A National Swedish Study Evaluating Dd-cfDNA for as a Diagnostic Biomarker for Rejection Surveillence in Heart Transplantation (SweD-HTx)

April 12, 2026 updated by: Michael Melin, MD, Karolinska Institutet

A National Swedish Study Evaluating Donor-derived Cell-free DNA as a Diagnostic Biomarker in Heart Transplantation (SweD-HTx)

The SweD-HTx-study is an observational, multicenter cohort study including adult HTx recipients from Skåne University Hospital (Lund), Sahlgrenska University Hospital (Gothenburg), and Karolinska University Hospital (Stockholm). The aim of the study is to establish a robust, nationwide protocol for dd-cfDNA-based rejection monitoring in Swedish HTx recipients and to enhance our understanding of rejection mechanisms and immune activation. All participants undergo endomyocardial biopsies as part of routine post-transplant surveillance. Heart transplantations are performed at Skåne University Hospital or Sahlgrenska University Hospital, with post-transplant follow-up conducted at the outpatient transplant clinics at the participating centers.

Eligible participants are adults (≥18 years) who undergo orthotopic HTx. Exclusion criteria include pregnancy, multi-organ transplantation, or a history of other solid organ or hematopoietic stem cell transplantation.

Peripheral blood samples are collected according to standardized operating procedures and transported at ambient temperature to the immunology laboratory for processing. A subset of samples is immediately cryopreserved upon collection. Clinical and demographic data are extracted from the electronic medical record (EMR) using standardized data collection forms. The main outcome is the correlation between analyzed dd-cfDNA fraction levels and biopsy-proven rejection, defined by International Society of Heart and Lung Transplantation (ISHLT)'s histopathological criteria. The longitudinal changes in dd-cfDNA fraction and DSA will be analyzed as well as the association between DSA and dd-cfDNA fraction.

Study Overview

Status

Recruiting

Conditions

Intervention / Treatment

Detailed Description

Introduction:

Heart transplantation (HTx) and left ventricular assist device (LVAD) therapy are the primary treatment options for advanced heart failure. While HTx improves survival, it presents both short- and long-term risks, including immune-mediated injury and adverse effects from immunosuppressants. Cardiac allograft rejection affects 15-20% of recipients and often necessitates increased immunosuppression. Early detection is crucial, and serial endomyocardial biopsies (EMBs) remain the standard surveillance method.

Recently, biomarkers such as donor-derived cell-free DNA (dd-cfDNA) have emerged for detecting inflammation and cellular damage. Dd-cfDNA reflects apoptosis and necrosis in the transplanted organ and can be measured as a fraction of total cell-free DNA via PCR-based assays. It is a sensitive marker of early antibody-mediated rejection (AMR) and acute cellular rejection (ACR), often rising before histopathological changes are seen. In the US, dd-cfDNA assays are common post-transplant, but in Europe, their use is limited by cost and access.

In Sweden, 60-70 heart transplants are performed each year, with national protocols guiding post-transplant care. Frequent EMBs are performed in the first year. There is a need for non-invasive monitoring to reduce patient discomfort and improve diagnostics. This study aims to establish a national dd-cfDNA testing protocol using next-generation sequencing and to advance understanding of rejection and immune activation.

Materials and Methods:

Study Design:

The SweD-HTx study is a multicenter, observational cohort involving adult HTx recipients from Skåne University Hospital (Lund), Sahlgrenska University Hospital (Gothenburg), and Karolinska University Hospital (Stockholm). Transplants are performed at Skåne or Sahlgrenska, with follow-up at all three sites. Eligible patients are adults (≥18 years) undergoing orthotopic HTx. Exclusion criteria: pregnancy, multi-organ transplantation, or prior solid organ/hematopoietic stem cell transplant.

Blood samples are collected per standard protocols and sent to immunology labs. Some samples are cryopreserved. Clinical and demographic data are gathered from electronic records.

Study Population:

Patients are recruited after being accepted for HTx, aiming to enroll 120 participants nationwide, with recruitment expected to conclude within 2 years (first patient: Feb 2025). Written informed consent is required.

Study Visits and Sample Collection:

Blood for dd-cfDNA and DSA is collected prospectively at set intervals, coordinated with routine EMBs: weeks 1-4, months 2, 2.5, 3, 4, 5, 6, 8-9, 10-12, 16, 20, and 24 post-transplant, varying by center protocol. Samples are processed and plasma stored at -80 °C. DSA analysis is performed at each visit. Patients are monitored for five years with annual data collection.

The primary outcome is the correlation between dd-cfDNA levels and biopsy-proven rejection (per ISHLT criteria). Longitudinal changes in dd-cfDNA and DSA, as well as their association, will be analyzed.

Planned Substudies:

  1. Incidence of graft dysfunction (GDF) and CAV over five years, examined in relation to DSA and dd-cfDNA.
  2. Association between dd-cfDNA and circulating biomarkers of graft injury or inflammation.

dd-cfDNA Analysis: Dd-cfDNA quantification is done with a next-generation sequencing (NGS) assay. The dd-cfDNA fraction (%) is calculated as: (donor-derived cfDNA / total cfDNA) × 100. All analyses follow validated protocols and manufacturer instructions.

Histopathological Evaluation:

EMBs are graded locally by cardiovascular pathologists per ISHLT guidelines (2005 for ACR, 2013 for AMR). Rejection is defined as pAMR1(H+), pAMR1(I+), pAMR2, pAMR3, ACR grade 2R or 3R, or combinations thereof. Non-rejection: pAMR0, ACR grades 0 or 1R. Results are documented in electronic records.

