Search Results (172)

Background: Mesenteric panniculitis (MP) is a chronic fibroinflammatory disorder of the mesenteric adipose tissue and is frequently considered an idiopathic condition. Its association with inflammatory bowel disease (IBD), particularly ulcerative colitis (UC), remains poorly characterized, with only limited evidence available in the literature. In addition to presenting a clinical case, we performed a narrative review of the literature regarding the relationship between MP and IBD, including epidemiology, pathophysiological mechanisms, diagnostic challenges, and therapeutic approaches. Case Presentation: We report the case of a 32-year-old woman with UC in deep clinical, endoscopic, and histological remission while receiving vedolizumab therapy, who developed symptomatic MP diagnosed by contrast-enhanced computed tomography. Infectious, neoplastic, and selected fibroinflammatory causes were excluded during the diagnostic work-up. Histological confirmation was not obtained. The patient was treated with prednisone and tamoxifen, resulting in complete clinical and radiological remission while vedolizumab therapy was continued. Conclusions: This case describes the rare co-occurrence of MP and UC in deep remission during ongoing vedolizumab treatment. Given the absence of histological confirmation and the frequently idiopathic nature of MP, a causal relationship with either UC activity or vedolizumab therapy cannot be established. The observation should therefore be regarded as hypothesis-generating. Further studies are required to clarify the potential relationship between MP, IBD, and biologic therapies. Full article

Background: Ulcerative colitis (UC) is a chronic inflammatory bowel disease associated with extraintestinal manifestations, including primary sclerosing cholangitis (PSC). Systemic lupus erythematosus (SLE) is a multisystem autoimmune disease that rarely coexists with UC or PSC. The concurrent occurrence of UC, PSC, and SLE in a single individual represents a unique diagnostic and therapeutic challenge. Vedolizumab, a gut-selective biologic agent, is effective for managing UC; however, its utility in patients presenting with this triad of conditions has not yet been explored. Case summary: A 32-year-old man presented with a 10-year history of recurrent upper abdominal pain, frequently accompanied by high-grade fever, along with recent onset of jaundice, diarrhea, hematochezia, and chronic rashes. Diagnostic evaluation confirmed PSC, SLE, and severe UC. During hospitalization, the patient also developed bacteremia. Initial management of UC with mesalazine and immunosuppressants (azathioprine followed by cyclosporine) resulted in limited clinical improvement. Vedolizumab was subsequently initiated, resulting in marked clinical improvements and near-complete endoscopic remission of UC. PSC and SLE remained clinically stable with ongoing therapies; however, the patient is currently awaiting liver transplantation for PSC. Conclusions: This case highlights the potential utility of vedolizumab in the treatment of UC in patients with concurrent PSC and SLE. Full article

Introduction: Live attenuated vaccines (LAVs) are generally avoided in patients with inflammatory bowel disease (IBD) receiving immunomodulatory therapy due to concerns about infection risk. However, real-world data evaluating their safety in this population remain limited. We aimed to assess adverse outcomes following LAV administration in IBD patients treated with biologic agents. Methods: We conducted a retrospective cohort study using the TriNetX multi-institutional database. Adults with IBD receiving immunomodulatory therapy were categorized into two cohorts: those who received an LAV and those who did not. Biologic therapies included tumor necrosis factor inhibitors (infliximab, and adalimumab), integrin antagonists (vedolizumab), interleukin (IL)-12/23 inhibitors (ustekinumab), IL-23 inhibitors (risankizumab, and guselkumab), and Janus kinase inhibitors (tofacitinib, and upadacitinib). LAVs included measles–mumps–rubella (MMR), varicella (Varivax), and yellow fever vaccines. Propensity score matching was performed based on age, sex, IBD subtype (Crohn’s disease vs. ulcerative colitis), and biologic class. Patients with outcomes prior to the risk window were excluded. Adverse outcomes within six months included hospitalization, emergency department (ED) visits, fever, rash, and encephalitis. Results: A total of 672 patients were included in each propensity-score-matched cohort. Live attenuated vaccine (LAV) administration was not associated with significantly increased adverse outcomes compared with no LAV exposure during the six-month follow-up period. Hospitalization occurred in 14.9% versus 15.3% of patients, respectively (risk ratio [RR] 0.97; 95% confidence interval [CI] 0.75–1.25; p = 0.819), while emergency department visits occurred in 12.6% vs 11.3% (RR 1.12; 95% CI 0.84–1.50; p = 0.450). There were no significant differences in fever (3.6% vs. 3.3%; RR 1.09; 95% CI 0.62–1.93; p = 0.764) or rash (4.0% vs. 2.7%; RR 1.50; 95% CI 0.83–2.70; p = 0.172). No cases of measles, mumps, rubella, varicella, yellow fever, or encephalitis were identified in either cohort during follow-up. Conclusions: LAVs were not associated with an increased risk of adverse outcomes within one day to six months among IBD patients receiving immunomodulatory therapy. These real-world findings suggest comparable short-term outcomes between the cohorts of patients with IBD receiving biologic or targeted synthetic therapy who met the predefined eligibility criteria including age ≥ 18 years, and vaccination occurring between two weeks and six months after biologic initiation regarding LAV use in patients with IBD receiving biologic agents. Full article

