Pabla, Baldeep

INTRODUCTION: Advanced therapies infrequently achieve complete fistula closure in patients with Crohn's disease (CD). The primary objective of the STOMP2 clinical trial was to determine whether the implantable autologous cell therapy AVB-114 is effective in inducing remission of persistent Crohn's perianal fistulas versus standard of care. METHODS: Eligible patients had a single perianal fistula tract and had failed previous treatment or had documented medication intolerance to biologic or conventional CD therapy. All enrolled subjects underwent surgical fistula optimization and adipose tissue biopsy collection (to manufacture AVB-114) followed by 1:1 randomization to either standard of care (repeat fistula optimization including seton replacement) or AVB-114 implantation. The primary end point was combined fistula remission at 36 weeks, defined as closure of the external opening, no drainage of fluid despite gentle finger compression, and no collections >2 cm in at least 2 of the 3 dimensions on MRI. RESULTS: Subjects at 14 US sites were equally randomized to SoC (N = 24) or AVB-114 (N = 24). Week 36 combined remission was 8.3% and 45.8% for subjects randomized to SoC and AVB-114, respectively (38% difference, 95% CI 11%–60%; P = 0.0078). At week 36, MRI revealed no subjects with collections >2 cm, radiological improvement (≥50% decrease in the Magnetic Resonance Novel Index for Fistula Imaging in Crohn's Disease (MAGNIFI-CD) score from baseline) in 1 SoC subject and 3 AVB-114 subjects, and radiological healing (complete resolution of T2-weighted hyperintensity in fistula tract) in 2 SoC subjects and 5 AVB-114 subjects. Through week 36, there were 40 and 56 treatment emergent adverse events for SoC and AVB-114, respectively. There were no serious treatment emergent adverse events in the AVB-114 group through week 36. DISCUSSION: A significantly higher proportion of patients treated with AVB-114 achieved combined remission vs SoC, and the treatment was well tolerated. These data support the safety and efficacy of AVB-114 in persistent Crohn's perianal fistulas.

Abstract Background The STOMP2 trial sought to determine whether the implantable autologous cell therapy AVB-114 is an effective add-on therapy for patients with persistent Crohn’s perianal fistulas. The trial design incorporated wait-list controlled (WLC) elements, allowing eligible control group subjects who completed the 9 mo primary endpoint visit in Part 1 to request AVB-114 treatment in Part 2 and strengthen the evaluation of AVB-114’s safety and effectiveness. Methods Eligible patients had a single perianal fistula tract and had failed prior treatment or had documented medication intolerance to biologic or conventional Crohn’s disease therapy. Subjects at 14 U.S. sites were randomized 1:1 to either standard of care (SoC; fistula optimization including seton placement) or AVB-114 implantation. The primary endpoint was combined fistula remission at 9 mo, defined as no collections >2cm on MRI, visual closure of the external opening, and no drainage of fluid despite gentle finger compression. A logistic regression time from exposure model through 9 mo utilized complete Part 1 data and all available Part 2 data to estimate combined AVB-114 effectiveness. Results Part 1 combined remission (using Non-Responder Imputation) was 8.3% (2/24) for SoC and 45.8% (11/24) for AVB-114 (38% difference, 95% CI 11 – 60%, post-hoc p-value of 0.0078). Twenty SoC subjects were treated with AVB-114 in Part 2. Four of the 9 Part 2 subjects with 9 mo combined remission data available were in combined fistula remission (44.4%). No subjects failed 9 mo radiological remission (first component of the primary endpoint), thus clinical remission (composite of the latter two components) was equivalent to combined remission. AVB-114 clinical remission in Part 1 and Part 2 to-date were similar, and when combined provided narrower estimates with the same coverage (Figure 1). Mean (SD) 9 mo perianal disease activity index (PDAI) scores for SoC, Part 1 AVB-114, and Part 2 AVB-114 were 5.0 (2.6), 4.1 (2.9), and 3.8 (3.5), respectively. Lower 9 mo scores and decreases from baseline were independently associated with an increased probability of clinical remission. Two serious treatment-emergent adverse events (TEAEs; pseudopolyposis and proctalgia) occurred, with the latter attributed to AVB-114. Non-serious product related TEAE were predominantly related to postoperative perianal pain. Two grade 2 (moderate) AEs of cellulitis and abdominal wall abscess were attributed to adipose tissue collection. Conclusion Both the randomized and combined (all-treated) analyses demonstrated substantial AVB-114 effectiveness through 9 mo in this challenging patient population. AEs were anticipated, and generally mild and infrequent. Conflict of interest: Schwartz, David: 1) Abbvie: consultant 2) Janssen: Consultant 3) Takeda: Consultant 4) Avbios- consultant 5) Olympus- consultant Dozois, Eric: TBD Ehman, Eric: TBD Faubion, William: TBD Hudesman, David: Consultant: Avalo, Abbvie, Abivax, Biocon, BMS, CorEvitas, Eli Lilly, Johnson and Johnson, Pfizer, Prometheus, Sanofi, Takeda, Fresenius Kabi Research Support: Pfizer and Johnson and Johnson Espen, Benjamin: employee of Avobis Bio LLC Pabla, Baldeep: Astellas, J & J - Advisory Board Prometheus - Speaker Eli Lilly - Speaker Papadakis, Konstantinos: TBD