A Study Using Real-world Data to Examine Outcomes in Children and Adults Who Develop a Blood Clotting Disorder Called Thrombotic Microangiopathy (TMA) After Undergoing a Hematopoietic Stem Cell Transplant (HSCT). (ALX-TMA-502)

A Secondary Real-world Data Study of Pediatric and Adult Participants With Thrombotic Microangiopathy (TMA) After Hematopoietic Stem Cell Transplant (HSCT)

The purpose of this study was to assess OS outcomes in pediatric (≥ 28 days of age at the time of HSCT-TMA diagnosis) and adult participants diagnosed with HSCT-TMA(referred to as TMA from hereon) within 52 weeks after HSCT and who were either complement inhibitor treatment naïve or had been treated with eculizumab.

Study Overview

• Status: Completed
• Conditions: Thrombotic Microangiopathy; Hematopoietic Stem Cell Transplant

• Study Type: Observational
• Enrollment (Actual): 307

Contacts and Locations

Study Locations

• Belgium
  • Liège, Belgium, 1020
    • Research Facility
  • Brussels Capital
    • Brussels, Brussels Capital, Belgium, 1020
      • Research Facility
• Brazil
  • Rio de Janeiro, Brazil, 20230-130
    • Research Facility
  • São Paulo, Brazil, 04023-064
    • Research Facility
  • São Paulo, Brazil, 05403-000
    • Research Facility
  • São Paulo, Brazil, 05410-030
    • Research Facility
  • São Paulo, Brazil, 15090-000
    • Research Facility
  • Ceará
    • Fortaleza, Ceará, Brazil, 60430-372
      • Research Facility
  • Federal District
    • Brasília, Federal District, Brazil, 70684-831
      • Research Facility
  • Paraná
    • Curitiba, Paraná, Brazil, 80060-900
      • Research Facility
  • Pernambuco
    • Recife, Pernambuco, Brazil, 52010-010
      • Research Facility
  • Rio Grande do Sul
    • Porto Alegre, Rio Grande do Sul, Brazil, 90035-903
      • Research Facility
  • São Paulo
    • Jaú, São Paulo, Brazil, 17210-120
      • Research Facility
• France
  • Paris, France, 75475
    • Research Facility
  • Gironde
    • Pessac, Gironde, France, 33604
      • Research Facility
  • Haute Garonne
    • Toulouse, Haute Garonne, France, 31059
      • Research Facility
  • Isere
    • Grenoble, Isere, France, 38043
      • Research Facility
• Greece
  • Central Macedonia
    • Thessaloniki, Central Macedonia, Greece, 57010
      • Research Facility
  • West Greece
    • Pátrai, West Greece, Greece, 26500
      • Research Facility
• Italy
  • Ancona, Italy, 60126
    • Research Facility
  • Brescia, Italy, 25123
    • Research Facility
  • Florence, Italy, 50134
    • Research Facility
  • Genova, Italy, 16147
    • Research Facility
  • Naples, Italy, 80123
    • Research Facility
  • Pavia, Italy, 27100
    • Research Facility
  • Roma, Italy, 00165
    • Research Facility
  • Torino, Italy, 10126
    • Research Facility
  • Lazio
    • Rome, Lazio, Italy, 00168
      • Research Facility
• Japan
  • Fukushima
    • Fukushima, Fukushima, Japan, 960-1295
      • Research Facility
  • Ibaraki
    • Tsukuba, Ibaraki, Japan, 305-8576
      • Research Facility
  • Saitama
    • Saitama-shi, Saitama, Japan, 330-8777
      • Research Facility
  • Wakayama
    • Wakayama, Wakayama, Japan, 641-8510
      • Research Facility
• South Korea
  • Seoul, South Korea, 03080
    • Research Facility
  • Seoul, South Korea, 05505
    • Research Facility
  • Seoul, South Korea, 06351
    • Research Facility
• Spain
  • Barcelona, Spain, 08041
    • Research Facility
  • Barcelona, Spain, 08950
    • Research Facility
• United Kingdom
  • Greater London
    • London, Greater London, United Kingdom, W12 0HS
      • Research Facility
  • Tyne & Wear
    • Newcastle, Tyne & Wear, United Kingdom, NE1 4LP
      • Research Facility
  • West Midlands
    • Birmingham, West Midlands, United Kingdom, B4 6NH
      • Research Facility
• United States
  • Massachusetts
    • Boston, Massachusetts, United States, 02215
      • Research Facility
  • Ohio
    • Akron, Ohio, United States, 44308
      • Research Facility
  • Utah
    • Salt Lake City, Utah, United States, 84108
      • Research Facility