Bacteroides 2 (Bact2) is a dysbiotic enterotype often associated with susceptibility to developing diseases such as inflammatory bowel disease (IBD). Carriers of Bact2 are found to be less responsive to therapeutic treatments like vedolizumab. This enterotype is characterised by a large amount of Bacteroides, low diversity in bacteria, fewer butyrate-producing species, and generally a low abundance of microbes in the gut. However, it remains unclear whether this dysbiosis contributes to IBD pathology or if it is merely a result of inflammation in the gut. Due to its ability to influence treatment responses, it is crucial to understand the molecular mechanisms behind this enterotype, as well as the effect of diet on this dysbiosis. A high concentration of pro-inflammatory cytokine IL-1$\beta$ was found in the faecal water of Bact2 patients, as well as an abundance of conjugated bile acids, whereas butyrate was found in decreased amounts. Through the consumption of a less industrialised diet, it could be possible to shift away from a dysbiotic enterotype like Bact2. This includes the consumption of whole-grain carbohydrates to increase the growth of butyrate-producers and maintaining a low-fat diet to decrease bile acid production. Full article

Background: The optimal first-line biologic therapy for refractory ulcerative proctitis (UP) remains uncertain, largely because patients with UP are frequently excluded from biologic clinical trials, limiting evidence to guide treatment selection. This study evaluated outcomes among patients with UP treated with first-line TNF inhibitors or vedolizumab. Methods: We performed a retrospective cohort study using the TriNetX database between 1995 and 2023. Propensity score matching was applied to balance demographics, laboratory parameters, and baseline medications. Primary outcomes included corticosteroid use, all-cause emergency room (ER) visits and hospitalizations, and colectomy, assessed at 6, 12, and 24 months after initiation of TNF inhibitors or vedolizumab. Secondary outcomes described real-world biologic usage patterns in UP. Results: Among 641 patients with UP receiving advanced therapy, the most commonly used biologics were adalimumab (39%), infliximab (27%), and vedolizumab (26%). Ustekinumab was used in 12% of patients. In matched analyses, TNF inhibitor therapy was associated with reduced ER visits and hospitalizations at 6 and 12 months compared with vedolizumab (6 months: 14.3% vs. 25%, aOR 0.50, p-value 0.03; 12 months: 16.1% vs. 35.2%, aOR 0.35, p-value 0.01). By 24 months, no significant differences were observed. Corticosteroid use and colectomy rates were similar across therapies at all time points. In a subgroup comparison between adalimumab and vedolizumab, results were consistent with the primary analysis, with lower short-term ER visits and/or hospitalizations among patients receiving adalimumab. Conclusions: In this propensity-matched analysis, TNFi therapy was associated with lower short-term healthcare utilization, with no significant differences observed in corticosteroid use. These findings should be interpreted cautiously given nonspecific outcomes and potential residual confounding from unmeasured disease variables such as endoscopic activity. Full article

