P0626The new IOIBD25 classification in a Belgian inception cohort of patients with inflammatory bowel disease (PANTHER)

Abstract Background The Montreal classification is widely adopted to classify inflammatory bowel disease (IBD), but does not fully capture disease progression. The newly proposed IOIBD25 classification introduces “disease velocity” as a central element.1 This study evaluated the performance of this velocity component in a Belgian inception cohort. Methods The PANTHER cohort includes newly diagnosed adult IBD patients from 3 Belgian IBD referral centres, enrolled within 3 months after diagnosis; and prior to any immunosuppressives, advanced therapies, or IBD-related surgery. Clinical data, incl. velocity events, were prospectively collected. Velocity, being time from diagnosis to first advanced therapy (T-class) or another predefined event (V-class), was grouped as none (T0 or V0), ≥3 years (T1 or V1), 6 months–3 years (T2 or V2), and ≤6 months (T3 or V3) (Fig 1A-B). Class patterns were assessed with alluvial plots, and time-to-event analyses with Kaplan–Meier methods. Candidate class cut-offs were identified through maximally selected rank statistics and grid-search with nested likelihood ratio tests (GraphPad Prism 10.3.0, R 4.3.2). Results Between 2015 and 2025, a total of 597 newly diagnosed patients were recruited, with a median (IQR) follow-up time of 3.6 (1.6-5.4) years. Of these, 270 patients (155 CD; 105 UC) had ≥3.5 years of follow-up and were included in the velocity analysis. The distribution of both T- and V-classes differed significantly between CD and UC (T: χ² p = 1.24E-05; V: χ² p = 9.50E-06) (Fig. 1A-B). Early initiation of advanced therapy was common in CD (T3: 56%), whereas 17% remained without (T0). For other velocity events, 54% of CD patients remained event-free (V0) and 21% had a fast velocity (V3). In UC, early advanced therapy was less frequent (T3: 30%; T0: 42%); and most patients were event-free for V (V0: 81%). Combining T and V, a mild, event-free trajectory (T0V0) was found in 11% of CD and 42% of UC, while a successful top-down approach (T3V0) occurred in 29% of CD and 18% of UC (Fig. 1A-B). Time-to-event distributions suggested the need to refine the current velocity cutoffs (Fig. 2A-B): optimal T velocity cutoffs were identified at 0.5 and 1.6 years for CD, and at 1.0 and 3.3 years for UC, with two-cutoff models significantly outperforming single-cutoff models (ΔAkaike Information Criterion (AIC) = 121 and 51, respectively; p 0.001). Conclusion Incorporating disease velocity into IBD classification captures clinically meaningful heterogeneity in disease trajectories, as observed in this Belgian inception cohort. Refinement of the proposed time cut-offs of velocity events in real-world settings is warranted, and longer follow-up data will clarify how velocity-based classification informs disease modification assessment. Reference: 1. SCI07: Sustainable classification of IBD (McGovern et al. ECCO 2025) Conflict of interest: Ms. Verstockt, Sare: No conflict of interest D’hooghe, Anna-Teresa: No conflict of interest Glorieus, Elien: No conflict of interest De Wolf, Marijke: No conflict of interest Cuvry, Arno: No conflicts of interest to declare. Lenfant, Matthias: None Truyens, Marie: No conflict of interest Guedelha Sabino, João: Speaker’s fees: Lilly, Pfizer, Abbvie, Ferring, Falk, Takeda, Janssen, Fresenius, and Galapagos. Consultancy fees: Takeda, Pfizer, Janssen, Ferring, Fresenius, Abbvie, Galapagos, Celltrion, Pharmacosmos, and Pharmanovia. Research support: Galapagos, Viatris, and Eurogenerics. JS is supported by a Senior Clinical researcher grant from the Research foundation – Flanders. Ferrante, Marc: Research grants from AbbVie, EG Pharma, Celltrion, Janssen, Pfizer, Takeda and Viatris Consultancy fees from AbbVie, AgomAb Therapeutics, Boehringer Ingelheim, Celgene, Celltrion, Eli Lilly, Janssen-Cilag, MRM Health, Merck Sharp and Dohme, Pfizer, Takeda and ThermoFisher Speakers’ fees from AbbVie, Biogen, Boehringer Ingelheim, Dr Falk Pharma, Ferring, Janssen-Cilag, Merck Sharp and Dohme, Pfizer, Takeda, Truvion Healthcare and Viatris Hens, Brecht: BH reports speakers’ fees from Takeda and consultancy fees from AbbVie. Geldof, Jeroen: Personal Fees: Jeroen Geldof has served as an advisory board member for Arena and as a speaker for Janssen and Galapagos. Laukens, Debby: Personal Fees: RedX Pharmaceuticals Cleynen, Isabelle: Grants: research support from FWO/SBO and FWO large infrastructure. Personal fees: none. Non-financial support: none. Other: none. Vermeire, Séverine: Grant: AbbVie, Pfizer, Takeda, J & J, Galapagos Personal Fees: AbbVie - AbolerIS Pharma - AgomAb - Alimentiv - Arena Pharmaceuticals - AstraZeneca - Avaxia- BMS - Boehringer Ingelheim - Celgene - CVasThera - Dr Falk Pharma - Ferring - Galapagos - Genentech-Roche - Gilead - GSK - Hospira - Imidomics - Janssen - J & J - Lilly - Materia Prima - MiroBio - Morphic - MrMHealth - Mundipharma - MSD - Pfizer - Prodigest - Progenity - Promakhos Therapeutics - Prometheus - Robarts Clinical Trials - Second Genome - Shire - Surrozen - Takeda - Theravance - Tillots Pharma AG - Zealand Pharma - Other: AbbVie, MSD, Takeda, Ferring, Genentech/Roche, Shire, Pfizer Inc, Galapagos, Mundipharma, Vandermeulen, Liv: No conflict of interest Lobatón Ortega, Triana: Grant: Abbvie, Ferring, Viatris, MSD, EG, Mundipharma, Biogen, Janssen, Pfizer, Takeda, Galapagos, Afasigma and Sandoz. Personal Fees: Speaker fees from MSD, Abbvie, Janssen, Amgen, Fresenius Kabi, Galapagos, Viatris, Ferring, Celltrion, Alfasigma, Lilly and Takeda. Consultancy fee from Janssen, Galapagos, Alfasigma, Amgen, Bristol Myers, Squibb Fresenius Kabi, Takeda and Abbvie Verstockt, Bram: Research support from AbbVie, Biora Therapeutics, Celltrion, Landos, Pfizer, Sanofi, Sossei Heptares/Nxera and Takeda. Speaker’s fees from Abbvie, Agomab, Alfasigma, Biogen, Bristol Myers Squibb, Celltrion, Eli Lily, Falk, Ferring, Galapagos, Materia Prima, Johnson and Johnson, Pfizer, Sandoz, Takeda, Tillots Pharma, Truvion and Viatris. Consultancy fees from Abbvie, Alfasigma, Alimentiv, Anaptys Bio, Applied Strategic, Astrazeneca, Atheneum, BenevolentAI, Biora Therapeutics, Boxer Capital, Bristol Myers Squibb, Domain Therapeutics, Eli Lily, Galapagos, Guidepont, Landos, Merck, Mirador Therapeutics, Mylan, Nxera, Inotrem, Ipsos, Johnson and Johnson, Pfizer, Sandoz, Sanofi, Santa Ana Bio, Sapphire Therapeutics, Sosei Heptares, Takeda, Tillots Pharma and Viatris. Stock options Vagustim and Thethis Pharma.