Efficacy and Safety Study of ABX464 as Maintenance Therapy in Patients With Moderate to Severe Ulcerative Colitis

Inclusion Criteria: * Patients must have completed the 16-week induction treatment period (ABX464-103); * Patients are able and willing to comply with study visits and procedures as per protocol; * Patients should understand, sign and date the written voluntary informed consent form prior to any protocol-specific procedures are performed; * Patients should be affiliated to a social security regimen (for French sites only); * Females and males receiving the study treatment (potentially in combination with immunosuppressant) and their partners must agree to use a highly effective contraceptive method during the study and for 6 months (180 days) after end of study or early termination. Contraception should be in place at least 2 weeks prior to screening. Women must be surgically sterile (bilateral oophorectomy, bilateral salpingectomy, or hysterectomy) or in the postmenopausal state (no menses for 12 months without an alternative medical cause) or if of childbearing potential must use a highly effective contraceptive method. Women of childbearing potential (WOCBP) will enter the study after confirmed menstrual period and a negative pregnancy test. Highly effective methods of contraception include true abstinence, intrauterine device (IUD) or hormonal contraception aiming at inhibition of ovulation, intrauterine hormone releasing system, bilateral tubal ligation, vasectomized partner. True abstinence is defined when this is in line with the preferred and usual lifestyle of the p…