**Background:** Pediatric inflammatory bowel disease (PIBD) is increasingly common and often more aggressive than adult-onset disease. Anti-TNF agents frequently fail, necessitating alternative therapies. Vedolizumab, an anti-α4β7 integrin antibody with gut-selective anti-inflammatory activity, has proven effective in adult IBD but pediatric data beyond 6 months are limited. This study aimed to evaluate long-term (1- and 2-year) efficacy of vedolizumab in anti-TNF-refractory PIBD patients at a tertiary center.
**Methods:** This was a real-life, single-center, retrospective study conducted at Texas Children's Hospital, Houston, TX. Pediatric patients initiated on vedolizumab between September 2015 and September 2018 who completed induction (through week 14) were included. Data were collected through September 2020. Demographics, prior and concomitant treatments, disease activity (by PUCAI score for all patients), dosing regimens, surgical history, and adverse events were recorded. The primary outcome was corticosteroid- and other biologic-free remission (PUCAI <10) at 26 weeks and 1 year. Secondary outcomes included remission at 14 weeks and 2 years, discontinuation rates, need for surgical intervention, and time to surgery. Statistical analysis used Fisher's exact test with significance set at P < 0.05.
**Key Results:** Thirty-nine patients were included (19 CD, 20 UC; 49% male; mean age 14.5 years, range 5-19). 97% were refractory to prior anti-TNF therapy; 41% had failed two anti-TNF agents. At week 14, 26% (5/19) of CD and 60% (12/20) of UC patients achieved clinical remission; corticosteroid- and other biologic-free remission was 11% (2/19) for CD and 45% (9/20) for UC. At 26 weeks, 24% (4/17) of CD and 32% (6/19) of UC achieved clinical remission; corticosteroid- and other biologic-free remission was 18% (3/17) for CD and 32% (6/19) for UC. At 1 year, corticosteroid- and other biologic-free remission was 29% (5/17) for CD and 16% (3/19) for UC. At 2 years, 21% (3/14) of CD and 40% (6/15) of UC patients achieved corticosteroid- and other biologic-free remission. Therapy durability declined over time: at 26 weeks, 76% of CD and 74% of UC remained on therapy; at 1 year, 65% of CD and 68% of UC; at 2 years, 36% of CD and 47% of UC. Among patients remaining on vedolizumab at 1 year, 64% of CD and 85% of UC were on intensified regimens (every 4 or 6 weeks vs standard every 8 weeks); by 2 years, this increased to 80% of CD and 100% of UC. Nine patients (23%; 7 UC, 2 CD) required surgical intervention within a median of 14 months (range 3-26 months) from vedolizumab initiation. No significant difference in outcomes was found between CD and UC (P > 0.05). Patients not on dual biologic therapy at 2 years were more likely to be in corticosteroid-free remission compared with those on dual therapy (P = 0.004). No serious adverse reactions were reported; one patient discontinued due to nausea/vomiting after the fourth dose. Therapeutic drug monitoring was performed in 20 patients (51%); no antibodies to vedolizumab were detected, but meaningful analysis was precluded by inconsistent timing.
**Clinical Implications:** Vedolizumab is a safe therapeutic option for anti-TNF-refractory pediatric IBD, but its effectiveness declines over time, with only 21-40% of patients maintaining corticosteroid- and biologic-free remission at 2 years. Intensified dosing regimens (every 4-6 weeks) appear necessary for long-term maintenance, particularly in UC where 100% of patients required intensification by 2 years. The high surgical rate (23%) underscores the severity of disease in this refractory cohort. These findings support the need for prospective optimization of vedolizumab dosing and therapeutic drug monitoring in children, as well as continued development of novel therapies for this highly morbid disease group. Limitations include the retrospective design, small sample size, use of PUCAI for CD patients, and lack of standardized TDM.