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Primary Immune ThrombocytopeniaPhase 2NCT05070845

Safety and Efficacy Study of PF-06835375 in Primary Immune Thrombocytopenia

A Phase 2 study testing PF-06835375 in people with Primary Immune Thrombocytopenia, run by Pfizer at 24 sites in 7 countries.

Terminated

Stopped early. The study ended before it was planned to and will not resume.

Official record
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Trial summary

This is a Phase 2, open-label, multicenter, multiple subcutaneous injection, safety and efficacy study of PF-06835375 in adult participants with primary immune thrombocytopenia (ITP). This study will focus on participants with persistent (>3 months and ≤12 months), or chronic (>12 months) ITP Read more about this study

Who is it for?
Ages 18 to 70 years
Conditions the study is for
Primary Immune Thrombocytopenia
What is being tested?
PF-06835375
Type of treatment
Injection or infusion
Could I receive a placebo?
No, everyone receives an active treatment
How many people
61 participants
Where
24 sitesin 7 countries
Study dates
2 Feb 2022to 23 Sep 2026
Phase
Phase 2
Are there results?
None posted in the registry

Key requirements

Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.

  • Ages 18 to 70 years
  • All sexes
  • No healthy volunteers
  • Adult, Older adult

Who may be able to join

  • Diagnosis of Primary ITP. Ongoing ITP (platelet counts <50 x 109/L) [No severe bleeding within 1 month or during screening] AND Persistent ITP (3 to 12 months) or Chronic ITP >12 months

Who cannot join

  • Bleeding event according to the WHO grading scale ≥2 occurring ≤4 weeks prior to screen OR a current bleeding event that, in the opinion of the investigator, requires treatment with standard of care therapy OR require blood or blood products during screening
  • Splenectomy within 3 months of randomization or planned during the study duration.

Trial locations and contacts

24 sites in 7 countries.

24 sites in 7 countries

Australia8 sites

  • Flinders Medical Centre

    Bedford Park, South Australia, 5042

  • ICON Cancer Centre - Kurralta Park

    Kurralta Park, South Australia, 5037

  • Liverpool Hospital

    Liverpool, New South Wales, 2170

  • South West Radiology

    Liverpool, New South Wales, 2170

  • The Alfred Hospital

    Melbourne, Victoria, 3004

  • Slade Pharmacy

    Mount Kuring-Gai, New South Wales, 2080

  • Royal Perth Hospital

    Perth, Western Australia, 6000

  • Calvary Mater Newcastle

    Waratah, New South Wales, 2298

Other trials in Australia

Poland6 sites

  • InterHem

    Bialystok, 15-732

  • Klinika Hematologii i Transplantologii Uniwersyteckie Centrum Kliniczne

    Gdansk, 80-214

  • Pratia Onkologia Katowice

    Katowice, 40-519

  • Uniwersytecki Szpital Kliniczny w Poznaniu

    Poznan, 60-569

  • AIDPORT Sp. z o.o.

    Skórzewo, Greater Poland Voivodeship, 60-185

  • Uniwersytecki Szpital Kliniczny im. Jana Mikulicza-Radeckiego we Wroclawiu

    Wroclaw, 50-367

Other trials in Poland

Hungary4 sites

  • Semmelweis University

    Budapest, 1088

  • Somogy Megyei Kaposi Mór Oktató Kórház

    Kaposvár, Somogy County, 7400

  • Pécsi Tudományegyetem Klinikai Központ

    Pécs, Baranya, 7624

  • Tolna Varmegyei Balassa Janos Korhaz

    Szekszárd, 7100

Other trials in Hungary

Canada2 sites

  • McGill University Health Centre

    Montreal, Quebec, H4A 3J1

  • Unity Health Toronto, St. Michael's Hospital

    Toronto, Ontario, M5B 1W8

Other trials in Canada

Czechia2 sites

  • Fakultni nemocnice Hradec Kralove

    Hradec Králové, 500 05

  • Fakultni nemocnice Ostrava

    Ostrava - Poruba, 708 52

Other trials in Czechia

United States1 site

  • East Carolina University

    Greenville, North Carolina, 27834

Other trials in United States

United Kingdom1 site

  • Hammersmith Hospital

    London, W12 0HS

Other trials in United Kingdom

About this study

Official title: AN INTERVENTIONAL PHASE 2, OPEN-LABEL, MULTI-CENTER STUDY TO EVALUATE SAFETY AND EFFICACY OF PF-06835375 IN ADULT PARTICIPANTS WITH MODERATE TO SEVERE PRIMARY IMMUNE THROMBOCYTOPENIA

This is a Phase 2, open-label, multicenter, multiple subcutaneous injection, safety and efficacy study of PF-06835375 in adult participants with primary immune thrombocytopenia (ITP). This study will focus on participants with persistent (>3 months and ≤12 months), or chronic (>12 months) ITP

Read the detailed description

This study is designed to elucidate the effects of PF-06835375 on platelet counts in participants with moderate to severe primary ITP. Based on the experience with other B-cells depleting agents, it is expected that the platelet counts will increase following a standard treatment. Each participant in cohort 1 received 1 subcutaneous injection of dose 1 every month for 3 months during the 12-week treatment period. Each participant in cohorts 2, 3, or 4 (will) receive(d) subcutaneous injection(s) of dose 2, 3, or 4 every month for 4 months during the 16-week treatment period. This should provide sufficient levels of exposure and depletion of CXCR5 positive cells to sustain the effects of PF-06835375 during the treatment period. Additional depletion of Tfh cells may provide sustained increase in platelet count following the last treatment.

