Study of PF-08653945 Bioavailability After Subcutaneous Injection in the Thigh, Upper Arm, or Abdomen in Adults with Obesity

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What is this study about?

Adults who have obesity or are classified as overweight often face health problems linked to excess weight. In this study a single dose of the experimental medicine PF-08653945 is given as a subcutaneous injection, which means the drug is placed just under the skin.

The main aim is to learn how the medicine is taken up into the blood when it is injected in different places on the body. Researchers will compare injections given in the thigh, the upper arm, and the abdomen to see which site allows the best bioavailability. Two key measurements are used: AUCinf, which reflects the total amount of drug that reaches the bloodstream over time, and Cmax, which shows the highest level of drug in the blood after the injection.

Participants will receive one injection and then stay for a short monitoring period. During this time blood samples are taken, vital signs such as blood pressure are checked, and a heart test called an ECG is performed. Safety is also assessed with two questionnaires: the C-SSRS, which looks for thoughts of self‑harm, and the PHQ-8, which screens for symptoms of depression.

1 baseline assessments

on the day you join the study you undergo a series of baseline assessments before receiving the study medicine.

these assessments include a review of your medical history, a physical examination, measurement of vital signs such as blood pressure and heart rate, laboratory tests of blood and urine, a 12‑lead ecg (electrocardiogram) that records the electrical activity of the heart, and two questionnaires: the c‑ssrs (columbia suicide severity rating scale) and the phq‑8 (patient health questionnaire for depression).

2 single dose administration

after the baseline assessments you receive a single subcutaneous injection of pf-08653945.

the injection is given once, into either the thigh, the upper arm, or the abdomen, as assigned by the study design.

the exact amount of the medicine is determined by the study protocol and is administered only one time.

3 post‑injection monitoring and blood sampling

following the injection you remain in the clinic for a monitoring period during which vital signs are checked regularly.

blood samples are collected at several time points after the injection to measure how much of the medicine enters the bloodstream; sampling continues for up to 48 hours according to the study schedule.

any adverse events (side effects) are recorded and evaluated during this time.

4 follow‑up safety visits

after you leave the clinic you return for scheduled follow‑up visits that include repeat vital‑sign measurements, laboratory tests, ecg recordings, and the same questionnaires (c‑ssrs and phq‑8) to assess safety.

the follow‑up visits occur over the days and weeks after the injection as defined by the study protocol.

Who Can Join the Study?

Be at least 18 years old at the time of screening.
Be considered healthy based on a medical evaluation that includes your medical history, a physical exam, laboratory tests, and an ECG (a test that records the heart’s electrical activity).
Have a Body Mass Index (BMI) between 27 and 45 kg/m² and a total body weight greater than 50 kg (110 lb). (BMI is a number that relates your weight to your height.)
If you are enrolling in the optional Japanese group, your BMI may be between 22 and 45 kg/m², you must still weigh more than 50 kg (110 lb), and you must have four biological Japanese grandparents who were born in Japan.
Both men and women can take part in the study.

Who Cannot Join the Study?

Women who are pregnant, are breast‑feeding, or plan to become pregnant during the study.
Anyone who received another experimental drug or vaccine within the past 30 days (or for a longer period based on the drug’s half‑life) or who is taking part in another experimental study at the same time.
People who have already taken part in a study of the drug PF‑08653945 and received at least one dose.
A score of 15 or higher on the PHQ‑8 questionnaire, which measures symptoms of depression.
Answering “yes” to recent thoughts of suicide or violent behavior on the CSSRS safety questionnaire, or being judged by the doctor as having a high risk of suicide or violence.
A positive result on a urine drug test, indicating recent use of illegal or non‑prescribed substances.
Blood pressure that is 140/90 mm Hg or higher for participants under 60 years old, or 150/90 mm Hg or higher for those 60 years and older, after resting lying down for five minutes.
Kidney function measured by eGFR (estimated glomerular filtration rate) that is less than 60 mL/min/1.73 m², indicating reduced kidney performance.
A standard 12‑lead ECG (heart rhythm test) that shows serious problems such as a QTc interval longer than 450 ms, a wide QRS complex over 120 ms, signs of a recent heart attack, severe heart block, or dangerous fast or slow heart rhythms.
Laboratory results that are outside the normal range, including:
- ALT or AST (liver enzymes) 1.5 times higher than the upper normal limit.
- Total bilirubin 1.5 times higher than normal (unless the person has Gilbert’s syndrome and the direct bilirubin is normal).
- HbA1c (average blood sugar over three months) 6.5% or higher.
- Fasting blood glucose 126 mg/dL (7 mmol/L) or higher.
- TSH (thyroid‑stimulating hormone) 1.5 times higher than the upper normal limit.
Having a significant medical condition affecting the blood, kidneys, hormones, lungs, digestive system (such as pancreatitis or gallbladder disease), heart, liver, mind, nerves, or having serious drug allergies (excluding mild seasonal allergies).
Testing positive for HIV, hepatitis B, or hepatitis C infections.
A personal or first‑degree family history of MTC (medullary thyroid carcinoma) or MEN2 (multiple endocrine neoplasia type 2), or suspicion of these conditions.
Any other medical or psychiatric problem that, in the doctor’s opinion, makes participation unsafe, including recent thoughts of suicide (within the past year) or suicidal behavior (within the past five years).
A serious problem with stomach emptying, such as a gastric outlet obstruction.
Current acute gastrointestinal symptoms like nausea, constipation, vomiting, diarrhea, or heartburn at the time of screening or before the study drug is given.
History of a severe allergic reaction to medicines that contain amylin agonists, calcitonin agonists, or any ingredients (excipients) of PF‑08653945.
Use of any prescription or over‑the‑counter medicines, dietary supplements, or herbal products within the past 14 days (or for a longer period based on the drug’s half‑life) before the first dose.
Use of a DACRA (dual amylin and calcitonin receptor agonist) or other amylin‑like drugs within the past 90 days before the first dose.

Where you can join this trial?

Verified and Recommended Sites

No sites found in this category

Verified Sites

Site Name	City	Country	Status
Pfizer Clinical Research Unit	Brussels	Belgium

Other Sites

No sites found in this category

Trial status

Country	Status	Recruitment Start
Belgium	Not yet recruiting	22.07.2026

Trial locations

PF-08653945 is an experimental drug being tested for the first time in humans. In this study, it is given as a single injection under the skin (subcutaneous injection) in a liquid form. The researchers are looking at how the body absorbs the medicine when it is injected in three different places: the abdomen, the thigh, or the upper arm. By comparing the amount of drug that reaches the bloodstream from each site, they can learn which injection location works best. The participants are adults who are overweight or have obesity, and the study helps determine the best way to give this new medication if it moves forward in later trials.

Investigated diseases:

Overweight

Obesity – Obesity is a condition where excess body fat builds up to a level that may affect health. It usually develops slowly as a result of an imbalance between calorie intake and energy use. Over time, the extra weight can become more difficult to lose and may spread to different parts of the body. The condition often persists and can lead to additional weight‑related problems. People may notice a gradual increase in waist size and a feeling of heaviness as the condition advances.

Trial ID:

2026-526334-67-00

Protocol code:

C6501003

Trial Phase:

Human Pharmacology (Phase I) – Other

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Study of PF-08653945 Bioavailability After Subcutaneous Injection in the Thigh, Upper Arm, or Abdomen in Adults with Obesity

What is this study about?

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