Phase 2a to Evaluate PL-8177 in Subjects with Active Ulcerative Colitis (UC)

Inclusion Criteria: * Age ≥18 to ≤75 years of age at Screening. * Has a history of UC diagnosis prior to screening; confirmed by endoscopic and histologic evidence in the subject chart. If the historical evidence is not available, then endoscopic and histologic evidence can be confirmed during the screening period. Note: If no complete colonoscopy (adequate in quality to assess for dysplasia and colorectal polyps) has been performed and documented (with reports) within the past 1 year as recommended by local and national guidelines depending on Colorectal cancer risk factors in the specified subject, a full colonoscopy should be performed at screening. If such results are available within one year, a flexible sigmoidoscopy with examination up to the splenic flexure will be used for screening. * Has active UC defined as a MES ≥2 during screening sigmoidoscopy. * Has evidence of endoscopic disease extending to at least 5 cm proximal to the anal verge. * If currently receiving 5-ASA, the duration and dose prior to the screening endoscopy must be as specified below, and a stable dose must be maintained throughout the double-blind trial: 5-aminosalicylates (5-ASA) (e.g., mesalamine, sulfasalazine, olsalazine, balsalazide) for ≥4 weeks with the dose stable for ≥3 weeks prior to the screening endoscopy. * If recently has received any of the following treatments, they must have discontinued as specified below: * If 5-ASA has been recently discontinued, it must have been stopped…