ffectiveness and safety of ustekinumab dose escalation in Crohn’s disease: a multicenter observational study / Efectividad y seguridad del aumento de dosis de ustekinumab en la enfermedad de Crohn: un estudio observacional multicéntrico

Background: ustekinumab has proven effective in Crohn’s disease (CD). However, some patients will partially respond or lose response over time. Data supporting the effectiveness of dose escalation in this scenario is scarce. Aim: to evaluate the effectiveness of ustekinumab dose escalation in CD. Methods: patients with active CD (Harvey-Bradshaw ≥ 5) who had received intravenous (IV) induction and at least a subcutaneous (SC) dose were included in this retrospective observational study. Ustekinumab dose was escalated, either via shortening of the interval to six or four weeks or IV reinduction plus shortening to every four weeks. Results: ninety-one patients were included, and ustekinumab dose was escalated after a median of 35 weeks of treatment. At week 16 after intensification, steroid-free clinical response and remission were observed in 62.6 % and 25.3 % of patients, respectively. Systemic corticosteroids were discontinued in 46.7 % of patients who were on corticosteroids at baseline. Follow-up data beyond week 16 were available for 78 % of patients; at the last visit, 66.2 % and 43.7 % were in steroid-free clinical response and remission, respectively. After a median follow-up of 64 weeks, 81 % of patients were still treated with ustekinumab. Adverse events were reported in 4.3 % of patients; these were all mild and did not lead to hospitalization or discontinuation of treatment. Five patients (5.5 %) underwent surgical resection, with no immediate postsurgical complications. Conclusion: ustekinumab dose escalation was effective in recapturing response in over half of the patients. These findings suggest that dose escalation should be considered in patients who experience loss or partial response to the standard maintenance.(AU)

Tratamiento quirúrgico de estenosis duodenal secundaria a enfermedad de Crohn / Duodenal stenosis surgical treatment in Crohn’s disease

We present the case of a 34-year-old man with daily vomiting and 20% weight loss in a year. A gastroduodenoscopy was performed, noticing 2nd and 3rd duodenal portion dilatation and inflammatory involvement of the 3rd and 4th portion, causing luminal stenosis. These findings are the same than in the magnetic resonance . The biopsy proves the histological diagnosis of Crohn's disease. At the beginning the patient was treated with Prednisone, Adalimumab and Ustekinumab. After 9 months, surgery was decided because the disease was refractory to treatment and there was corticosteroid dependence. A partial resection of 3rd and 4th portion of the duodenum and the first loop of jejunum was performed, with duodenojejunal anastomosis. The patient presents good postoperative evolution and after 1 year he remained asymptomatic under treatment with Ustekinumab.(AU)

Systematic review with meta-analysis: loss of response and requirement of ustekinumab dose escalation in inflammatory bowel diseases.

BACKGROUND: Ustekinumab is effective in treating Crohn's disease (CD) and ulcerative colitis (UC). However, the loss of response (LOR) to ustekinumab and the efficacy of dose escalation have not been systematically explored. METHODS: Databases were searched for eligible studies from inception through July 2021. Summary estimates were pooled, and subgroup analyses were performed to explore heterogeneity. RESULTS: We included 14 studies (CD: 13; UC: 1). In CD patients, the annual risk of LOR to ustekinumab and dose escalation among primary responders was 21% (95% confidence interval [CI] 12-31%, 1530 person-years, n = 9) per person-year and 25% (95% CI 12-32%, 657 person-years, n = 5) per person-year respectively. Clinical response was regained in 58% (95% CI 49-67%, 279 patients, n = 8) of secondary non-responders after dose escalation (interval reduction or intravenous reinduction). In UC patients, no studies provided data on LOR, but only one study showed that 35% (100/284) of patients underwent dose escalation (or sham dose adjustment), leading to an annual risk of dose escalation of 18% per person-year. After dose escalation, 58% (14/24) of the patients regained symptomatic remission. CONCLUSIONS: Primary responders with CD experienced LOR to ustekinumab at a risk of 21% per person-year and required dose escalation at a risk of 25% per person-year. Fifty-eight per cent of secondary non-responders with CD may benefit from dose escalation. LOR has not been well characterized in patients with UC.

Safety evaluation of ustekinumab for moderate-to-severe ulcerative colitis.

