SERB Pharmaceuticals reports 90% graft survival in Idefirix PAES data
SERB Pharmaceuticals has announced that the post-authorisation efficacy study (PAES) of Idefirix (imlifidase) met its primary objective, with one-year graft failure-free survival of 90% across 50 highly sensitised kidney transplant patients. The results were presented at the American Society of Nephrology Kidney Week 2026 in Denver by Professor Oriol Bestard of Vall d'Hebron University Hospital, Barcelona.
The study population represented some of the most difficult-to-transplant patients in nephrology. The median time on dialysis was 9.1 years, 88% of participants had received at least one prior kidney transplant, and the median calculated Panel Reactive Antibody score was 99.98%, meaning compatible donors are exceptionally rare under standard allocation systems. All 50 transplanted patients converted to a negative crossmatch following imlifidase treatment, enabling surgery to proceed.
Study outcomes
Beyond the primary endpoint, graft survival and patient survival at one year were 92% and 98% respectively. Mean estimated glomerular filtration rate at 12 months was 51.0 mL/min/1.73m² (95% CI 44.2–57.9), a level broadly consistent with adequate kidney function in a post-transplant population. No infusion reactions led to interruption of treatment, and no new safety signals emerged relative to earlier Phase 2 experience.
Professor Bestard characterised the findings as providing "further clinical data on outcomes following imlifidase-enabled transplantation in highly sensitised patients," a deliberately measured framing given the non-randomised, open-label design of the study. Without a contemporaneous control arm receiving standard care, direct causal attribution of the survival rates to imlifidase requires care, though the extreme sensitisation levels in the study cohort make spontaneous transplantation under conventional allocation essentially implausible.
SERB's Chief Medical Officer, Vignesh Rajah, confirmed the company intends to submit an application to the EMA to convert Idefirix's conditional marketing authorisation to a full authorisation before the end of 2026. The conditional authorisation was granted in August 2020 under the PRIME priority medicines programme, with the PAES mandated by the EMA as a condition of that approval.
Regulatory and market context
SERB acquired the European and Middle East and North Africa rights to Idefirix from originator Hansa Biopharma in July 2026, meaning this is the first major clinical dataset the company has presented under its own stewardship. Topline data from the same study were disclosed by Hansa Biopharma in May 2026.
The highly sensitised kidney transplant segment remains a relatively narrow but medically significant niche. Sensitised patients accumulate on waiting lists disproportionately, and waitlist mortality in this group is substantially elevated compared with the broader transplant population. No other desensitisation agent currently holds EMA marketing authorisation for this indication, giving Idefirix an effective regulatory monopoly in Europe for the foreseeable term, subject to conversion of the conditional approval.
Conversion to full authorisation would remove the requirement for annual submission of additional data to the EMA and would likely ease market access negotiations in several European markets where reimbursement bodies have applied restrictions pending the full approval outcome. Transplant centres, payers, and procurement authorities across the EU will now be watching the EMA's review timeline closely, with the application expected before year-end.