Being tested
PF-06835375
Keywords
ITP, platelets
Medical subject headings
Purpura, Thrombocytopenic, Idiopathic

What participants receive

What participants receive. In a randomised study each person is assigned to one group by chance.

  • PF-06835375Biological

    CXCR5 inhibitor

Study groups in NCT05070845
Study groupRoleWhat they receive
Open Label PF-06835375 dose 1 TreatmentExperimentalsubcutaneous injection once monthly for 3 months
Receives: Biological: PF-06835375
Open Label PF-06835375 dose 2 TreatmentExperimentalsubcutaneous injection once monthly for 4 months
Receives: Biological: PF-06835375
Open Label PF-06835375 dose 3 TreatmentExperimentalsubcutaneous injection once monthly for 4 months
Receives: Biological: PF-06835375
Open Label PF-06835375 dose 4 TreatmentExperimentalsubcutaneous injections once monthly for 4 months
Receives: Biological: PF-06835375

What is being measured

The primary outcome is the main question the study is designed to answer.

  1. Proportion of participants with change from baseline of platelet counts

    To evaluate absolute value of platelet count of treated participants

    Measured: baseline through 12 and 16 weeks

Secondary outcomes (6)

  1. proportion of participants with modified overall response (mOR)

    To evaluate the modified overall response of platelet count of treated participants

    Measured: baseline through 12 and 16 weeks

  2. proportion of participants with complete response (CR)

    To evaluate the complete response of platelet count of treated participants

    Measured: baseline through 12 and 16 weeks

  3. Number of Participants With Treatment Emergent Treatment-Related Adverse Events (AEs)

    Measured: baseline through end of study (Week 20 for cohort 1 and Week 24 for cohorts 2 and 3)

  4. Proportion of participants with change from baseline of platelet counts

    Measured: baseline to Week 20 and Week 24

  5. Proportion of participants with change from baseline of circulating B cells

    Measured: baseline to Week 20 and Week 24

  6. Proportion of participants with change from baseline of circulating cTfh cells

    Measured: baseline to Week 20 and Week 24

Timeline

From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.

  1. First posted7 Oct 2021
  2. Study start2 Feb 2022
  3. Primary completion23 Sep 2026
  4. Study completion23 Sep 2026

Why it stopped: The study terminated due to a business decision. The decision to terminate the trial was not based on any safety concerns.

Resources

More details

For doctors and researchers: how the study is designed, who runs it, and its registry IDs.

Study design
Study type
Interventional
Phase
Phase 2
Primary purpose
Treatment
Allocation
Not applicable
Intervention model
Parallel groups
Masking
None (open label)
Enrolment
61 participants (actual)
IDs, dates and publications
ClinicalTrials.gov ID
NCT05070845
Sponsor's protocol ID
C1131003
Other IDs
2023-509338-21-00, 2023
Status last verified
Oct 2026
First submitted
27 Sep 2021
Last updated
16 Oct 2026
Results posted
No
Data monitoring committee
No
FDA-regulated drug
Yes
FDA-regulated device
No
Individual data sharing
Yes: Pfizer will provide access to individual de-identified participant data and related study documents (e.g. protocol, Statistical Analysis Plan (SAP), Clinical Study Report (CSR)) upon request from qualified researchers, and subject to certain criteria, conditions, and exceptions. Further details on Pfizer's data sharing criteria and process for requesting access can be found at: https://www.pfizer.com/science/clinical\_trials/trial\_data\_and\_results/data\_requests.

Questions about this trial

What is this clinical trial studying?

A Phase 2 study testing PF-06835375 in people with Primary Immune Thrombocytopenia, run by Pfizer at 24 sites in 7 countries.

The full registered description is in the About this study section and the official record.

Who may be eligible to take part?

The sponsor lists 1 inclusion and 2 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.

Is this clinical trial currently recruiting?

The record says: stopped early, as of the sponsor's last update on 16 Oct 2026. Status can change between updates, so confirm with the study contact before making plans.

Where is the study taking place?

The record lists 24 sites in Australia, Poland, Hungary, Canada, Czechia and 2 more countries. Whether a site is taking part right now should be confirmed with that site. See every site.

What are the possible benefits and risks?

They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.

What does this phase mean?

Phase 2 studies give the treatment to a larger group to see whether it has the intended effect and to keep checking safety.

Not every study follows the same path, and some studies (observational studies, device studies) have no phase.

Are results available for this study?

The study was stopped early (reason given: The study terminated due to a business decision. The decision to terminate the trial was not based on any safety concerns.). Results are not available in the source record.

How can a doctor refer a patient or contact the research team?

The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.

What does the primary outcome measure?

Proportion of participants with change from baseline of platelet counts (time frame: baseline through 12 and 16 weeks). It is what the study was designed to measure, not a finding.

Where can I read the original study information?

On the ClinicalTrials.gov record for NCT05070845.

Does a listing mean the treatment is approved or proven to work?

No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.

How often is this information updated?

AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 16 Oct 2026.

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