R-3750 in Patients With Crohn's Disease

Inclusion Criteria: * Age 18 to 80 years, inclusive, at the time of informed consent. * Able and willing to provide written informed consent and comply with study procedures and study visits. * Documented diagnosis of Crohn's disease with symptoms/onset of disease at least 3 months prior to Screening. * Active Crohn's disease defined by Harvey-Bradshaw Index (HBI) score between 5 and 15 at Screening. * Evidence of active inflammatory disease, defined by at least one of the following: CRP ≥5 mg/L, fecal calprotectin ≥50 µg/g, biopsy-verified inflammation, or endoscopic evidence of active inflammation. * Women of childbearing potential must have a negative pregnancy test at Screening and before dosing and agree to use highly effective contraception during the study and for at least 3 months after the last dose. * Men with partners of childbearing potential must agree to use contraception according to institutional requirements during the study and for at least 3 months after the last dose. Exclusion Criteria: * Crohn's disease in clinical remission, including HBI \<5 or CDAI \<150 at Screening. * Severe Crohn's disease requiring urgent escalation of therapy, hospitalization, or surgery in the opinion of the Investigator. * Imminent risk of scheduled intestinal surgery, including clinically significant stenosis, strictures, internal fistula, abscess, or obstructive complications. * History of partial or incomplete bowel obstruction within 6 months prior to Screening; current stoma, ileostomy, colostomy, or anticipated need for ostomy during the study; diagnosis of short bowel syndrome or clinically significant malabsorptive condition; uncontrolled chronic diarrhea due to a condition other than Crohn's disease; or bowel resection within 3 months prior to Screening. Subjects with prior bowel resection may be eligible if, in the opinion of the Investigator and Sponsor, the remaining bowel anatomy is adequate for study participation and interpretation of study endpoints. * History (past 6 months) or current Clostridioides difficile infection, clinically significant enteric infection, other active infection or chronic infection requiring ongoing antimicrobial treatment. * Treatment with antibiotics within 2 weeks prior to Day 1 or expected during the study period. * Use of biologic, targeted synthetic, or systemic immunomodulatory/immunosuppressive therapy for Crohn's disease within the 4 weeks washout period prior to Day 1, unless specifically permitted. Stable doses of aminosalicylates, budesonide, or low-dose systemic corticosteroids are permitted if stable for at least 2 weeks prior to Day 1 and expected to remain stable during the treatment period. Low-dose systemic corticosteroids are defined as prednisone ≤20 mg/day or equivalent. * Use of probiotics or live biotherapeutic products within 2 weeks prior to Day 1. * Severe comorbidities, including uncontrolled diabetes, clinically significant cardiopulmonary failure, severe liver disease, severe renal disease, or other clinically significant condition that would place the subject at risk or confound study interpretation. * Abnormal hepatic function, including ALT or ALP \>2.5 × ULN, liver cirrhosis, portal hypertension, or clinically significant active liver disease. * Abnormal renal function, including cystatin C \>ULN or other clinically significant renal abnormality. * Known active blood-borne infection, including HIV, active hepatitis A, B, or C infection, or tuberculosis. * History of malignancy within 5 years prior to Day 1, except adequately treated non-metastatic basal cell carcinoma, squamous cell carcinoma of the skin, or carcinoma in situ of the cervix. * Pregnant, breastfeeding, or planning to become pregnant during the study. Clinically significant mental disorder, substance use disorder, alcohol or drug addiction that may interfere with participation or compliance. * Participation in another interventional clinical trial within 30 days prior to Day 1 or simultaneous participation in another interventional clinical trial. * Any significant disease, disorder, laboratory abnormality, or circumstance that, in the opinion of the Investigator, may put the subject at risk, affect study results, or interfere with study participation.