with Crohn's disease. METHODS: We prospectively included patients with active Crohn's disease and at least one segment with severe inflammation [ulcers] at ileocolonoscopy, who required treatment with biologic drugs. Patients were evaluated by both magnetic resonance enterography [MRE] and ileocolonoscopy at baseline and 46 weeks after initiation of medical treatment. We compared the quantification of disease activity and response to treatment with sMARIA versus with ileocolonoscopy Crohn's Disease Index of Severity [CDEIS], considered the gold standard. RESULTS: Data from both MRE and ileocolonoscopy 46 weeks after treatment initiation were available for 39 of the 50 patients. As in the derivation study, the optimal cutoffs were sMARIA ≥1 for predicting active disease (area under the curve [AUC] 0.92) and sMARIA ≥2 for predicting the presence of ulcers at ileocolonoscopy [AUC 0.93]. In evaluating the response to treatment, the sMARIA detected endoscopic ulcer healing at the segment level [sMARIA <2] with 89.5% sensitivity and 87.5% specificity. The sMARIA decreased significantly [p <0.001] in segments achieving endoscopic ulcer healing, but did not change [p = 0.222] in segments with persistent ulceration. CONCLUSIONS: The sMARIA is accurate and reliable in quantifying disease activity and response to treatment in luminal Crohn's disease, without the need for gadolinium-enhanced sequences.

JAK Inhibition: The Most Promising Agents in the IBD Pipeline?

Under current therapeutic algorithms, half of the patients with moderate-severe ulcerative colitis or Crohn's disease fail in achieving a sustained remission. New drugs with different mechanisms of action are needed. After two decades of new drug avenues in inflammatory bowel disease dominated by the development of monoclonal antibodies, in recent years we are witnessing promising developments of small molecules for these conditions. Their intrinsic characteristics make them attractive compared to the monoclonal antibodies based on their oral administration, short plasma half-life, lack of immunogenicity and predictable pharmacokinetics. Among them, Janus kinase (JAK) inhibitors are a promising new class that have demonstrated efficacy with a favorable safety profile in clinical trials. Tofacitinib has been the first JAK inhibitor approved for the treatment of ulcerative colitis. This review discusses the molecular aspects of the JAK-STAT pathway, its role in the pathogenesis of inflammatory bowel disease, and the rational use of JAK inhibitors in these conditions. The different compounds with JAK inhibitory activity tested are reviewed and we provide an overview of recent evidence from clinical trials. Finally, we consider the positioning of these drugs in the treatment of inflammatory bowel diseases.

Development and Validation of a Simplified Magnetic Resonance Index of Activity for Crohn's Disease.

BACKGROUND & AIMS: The magnetic resonance index of activity (MARIA) for Crohn's disease (CD) is used to assess the activity of luminal CD. However, it has a number of practical limitations. We aimed to develop and validate a simplified MARIA to more easily and quickly assess CD activity and response to therapy. PATIENTS AND METHODS: We performed a retrospective analysis of magnetic resonance imaging data from 98 participants in 2 studies. We used logistic regression analysis to identify magnetic resonance imaging parameters independently associated with CD endoscopic index of severity (CDEIS) scores (the reference standard). We validated the responsiveness and reliability of the simplified MARIA in an independent cohort of 37 patients who underwent magnetic resonance imaging and endoscopy before and after a therapeutic intervention. RESULTS: Logistic regression analysis showed that dichotomous qualitative assessment of wall thickening (>3 mm), presence of mural edema, perienteric fat stranding, and ulcers were independently associated with CDEIS scores; we used these factors to create a simplified MARIA. Simplified MARIA scores greater than 1 identified segments with active CD with 90% sensitivity and 81% specificity (area under the curve 0.91; 95% confidence interval 0.88-0.94). Simplified MARIA scores of 2 or more detected severe lesions (ulcers) with 85% sensitivity and 92% specificity (area under the curve 0.94; 95% confidence interval 0.91-0.96). For each patient, there was a high level of correlation between simplified MARIA scores and CDEIS scores (r = 0.83) and simplified MARIA scores and original MARIA scores (and r = 0.93) (P < .001). The simplified MARIA score accurately detected changes in lesion severity in response to therapy and was as reliable as endoscopy for the assessment of mucosal healing. CONCLUSION: We developed and validated a simplified MARIA for easier and faster assessment of CD activity and severity. This index identifies patients with a response to therapy with a high level of accuracy. These findings require confirmation in independent, multireader studies.

