A Study of Danavorexton in People With Obstructive Sleep Apnea After General Anesthesia for Abdominal Surgery

The main aim is to see if danavorexton can help improve people's breathing in the recovery room after abdominal surgery.

The drug being tested in this study is called danavorexton. Danavorexton is being tested in people who have moderate to severe obstructive sleep apnea undergoing general anesthesia for abdominal surgery.

The study will enroll approximately 180 participants. Participants will be randomly assigned (by chance, like flipping a coin) to one of the three groups-which will remain undisclosed/unknown to the participant and study doctor during the study (unless there is an urgent medical need):

* Danavorexton high dose
* Danavorexton low dose
* Placebo All participants will receive an intravenous (IV) infusion on Day 1 of the treatment period.

This multi-center study will be conducted in approximately 20 sites in the United States. The overall time for participants to participate in the study will be up to approximately 12 months.

Eligibility Criteria:
Key Inclusion Criteria:

1. The participant has a body mass index (BMI) within the range of 18.5 to 50 kg/m\^2, inclusive.
2. The participant has diagnosed or suspected moderate or severe obstructive sleep apnea (OSA) based on one of the criteria below:

   a. The participant has a snoring, tiredness, observed apnea, high blood pressure, body mass index, age, neck circumference, and gender questionnaire (STOP-Bang) score ≥5 at the screening visit. OR b. The participant has a diagnosis of moderate or severe OSA based on an in-clinic polysomnography (PSG) or home sleep test with an apnea-hypopnea index (AHI) or respiratory event index (REI) score of ≥15 and they have not had significant weight loss since their diagnostic test, in the judgment of the investigator.
3. The participant is scheduled for major abdominal surgery invading the intraperitoneal or retroperitoneal space (open or laparoscopic) that will require at least 1 inpatient overnight stay.
4. The participant is scheduled to undergo a surgery requiring general anesthesia and endotracheal intubation.
5. The participant's surgery, as planned, is anticipated to require use of IV opioids in the postanesthesia care unit (PACU).
6. The duration of the participant's surgery (i.e., incision to last stitch) is expected to be at least 2 hours and up to approximately 8 hours.
7. The participant has an American Society of Anesthesiologists (ASA) Classification of II to III.

Key Exclusion Criteria:

1. The participant has an AHI or REI score \<15 based on in-clinic PSG test or at-home sleep test within 2 years before screening.
2. The participant is undergoing liver or kidney surgery.
3. The participant has a planned transfer to the intensive care unit (ICU) from the operating room.
4. For the participant, immediate (continuous positive airway pressure \[CPAP\]/ bilevel positive airway pressure \[BiPAP\]) use in the PACU is anticipated or planned.
5. The participant has undergone major surgery or donated or lost ≥1 unit of blood (approximately 500 mL) within 4 weeks before the screening visit.
6. The participant has received chemotherapy or radiation therapy within 4 weeks before administration of the study drug.
7. The participant has poorly controlled diabetes with an episode of ketoacidosis within 6 months of the screening visit.
8. The participant has a positive test result for hepatitis B surface antigen, hepatitis C virus (HCV), human immunodeficiency virus antibody/antigen at screening.
9. The participant has uncontrolled hypertension or unstable cardiovascular disease (presence of acute coronary syndrome, unstable angina, myocardial infarction \<3 months, severe valvular disease, or severe structural heart disease), severe heart failure, or any condition requiring a pacemaker or defibrillator.
10. The participant has a screening electrocardiogram (ECG) with a QT interval with Fridericia correction method (QTcF) \>450 milliseconds \[ms\] (for men) or \>470 ms (for women).