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Study on the Safety and Efficacy of PF-06835375 and Diphenhydramine Hydrochloride for Adults with Moderate to Severe Primary Immune Thrombocytopenia

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What is this trial about?

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

This clinical trial is focused on studying a condition known as Primary Immune Thrombocytopenia (ITP), which is a disorder that can lead to easy or excessive bruising and bleeding due to low levels of platelets in the blood. The study is testing a new treatment called PF-06835375 Injection, which is given as a solution for injection under the skin. The purpose of the study is to evaluate the safety and effectiveness of this treatment in adults with moderate to severe ITP.

Participants in the study will receive the PF-06835375 Injection over a period of 12 weeks. The study will monitor the participants' platelet counts, which are important for blood clotting, at different points during the study. The goal is to see if the treatment can help increase platelet counts and improve the condition of those with ITP. Another medication, Diphenhydramine Hydrochloride, which is commonly used as an antihistamine, may also be used in the study.

The study will involve regular visits to the clinic for monitoring and assessments. Participants will be closely observed for any side effects or changes in their condition throughout the study period. The information gathered from this study will help determine the potential benefits and risks of using PF-06835375 Injection as a treatment for Primary Immune Thrombocytopenia.

The research process

The trial runs in 6 steps – from screening to follow-up. Each step says what happens and what the team monitors.

  1. Step 1

    Initial assessment

    Upon joining the study, an initial assessment is conducted to confirm eligibility. This includes reviewing medical history and current health status.

    Participants must be between 18 and 70 years old, have a diagnosis of primary immune thrombocytopenia (ITP), and meet specific health criteria.

  2. Step 2

    Treatment initiation

    Participants begin treatment with PF-06835375, administered as a solution for injection.

    The medication is given subcutaneously, which means it is injected under the skin.

  3. Step 3

    Treatment schedule

    The study involves two dosage groups: 6 mg and 18 mg of PF-06835375.

    Participants receive the medication according to their assigned dosage group.

  4. Step 4

    Monitoring and evaluation

    Regular monitoring of platelet counts is conducted to evaluate the treatment's effectiveness.

    For the 6 mg group, the primary evaluation occurs at Week 12. For the 18 mg group, it occurs at Week 16.

  5. Step 5

    Safety assessments

    Throughout the study, safety assessments are performed to monitor any adverse effects.

    These assessments include tracking the type, frequency, and severity of any side effects experienced.

  6. Step 6

    Study completion

    The study is estimated to conclude by March 29, 2025.

    Final evaluations are conducted to assess the overall response to the treatment and any changes in health status.

Who can join the trial?

8 criteria

  • Participants must be between the ages of 18 and 70 years old.
  • Participants must be willing and able to attend all scheduled visits, follow the treatment plan, undergo laboratory tests, and adhere to lifestyle considerations and other study procedures.
  • Participants must have a diagnosis of Primary Immune Thrombocytopenia (ITP). This means their body has a low number of platelets, which are cells that help blood clot. The diagnosis should follow established guidelines.
  • Participants must have ongoing ITP with platelet counts less than 50,000 per microliter of blood, without severe bleeding in the past month or during screening.
  • Participants must have persistent ITP (lasting 3 to 12 months) or chronic ITP (lasting more than 12 months).
  • Participants must have either not responded to initial therapy or need alternative therapy for ITP, as determined by the study doctor.
  • Participants must have a Body Mass Index (BMI) between 17.5 and 40 kg/m² and weigh more than 40 kg (88 lbs). BMI is a measure of body fat based on height and weight.
  • Participants must be capable of giving signed informed consent, which means they understand the study and agree to participate.

Who cannot join the trial?

10 criteria

  • Participants with other serious health conditions that might interfere with the study.
  • Individuals who are currently pregnant or breastfeeding.
  • People who have participated in another clinical trial recently.
  • Participants who have a history of allergic reactions to similar treatments.
  • Individuals with a history of drug or alcohol abuse.
  • People who are unable to follow the study procedures or attend scheduled visits.
  • Participants who have received certain medications that might affect the study results.
  • Individuals with a history of certain blood disorders.
  • People with an active infection that requires treatment.
  • Participants who have had a recent major surgery.
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Investigated drugs

PF-06835375 is a medication being studied for its safety and effectiveness in treating adults with moderate to severe primary immune thrombocytopenia. This condition is characterized by a low platelet count, which can lead to easy or excessive bruising and bleeding. The trial aims to assess how well this medication can increase platelet counts in participants over a specified period.

What is already known about the treatment

PF-06835375 – This medication is administered orally and is currently being studied in clinical trials for its safety and effectiveness in treating primary immune thrombocytopenia, a condition characterized by low platelet counts. It is in the phase 2 stage of clinical trials, indicating that it is still under investigation and not yet widely available for general medical use. The main therapeutic indication for PF-06835375 is to increase platelet counts in individuals with moderate to severe primary immune thrombocytopenia. At the molecular level, it works by modulating the immune system to prevent the destruction of platelets. It is classified pharmacologically as an immunomodulatory agent.

Investigated diseases

Primary Immune Thrombocytopenia – This is a disorder characterized by a low platelet count, which can lead to easy or excessive bruising and bleeding. The condition occurs when the immune system mistakenly attacks and destroys platelets, which are essential for normal blood clotting. It can develop suddenly or gradually and may persist for a short period or become a long-term condition. Symptoms can vary from mild to severe and may include petechiae, which are small red or purple spots on the skin, and bleeding from the gums or nose. The progression of the disease can be unpredictable, with periods of remission and relapse. The exact cause of the immune system's attack on platelets is often unknown.
Trial detailsLast updated 2 Oct 2026
Age18+ yearsPhasePhase IITrial ID2023-509338-21-00Protocol codeC1131003Estimated enrolment111 patientsSponsorPfizer Inc.

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