Abemaciclib in healthy adults: comparing tablet and granule forms to see how they enter the bloodstream

Inclusion Criteria:

* Are overtly healthy as determined by medical evaluation including medical history, physical examination, laboratory tests, and cardiac monitoring.
* Have a body mass index (BMI) within the range of 18 to 32 kilograms per square meter (kg/m²), inclusive, and have a body weight of 45 kilograms (kg) or greater.
* Individuals assigned male at birth (AMAB) should be sterile, including vasectomy.
* Individuals who are assigned female at birth (AFAB) and are individuals not of childbearing potential (INOCBP).
* Have clinical laboratory test results within normal reference range for the population or investigative site.
* Have a hemoglobin level of 12.5 grams per deciliter (g/dL) or greater for males, or 11.4 g/dL for females.
* Have venous access sufficient to allow for blood sampling.

Exclusion Criteria:

* Have known allergies to abemaciclib, related compounds, or any components of the formulations, or have a history of significant atopy.
* Have a 12-lead electrocardiogram (ECG) abnormality at screening that, in the opinion of the investigator, increases the risks associated with participating in the study or may confound ECG data analysis.
* Have abnormal blood pressure as determined by the investigator.
* Have a gastrointestinal disorder causing clinically significant symptoms such as nausea, vomiting, and diarrhea, or malabsorption syndromes.
* Have a history or presence of cardiovascular, respiratory, hepatic, renal, gastrointestinal, endocrine, hematological, or neurological disorders that could significantly alter the absorption, metabolism, or elimination of drugs, of constituting a risk when taking the study medication, or of interfering with the interpretation of study data.
* Have known or ongoing psychiatric disorders.
* Have used or intend to use over the counter or prescription medication, or herbal supplements, within 14 days prior to the first dose. The use of topical medicine, provided there is no evidence of chronic dosing with risk of systemic exposure, and occasional acetaminophen is acceptable.
* Use or intend to use any medications or products known to alter drug absorption, metabolism, or elimination processes, including St. John's wort, within 14 days prior to Study Day 1, unless deemed acceptable by the investigator or designee.
* Use or intend to use medications that are moderate or strong inhibitors or inducers of Cytochrome P450 3A4 (CYP3A4), including cannabidiol- or cannabis-containing products, within 14 days prior to Study Day 1 until completion of the follow-up phone call.
* Regularly use known drugs of abuse.
* Show evidence of Human Immunodeficiency Virus (HIV) infection or positive HIV antibodies.
* Have a positive Hepatitis C Virus (HCV) antibody test. Participants with a positive HCV antibody test at screening can be included only if a confirmatory HCV Ribonucleic Acid (RNA) test is negative.
* Show evidence of hepatitis B or positive hepatitis B surface antigen.
* Have made a blood donation of 450 milliliters (mL) or greater, or have participated in a clinical study that required a blood volume of 400 mL or more since the last study visit, within the last 3 calendar months.
* Are unwilling to refrain from strenuous exercise for at least 72 hours prior to each dose and during each inpatient stay.
* Have alcohol intake that exceeds recommended average weekly alcohol consumption limits per local regulation, or an amount deemed significant by the investigator, or are unwilling to stop alcohol consumption for at least 48 hours prior to each Clinical Research Unit (CRU) admission until discharge from the CRU in each treatment period.
* Are unwilling to refrain from consuming caffeine- or xanthine- containing products from at least 48 hours prior to each CRU admission until discharge from the CRU in each treatment period.
* Are currently, or have been, smokers or users of tobacco or nicotine replacement products within the 6 months prior to the first CRU admission, or have a positive cotinine test at screening.
* Are unwilling to comply with the dietary requirements and restrictions of this study.