INTRODUCTION: Ustekinumab is a human IgG1 kappa monoclonal antibody that targets the p40 subunit of interleukin (IL)-12 and IL-23 and blocks the binding of these cytokines to the IL-12Rß1 chain of their receptors. Ustekinumab is approved for treating moderate-to-severe ulcerative colitis (UC). AREAS COVERED: We reviewed the mechanism of action, pharmacokinetics, efficacy, and safety of ustekinumab. Future challenges for optimizing UC treatment with ustekinumab are discussed. EXPERT OPINION: Ustekinumab has favorable clinical efficacy and safety profiles for moderately-to-severely active UC. Ustekinumab is the first biologic for targeting IL-12/IL-23 pathways. Therefore, ustekinumab can be a therapeutic option following the failure of other biologics, including anti-tumor necrosis factor-α antagonists and anti-α4ß7 integrin antagonists. However, the positioning of ustekinumab in the therapeutic strategy for UC remains unclear. The efficacy of combinations of ustekinumab and immunomodulators over ustekinumab monotherapy has not been supported in studies. Ustekinumab is a human immunoglobulin G monoclonal antibody with low immunogenicity. Therefore, ustekinumab monotherapy, which should be safe, could be sufficient for treating UC. Further studies are required to understand the efficacy and safety of ustekinumab in patients with UC, particularly in special situations, and to optimize UC treatment with ustekinumab.

Comparative efficacy and safety of biologic therapies for moderate-to-severe Crohn's disease: a systematic review and network meta-analysis.

BACKGROUND: Data are needed to inform the positioning of biologic therapy in the treatment of moderate-to-severe Crohn's disease, both first line and after previous biologic exposure. We aimed to assess the comparative efficacy and safety of biologics in patients with Crohn's disease. METHODS: We did a systematic review and network meta-analysis of phase 2 and phase 3 randomised controlled trials done in adults (≥18 years) with moderate-to-severe Crohn's disease (Crohn's Disease Activity Index [CDAI] 220-450) treated with tumour necrosis factor (TNF) antagonists, anti-integrin, anti-interleukin (IL)-12 and IL-23p40, or anti-IL23p19 agents, either alone or in combination with immunosuppressants, as their first-line biologic or after previous biologic exposure, compared with placebo or an active comparator. The minimum duration of therapy was 14 days for trials reporting induction of remission in active disease and 22 weeks in trials reporting maintenance of remission. We searched Medline, EMBASE, the Cochrane CENTRAL Register of Controlled Trials, conference proceedings, trial registries, and unpublished data from inception to June 3, 2021, without any language restrictions. Summary estimates of the primary and secondary outcomes were extracted from the published reports; individual patient-level data were not sought. The primary endpoint was induction of clinical remission in patients with active disease (CDAI <150) and maintenance of remission in patients with response to induction therapy, with data extracted from published reports. A network meta-analysis with multivariate consistency model random-effects meta-regression was done, with rankings based on surface under the cumulative ranking curve (SUCRA) values. FINDINGS: The search strategy yielded 18 382 citations, of which 31 trials were eligible for inclusion. On the basis of 15 randomised controlled trials including 2931 biologic-naive patients, infliximab monotherapy (odds ratio [OR] 4·53 [95% CI 1·49-13·79]), infliximab combined with azathioprine (7·49 [2·04-27·49]), adalimumab (3·01 [1·25-7·27]), and ustekinumab (2·63 [1·10-6·28]) were associated with significantly higher odds of inducing remission compared to certolizumab pegol (all moderate confidence); infliximab and azathioprine combination therapy was also associated with significantly higher odds of inducing remission than vedolizumab (3·76 [1·01-14·03]; low confidence). On the basis of ten randomised controlled trials including 2479 patients with previous biologic exposure, adalimumab after loss of response to infliximab (OR 2·82 [95% CI 1·20-6·62]; low confidence), and risankizumab (2·10 [1·12-3·92]; moderate confidence), were associated with higher odds of inducing remission than vedolizumab. No differences between active interventions were observed in maintenance trials. Most trials were at low or uncertain risk of bias. INTERPRETATION: Although biologic treatment choices in patients with moderate-to-severe Crohn's disease must be individualised for each patient, this analysis suggests that either infliximab with azathioprine or adalimumab might be preferred as a first-line therapy, and adalimumab (after infliximab loss of response) or risankizumab might be preferred as a second-line therapy, for induction of clinical remission. FUNDING: None.

