A Study of JNJ-66525433 in Healthy Participants and Participants With Ulcerative Colitis

A Phase 1, Randomized, Double-blind, Placebo-controlled, Single and Multiple Ascending Dose Study in Healthy Participants and Multiple Dose Study in Participants With Ulcerative Colitis to Assess the Safety, Tolerability, Pharmacokinetics and Pharmacodynamics of JNJ-66525433

The purpose of this study is to evaluate safety and tolerability of JNJ 66525433 compared with placebo after administration of: 1) single ascending oral doses of JNJ 66525433 administered to healthy participants (Part 1), 2) multiple, ascending oral doses of JNJ 66525433, administered to healthy participants once daily over 14 consecutive days (Part 2), and 3) multiple oral doses of JNJ 66525433, administered once daily over 14 consecutive and once daily over 42 consecutive days in participants with ulcerative colitis (UC) (Part 3).

Inclusion Criteria:

For Part 1 and Part 2, healthy volunteers

• Have a body mass index (BMI) between 18 and 30 kilogram per meter square (kg/m^2) (BMI = weight/height), inclusive, and a body weight of no less than 50 kilogram (kg) and maximum weight of 100 kg
• Have normal bowel movements, ranging from 1 to 3 times daily to every other day and have normal consistencies according to the Bristol Stool Scale, ranging from 3 to 5 at admission

For Part 3, participants with ulcerative colitis (UC)

• Have a clinical diagnosis of UC at least 3 months before screening
• Have moderately to severely active UC, defined as a Week 0 mayo score of 6 to 12, inclusive, based on central read of the video endoscopy performed during the screening
• Have a greater than or equal to (>=) 2 endoscopy subscore of the Week 0 mayo score based on central read of the video endoscopy performed during the screening

Exclusion Criteria:

For Part 1 and Part 2, healthy volunteers

• History of liver or renal insufficiency, significant cardiac, vascular, pulmonary, gastrointestinal, endocrine, neurologic, hematologic, rheumatologic, psychiatric, or metabolic disturbances
• Known allergies, hypersensitivity, or intolerance to antisense oligonucleotides, JNJ-66525433 or its excipients

For Part 3, participants with UC

• Has UC limited to the rectum only or to <20 centimeter (cm) of the colon evaluated by endoscopy at screening
• Presence of a stoma
• Presence or history of a fistula at any time

COVID-related

• If a participant is excluded due to recent Coronavirus disease (COVID-19) related features, the reason for screen failure should be documented in the case report form under the exclusion criterion of having a condition for which participation would not be in the participant's interest or could confound study assessments
• The field of COVID-related testing (for presence of, and immunity to, the severe acute respiratory syndrome coronavirus 2 [SARS-CoV-2] virus) is rapidly evolving. Additional testing may be performed as part of screening and/or during the study if deemed necessary by the investigator and in accordance with current regulations / guidance from authorities / standards of care