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Effect of a single oral dose of acalabrutinib on skin prick test wheal size in adults with grass pollen allergy using histamine dihydrochloride and phleum pratense

Verified siteRegistered drugNo placebo
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What is this trial about?

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

Adults with grass pollen allergy experience sneezing, runny nose, itchy eyes and sometimes skin rash when they are exposed to pollen from grasses such as timothy grass. The study is testing a single oral dose of the medication acalabrutinib, which is normally used for other conditions, to see if it can change the skin’s reaction to the pollen.

The purpose of the study is to determine whether the drug alters the size of the raised bump, called a wheal, that appears after a skin prick test. Participants will have a skin prick test with a small amount of grass pollen extract shortly before taking the medication, and then the same test will be repeated at several short intervals after the dose. Small blood samples will be taken to check the amount of drug in the blood, and basic health checks such as heart rhythm and blood pressure will be performed throughout the visit.

Researchers will compare the size of the wheal before and after the dose to see if there is a difference. They will also record any side effects or uncomfortable feelings that occur during the short observation period. The entire visit is expected to last only a few hours, and participants will be monitored closely for safety.

The research process

The trial runs in 11 steps – from screening to follow-up. Each step says what happens and what the team monitors.

  1. Step 1

    Check‑in and confirmation

    Upon arrival at the clinic, personal information is verified and the study visit is confirmed.

    The staff ensures that the eligibility criteria are still met before any procedures begin.

  2. Step 2

    Initial safety assessments

    Basic vital signs such as blood pressure, pulse and temperature are recorded.

    An electrocardiogram (ecg) is performed to check heart rhythm.

    A small blood sample may be taken to obtain baseline laboratory values.

  3. Step 3

    Baseline skin prick test (spt)

    Approximately fifteen minutes before taking the study medication, a skin prick test is performed.

    Three solutions are applied to the forearm: a grass pollen extract (phleum pratense, 10 hep), a positive control containing histamine (10 mg/ml), and a negative control containing only the diluent.

    Each prick is made with a small sterile lancet, and the size of the resulting wheal (raised bump) is measured in millimetres.

  4. Step 4

    Administration of acalabrutinib

    A single oral dose of acalabrutinib 200 mg is swallowed with water.

    The capsule is hard‑filled and taken only once during the visit.

  5. Step 5

    Immediate post‑dose assessments (time 0)

    Right after the dose is taken, another skin prick test is performed using the same three solutions.

    The wheal size for each solution is measured again.

    A blood sample is drawn to determine the plasma concentration of acalabrutinib at time zero.

  6. Step 6

    Post‑dose assessment at 5 minutes

    Five minutes after the dose, the skin prick test is repeated with the same three solutions.

    The wheal sizes are recorded.

    A second blood sample is collected to measure the drug level.

  7. Step 7

    Post‑dose assessment at 10 minutes

    Ten minutes after taking the medication, the skin prick test is performed again.

    Wheal measurements are taken for the grass pollen extract, positive control and negative control.

    A blood sample is drawn to assess the drug concentration.

  8. Step 8

    Post‑dose assessment at 15 minutes

    Fifteen minutes after the dose, the skin prick test is repeated and wheal sizes are documented.

    Another blood sample is taken to continue tracking the drug level in the bloodstream.

  9. Step 9

    Post‑dose assessment at 30 minutes

    Thirty minutes after the dose, the skin prick test is carried out for the third time.

    Wheal measurements are recorded and a blood sample is collected for drug concentration analysis.

  10. Step 10

    Post‑dose assessment at 60 minutes

    Sixty minutes after taking the medication, the final skin prick test of the visit is performed.

    The size of each wheal is measured and a final blood sample is drawn to determine the plasma level of acalabrutinib.

  11. Step 11

    Final safety check and visit completion

    Vital signs are measured again to ensure stability.

    The study staff reviews any adverse events that may have occurred during the hour.

    The visit is concluded and the participant is thanked for completing the procedures.

Who can join the trial?

8 criteria

  • You must sign a written informed consent form before any study procedures begin.
  • You need to be in overall good health, as shown by your medical history, physical exam, vital signs, heart test (ECG), and laboratory tests.
  • You must be a male or female, any race or ethnicity, aged 18 to 65 years on the day of screening.
  • You must have a documented history of an allergic reaction to grass pollen that is caused by IgE antibodies (a type of protein the immune system uses to react to allergens). If written records are not available, a verbal description from you or a caregiver can be used and recorded by the doctor.
  • You must have both of the following test results at screening:
    • A positive specific IgE blood test (level ≥ 0.70 kU/L) for Phleum pratense (the scientific name for common grass pollen), showing that your blood contains antibodies that react to that pollen.
    • A skin prick test (SPT) for Phleum pratense that shows a wheal (raised bump) size of at least 5 mm but no more than 20 mm when measured twice and averaged. The skin prick test is a quick way to see if your skin reacts to the pollen.
    • If you are a female who could become pregnant, you must have a negative pregnancy test at screening and at admission, and you must agree to use an approved form of birth control (such as oral pills, patches, injections, intra‑uterine device, implant, vaginal ring, condoms with spermicide, or a partner who has had a vasectomy) until the study ends. Women who are post‑menopausal or have had sterilization are not required to use birth control.
    • You must be willing and able to follow the study instructions and attend all required visits and procedures.

