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

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

Study Overview

• Status: Recruiting
• Conditions: Primary Immune Thrombocytopenia
• Intervention / Treatment: Biological: PF-06835375

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.

• Study Type: Interventional
• Enrollment (Estimated): 91
• Phase: Phase 2

Contacts and Locations

• Study Contact: Name: Pfizer CT.gov Call Center; Phone Number: 1-800-718-1021; Email: ClinicalTrials.gov_Inquiries@pfizer.com

Study Locations

• Australia
  • New South Wales
    • Liverpool, New South Wales, Australia, 2170
      • Recruiting
      • Liverpool Hospital
    • Liverpool, New South Wales, Australia, 2170
      • Recruiting
      • South West Radiology
    • Mount Kuring-Gai, New South Wales, Australia, 2080
      • Recruiting
      • Slade Pharmacy
    • Waratah, New South Wales, Australia, 2298
      • Recruiting
      • Calvary Mater Newcastle
  • South Australia
    • Bedford Park, South Australia, Australia, 5042
      • Recruiting
      • Flinders Medical Centre
    • Kurralta Park, South Australia, Australia, 5037
      • Recruiting
      • ICON Cancer Centre - Kurralta Park
  • Victoria
    • Melbourne, Victoria, Australia, 3004
      • Recruiting
      • The Alfred Hospital
  • Western Australia
    • Perth, Western Australia, Australia, 6000
      • Recruiting
      • Royal Perth Hospital
• Canada
  • Ontario
    • Toronto, Ontario, Canada, M5B 1W8
      • Recruiting
      • Unity Health Toronto, St. Michael's Hospital
  • Quebec
    • Montreal, Quebec, Canada, H4A 3J1
      • Recruiting
      • McGill University Health Centre
• Czechia
  • Hradec Králové, Czechia, 500 05
    • Recruiting
    • Fakultni nemocnice Hradec Kralove
  • Ostrava - Poruba, Czechia, 708 52
    • Recruiting
    • Fakultni Nemocnice Ostrava
  • Prague, Czechia, 100 34
    • Recruiting
    • Fakultni nemocnice Kralovske Vinohrady
  • Prague, Czechia, 12808
    • Recruiting
    • Vseobecna fakultni nemocnice v Praze
• Hungary
  • Budapest, Hungary, 1088
    • Recruiting
    • Semmelweis University
  • Győr, Hungary, 9024
    • Recruiting
    • Petz Aladar Egyetemi Oktato Korhaz
  • Szekszárd, Hungary, 7100
    • Not yet recruiting
    • Tolna Varmegyei Balassa Janos Korhaz
  • Tatabánya, Hungary, H-2800
    • Not yet recruiting
    • Komarom-Esztergom Varmegyei Szent Borbala Korhaz
  • Baranya
    • Pécs, Baranya, Hungary, 7624
      • Active, not recruiting
      • Pécsi Tudományegyetem Klinikai Központ
  • Somogy County
    • Kaposvár, Somogy County, Hungary, 7400
      • Recruiting
      • Somogy Megyei Kaposi Mor Oktato Korhaz
• Poland
  • Bialystok, Poland, 15-732
    • Active, not recruiting
    • Interhem
  • Gdansk, Poland, 80-214
    • Active, not recruiting
    • Klinika Hematologii i Transplantologii Uniwersyteckie Centrum Kliniczne
  • Katowice, Poland, 40-519
    • Recruiting
    • Pratia Onkologia Katowice
  • Poznan, Poland, 60-569
    • Active, not recruiting
    • Uniwersytecki Szpital Kliniczny w Poznaniu
  • Wroclaw, Poland, 50-367
    • Recruiting
    • Uniwersytecki Szpital Kliniczny Im. Jana Mikulicza-Radeckiego We Wroclawiu
  • Greater Poland Voivodeship
    • Skórzewo, Greater Poland Voivodeship, Poland, 60-185
      • Recruiting
      • AIDPORT Sp. z o.o.
• United Kingdom
  • London, United Kingdom, W12 0HS
    • Recruiting
    • Hammersmith Hospital
  • Cambridgeshire
    • Cambridge, Cambridgeshire, United Kingdom, CB2 2QQ
      • Recruiting
      • Addenbrooke's Hospital
  • Devon
    • Plymouth, Devon, United Kingdom, Pl6 8DH
      • Recruiting
      • Derriford Hospital
  • England
    • Truro, England, United Kingdom, TR1 3LJ
      • Recruiting
      • The Royal Cornwall Hospital
• United States
  • North Carolina
    • Greenville, North Carolina, United States, 27834
      • Recruiting
      • East Carolina University