Ustekinumab as the First Biological Agent for Crohn's Disease in a 10-Year-Old Girl.

Pediatric inflammatory bowel disease is associated with growth failure due to chronic inflammation, nutrient disorder, and the side effects of drugs, such as corticosteroids. Biological agents are therapeutic drugs that significantly improve the prognosis of patients with inflammatory bowel disease. The effectiveness of ustekinumab has been reported in the management of adult patients with inflammatory bowel disease. There are very few reports regarding the effectiveness and safety of ustekinumab in pediatric patients with inflammatory bowel disease, especially those who are biologically naive. A 10-year-old girl presented with chronic abdominal pain, diarrhea, and weight loss. Colonoscopy showed a longitudinal ulcer and cobblestone appearance in the ileum and discontinuous inflammation of the colon; therefore, she was diagnosed with Crohn's disease. She was prescribed a fat-restricted diet, elemental diet, 5-aminosalicylic acid, transient prednisolone, and ustekinumab. She achieved clinical and endoscopic remission based on the weighted Pediatric Crohn's Disease Activity Index, fecal calprotectin, and colonoscopy findings at week 75. This patient developed no adverse events, such as infusion reaction or susceptibility to infection over the 75 weeks. The use of ustekinumab as the first biological agent may be an effective and safe treatment for pediatric Crohn's disease.

Mucosal IL23A expression predicts the response to Ustekinumab in inflammatory bowel disease.

BACKGROUND: Biologics against tumor necrosis factor-α (TNF) and the p40 subunit of interleukin (IL)-12 and IL-23 are increasingly used in inflammatory bowel disease (IBD) treatment. However, information on response prediction to these agents is limited. Thus, we aimed to identify factors for IBD treatment response prediction. METHODS: We conducted a retrospective study in 33 IBD subjects for anti-TNF and a prospective study of 23 IBD and 11 non-IBD subjects for ustekinumab (UST). Mucosal biopsy specimens were obtained before treatment with biologics. The expression of 18 immune-related genes encoding representative cytokines and transcription factors was analyzed by quantitative polymerase chain reaction. RESULTS: There was no difference between the treatment-resistant and -sensitive groups with regard to clinical characteristics. A higher expression of oncostatin M (OSM) and its receptor OSMR in the intestinal mucosa was most strongly associated with anti-TNF resistance, whereas lower IL23A expression was most strongly associated with UST resistance. In addition to the absolute expression levels of genes, concordant or discordant expression patterns of particular gene sets were associated with treatment sensitivity and resistance. CONCLUSIONS: The association of anti-TNF resistance and mucosal OSM and OSMR expression was consistent with the results of a previous study in a European cohort. Our observation that IBD subjects with higher mucosal IL23A expression were more likely to achieve remission by UST has not been previously reported. The response to biologics may thus be predicted in IBD patients through the analysis of mucosal gene expression levels and patterns.

The impact of ustekinumab on extraintestinal manifestations of Crohn's disease: A post hoc analysis of the UNITI studies.

This post hoc analysis of the UNITI studies found ustekinumab (UST) did not significantly improve overall extraintestinal manifestations (EIMs) of Crohn's disease compared to placebo-treated patients at weeks 6 and 52. BACKGROUND AND AIMS: The UNITI trials demonstrated that UST was effective in inducing and maintaining clinical remission in Crohn's disease (CD). However, limited data exists regarding its effectiveness for treatment of EIMs. This post hoc analysis evaluated the efficacy of UST in treatment of EIMs. METHODS: Data from UNITI-1/2 and IM-UNITI (NCT01369329, NCT01369342, NCT01369355) were obtained from the Yale Open Data Access Project (2019-4104). Nine hundred and fourty-one patients eligible for UST induction and 263 patients eligible for maintenance UST were included. The primary outcome of interest was EIM resolution at Week 6 in UST and placebo-treated patients using the chi-square test. EIM resolution at Week 52 was also assessed. McNemar's test was used to compare the proportion of patients who reported active EIMs at weeks 6 and 52 versus baseline. RESULTS: From 941 UST-treated patients in UNITI-1/2, 504 had 527 EIMs at baseline. Overall, there was no significant difference in EIM resolution observed in UST-treated patients (186/504, 36.9%) compared to placebo (90/230, 39.1%; p = 0.564) at Week 6. Patients treated with continuous UST (91/119, 76.4%) had no significant difference in overall EIMs resolved at Week 52 compared to placebo (72/90, 80.0%; p = 0.542). Although many EIMs demonstrated reduction in prevalence compared to baseline at initiation of UST, only erythema nodosum was more likely to improve at Week 52 on treatment versus placebo. CONCLUSION: Overall, UST did not lead to significant resolution of EIMs for CD compared to placebo at weeks 6 and 52.