Who cannot join the trial?

17 criteria

  • Previous participation: You cannot join if you have already enrolled in this same study before.
  • Allergy or intolerance to the study drug or its ingredients: If you are known to be allergic, hypersensitive, or unable to tolerate the medication being tested, you are excluded.
  • Relationship with trial staff or sponsor: You must not have a business or personal connection with anyone directly running the study.
  • Use of prohibited medicines: You cannot take any medication that is on the study’s prohibited list.
  • Blood cell problems: Low levels of red blood cells (anemia), white blood cells (leukopenia), or platelets (thrombocytopenia) that are below normal limits exclude you.
  • Acute illness: Having a sudden, serious illness at the time of screening prevents participation.
  • Atrial fibrillation: A history of this irregular heart rhythm excludes you.
  • Severe kidney problems: If your kidney function, measured by glomerular filtration rate, is less than 30 ml/min, you cannot join.
  • Severe asthma treated with high‑dose inhaled steroids or systemic steroids: If you have severe asthma that requires strong inhaled or oral steroid medication, you are excluded.
  • Liver function problems: High bilirubin (≥ 34 µmol/L), low blood albumin (< 35 g/L), or an International Normalised Ratio (INR) of 1.7 or higher disqualify you.
  • History of alcohol or drug abuse: Past misuse of alcohol or drugs makes you ineligible.
  • Positive tests for hepatitis or alcohol: A positive test for Hepatitis B surface antigen, Hepatitis C antibody, or a urine test showing alcohol at screening prevents participation.
  • Positive urine drug test: Detection of illegal substances (such as cocaine, amphetamines, barbiturates, opiates, benzodiazepines, or cannabinoids) in urine excludes you.
  • Breastfeeding: Women who are currently breastfeeding cannot take part.
  • Unlikely to follow study rules: If you are expected to be uncooperative, unable to attend required visits, or unlikely to complete the study, you are excluded.
  • Vulnerable status: People who may feel pressured to join (for example, minors, detainees, or those unable to give consent) are not allowed to participate.
  • Other active diseases: Any other current disease that the investigator believes could affect your safety or the study results will exclude you.
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Investigated drugs

  • Calquence

    is an oral medication that contains the active ingredient acalabrutinib. In this study participants take a single dose of the drug by mouth. The purpose of giving Calquence is to see whether it can change the size of the skin reaction (wheal) that occurs after an allergy skin prick test. Acalabrutinib works by affecting certain cells in the immune system that are involved in allergic responses.

  • ALK-prick Positiv-Kontrolle

    is a solution used for skin prick testing that contains histamine. Histamine is a substance that reliably causes a small raised bump on the skin when applied, showing that the test is working correctly. In this trial the positive control is applied to the skin to confirm that the participants’ skin can react and to provide a reference point for comparing the reaction to the grass pollen extract.

  • ALK-prick SQ - 225 Wiesenlieschgras

    is a liquid preparation that contains an extract of grass pollen (Phleum pratense). It is used in the skin prick test to trigger an allergic reaction in people who are sensitive to grass pollen. The size of the bump that forms after this extract is applied is measured to assess the participants’ allergy response and to see if Calquence changes that response.

  • ALK-prick Negativ-Kontrolle

    is a solution used as a negative control in the skin prick test. It does not contain any allergen or active substance that would cause a reaction, allowing researchers to see what a normal, non‑reactive skin response looks like. This helps ensure that any bumps seen with the other solutions are due to the tested substances and not to the testing procedure itself.

What is already known about the treatment

  • Acalabrutinib

    This medication is taken as a hard capsule taken by mouth, typically 200 mg per dose. It is approved for certain blood cancers and is being studied here to see if it changes skin allergy test reactions. It works by blocking a protein called Bruton’s tyrosine kinase, which reduces signals that activate immune cells. It belongs to the class of Bruton’s tyrosine‑kinase inhibitors.

  • Histamine dihydrochloride

    This is a liquid solution used for skin‑prick testing, applied by placing a small drop on the skin and lightly pricking it. In medical practice it serves as a positive control to show that the test works, because it reliably produces a small wheal. It causes a local reaction by binding to histamine receptors on blood vessels, leading to swelling. It is classified as a histamine preparation for diagnostic use.

  • Phleum pratense (225)

    This is a liquid extract of grass pollen used for skin‑prick testing, applied in the same way as other test solutions. It is the specific allergen that people with grass pollen allergy react to, allowing doctors to measure the size of the skin reaction. The extract contains proteins that trigger an immune response in sensitized individuals. It is classified as an allergen extract for diagnostic testing.

Investigated diseases

Grass pollen allergy - Grass pollen allergy is an allergic reaction that occurs when the immune system responds to proteins in grass pollen. Exposure to the pollen triggers symptoms such as sneezing, runny nose, itchy eyes, and throat irritation. Repeated seasonal exposure can cause the symptoms to become more intense or last longer during the grass‑pollen season. The condition typically eases when pollen levels drop.
Trial detailsLast updated 7 Oct 2026
Age18+ yearsPhasePhase ITrial ID2023-505783-11-00Protocol codeAC-01Estimated enrolment12 patientsSponsorAlk-Abello A/S

sourced from the EU Clinical Trials Register and site verification

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