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years to 70 years (Adult, Older Adult)
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

• 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

Exclusion Criteria:

• 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.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: N/A
• Interventional Model: Single Group Assignment
• Masking: None (Open Label)

Number of Arms

4

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Open Label PF-06835375 dose 1 Treatment; subcutaneous injection once monthly for 3 months	Biological: PF-06835375; CXCR5 inhibitor
Experimental: Open Label PF-06835375 dose 2 Treatment; subcutaneous injection once monthly for 4 months	Biological: PF-06835375; CXCR5 inhibitor
Experimental: Open Label PF-06835375 dose 3 Treatment; subcutaneous injection once monthly for 4 months	Biological: PF-06835375; CXCR5 inhibitor
Experimental: Open Label PF-06835375 dose 4 Treatment; subcutaneous injections once monthly for 4 months	Biological: PF-06835375; CXCR5 inhibitor

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Proportion of participants with change from baseline of platelet counts	To evaluate absolute value of platelet count of treated participants	baseline through 12 and 16 weeks

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
proportion of participants with modified overall response (mOR)	To evaluate the modified overall response of platelet count of treated participants	baseline through 12 and 16 weeks
proportion of participants with complete response (CR)	To evaluate the complete response of platelet count of treated participants	baseline through 12 and 16 weeks
Proportion of participants with change from baseline of platelet counts		baseline to Week 20 and Week 24
Proportion of participants with change from baseline of circulating B cells		baseline to Week 20 and Week 24
Proportion of participants with change from baseline of circulating cTfh cells		baseline to Week 20 and Week 24
Number of Participants With Treatment Emergent Treatment-Related Adverse Events (AEs)		baseline through end of study (Week 20 for cohort 1 and Week 24 for cohorts 2 and 3)

Collaborators and Investigators

• Sponsor: Pfizer
• Investigators: Study Director: Pfizer CT.gov Call Center, Pfizer

Publications and helpful links

Helpful Links

• To obtain contact information for a study center near you, click here.

Study record dates

Study Major Dates

• Study Start (Actual): February 2, 2022
• Primary Completion (Estimated): August 2, 2028
• Study Completion (Estimated): August 2, 2028

Study Registration Dates

• First Submitted: September 27, 2021
• First Submitted That Met QC Criteria: September 27, 2021
• First Posted (Actual): October 7, 2021

Study Record Updates

• Last Update Posted (Actual): May 12, 2026
• Last Update Submitted That Met QC Criteria: May 11, 2026
• Last Verified: May 1, 2026

More Information

Terms related to this study

• Keywords: platelets; ITP
• Additional Relevant MeSH Terms: Cytopenia; Pathologic Processes; Autoimmune Diseases; Immune System Diseases; Hemorrhage; Skin Manifestations; Hematologic Diseases; Blood Coagulation Disorders; Hemorrhagic Disorders; Blood Platelet Disorders; Thrombotic Microangiopathies; Purpura, Thrombocytopenic; Purpura; Thrombocytopenia; Pathological Conditions, Signs and Symptoms; Signs and Symptoms; Hemic and Lymphatic Diseases; Purpura, Thrombocytopenic, Idiopathic
• Other Study ID Numbers: C1131003; 2023-509338-21-00 (Registry Identifier: CTIS (EU))

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: YES
• IPD Plan Description: 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.

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: Yes
• Studies a U.S. FDA-regulated device product: No