Ustekinumab is more effective than azathioprine to prevent endoscopic postoperative recurrence in Crohn's disease.

BACKGROUND: Preventing postoperative recurrence (POR) is a major concern in Crohn's disease (CD). While azathioprine is an option, no data is available on ustekinumab efficacy in this situation. AIMS: We compared the effectiveness of ustekinumab versus azathioprine in preventing endoscopic POR in CD. METHODS: We retrospectively collected data from all consecutive CD patients treated with ustekinumab after intestinal resection in 9 centers. The control group (azathioprine alone) was composed of patients who participated in a randomized controlled trial conducted in the same centers comparing azathioprine alone or in combination with curcumin. Propensity score analyses (inversed probability of treatment weighting = IPTW) were applied to compare the two groups. The primary endpoint was endoscopic POR (Rutgeerts' index ≥ i2) at 6 months. RESULTS: Overall, 32 patients were included in the ustekinumab group and 31 in the azathioprine group. The propensity score analysis was adjusted on the main risk factors (smoking, fistulizing phenotype, prior bowel resection, resection length >30 cm and ≥2 biologics before surgery) and thiopurines or ustekinumab exposure prior to surgery making the two arms comparable (∣d∣ < 0.2). After IPTW, the rate of endoscopic POR at 6 months was lower in patients treated with ustekinumab compared to azathioprine (28.0% vs. 54.5%, p = 0.029). After IPTW, the rates of i2b-endoscopic POR (Rutgeerts' index ≥ i2b) and severe endoscopic POR (Rutgeerts' index ≥ i3) were 20.8% versus 42.5% (p = 0.066) and 16.9% versus 27.9% (p = 0.24), in the ustekinumab and azathioprine groups, respectively. CONCLUSION: Ustekinumab seemed to be more effective than azathioprine in preventing POR in this cohort of CD patients.

Effectiveness and Safety of Ustekinumab in Ulcerative Colitis: Real-world Evidence from the ENEIDA Registry.

BACKGROUND AND AIMS: The development programm UNIFI has shown promising results of ustekinumab in ulcerative colitis [UC] treatment which should be confirmed in clinical practice. We aimed to evaluate the durability, effectiveness, and safety of ustekinumab in UC in real life. METHODS: Patients included in the prospectively maintained ENEIDA registry, who received at least one intravenous dose of ustekinumab due to active UC [Partial Mayo Score [PMS]>2], were included. Clinical activity and effectiveness were defined based on PMS. Short-term response was assessed at Week 16. RESULTS: A total of 95 patients were included. At Week 16, 53% of patients had response [including 35% of patients in remission]. In the multivariate analysis, elevated serum C-reactive protein was the only variable significantly associated with lower likelihood of achieving remission. Remission was achieved in 39% and 33% of patients at Weeks 24 and 52, respectively; 36% of patients discontinued the treatment with ustekinumab during a median follow-up of 31 weeks. The probability of maintaining ustekinumab treatment was 87% at Week 16, 63% at Week 56, and 59% at Week 72; primary failure was the main reason for ustekinumab discontinuation. No variable was associated with risk of discontinuation. Three patients reported adverse events; one of them had a fatal severe SARS-CoV-2 infection. CONCLUSIONS: Ustekinumab is effective in both the short and the long term in real life, even in a highly refractory cohort. Higher inflammatory burden at baseline correlated with lower probability of achieving remission. Safety was consistent with the known profile of ustekinumab.

Real-life efficacy and safety of Ustekinumab as second- or third-line therapy in Crohn's disease: results from a large Italian cohort study.

