Studie zur Beurteilung der Wirksamkeit und Sicherheit von GS-4875 bei Erwachsenen mit mittelschwerer bis schwerer aktiver Colitis ulcerosa (Falcon)

Drug: Tilpisertib;Drug: Placebo

Key Inclusion Criteria:

- Males, or non-pregnant, non-lactating females, at least 18 years of age based on the
date of the screening visit.

- UC of at least 3 months duration before randomization confirmed by endoscopy and
histology at any time in the past AND a minimum disease extent of 15 centimeter (cm)
from the anal verge. Documentation of endoscopy and histology consistent with the
diagnosis of UC must be available in the source documents prior to the initiation of
screening.

- Moderately to severely active UC as determined during screening by a centrally read
endoscopy score = 2, a Rectal Bleeding subscore = 1, a Stool Frequency subscore = 1
and Physicians Global Assessment (PGA) of = 2 as defined by the Mayo Clinic Score;
total MCS must be between 6 and 12, inclusive.

- Previously demonstrated an inadequate response (primary non-response) or loss of
response (secondary non-response) to a tumor necrosis factor-alpha (TNFa) inhibitor
(ie, infliximab, adalimumab, golimumab, or biosimilars). The induction treatment
regimen resulting in inadequate response or loss of response should have been in
accordance with local prescribing information/guidelines or as outlined below.

- Infliximab: 5 mg/kg at Weeks 0, 2, and 6

- Adalimumab: 160 mg on Day 1 (given in 1 day or split over consecutive days),
followed by 80 mg 2 weeks later (Day 15), 40 mg 2 weeks later (Day 29) and every
2 weeks thereafter until Day 57

- Golimumab: 200 mg on Day 1 followed by 100 mg at Week 2

- May be receiving concomitant therapy for UC at the time of enrollment as specified in
the protocol, provided the dose prescribed has been stable as indicated prior to
randomization.

- Meet the following Tuberculosis (TB) screening criteria:

- No evidence of active TB, latent TB, or inadequately treated TB as evidenced by 1
of the following:

- A negative QuantiFERON test or equivalent assay reported by the central lab
at screening or within 90 days prior to randomization date. OR

- A history of fully treated active or latent TB according to local standard
of care. Investigator must verify adequate previous anti-TB treatment and
provide documentation; these individuals do not require QuantiFERON testing
and eligibility must be approved by the sponsor prior to enrollment in the
study. AND

- A chest radiograph (views as per local guidelines with the report or films
available for investigator review) taken at screening or within the 4 months
prior to randomization without evidence of active or latent TB infection.

- Laboratory assessments at screening within the following parameters:

- Aspartate aminotransferase (AST) and alanine aminotransferase (ALT) and total
bilirubin = 2 X ULN (upper limit of normal)

- Estimated glomerular filtration rate (eGFR) = 60 ml/min (1.0 mL/sec) as
calculated by the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI)
Cystatin C formula as described in protocol.

- Hemoglobin = 8 g/dL (= 80 g/L)

- Absolute neutrophil count (ANC) = 1.5 × 10^3/µL (= 1.5 GI/L)

- Platelets = 100 × 10^3/µL (= 100 GI/L)

- White blood cells (WBC) = 3 × 10^3/µL (= 3 GI/L)

- Absolute lymphocyte count = 0.75 × 10^3/µL (= 0.75 GI/L)

Key Exclusion Criteria:

- Currently displaying clinical signs of acute severe colitis, fulminant colitis, or
toxic megacolon.

Note: Other protocol defined Inclusion/Exclusion criteria may apply.