Inclusion Criteria:

Subjects must meet all of the following inclusion criteria to be eligible for participation in this study:

• Must have the ability to understand and sign a written ICF, which must be obtained prior to initiation of study procedures associated with this trial.
• Must have enrolled in Gilead-sponsored UC parent protocol GS-US-418-3898.
• Must have completed all required procedures or met protocol specified efficacy discontinuation criteria in a prior Gilead-sponsored filgotinib treatment study for UC.
• Females of childbearing potential must have a negative pregnancy test at Day 1 and must agree to continued monthly pregnancy testing during use of filgotinib treatment.
• Male subjects and female subjects of childbearing potential who engage in heterosexual intercourse must agree to use protocol specified method(s) of contraception for the duration described.
• Willingness to refrain from live or attenuated vaccines during the study and for 12 weeks after last dose of study drug.

Exclusion Criteria:

Subjects who meet any of the following exclusion criteria are not to be enrolled in this study:

• Subjects who are discontinued from a parent study for reasons other than disease worsening, or lack of response or remission; eg, subjects who discontinue for safety or tolerability issues are not eligible for the present study.
• Known hypersensitivity to the study drug.
• Any chronic medical condition (including, but not limited to, cardiac or pulmonary disease, alcohol or drug abuse) that, in the opinion of the Investigator or Sponsor, would make the subject unsuitable for the study or would prevent compliance with the study protocol
• Females who may wish to become pregnant and/or plan to undergo egg donation or egg harvesting for the purpose of current or future fertilization during the course of the study and for at least 35 days of the last dose of the study drug.
• Male subjects unwilling to refrain from sperm donation for at least 90 days after the last dose of study drug.
• Males or females of reproductive potential who are unwilling to abide by protocol-specified contraceptive methods.
• Use of prohibited concomitant medications.