Across 100 unique inflammatory bowel disease (IBD) phase II–III trials, the dataset contains 3,123 CTIS-country site slots, 787 normalized site names, and 13,636 country-level planned participant allocations. Medical Network Sp. z o.o. is the leading site by trial participation, appearing in 37 of 100 trials, while Poland is the largest country hub with 611 site slots and 3,254 planned participants. Monoclonal antibodies remain the dominant modality, covering 43 of 100 trials and 6,601 planned participants.
The top 10 sites account for 252 cumulative trial participations across 100 IBD phase II–III trials. Medical Network Sp. z o.o. leads with 37 trial participations, followed by UZ Leuven and Semmelweis University with 30 each.
IBD site leadership is not concentrated only in major Western European academic centers. The top 10 includes Poland, Belgium, Hungary, France, Italy, and Germany, showing that high-volume IBD execution capacity is distributed across both hospital systems and specialized private/site-network models.
Poland is the largest country hub by both site slots and planned participants: 611 of 3,123 site slots (19.6%) and 3,254 of 13,636 participants (23.9%). France ranks second with 372 site slots and 2,329 participants.
| Country | Sites | Site share | Patients | Patient share |
|---|---|---|---|---|
| Poland | 611 | 19.6% | 3,254 | 23.9% |
| France | 372 | 11.9% | 2,329 | 17.1% |
| Italy | 312 | 10.0% | 847 | 6.2% |
| Germany | 284 | 9.1% | 1,530 | 11.2% |
| Belgium | 180 | 5.8% | 489 | 3.6% |
| Spain | 178 | 5.7% | 475 | 3.5% |
| Hungary | 168 | 5.4% | 604 | 4.4% |
| Czechia | 166 | 5.3% | 665 | 4.9% |
| Romania | 120 | 3.8% | 736 | 5.4% |
| Bulgaria | 107 | 3.4% | 407 | 3.0% |
Poland and France are the clearest country-level recruitment anchors: together they represent 983 of 3,123 site slots (31.5%) and 5,583 of 13,636 planned participants (40.9%). Germany contributes fewer sites than Italy but nearly twice as many participant allocations, suggesting larger expected enrollment per country authorization.
Ulcerative colitis accounts for 49 of 100 trials and 7,288 of 13,636 planned participants. Crohn’s disease accounts for 37 of 100 trials but uses 1,409 of 3,123 site slots, slightly more than ulcerative colitis.
Ulcerative colitis is the larger patient-allocation market, but Crohn’s disease appears more site-intensive: Crohn’s trials average 38.1 site slots per trial versus 27.2 for ulcerative colitis. This implies Crohn’s programs may require broader site activation to reach comparable enrollment goals.
Monoclonal antibodies are the dominant modality, appearing in 43 of 100 trials, 1,511 of 3,123 site slots, and 6,601 of 13,636 planned participants. Small molecules are second with 29 trials, 917 site slots, and 3,925 planned participants.
IBD development remains biologic-heavy, but oral small molecules are a meaningful second pillar. The route mix shows why IBD trial sites need both infusion/injection infrastructure and conventional oral-drug trial workflows; 12 of 100 trials also involve combination treatment.
CROs or external operational vendors are present in 67 of 100 trials and cover 2,683 of 3,123 site slots (85.9%). CRO use rises sharply once trials exceed 15 site slots: 14 of 21 trials with 16–30 sites use CROs, and 35 of 39 trials with 31+ sites use CROs.
The practical CRO-use threshold in IBD appears around 16 site slots. Below 16 sites, CRO presence is under 16%; above 30 sites, it approaches 90%. Trial managers planning broad IBD programs should expect external support to be the norm, especially for central lab, eCOA, imaging/endoscopy review, monitoring, data, and logistics workflows.
Phase III trials make up 50 of 100 trials and 6,958 of 13,636 planned participants. Phase II trials make up 44 of 100 trials and 5,167 planned participants, while phase II/III hybrid trials account for 6 trials and 1,511 planned participants.
| Authorization year | Trials | Site slots | Planned participants |
|---|---|---|---|
| 2024 | 54 | 1,802 | 7,956 |
| 2025 | 32 | 1,043 | 3,860 |
| 2026 | 14 | 278 | 1,820 |
The IBD site landscape is almost evenly split between phase II and phase III by trial count, but phase III contributes the largest patient allocation. The 2024 cohort is the largest contributor, representing 54.0% of trials, 57.7% of site slots, and 58.3% of planned participants.
IBD means inflammatory bowel disease, primarily Crohn’s disease and ulcerative colitis. A CTIS-country site slot counts a site listed within a country-level trial authorization; a single normalized site may appear across multiple trials. Planned participants are country-level participant allocations summed across trials.