A Study of MK-6194 (PT101) in Participants With Active Ulcerative Colitis (UC) (MK-6194-002)

- Diagnosis of UC at least 3 months prior to screening.

- Mildly to severely active UC.

- Inadequate response, loss of response, or intolerance to at least 1 prior conventional therapy, and no more than 2 prior advanced therapies.

- Participants at risk for colorectal cancer must have a colonoscopy prior to or at screening as follows:

- No evidence of active tuberculosis (TB), latent TB, or inadequately treated TB.

- Women of childbearing potential (WOCBP) and males with female partners of childbearing potential must utilize highly effective contraceptive methods beginning 4 weeks prior to first dose of study drug and continue for 30 days after the last dose of study drug.

- Body mass index (BMI) 18 to 35 kg/m^2 inclusive and weight ≥ 50 kg.

- Prior treatment with recombinant IL-2 or modified IL-2 therapy, including MK-6194 (PT101).

- Known sensitivity to MK-6194 (PT101) or its excipients.

- Known history of hypersensitivity to interleukin-2 (IL-2).

- Disease limited to the rectum (i.e., within 15 cm of the anal verge).

- Diagnosis of toxic megacolon.

- Suspected or known colon stricture or stenosis.

- Diagnosis of Crohn's disease, or indeterminant colitis.

- Has severe colitis as evidenced by:

- Previously had surgery for UC, or likely to require surgery for UC during the study period in the opinion of the Investigator.

- History of abnormal thallium stress test or functional cardiac function test.

- History of significant cardiac, pulmonary, renal, hepatic, or central nervous system (CNS) impairment.

- Active clinically significant infection, or any infection requiring hospitalization or treatment with intravenous anti-infectives within 8 weeks of randomization, or any infection requiring oral anti-infective therapy within 6 weeks of randomization.

- History of opportunistic infection.

- History of symptomatic herpes zoster within 16 weeks of randomization, or any history of disseminated herpes simplex, disseminated herpes zoster, ophthalmic zoster, or central nervous system (CNS) zoster.

- Currently on any chronic systemic (oral or IV) anti-infective therapy for chronic infection (such as pneumocystis, cytomegalovirus, herpes zoster, or atypical mycobacteria).

- Currently receiving lymphocyte depleting therapy.

- History of abnormal pulmonary function tests.

- Participants with organ or tissue allograft.

- Malignancy within 5 years of screening, with the exception of adequately treated or excised non-metastatic basal cell or squamous cell cancer of the skin.

- Exposure to advanced therapy within 5 half-lives of the Day 1 visit, or documentation of detectable drug during screening.

- Received a live attenuated vaccine < 1 month prior to screening or is planning to receive a live attenuated vaccine during the study period or within 12 weeks of the end of participation in the study.

- Is pregnant or nursing or is planning to become pregnant during the study.

- Any uncontrolled or clinically significant concurrent systemic disease other than UC.