Donor-Specific Antibody Analysis:

DSAs are analyzed at each center using the Luminex xMAP platform, reported as mean fluorescence intensity (MFI). Relationships among DSA, dd-cfDNA, and biopsy findings will be explored.

Ethical Considerations:

The study has ethics approval (Reference: 2024-03357-01, 2025-04085-02) and follows the Declaration of Helsinki, ISHLT ethics guidelines, Good Clinical Practice, and relevant regulations. Written informed consent is obtained from all participants.

Data Management and Statistical Analysis:

Data are stored in a secure, password-protected database with coded identifiers. Descriptive statistics summarize baseline characteristics. Associations among dd-cfDNA, DSA, and biopsies will be analyzed with non-parametric tests and multivariable regression models. Analyses are performed using R.

Trial Governance:

The SweD-HTx is an investigator-initiated study. DEVYSER supplies the DNA test kits, with testing performed at local immunology labs using NGS and standardized controls. The investigators and an independent steering committee oversee the trial. DEVYSER has no role in data collection, analysis, interpretation, or publication decisions. The study has received funding from Region Stockholm (ALF grants).

Results:

As of 1 January 2026, 72 participants have been enrolled from all centers, with 436 samples collected. Data include demographics, lab results, and immunosuppressive regimens at each sampling time point. DSA and dd-cfDNA levels will be correlated and analyzed longitudinally, with planned substudies on imaging and long-term follow-up.

Study Type

Observational

Enrollment (Estimated)

120

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Contact Backup

Study Locations

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

  • Adult
  • Older Adult

Accepts Healthy Volunteers

No

Sampling Method

Probability Sample

Study Population

This study will include adult HTx recipients from Skåne University Hospital (Lund), Sahlgrenska University Hospital (Gothenburg), and Karolinska University Hospital (Stockholm). All participants undergo endomyocardial biopsies as part of routine post-transplant surveillance. Heart transplantations are performed at Skåne University Hospital or Sahlgrenska University Hospital, with post-transplant follow-up conducted at the outpatient transplant clinics at the participating centers.

Description

Inclusion Criteria:

  • Adults (≥18 years) who undergo orthotopic HTx.

Exclusion Criteria:

  • Pregnancy,
  • Multi-organ transplantation
  • Solid organ
  • Hematopoietic stem cell transplantation.

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

Cohorts and Interventions

Group / Cohort
Intervention / Treatment
Heart transplant patients
Diagnostic test: dd-cfDNA
Analysis of correlation between analyzed dd-cfDNA fraction levels and biopsy-proven rejection,

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Correlation between dd-cfDNA fraction levels and biopsy-proven rejection
Time Frame: through study completion, an average of 1 year
The main outcome is the correlation between analyzed dd-cfDNA fraction levels and biopsy-proven rejection, defined by International Society of Heart and Lung Transplantation (ISHLT)'s histopathological criteria. The longitudinell changes in dd-cfDNA fraction and DSA will be analyzed as well as the the association between DSA and dd-cfDNA fraction.
through study completion, an average of 1 year

Other Outcome Measures

Outcome Measure
Measure Description
Time Frame
Incidence of graft dysfunction and cardiac allograft vasculopathy (CAV) + association between ddcf-DNA and biomarkers
Time Frame: From enrolment up to five years

A. The primary outcome is the correlation between dd-cfDNA levels and biopsy-proven rejection (per ISHLT criteria). Longitudinal changes in dd-cfDNA and DSA, will be analyzed.

B. Incidence of graft dysfunction and CAV during 5 year follow up will be studied and the association between DSA, dd-cfDNA and outcome will be analyzed.

C. Association between dd-cfDNA and circulating biomarkers of graft injury or inflammation will be anlayzed.

1. Rejection is defined as pAMR1(H+) pAMR1(I+) pAMR2 pAMR3 ACR grade 2R ACR 3R Non-rejection: pAMR0 2. dd-cfDNA is measured as

  • Fractional Abundance (%): ≥0.2% specific for biopsy-proven acute rejection 3. DSA is measured as Mean Fluorescence Intensity (MFI).
  • An MFI threshold >5000 is used to define positivity. 4. Graft dysfunction is measured as LVEF <40%. 5. CAV is measured as
  • CAV 0 (none)
  • CAV 1 (mild)
  • CAV 2 (moderate)
  • CAV 3 (severe) 4. B. It is not known today which biomarkers of graft injury or inflammation will be analyzed.
From enrolment up to five years

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Karolinska Institutet

Collaborators

Region Stockholm

Investigators

  • Principal Investigator: Michael Melin, MD, PhD, Region Stockholm
  • Principal Investigator: Michael Melin, Region Stockholm

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

February 1, 2025

Primary Completion (Estimated)

December 31, 2027

Study Completion (Estimated)

December 31, 2036

Study Registration Dates

First Submitted

March 26, 2026

First Submitted That Met QC Criteria

April 12, 2026

First Posted (Actual)

April 15, 2026

Study Record Updates

Last Update Posted (Actual)

April 15, 2026

Last Update Submitted That Met QC Criteria

April 12, 2026

Last Verified

April 1, 2026

More Information

Terms related to this study

Keywords

Other Study ID Numbers

  • 2024-03357-01, 2025-04085-02

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

IPD Plan Description

Technical and operational constraints

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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