Evaluate REC-4881 in Participants With Familial Adenomatous Polyposis (FAP)

Exclusion Criteria37

• Has any clinically significant laboratory abnormality, medical or psychiatric illness which, in the opinion of the Investigator, could interfere with the conduct or interpretation of the study or put the participant at risk.
• Has had prior pelvic irradiation.
• Has gastrointestinal disease or recent gastrointestinal procedure that could interfere with oral absorption of REC-4881, including difficulty swallowing capsules.
• Has received treatment with other investigational agents within the 4 weeks prior to Study Day 1 or a period during which the investigational agent has not been cleared from the body (that is, at least a period of 5 half-lives, if known), whichever is longer.
• Treatment with other FAP-directed drug therapy (such as off-label use of Balsalazide) within 8 weeks of screening endoscopy (Part 2 only) or had a Whipple procedure.
• Is currently under treatment for desmoid tumors.
• Use of omega-3 fatty acids or oral corticosteroids prior to Study Day 1
• Use of strong cytochrome P3A (CYP3A) inhibitors or inducers prior to Study Day 1
• History of an ongoing or newly diagnosed eye abnormality, including:
• Retinal pathologies such as diabetic retinopathy, veno-occlusion, or macular edema
• Corneal pathologies such as herpes keratitis, corneal dystrophy, corneal erosions, corneal degeneration, active or recurrent keratitis, or uveitis (intermittent, posterior, and/or panuveitis)
• Other clinically significant ophthalmologic abnormalities (for example, retinal detachment) or has findings at Screening. \[Participants with corrected myopia may be enrolled.\]
• Has cancer at screening endoscopy in gastrointestinal (GI) tract (including stomach, duodenum, and colon/rectum/pouch) (Part 2 only).
• Has a large polyp (\>1 centimeter \[cm\]) not amenable to complete removal
• Has active pancreatitis secondary to pancreatic duct obstruction
• Has active gall bladder disease
• Is pregnant, lactating or is planning to attempt to become pregnant during this study or within 4 months after the last dose of study drug (women) or is planning to attempt to impregnate someone or donate sperm during the study or within 14 weeks after the last dose of study drug (men).
• Has had major surgery prior to Study Day 1
• Has an active infection requiring systemic therapy.
• Has known hypersensitivity to the study drug or its excipients.
• Has a history of alcohol or substance abuse within 1 year prior to screening for study participation, or is currently using alcohol, drugs of abuse, or any prescribed or over-the-counter medication in a manner which, in the opinion of the Investigator, indicates abuse.
• Received treatment with another mitogen-activated protein kinase (MEK) inhibitor 8 weeks prior to Screening and throughout the treatment period of the study.
• Any of the following known active infections:
• Human immunodeficiency virus (HIV) not optimally controlled or treated. Participants with HIV who are on sustained stable antiretrovirals (for \>4 weeks) and have cluster of differentiation (CD)4+ counts ≥ 350 cells/microliter (μL) may be enrolled. No HIV testing is required unless clinically indicated or mandated by local health authority.
• Chronic hepatitis B virus (HBV) infection with surface antigen positive: participants with a prior history of treated HBV infection who are hepatitis B surface antigen-negative may be enrolled. No testing is required for hepatitis B unless clinically indicated or mandated by local health authority.
• Chronic hepatitis C virus (HCV) infection: untreated or on active treatment. Participants with a prior history of treated HCV infection who are HCV RNA-undetectable may be enrolled. No testing is required for hepatitis C unless clinically indicated or mandated by local health authority.
• Has a severe or uncontrolled medical condition (for example, dermatologic disease, etc.) that, in the opinion of the Investigator, would pose a significant clinical risk for the participant.
• Use of strong Breast Cancer Resistance Protein (BCRP) or Multidrug Resistance-Associated Protein 2 (MRP2) inhibitors within 14 days of Study Day 1 and throughout the treatment period of the study.
• Clinically significant cardiovascular disease ≤ 6 months before first dose
• Myocardial infarction or unstable angina
• Clinically significant cardiac arrhythmias
• Uncontrolled hypertension: systolic blood pressure (SBP) \> 180 millimeters of mercury (mmHg), diastolic blood pressure (DBP) \> 100 mmHg
• Pulmonary embolism, symptomatic cerebrovascular events or any other serious cardiac condition (for example, pericardial effusion or restrictive cardiomyopathy)
• QTcF prolongation \>450 msec in males and \>470 msec in females at screening or history of long QTc syndrome
• Congestive heart failure (New York Heart Association class III-IV)
• Myocarditis / clinically significant pericarditis.
• Atrial enlargement.