Persistent damage on magnetic resonance enterography in patients with Crohn's disease in endoscopic remission.

BACKGROUND: In Crohn's disease, it is essential to distinguish between persistent damage and abnormalities that can heal with anti-inflammatory therapy. AIM: To assess magnetic resonance enterography (MRE) lesions that persist in patients in long-standing endoscopic remission, analyse their relationship with baseline characteristics, and determine their prognostic implications. METHODS: We systematically reviewed pre- and post-treatment MRE findings in patients with Crohn's disease and severe inflammation (segmental CDEIS ≥ 7 or ulcers in at least one segment) who achieved endoscopic remission (CDEIS < 2) after 1 year of treatment with TNF-inhibitors or autologous haematopoietic stem-cell transplantation. Logistic regression analysis was used to identify predictors of persistent abnormalities. RESULTS: Endoscopic remission was achieved in 73 intestinal segments in 28 patients (69% females; 9.95 years disease duration, 67.9% inflammatory phenotype; 39.3% ileal location). Creeping fat and intestinal wall fat deposits were unchanged on pre- and post-treatment MRE despite the endoscopic remission. Luminal strictures persisted in 6 out of the 8 segments with baseline strictures, and wall thickening in 23 out of the 72 of segments with thickening at baseline. Predictors of persistent mural thickening were pre-treatment wall thickness > 5.9 mm (OR = 4.38, P = 0.027) and refractory disease prior to baseline (OR = 2.35, P = 0.001). Creeping fat was the only predictor for persistence of creeping fat (OR = 36.43, P < 0.001). Persistence of strictures at MRE is associated with earlier recurrence (P = 0.014). CONCLUSIONS: Persistent MRE abnormalities are frequent in patients with Crohn's disease despite achieving endoscopic remission. Significant wall thickening, intestinal fat deposition, strictures, and creeping fat at baseline MRE are signs of established damage.

Tofacitinib for the treatment of ulcerative colitis.

INTRODUCTION: New generations of small molecules are being developed for the treatment of ulcerative colitis. Among them, tofatinib (a Janus kinase (JAK) inhibitor) has demonstrated efficacy for inducing and maintaining remission and achieving mucosal healing with a reasonable safety profile. Oral administration is attractive for patients and lack of immunogenicity represents an advantage over biologic drugs. Areas covered: This review discusses the molecular aspects of the JAK-STAT pathway; the mechanism of action of tofacitinib pertinent to ulcerative colitis and the evidence on the efficacy of tofacitinib for achieving clinically relevant outcomes, including clinical remission, mucosal healing, and normalization of quality of life, as well as safety aspects with special attention to adverse events related to the mode of action of the drug. Expert commentary: Tofacitinib will be the first drug on the class of JAK inhibitors to be available for treatment of ulcerative colitis. The efficacy of the drug, with a rapid onset of action even in cases of severe colitis, oral administration, and possibility to use the drug intermittently without generating immunogenicity, will bring about a redesign of current treatment paradigms for ulcerative colitis.

Mesenchymal stromal cells in the treatment of perianal fistulas in Crohn's disease.

Significant unmet needs remain in patients with Crohn's disease and perianal fistulas. Mesenchymal stromal cells have potent immunomodulatory actions. The Phase II studies reported efficacy of local injection of mesenchymal stromal cells to achieve closure of fistulas. A Phase III trial demonstrated that in patients with Crohn's disease and refractory complex perianal fistulas, a single injection of 120 × 106 cells was superior to local injection of placebo associated with the same surgical procedure, in obtaining closure of the fistula tracts together with absence of abscesses >2 cm, 24 weeks after the injection, a stringent combined primary end point. The benefit over placebo was sustained 52 weeks after the single injection. The therapy is safe with adverse events limited to local pain.