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Child; Adult; Older Adult
• Accepts Healthy Volunteers: No

• Sampling Method: Non-Probability Sample

Study Population

The study included pediatric and adult participants who were diagnosed with TMA within 52 weeks after an HSCT procedure and who were either complement inhibitor treatment naïve or had been treated with eculizumab. Data was collected from medical records in 41 study centers across 10 countries

Description

Inclusion Criteria:

• Participant must be ≥ 28 days of age at the time of TMA diagnosis.
• Body weight ≥ 5 kg at the time of TMA diagnosis.
• Documented TMA on/after 01 Jan 2010 to 30 Jun 2024 with concurrent renal dysfunction with no documented alternative explanation ≤ 52 weeks from the HSCT.
• Documentation of participant's vital status through 52 weeks after the date of TMA diagnosis.
• Documentation of date and type of HSCT, date of TMA, absence of acute GVHD, and infection status at time of TMA diagnosis.
• Documentation of at least 2 of the following: indication for most recent HSCT, serum creatinine at time of TMA diagnosis, presence of multiorgan dysfunction at time of TMA diagnosis.
• Informed consent obtained if required by local regulations.

Exclusion Criteria:

• Medical Conditions (Ongoing at the Time of TMA Diagnosis): TTP, ST-HUS, Immune-mediated hemolysis not due to TMA, DIC, Bone marrow/graft failure of HSCT, VOD (regardless of severity), HIV infection, Sepsis that required vasopressor support.
• Prior/Concomitant Therapy: Received a complement inhibitor other than eculizumab from time of suspicion of HSCT-TMA diagnosis through 52 weeks post-HSCT-TMA diagnosis..
• Other Exclusions: Participation in an investigational drug or device study for the treatment of TMA within 30 days prior to TMA diagnosis or during the 52 weeks following TMA diagnosis.

Study Plan

How is the study designed?

Number of groups / cohorts

4

Cohorts and Interventions

Group / Cohort
TMA after HSCT pediatric participants, complement inhibitor treatment naïve; The study included pediatric participants who were diagnosed with TMA within 52 weeks after an HSCT procedure and who were complement inhibitor treatment naïve
TMA after HSCT pediatric participants who had been treated with eculizumab; The study included pediatric participants who were diagnosed with TMA within 52 weeks after an HSCT procedure and who had been treated with eculizumab
TMA after HSCT adult participants, complement inhibitor treatment naïve; The study included adult participants who were diagnosed with TMA within 52 weeks after an HSCT procedure and who were complement inhibitor treatment naïve
TMA after HSCT adult participants who had been treated with eculizumab; The study included adult participants who were diagnosed with TMA within 52 weeks after an HSCT procedure and who had been treated with eculizumab

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Overall Survival (OS)	To assess OS through 52 weeks after TMA diagnosis.	52 weeks after TMA diagnosis

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Overall Survival (OS)	OS through 100 days and 26 weeks after TMA diagnosis.	100 days and 26 weeks after TMA diagnosis
Non-relapse mortality	Non-relapse mortality, defined as death due to any cause other than primary disease progression (i.e. indication fror transplant) or relapse.	Through 100 days, 26 weeks, and 52 weeks after TMA diagnosis

Collaborators and Investigators

• Sponsor: Alexion Pharmaceuticals, Inc.

Study record dates

Study Major Dates

• Study Start (Actual): January 22, 2025
• Primary Completion (Actual): March 31, 2026
• Study Completion (Actual): March 31, 2026

Study Registration Dates

• First Submitted: July 23, 2026
• First Submitted That Met QC Criteria: July 24, 2026
• First Posted (Actual): July 28, 2026

Study Record Updates

• Last Update Posted (Actual): July 28, 2026
• Last Update Submitted That Met QC Criteria: July 24, 2026
• Last Verified: July 1, 2026

More Information

Terms related to this study

• Keywords: Hematopoietic Stem Cell Transplant; Observational Study; HSCT; Retrospective; Thrombotic Microangiopathy; TMA; Real-world Data
• Additional Relevant MeSH Terms: Cytopenia; Hematologic Diseases; Blood Platelet Disorders; Thrombocytopenia; Hemic and Lymphatic Diseases; Thrombotic Microangiopathies
• Other Study ID Numbers: D9284C00003 (Other Identifier: AstraZeneca); ALX-TMA-502 (Other Identifier: Alexion Protocol Number:)

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: YES
• IPD Plan Description: Alexion has a public commitment to allow requests for access to study data and will be supplying a protocol, CSR, and plain language summaries.
• IPD Sharing Supporting Information Type: STUDY_PROTOCOL; SAP; CSR

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No
• product manufactured in and exported from the U.S.: No