Efficacy and Safety of Rosnilimab in Subjects with Ulcerative Colitis

Prior treatment

• Prior exposure to a PD-1 or PD-L1 agonist, antagonist, or modulator
• Clostridioides difficile infection within 30 days before Screening or a positive C. difficile toxin stool assay result at Screening, or infection with other intestinal pathogens within the 30 days before Screening
• Prior or current gastrointestinal (GI) dysplasia in any biopsy performed before or during the Screening endoscopy
• Current treatment with any of the following: o Oral corticosteroids equivalent to prednisone > 20 mg per day o Oral corticosteroids equivalent to prednisone ≤ 20 mg per day that have been at a stable dose for < 4 weeks before Day 1 o Immunomodulatory biologic agents (including investigational biologics) received within 8 weeks or 5 half-lives (whichever is longer) before Day 1. o Live or live-attenuated vaccines within 12 weeks before Day 1. o Fecal-microbial transplantation within 30 days prior to Day 1

Other illness

• Clinical diagnosis of Crohn’s disease, indeterminate colitis, fulminant colitis, and/or toxic megacolon
• Disease limited to the rectum (within 15 cm from anal verge; ulcerative proctitis) during the Screening endoscopy
• History of colectomy, ileoanal pouch, Kock pouch, or ileostomy or is planning bowl surgery
• Evidence of colonic infection during Screening
• History of an inadequate response, loss of response, or intolerance to any combination of 4 or more advanced UC therapy classes defined as, but not limited to [1] anti-TNF antibodies (e.g., adalimumab, golimumab, infliximab), [2] anti-IL-12/23 biologics (e.g., ustekinumab, mirikizumab, risankizumab), [3] anti-integrins (e.g., vedolizumab), [4] oral JAK inhibitors (e.g., tofacitinib, upadacitinib), and [5] oral S1P receptor modulators (e.g., ozanimod, etrasimod)

• Male or female who is ≥18 years
• Clinical diagnosis of UC for > 90 days prior to Day 1, including appropriate documentation of biopsy results that are consistent with UC, based on the assessment of the Investigator. Note: For subjects with no documented histological confirmation of UC diagnosis or if previous diagnosis is not deemed conclusive, UC diagnosis must be confirmed at time of screening colonoscopy by local histological assessment.
• Moderate to severe active UC defined as a mMS ≥ 5 with an endoscopy subscore ≥ 2 (based on a central reader review) at Baseline.
• Surveillance colonoscopy did not detect potential dysplasia or colon cancer performed within 1 year of Day 1
• Subject has completed at least 3 consecutive or 4 nonconsecutive eDiary entries within 7 days before Day 1 (excluding days during bowel preparation for endoscopy)
• Subject has a history of an inadequate response, loss of response, or intolerance to any combination of at least 2 UC therapy classes. Note: For this study, UC therapy classes are defined as, but not limited to, [1] aminosalicylates (e.g., sulfasalazine, mesalamine, etc.), [2] corticosteroids, (e.g., prednisone, budesonide, dexamethasone, etc.), [3] immunomodulators(e.g., azathioprine, methotrexate, etc.), [4] calcineurin inhibitors (e.g., cyclosporine, tacrolimus, etc.) , [5] advanced UC therapies (e.g., biologics, JAK inhibitors, oral S1P receptor modulators, etc.)