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Phase 1 study of oral and intravenous unesbulin to assess absorption, metabolism and excretion in patients with solid tumors

InvestigationalNo placebo
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What is this trial about?

A plain-language summary of the goals, design and what participants do

The study focuses on patients with advanced solid tumors, which are cancers that grow as a lump in an organ or tissue. The investigational medicine is unesbulin, provided as a tablet, an oral liquid, or an injection. The purpose of the study is to determine how much of the drug reaches the bloodstream when taken by mouth compared with an injection, and to understand how the body absorbs, changes (metabolism), and eliminates the drug.

Participants will receive a single oral dose of 300 mg of the drug and, at a later visit, a very small intravenous dose that contains a trace amount of a harmless radioactive label (carbon‑14) used only to track the drug’s movement. Blood, urine, and stool samples will be collected over several days to measure the drug and its breakdown products. Routine safety checks such as heart rhythm monitoring, blood pressure measurements, and laboratory tests will be performed throughout the study to watch for any side effects.

The research process

The trial runs in 8 steps – from screening to follow-up. Each step says what happens and what the team monitors.

  1. Step 1

    Baseline assessments

    Upon joining the study, you will undergo a series of baseline measurements that include checking vital signs such as blood pressure and heart rate, a physical examination, a 12‑lead electrocardiogram (ECG), and routine laboratory tests on blood and urine. These assessments establish your health status before any medication is given.

  2. Step 2

    Oral dose of unesbulin

    You will receive a single oral dose of unesbulin in the form of a 300 mg tablet. The tablet is taken once, with water, under the supervision of study staff. This dose contains a trace amount of radioactive carbon (14c‑unesbulin) to allow tracking of the drug in the body.

  3. Step 3

    Blood and plasma sampling after oral dose

    After the oral tablet, blood samples will be drawn at multiple time points over the next 24 hours. The samples are used to measure the concentration of unesbulin and its radioactive label in the blood and plasma, helping determine how quickly the drug is absorbed, distributed, and eliminated.

  4. Step 4

    Urine and feces collection after oral dose

    You will be asked to collect all urine and feces produced for a period of up to several days following the oral dose. These collections allow the study team to calculate the total amount of drug and radioactive material that is excreted, providing information on the drug’s metabolism and elimination pathways.

  5. Step 5

    Intravenous dose of unesbulin

    After a washout period (the time needed for the previous dose to clear, as determined by the study protocol), you will receive a single intravenous (IV) injection of unesbulin at a dose of 100 µg (micrograms) containing the same radioactive label (14c‑unesbulin). the injection is administered slowly by a healthcare professional.

  6. Step 6

    Blood and plasma sampling after IV dose

    Following the IV injection, additional blood samples will be taken at scheduled intervals for up to 24 hours. These samples are analyzed to compare the drug’s behavior when given directly into the bloodstream with the oral administration.

  7. Step 7

    Urine and feces collection after IV dose

    As with the oral dose, you will collect all urine and feces produced for several days after the IV injection. The purpose is to assess how much of the drug and its radioactive label are eliminated through these routes after intravenous administration.

  8. Step 8

    Final assessments and discharge

    Once all sampling and collection periods are complete, final vital signs, a repeat ECG, and a review of any adverse events will be performed. After these assessments, you will be discharged from the study.

Who can join the trial?

11 criteria

  • Be between 18 and 75 years old.
  • Agree to take dietary fiber every day during the study.
  • Have blood test results that meet the following levels: absolute neutrophil count (a type of white blood cell) at least 1,500 per mm³, platelet count (cells that help blood clot) at least 100,000 per mm³, and hemoglobin (protein that carries oxygen) at least 9 g/dL, without recent use of growth‑factor medicines, platelet transfusions, or red‑blood‑cell transfusions.
  • Understand what the study involves and sign a written consent form.
  • Have a confirmed solid tumor that is either metastatic (has spread to other parts of the body) or unresectable (cannot be surgically removed), and the tumor must have gotten worse after at least one standard treatment or have no standard treatments available. This does not apply to glioblastoma patients.
  • Have an ECOG performance status score of 0, 1, or 2 (a measure of how well you can carry out daily activities, where 0 is fully active and 2 means up and about more than 50 % of waking hours).
  • If you are a woman who could become pregnant, you must have a negative pregnancy test at screening and on the day before the first dose, and you must use a highly effective birth‑control method (failure rate less than 1 % per year) together with a barrier method such as a diaphragm, cervical cap, or condom.
  • If you are a man who is not surgically sterile, you must use adequate birth‑control and agree not to donate sperm from the start of the study drug until 90 days after the last dose.
  • Be willing and able to follow all study instructions and visits.
  • Not use any tobacco products (cigarettes, e‑cigarettes, cigars, smokeless tobacco) or products with high caffeine content for at least two weeks before the first dose and agree to avoid them for the remainder of the study.
  • Have a history of regular bowel movements.