Background and Objectives: Despite surgical intervention for remission, recurrence is nearly inevitable in patients with Crohn’s disease (CD). While several maintenance therapies are available, the optimal strategy for preventing postoperative recurrence remains uncertain. Materials and Methods: This systematic review and network meta-analysis included placebo-controlled or head-to-head randomized controlled trials (RCTs) from MEDLINE, Embase, and Cochrane Central up to 4 July 2024. Studies assessed maintenance therapies for CD after curative resection. Data were extracted from intention-to-treat (ITT) and per-protocol (PP) analyses separately. The primary outcomes were endoscopic and clinical relapse. A Bayesian network meta-analysis provided risk ratios (RRs) and 95% confidence intervals (CIs). This study is registered with PROSPERO (CRD42024629013). Results: From 1492 screened records, 45 randomized controlled trials met the inclusion criteria. Compared with placebo, clinically significant prevention of clinical recurrence was achieved with adalimumab (RR = 0.17; GRADE High), nitroimidazoles (RR = 0.35; High), infliximab (RR = 0.59; Moderate), thiopurine analogs (RR = 0.41; Moderate), and high-dose mesalamine (RR = 0.74; High), while azathioprine-metronidazole combination therapy demonstrated superior efficacy to azathioprine monotherapy. For endoscopic recurrence mitigation, therapeutic efficacy was confirmed for adalimumab (RR = 0.24; Low), infliximab (RR = 0.32; Moderate), vedolizumab (RR = 0.36; Low), and thiopurine analogs (RR = 0.64; Moderate). Conclusions: This network meta-analysis establishes pharmacological hierarchies for preventing postoperative Crohn’s disease recurrence. Adalimumab is the most effective monotherapy for clinical recurrence prevention, while combination therapies of adalimumab/azathioprine plus nitroimidazole show superior efficacy. For endoscopic recurrence prevention, adalimumab also ranks as the most effective intervention. These findings guide therapy selection but require validation for newer agents through randomized trials. Full article

Introduction: Sequencing therapy for Crohn’s disease (CD) is currently being intensively discussed due to the development of novel drugs and lack of standardized criteria for drug positioning in first- and further-line treatment. The aim of this study was to compare the efficacy of a second-line advanced therapy in Romanian patients with CD who have failed an anti-TNF agent. Methods: We performed a multicenter retrospective study that included adult patients with CD who had secondary loss of response after an initial response with an anti-TNF drug. The main outcome was clinical remission at 12 weeks of second-line treatment (CDAI < 150). The secondary outcomes included clinical response (decrease in CDAI ≥ 70 points), persistence of therapy at 1 year and rates of adverse events. Results: From 2008 to 2024, 216 patients were either switched to another anti-TNF or swapped to another therapeutic class, due to the failure of a first anti-TNF drug. Secondary lines of treatment included infliximab (IFX), adalimumab (ADA), vedolizumab (VDZ), ustekinumab (UST). The highest rate of clinical remission (81%) was obtained with the sequence ADA-IFX in 26/32 (81%) patients and ADA-UST in 62/82 (76%) patients, followed by IFX-UST in 22/33 (67%) and IFX-ADA 34/51 (67%). Persistence in therapy at 1 year was better for the sequence ADA-UST (73%) and IFX-UST (67%) and ADA-IFX (63%) compared to IFX-ADA (59%) and IFX-VDZ (44%) (p < 0.001). Conclusions: There were significant baseline differences between the treatment groups, so this study represents an unadjusted comparison between the results obtained with different biologics in second-line treatment for Crohn’s disease. In patients with CD who have failed a first anti-TNF, the highest rate of clinical remission at 12 weeks was obtained with second-line IFX and UST whilst vedolizumab showed lower efficacy. UST demonstrated the most favorable long-term treatment persistence at 1 year. Full article

Background and Objectives: The vedolizumab clinical decision support tool (VDZ-CDST) was developed to predict treatment outcomes in inflammatory bowel disease (IBD). While validated in clinical trial and consortium settings, its real-world performance remains less clear. The aim of our study was to evaluate the predictive value of pre-treatment CDST stratification for clinical and endoscopic outcomes and treatment persistence in real-world VDZ-treated IBD patients. Materials and Methods: We conducted a retrospective analysis of consecutive IBD patients initiating vedolizumab therapy, stratified by CDST risk groups. Clinical remission (CR) and corticosteroid-free remission (CSFR) at weeks 14 and 52 were assessed using PRO-2 in both Crohn’s disease (CD) and ulcerative colitis (UC). Endoscopic outcomes and treatment persistence were also evaluated. Results: 129 IBD patients, 57 with CD and 72 with UC, treated with vedolizumab were retrospectively stratified according to VDZ-CDST. In CD at week 52 the differences in CSFR between CDST groups were statistically significant (p = 0.04). A statistically significant association (p < 0.001) was also observed between CDST groups and endoscopic activity (EA) at follow-up endoscopy. In the low-probability group 69.2% showed persistent EA, whereas in the high-probability group 68.8% achieved endoscopic remission (ER). We also found significant differences (p = 0.004 and p < 0.001, respectively) in treatment persistence between CDST groups in CD. VDZ discontinuation rates were 76.9%, 28.6%, and 6.3% in the low-, intermediate-, and high-response groups, respectively. In UC, no predictive association was observed for either clinical or endoscopic outcomes nor treatment persistence; however, we observed relatively high remission rates despite CDST-based stratification. Conclusions: Although the VDZ-CDST failed to predict CR measured by PRO-2 in real-world IBD patients, it demonstrated meaningful associations with long-term CSFR, endoscopic outcomes and treatment persistence in Crohn’s disease. These findings support its role as a supportive tool in therapeutic decision-making, particularly when objective outcomes such as mucosal healing are prioritized. Prospective multicentre studies incorporating biomarkers and pharmacokinetic data are needed to refine VDZ-CDST for broader clinical application. Full article