OBJECTIVE: Ustekinumab (UST) is an anti-IL12/23 antibody for the treatment of Crohn's Disease (CD). The aim of this study was to compare the efficacy and safety of UST in a large population-based cohort of CD patients who failed previous treatment with other biologics. PATIENTS AND METHODS: 194 CD patients (108 males and 86 females, mean age 48 years (range 38-58 years) were retrospectively reviewed. 147 patients were already treated with anti-TNFα (75.8%), and 47 (24.2%) patients were already treated with anti-TNFα and vedolizumab. Concomitant treatment with steroids was present in 177 (91.2%) patients. RESULTS: At week 12, clinical remission was achieved in 146 (75.2%) patients. After a mean follow-up of 6 months, clinical remission was maintained in 135 (69.6%) patients; at that time, mucosal healing was assessed in 62 (31.9%) patients, and it was achieved in 33 (53.2) patients. Three (1.5%) patients were submitted to surgery. Steroid-free remission was achieved in 115 (59.3%) patients. Both serum C-Reactive Protein and Fecal Calprotectin (FC) levels were significantly reduced with respect to baseline levels during follow-up. A logistic regression, UST therapy as third-line therapy (after both anti-TNFα and vedolizumab), FC >200 µg/g, and HBI ≥8 were significantly associated with lack of remission. Adverse events occurred in 5 (2.6%) patients, and four of them required suspension of treatment. CONCLUSIONS: UST seemed to be really effective and safe in CD patients unresponsive to other biologic treatments, especially when used as second-line treatment.

Evaluation of ustekinumab trough levels during induction and maintenance therapy with regard to disease activity status in difficult to treat Crohn disease patients.

ABSTRACT: Ustekinumab (UST) is approved for the treatment of moderate and severe Crohn disease (CD). Therapeutic drug monitoring (TDM) can help monitor the therapeutic effects of biologics. Therefore, the aim of this study was to evaluate the clinical outcomes of UST-treated CD patients and to determine the UST trough level in clinical and corticosteroid-free remission.This retrospective study included patients with moderate and severe active disease (AD) treated intravenously with a weight-adapted induction dose of UST. The maintenance therapy consisted of 90 mg UST subcutaneously at week 8 and thereafter every 8 or 12 weeks, depending on the clinical response. Clinical and corticosteroid-free remission, Harvey-Bradshaw-Index (HBI), UST trough level, and further laboratory parameters were measured just before the injection of UST at each follow-up evaluation until week 40.37 CD patients with a median HBI of 9 at week 0 were included in the study. Starting from 24% at the beginning of the monitoring period, and 38% of patients at the end of the monitoring period were treated with an 8-week interval (P = .18). There was a significant improvement in clinical (P = .0004), corticosteroid-free remission (P = .03), and HBI (P < .0001) from week 0 until the end of the observation period. The serum UST trough level decreased significantly from 2.0 at week 8 to 0.3, in the maintenance therapy and 0.4 µg/ml at the end of the therapy (P < .0001). Neither UST trough level nor levels of C-reactive protein (CRP) or fecal calprotectin (FC) were associated with disease outcome. Concomitant immunomodulator therapy did not appear to affect the UST trough level or clinical course.UST is an effective treatment option for difficult-to-treat patients with CD. UST trough levels may not be associated with treatment efficacy or the prediction of treatment outcomes in patients with CD. Further prospective randomized trials should be conducted to evaluate whether UST trough levels are associated with treatment outcomes in patients with CD.

Novel signatures associated with systemic lupus erythematosus clinical response to IFN-α/-ω inhibition.

OBJECTIVES: We aimed to identify transcriptional gene signatures predictive of clinical response, for pharmacodynamic evaluation, and to provide mechanistic insight into JNJ-55920839, a human IgG1κ neutralizing mAb targeting IFN-α/IFN-ω, in participants with systemic lupus erythematosus (SLE). METHODS: Blood samples were obtained from SLE participants at baseline and up to Day 130, who received six 10 mg/kg IV doses of JNJ-55920839/placebo every 2 weeks. Participants with mild-to-moderate SLE who achieved clinical responses using SLE Disease Activity Index 2000 Responder Index 4-point change were considered responders. Transcriptional signatures from longitudinally collected blood were generated by RNA-Seq; signatures were generated by microarray from baseline blood samples exposed in vitro to JNJ-55920839 versus untreated. RESULTS: Two gene signatures (IFN-I Signaling and Immunoglobulin Immune Response) exhibited pharmacodynamic changes among JNJ-55920839 responders. The Immunoglobulin signature, but not the IFN-I signature, was elevated at baseline in JNJ-55920839 responders. A gene cluster associated with neutrophil-mediated immunity was reduced at baseline in JNJ-55920839 responders, substantiated by lower neutrophil counts in responders. An IFN-I signature was suppressed by JNJ-55920839 in vitro treatment versus untreated blood to a greater extent in responders before in vivo dosing. CONCLUSIONS: These signatures may enable enrichment for treatment responders when using IFN-I-suppressing treatments in SLE.