Who cannot join the trial?

26 criteria

  • Use of any other cancer treatment (including experimental drugs) or radiation therapy within 3 weeks before the study drug.
  • Kidney function that is too low, measured as an estimated glomerular filtration rate (eGFR) below 45 mL/min/1.73 m².
  • Any laboratory test result that is clearly abnormal at screening, unless the doctor decides it is not important.
  • Taking strong cytochrome P450 (CYP)1A2 inhibitor medicines (such as certain antibiotics like ciprofloxacin or antidepressants like fluvoxamine) within 5 half‑lives before the study drug.
  • Taking moderate CYP1A2 inducer medicines (such as phenytoin, rifampin, ritonavir, teriflunomide, barbiturates) or using marijuana regularly within 4 weeks before the first dose and up to Day 14.
  • Using acid‑reducing agents (like antacids or proton‑pump inhibitors) within about 4 hours before or after the study drug.
  • Regular use of oral non‑steroidal anti‑inflammatory drugs (NSAIDs) for more than 2 years, unless the medical monitor agrees.
  • History of alcohol or drug abuse in the last 6 months, current dependence, or drinking more than 21 alcoholic drinks per week.
  • Positive test for illegal drugs or alcohol at screening or on the day before the first dose.
  • Being a nursing mother or planning to become pregnant.
  • Heart electrical measurement (QTcF) of ≥450 ms in men or ≥470 ms in women (measured three times and averaged).
  • Gastrointestinal diseases (such as irritable bowel syndrome, inflammatory bowel disease, chronic gastritis, or ulcers) that might affect how the drug is absorbed.
  • Resting heart rate of ≤45 beats per minute or ≥100 beats per minute at screening.
  • Resting blood pressure that is too low (systolic < 90 mmHg or diastolic < 50 mmHg) or too high (systolic > 160 mmHg or diastolic > 90 mmHg), even if medication is being taken.
  • Unwilling or unable to follow the study’s requirements.
  • Major surgery performed within 30 days before the first dose.
  • Positive test for HIV, hepatitis B, or hepatitis C.
  • Participation in another radiolabeled drug study in the past 12 months (or 90 days for very small microdose studies).
  • Recent exposure to diagnostic or therapeutic radioactive materials that have not been fully cleared from the body.
  • History of gastric surgery (such as gastric bypass, antrectomy, or gastrectomy).
  • History of fat malabsorption (the body’s inability to absorb fats properly).
  • Dietary restrictions that would prevent taking the study medication.
  • Inability to swallow oral medication.
  • Allergy or previous bad reaction to unesbulin, drugs that work in a similar way, or any ingredient in the study drug.
  • Any significant medical or psychiatric condition that the doctor believes could interfere with participation or increase risk.
  • Liver enzyme levels (alanine aminotransferase or aspartate aminotransferase) more than 1.5 times the normal upper limit, unless the doctor decides otherwise.
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Investigated drugs

Unesbulin is the experimental drug being studied in this trial. It is given to patients with advanced solid tumors to learn how much of the drug is absorbed when taken by mouth compared with when it is given by injection. The study looks at how the body processes the drug—how it is broken down, where it goes, and how it leaves the body through urine or stool. Researchers also measure the overall exposure of the drug in the blood and plasma after a single oral dose and after a single intravenous dose. This information helps determine the drug’s safety and how it might be used in future treatments. Unesbulin is an orphan drug, meaning it is intended for a rare condition.

What is already known about the treatment

Unesbulin - This drug can be taken as a 300 mg oral tablet, an oral liquid solution, or given by a single intravenous injection of 100 µg. It is still an experimental medicine and is currently being studied in a Phase 1 trial as an orphan drug for rare cancers. The main purpose of unesbulin is to treat patients with advanced solid tumors. It works by blocking a protein that cancer cells need to grow, and it is classified as a small‑molecule anticancer agent.

Investigated diseases

Solid tumors - Solid tumors are abnormal masses of tissue that arise in organs such as the breast, lung, colon, or prostate. They develop when cells begin to multiply uncontrollably and form a lump that can be felt or seen on imaging. As the tumor grows, it may push into surrounding tissues and can enter blood vessels or the lymphatic system. This allows cancer cells to travel to other parts of the body, a process called metastasis. Over time, the tumor cells can acquire new characteristics that make them more aggressive and harder to control.
Trial detailsLast updated 9 Oct 2026
Age18+ yearsPhasePhase ITrial ID2022-502118-10-00Protocol codePTC596-AME-101-ASTEstimated enrolment12 patientsSponsorPTC Therapeutics Inc.

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