Background/Objectives: Immune checkpoint inhibitors (ICIs) have revolutionized the treatment of various malignancies, but their use is frequently accompanied by immune-related adverse events, among which immune-mediated colitis (IMC) represents one of the most common and clinically significant gastrointestinal toxicities. IMC may lead to treatment interruption, increased morbidity, and compromised quality of life. This review aims to provide a comprehensive overview of the pathophysiology, risk factors, diagnosis, management, and emerging therapeutic strategies with particular emphasis on the role of the gut microbiota and fecal microbiota transplantation (FMT). Methods: This review integrates current international guidelines, meta-analyses, clinical trials, and recent translational studies addressing IMC. The available evidence on immunological mechanisms, predictive biomarkers, clinical presentation, diagnostic algorithms, and treatment options was critically synthesized to outline a structured and multidisciplinary management approach. Results: IMC is driven by dysregulated immune activation, cytokine release, and alterations in gut microbiota. Incidence and severity vary according to ICI class, combination regimens, tumor type, and patient-related factors. Diagnosis requires exclusion of infectious causes, laboratory assessment, and endoscopic and histologic evaluation with CTCAE-based severity grading. Corticosteroids remain the cornerstone of first-line therapy, while infliximab and vedolizumab are effective in steroid-refractory cases. Emerging therapies, including JAK inhibitors and FMT, have shown promising results in refractory disease. Conclusions: IMC is a complex and potentially severe complication of ICI therapy that necessitates early recognition, accurate grading, and individualized, multidisciplinary management. Severity-guided treatment, timely escalation to biologics, and careful balancing of immunosuppression with antitumor efficacy are essential for optimal outcomes. Future research should focus on biomarker validation, microbiome-targeted therapies, and prospective trials to refine therapeutic algorithms and define the optimal role and timing of FMT in clinical practice. Full article

Immunotherapy with immune checkpoint inhibitors (ICIs) has represented a major breakthrough in the treatment of multiple solid and hematological malignancies, significantly improving survival and tumor control. However, the blockade of immune regulatory pathways such as cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) and programmed cell death protein 1/programmed death-ligand 1 (PD-1/PD-L1) is associated with the development of immune-related adverse events, among which immune-mediated colitis (IMC) constitutes one of the most relevant gastrointestinal complications due to its frequency, potential severity, and impact on the continuation of oncologic treatment. IMC typically presents with diarrhea, abdominal pain, and gastrointestinal bleeding, and may progress to severe, life-threatening forms. Its incidence varies according to the type of ICI, and is higher with CTLA-4 inhibitors and particularly elevated with combination therapies. The pathophysiology is complex and multifactorial, involving dysregulated activation of proinflammatory T lymphocytes, impairment of immune regulatory mechanisms, disruption of the intestinal epithelial barrier, and a key modulatory role of the gut microbiota. Diagnosis requires a high index of clinical suspicion and relies on endoscopy with biopsies, given the poor correlation between clinical severity and endoscopic or histological findings. Fecal biomarkers, such as calprotectin and lactoferrin, are useful for risk stratification and disease monitoring. Treatment is based on a stepwise immunosuppressive approach, with corticosteroids as first-line therapy and biologic agents such as infliximab or vedolizumab in refractory cases. Emerging strategies, including fecal microbiota transplantation, offer new therapeutic perspectives. This article provides a comprehensive review of the current evidence on the epidemiology, pathophysiology, diagnosis, and management of IMC, as well as future challenges and opportunities in its clinical management. Full article