Ustekinumab in bio-naïve and bio-failure Crohn's disease patients: Results from a « real-life ¼ monocentric cohort.

BACKGROUND: The pivotal clinical trials have largely demonstrated the efficacy and safety of ustekinumab in Crohn's disease. Real-life cohorts published so far only include very few bio-naïve patients. This study assesses effectiveness and safety of ustekinumab in bio-naïve and bio-failure patients treated with ustekinumab in routine practice and look for predictors of response. METHODS: We performed a retrospective monocentric study. Initial response was assessed by maintenance therapy beyond week 16. Sustained response was assessed by the continuation or cessation of therapy over time for another reason than stopping in sustained remission. Treatment persistence was assessed by Kaplan Meier curves and predictors of treatment persistence were studied by univariate and multivariate Cox model. RESULTS: Out of 156 recorded patients, three patients were still in their induction phase at time of analysis and 5 patients were lost to follow-up, leaving 148 patients for clinical effectiveness analyses, including 35 bio-naïve when starting ustekinumab. A maintenance therapy was initiated in 79.7%. At one year, the probability to be still treated with ustekinumab was 73.8%. Treatment cessation increased with smoking in multivariate analysis. Previous biologic failure (as a whole), CRP and fecal calprotectin baseline levels did not influence initial response and treatment persistence. CONCLUSION: A large proportion of CD patients initially respond to ustekinumab and continue this treatment beyond one year. Treatment persistence is as high in bio-failure as in bio-naïve patients.

Continuation of Anti-TNF in Patients With Ulcerative Colitis in Remission Is Not Cost-effective Compared With Treatment Withdrawal: A Markov Model.

BACKGROUND AND AIMS: Anti-tumour necrosis factor alpha [anti-TNF] treatment accounts for 31% of health care expenditures associated with ulcerative colitis [UC]. Withdrawal of anti-TNF in patients with UC in remission may decrease side effects and infections, while promoting cost containment. Approximately 36% of patients relapse within 12-24 months of anti-TNF withdrawal, but reintroduction of treatment is successful in 80% of patients. We aimed to evaluate the cost-effectiveness of continuation versus withdrawal of anti-TNF in patients with UC in remission. METHODS: We developed a Markov model comparing cost-effectiveness of anti-TNF continuation versus withdrawal, from a health care provider perspective. Transition probabilities were calculated from literature, or estimated by an expert panel of 11 gastroenterologists. Deterministic and probabilistic sensitivity analyses were performed to account for assumptions and uncertainty. The cost-effectiveness threshold was set at an incremental cost-effectiveness ratio of €80,000 per quality-adjusted life-year [QALY]. RESULTS: At 5 years, anti-TNF withdrawal was less costly [-€10,781 per patient], but also slightly less effective [-0.04 QALY per patient] than continued treatment. Continuation of anti-TNF compared with withdrawal costs €300,390/QALY, exceeding the cost-effectiveness threshold. Continued therapy would become cost-effective if the relapse rate following anti-TNF withdrawal was ≥43% higher, or if adalimumab or infliximab [biosimilar] prices fell below €87/40 mg and €66/100 mg, respectively. CONCLUSIONS: Continuation of anti-TNF in UC patients in remission is not cost-effective compared with withdrawal. A stop-and-reintroduction strategy is cost-saving but is slightly less effective than continued therapy. This strategy could be improved by identifying patients at increased risk of relapse.

Immediate Infusion Reaction to Intravenous Ustekinumab in Three Crohn's Disease Patients: A Case Report and Review of the Literature.

Recently, ustekinumab has been approved for the treatment of Crohn's disease and ulcerative colitis. Treatment is started with an intravenous induction dose, followed by a subcutaneous dosage. We present details of three patients with therapy-refractory Crohn's disease who experienced an immediate infusion reaction to intravenous administration of ustekinumab. In two of these patients a subsequent reaction to subcutaneous injections occurred. Clinical features and pathophysiology are discussed.