For the WP1, patient recruitment progressed very strongly across all transplant cohorts, with heart transplant recruitment completed and only a limited number of kidney, liver and lung recipients remaining to reach targets. A total of 463 patients were included in cohort 1 (vs. 450 expected, including 28 additional kidney transplant recipients) and 235 patients in cohort 2 (vs. 150 expected). Clinical data collection and cohort management were implemented as planned, alongside sample logistics, with the first shipment of samples successfully completed (1,360 samples shipped) and further repatriations scheduled.
WP2 (R+) and WP3 (D+R-) implemented a common analytical strategy to assess the risk of CMV primo-infection, reactivation or superinfection after transplantation in the HORUS exploratory cohorts. Multiple analyses were performed, including ex vivo CMV detection by PCR on donor biopsies (WP3), Torque Teno Virus measurement, serology and neutralization assays (WP2 and WP3), with additional proteomic analyses conducted in WP3. Deep immune profiling of T and NK cells was achieved through harmonised flow cytometry, transcriptomic analyses and the initiation of integrated bioinformatic analyses, generating the first holistic datasets for R+ and R- transplant recipients.
WP4 focused on the pre-validation and harmonisation of ELISpot and flow cytometry assays across the three main laboratories (VHIR, USAAR and UBx) to ensure generation of comparable and robust data in order to validate our signatures obtained in WP2 and WP3 on our validation cohort obtained in WP1. Through joint meetings, shared training plans and on-site harmonisation sessions, common SOPs were reviewed, aligned and finalised, including agreement on equipment use, software, immune panels and workflows. A joint harmonisation session at VHIR in June 2025 successfully aligned key protocol parameters and analysis procedures, establishing a validated and shared framework for the implementation of WP4 experimental activities.
In WP5, in vitro experiments were initiated to assess the impact of different immunosuppressive drugs and preparations continued for murine in vivo models to evaluate immune modulation strategies, including mTOR inhibitors. Major progress was achieved with the HORUS-COPE clinical trial: the protocol and regulatory documents were submitted to Swiss Ethics in December 2025, with approvals and first patient inclusion expected in early 2026. Operational and trial preparation activities advanced as planned, positioning the study to start recruitment on schedule and to be completed within the overall project timeframe.