Background: Perianal fistulizing Crohn’s disease (CD) is associated with significant morbidity and remains difficult to treat. Although advanced medical therapies are widely used, much of the available evidence derives from heterogeneous fistula populations or luminal CD trials, with limited perianal-specific synthesis and inconsistent outcome definitions. We conducted a systematic review focusing exclusively on perianal-specific clinical, radiologic, and composite outcomes in adults with perianal fistula (PAF) CD. Methods: We performed a systematic review in accordance with PRISMA 2020. Electronic databases were searched from inception through November 2025. We included randomized controlled trials and cohort studies enrolling adults with CD reporting outcomes specific to PAF. Interventions included biologics and small-molecule therapies, compared with placebo or other therapies. Due to substantial heterogeneity in outcome definitions and study designs, a meta-analysis was not performed. Risk of bias was assessed using Risk of Bias 2 (RoB 2) for randomized trials and the Newcastle–Ottawa Scale for observational studies. Results: Seven studies including >1200 participants with PAF-CD met inclusion criteria. Follow-up ranged from 24 weeks to 5 years. Across studies, outcome definitions and assessment modalities varied. Upadacitinib demonstrated significantly higher clinical fistula closure compared with placebo across multiple dose regimens at 52 weeks. In observational comparisons, ustekinumab and vedolizumab were associated with higher clinical closure rates than anti-TNF therapies. However, infliximab demonstrated higher closure rates than adalimumab as a first-line treatment. The definition for radiologic remission was less consistent across studies and often did not parallel clinical outcomes. Composite clinical–radiologic remission and response were reported in a limited number of studies, with filgotinib showing higher composite outcomes in comparison to placebo in a phase 2 trial. Surgical interventions, relapse outcomes, biomarkers [C-reactive protein (CRP)/fecal calprotectin (FCP)], and patient-reported outcomes were variably reported and not consistently significant across comparisons. Conclusions: Evidence for advanced therapies in PAF CD remains limited by heterogeneity in endpoint definitions, subjectivity in clinical observation, inconsistent radiologic reporting, and reliance on subgroup or observational comparisons. While anti-TNF therapy remains the most established option in guidelines, emerging data suggest significant benefits with ustekinumab, vedolizumab, and JAK inhibitors in selected patients. There is a need for PAF-specific, adequately powered randomized trials using standardized composite clinical and radiologic endpoints. Full article

Inflammatory bowel disease is a recognized risk factor for venous thromboembolism, whereas arterial thrombotic events remain underappreciated despite their substantial clinical consequences. We report a 45-year-old man without significant comorbidities who developed severe ulcerative colitis complicated by diffuse arterial thrombosis, including cerebral infarctions, an ascending aortic mural thrombus, iliac artery thrombosis, and multi-organ infarctions. After stabilization with supportive care and anticoagulation, remission-directed ulcerative colitis therapy and a vascular safety–oriented maintenance strategy were initiated, including vedolizumab and individualized secondary thrombosis prevention. To contextualize this presentation, we integrate current evidence on the epidemiology, clinical phenotypes, underlying mechanisms, and risk factors for arterial thrombosis in inflammatory bowel disease, highlight disease activity as a dominant trigger, and summarize therapy-specific vascular safety considerations across IBD treatment classes. Full article

Background: Ulcerative colitis (UC) and sarcoidosis are chronic inflammatory diseases that share immunological pathways but rarely coexist. The increasing use of biologic agents in inflammatory bowel disease (IBD) has raised concerns regarding paradoxical inflammatory manifestations, including sarcoidosis-like reactions. Case presentation: We report the case of a 63-year-old man with long-standing UC treated with vedolizumab who developed systemic sarcoidosis characterized by bilateral hilar lymphadenopathy, mediastinal and abdominal lymph node enlargement, pulmonary involvement, and erythema nodosum. Extensive diagnostic work-up, including imaging and histopathology, confirmed non-necrotizing granulomatous disease consistent with sarcoidosis, while alternative infectious, malignant, and drug-induced causes were excluded. Vedolizumab was temporarily discontinued, leading to UC relapse, and subsequently reintroduced with rapid clinical remission of UC. Discussion: Sarcoidosis remained clinically and radiologically stable despite vedolizumab re-initiation, suggesting a coincidental association rather than a direct causal relationship. This case highlights the diagnostic challenges and therapeutic dilemmas in patients with immune-mediated diseases receiving biologic therapy. Conclusion: The coexistence of UC and sarcoidosis during vedolizumab therapy is rare. Although causality cannot be established, our findings suggest that vedolizumab may be safely continued in selected patients under close multidisciplinary monitoring. Full article

