Study of the Efficacy, Safety, Pharmacokinetics, Pharmacodynamics, and Immunogenicity of BCD-261 in Subjects With Moderate to Severe Active Ulcerative Colitis

Prior treatment

• Use of any of the indicated therapies within the specified time frame or need for therapy with these drugs during the study period:
  • (1) Use of Janus kinase inhibitors within 2 weeks prior to signing the ICF or during the screening period.
  • (2) Use of TNFa inhibitors within 8 weeks prior to signing the ICF or during the screening period.
  • (3) Using modulators of sphingosine-1-phosphate receptors within 10 weeks prior to signing the ICF or during the screening period.
  • (4) Use of anti-integrins, IL-12/23 inhibitors within 12 weeks before signing the ICF or during the screening period.
  • (5) Use of oral glucocorticoids at a dose equivalent to prednisone \>20 mg/day or budesonide \>9 mg/day or rectal administration of glucocorticoids at any dose within
  • 2 weeks prior to signing the ICF or during the screening period or parenteral administration of glucocorticoids at any dose within 4 weeks prior to signing the ICF or during the screening period.
  • (6) Rectal administration of 5-ASCs within 2 weeks prior to signing the ICF or during the screening period.
  • (7) Use of immunosuppressants not included in the approved therapy (tacrolimus, cyclosporine, mycophenolate mofetil, rapamycin, leflunomide, penicillamine, etc.) within 4 weeks before signing the ICF or during the screening period.
  • (8) Long-term regular use of non-steroidal anti-inflammatory drugs (≥3 times a week for ≥6 weeks) for 2 weeks prior to signing the ICF.
  • (9) Use of any other investigational drugs in other clinical trials at the time of signing the ICF or less than 8 weeks or 5 half-lives (whichever is longer) before the date of randomization.

Other illness

• A history of or current at the time of signing the ICF Crohn's disease, unspecified colitis, ischemic colitis, radiation colitis, microscopic colitis, complicated form of diverticular disease.
• A history of primary sclerosing cholangitis.
• A history of fulminant colitis, toxic dilation of the colon, intestinal obstruction, intestinal perforation (except for those caused by injury or appendicitis).
• A history of dysplasia of any grade in any part of the gastrointestinal tract at the time of signing the ICF.
• Failure of ≥3 classes of biologics/targeted immunosuppressors (according to INN) with different mechanisms of action (TNFa inhibitors, anti-integrins, IL-12/23 inhibitors, Janus kinase inhibitors, sphingosine-1-phosphate receptor modulators) or ≥4 biologics/targeted immunosuppressants, regardless of the mechanism of action.

Other

• Presence of intestinal stoma or artificial rectum or the need for them.

• 1\. Diagnosis of ulcerative colitis with involvement of the colon proximal to the rectum (≥15 cm from the distal edge of the anal canal), established ≥3 months before signing the ICF and confirmed by endoscopic examination data.
• 2\. Moderate to severe active ulcerative colitis with a modified Mayo score (mMS) of ≥4 and ≤9 points, which includes an endoscopic component of ≥2 points (according to a central independent review) and a stool blood score of ≥1 point.
• 3\. Inadequate response to therapy according to the investigator's assessment, manifested by at least one of the following signs:
• Persistent symptoms of disease activity despite treatment with at least one course of glucocorticoids including prednisolone at a dose of ≥40 mg/day or equivalent or budesonide ≥9 mg/day or equivalent for at least 2 weeks with oral administration (at least 1 week with intravenous administration at a dose equivalent to oral prednisolone ≥40 mg/day).
• Steroid dependence manifested by an increase in disease activity after initial improvement, with a decrease in the dose of glucocorticoids below the dose equivalent to 10 mg of oral prednisolone per day, within 3 months from the beginning of treatment, or a relapse of the disease within 3 months after the end of glucocorticoid use.
• Persistent symptoms of disease activity despite treatment with at least one course of immunosuppressants (azathioprine at a dose of ≥2.0 mg/kg and/or 6-mercaptopurine at a dose of ≥1.0 mg/kg) for ≥12 weeks, or in response to another treatment regimen with these drugs according to a regional standard of care.
• Primary lack of response to therapy with TNFa inhibitors and/or anti-integrins, and/or IL-12/23 inhibitors, and/or Janus kinase inhibitors, and/or sphingosine-1-phosphate receptor modulators, defined as the persistence of symptoms of disease activity despite at least one course of induction of remission according to a treatment scheme approved by the regional standard.
• Loss of response to therapy with TNFa inhibitors and/or anti-integrins, and/or IL-12/23 inhibitors, and/or Janus kinase inhibitors, and/or sphingosine-1-phosphate receptor modulators, defined as the appearance of symptoms of disease activity after initial improvement as a result of treatment with at least one course of induction of remission and at least one course of maintenance of remission according to a treatment scheme approved by the regional standard.
• A history of intolerance to glucocorticoids and/or immunosuppressants (azathioprine, 6-mercaptopurine) and/or biological therapy/targeted immunosuppressants (TNFa inhibitors, anti-integrins, anti-IL-12/23 monoclonal antibodies, Janus kinase inhibitors, sphingosine-1-phosphate receptor modulators) established by the treating physician.
  • 4\. Maintaining a stable dose of concomitant medications for ≥2 weeks prior to signing the ICF and in the screening period for glucocorticoids and 5-ASCs and for ≥4 weeks prior to signing the ICF and in the screening period for immunosuppressants (azathioprine, 6-mercaptopurine).