Overview

The goal of this clinical trial is to learn if BLKR201 is safe in healthy adults. Researchers will also learn how the body absorbs and processes BLKR201 and how food may affect it.

The main questions this study aims to answer are:

• Is BLKR201 safe and well tolerated when taken as a single dose or for several days in a row?
• How does BLKR201 move through and leave the body?
• Does taking BLKR201 with food change how the body absorbs it?

Researchers will compare BLKR201 to a placebo (a look-alike tablet that contains no drug) in most parts of the study to see how the drug affects participants.

Participants will:

• Take BLKR201 or a placebo by mouth
• Stay at a clinical research unit for several days during dosing
• Give blood and urine samples
• Have heart tests, vital signs, and lab tests
• Report any side effects

In one part of the study, a small group of participants will receive BLKR201 only (no placebo). These participants will also have a sample of spinal fluid collected to measure how much BLKR201 reaches the fluid around the brain and spinal cord.

Eligibility

Inclusion Criteria:

• Are a healthy man or woman 18 to 55 years old
• Weigh at least 50 kilograms (110 pounds)
• Have a body mass index (BMI) between 18 and 30
• Are willing to stay at the research unit for the required study visits
• Are willing to follow study rules about diet, alcohol, tobacco, and medications
• Are able to understand and sign the informed consent form

Women who can become pregnant must:

• Have a negative pregnancy test before starting
• Use a highly effective form of birth control during the study and for a period after the last dose

Men with partners who can become pregnant must:

• Use highly effective birth control during the study and for a period after the last dose
• Not donate sperm during that time

Exclusion Criteria:

• Have any significant medical condition involving the heart, lungs, liver, kidneys, stomach, intestines, brain, blood, or immune system
• Have abnormal laboratory test results at screening that the study doctor considers important
• Have a history of heart rhythm problems or abnormal electrocardiogram (ECG) results
• Have high blood pressure at screening
• Have had a serious infection within the past 6 months
• Test positive for HIV, hepatitis B, hepatitis C, or tuberculosis
• Have a history of cancer in the past 5 years (with limited exceptions for certain treated skin cancers)
• Have a history of serious stomach problems such as ulcers, stomach surgery, or stomach bleeding
• Use tobacco, nicotine, or marijuana products
• Test positive for drugs or alcohol at screening
• Have taken another investigational drug within the required time before this study
• Have received a live vaccine within 30 days before study start
• Are pregnant or breastfeeding
• Have a known allergy to the study drug or similar medicines

Additional exclusions:

• Regular heavy alcohol use
• Regular use of certain medications such as anti-inflammatory drugs, steroids, or blood thinners
• Donation of more than 500 milliliters (about one pint) of blood within 1 month before screening

For the spinal fluid (CSF) portion of the study, you cannot take part if you:

• Take blood-thinning medications
• Have bleeding or clotting problems
• Have medical conditions that make a spinal tap unsafe