Background: Vedolizumab (VDZ) is an α4β7 anti-integrin monoclonal antibody effective in Crohn’s disease (CD). While its short- and mid-term efficacy is well established, real-world data on long-term outcomes beyond 3 years are scarce. Recent studies suggest a progressive decline in persistence rates after 2 to 3 years, with very limited data beyond this period. The primary objective of this study was to evaluate the 5-year persistence of VDZ. Secondary objectives were to describe clinical, biological, and endoscopic responses at 2 years among patients remaining on treatment, and to identify predictors of long-term persistence, including the baseline Clinical Decision Support Tool (CDST) score. Methods: We conducted a retrospective observational study which included 60 adult patients with CD treated with VDZ before April 2025. Collected baseline variables included age, sex, BMI, smoking status, disease duration and location, prior biologic exposure, and CDST score. Treatment persistence was evaluated at 5 years. Clinical, biological, and endoscopic responses were assessed at 2 years. A global response was then defined as the achievement of a clinically significant improvement, normalization or marked reduction in inflammatory biomarkers, and endoscopic improvement. Predictors of persistence were also analyzed. Results: The mean age of this cohort was 45.4 ± 15.2 years, mean disease duration was 12.7 ± 10.1 years, and mean CDST score was calculated at 20.6 ± 2.7. At 5 years, 23/41 patients (56.1%) remained on VDZ therapy. Persistence was significantly associated with male sex (65.2% vs. 27.8%), longer disease duration (215 vs. 106 months), absence of rheumatologic manifestations (13.0% vs. 44.4%), and clinico-biological response at 12 months (65.2% vs. 30.8%). At 24 months, a global response was observed in all patients persisting at 5 years compared to 22.2% of those who discontinued (p < 0.001). At 2 years, 39/51 patients (76.5%) remained on VDZ. Persistence was associated with longer disease duration (189 vs. 75 months), male sex (61.5% vs. 25.0%), and absence of isolated colonic disease (0% vs. 16.7%). A global response at 2 years was achieved by 89.7% of persistent patients compared with none of the non-persistent group (p < 0.001). The CDST, uniformly elevated in this cohort, did not discriminate between persistent and non-persistent patients, but reflected appropriate initial patient selection. Conclusions: This real-world study documents 5-year outcome data on VDZ persistence in Crohn’s disease, a duration infrequently studied, with 56% of patients maintaining treatment. Early response at 12 and 24 months emerged as a key determinant of long-term persistence, highlighting the value of assessing 2-year outcomes to identify durable responders. Although not discriminatory in this homogeneous cohort, the CDST score emphasizes the potential role of predictive tools in guiding personalized therapeutic strategies. These results contribute to defining the long-term role of VDZ in the management of CD. Full article

Therapeutic drug monitoring of the intravenous formulations of infliximab in particular, but also vedolizumab, has become an important means of optimising these agents to minimise primary and secondary loss of response. More recently subcutaneous formulations of both infliximab and vedolizumab have become widely available. These new molecules offer patients the convenience of self-administration, and also have pharmacokinetic benefits via maintaining high drug levels, reducing the risk of the development of immunogenicity. It took many years before recommended therapeutic target ranges for intravenous biologics were agreed on, and it is now clear that target levels for the subcutaneous formulations are different, and further research is required before optimal drug levels are confirmed. This narrative review summarises the current literature of therapeutic drug monitoring of subcutaneous infliximab and vedolizumab, acknowledging that this evidence base is presently incomplete. We also aim to provide clinicians with some practical recommendations for the use of TDM with these formulations in clinical practice today. In summary, we recommend performing TDM of the IV formulations prior to switching and then measuring drug levels at 8 weeks after switching to SC infliximab and at 16 weeks for SC vedolizumab. We suggest provisional target drug levels obtained from post hoc analyses of >14 μg/mL for SC infliximab and 25–35 μg/mL for SC vedolizumab. We recommend performing reactive TDM in cases of loss of response to SC therapy. In conclusion we offer suggested areas for future research. Full article