HORUS General Assembly Highlights Progress in Signature Discovery, Clinical Research and Data Integration

The HORUS consortium met online on 29 June 2026 to review progress across the project. As HORUS moves into its final phase, the focus is shifting from patient recruitment to data integration, clinical validation and maximising project impact.

WP1 – Cohort and Biobank

Recruitment for the observational cohort has now been successfully completed, with 470 patients enrolled in Cohort 1, including 174 patients progressing to Cohort 2 following CMV infection and 78 additional de novo Cohort 2 participants.

The centralised biobank continues to grow, now holding samples from 548 participants and more than 32,000 blood specimens. Collection of biopsy samples remains a priority, with partners encouraged to continue follow-up activities and complete outstanding eCRF queries to ensure the highest quality dataset for downstream analyses.

WP2-WP3 – Biomarker Discovery

WP2 continues to generate and integrate high-dimensional datasets to identify immune signatures associated with CMV infection in solid organ transplantation.

Recent analyses of flow cytometry, single-cell RNA sequencing, cytokines and proteomics have identified several promising immune pathways and candidate biomarkers. Both flow cytometry and single-cell transcriptomic analyses consistently highlighted immune cell populations and inflammatory pathways associated with CMV infection. Proteomic analyses also identified candidate proteins that may contribute to future biomarker development in the graft biopsy of D+R- patients. Work is now focused on refining these signatures through integrated multi-omics analyses and validation across the different datasets.

WP3 – Preclinical Mouse Models

WP3 continues to make strong progress in developing an in vivo mouse model that reproduces CMV infection following solid organ transplantation under immunosuppression.

A first proof-of-concept study confirmed successful establishment of latent MCMV infection in donor mice and demonstrated that cyclosporine A modifies immune responses during infection, reducing effector CD4 and CD8 T-cell responses while preserving regulatory T cells. Changes were also observed in γδ T cells, NK cells and innate lymphoid cell populations, providing further insight into immune responses during CMV infection.

The spectral flow cytometry panels are nearing completion, with optimisation of both extracellular and functional panels almost finalised. Over the coming months, the team will complete analyses of additional organs, optimise immunosuppressive regimens and launch the first transplantation experiments, scheduled for September 2026, to investigate MCMV reactivation and dissemination under different immunosuppressive treatments.

WP5 – HORUS-COPE Clinical Trial

The HORUS-COPE interventional trial has officially launched.

The study will investigate whether modifying immunosuppressive therapy can influence CMV viral load and whether the HORUS immune signature can predict response to antiviral treatment.

A major milestone was achieved with the first patient recruited in Lausanne in May 2026. Regulatory submissions are progressing across the remaining European sites, with recruitment expected to expand to Bordeaux, Toulouse and Barcelona following approvals later this year.

WP6 – Project Management and Data

Since the previous General Assembly, the consortium has successfully launched the HORUS-COPE study, held its April Steering Committee meeting and continued delivery of key project milestones.

Work is ongoing to finalise remaining  deliverables from WP2 and WP3. The updated Data Management Plan has also been implemented, with the first HORUS metadata records now publicly available through Zenodo in line with FAIR data principles.

WP7 – Dissemination and Exploitation

Dissemination activities continue to gain momentum, with growing engagement across the HORUS website and social media channels.

Preparations are now underway for the HORUS Exploitation Strategy Workshop, taking place online on 7 October 2026. During the workshop, partners will review project results, identify opportunities for future exploitation and discuss potential intellectual property strategies to maximise the long-term impact of HORUS.

Looking Ahead

As the project enters its next phase, consortium efforts will focus on completing data collection and follow-up, validating the CMV immune signature through integrated analyses, expanding recruitment to the HORUS-COPE trial, progressing the preclinical transplantation model, and preparing the project's scientific results for future clinical translation and exploitation.