SERB Pharmaceuticals Announces Positive Results from the Post-Authorisation Efficacy Study of Idefirix® (imlifidase) Presented at ASN Kidney Week 2026

• Study met its primary objective: 1-year graft failure-free survival at 12 months post-transplant was 90%, which is clinically meaningful
• Graft and patient survival were 92% and 98%, respectively
• Idefirix^® was generally well tolerated with a safety profile consistent with previous clinical trial experience
• SERB acquired the European and MENA rights to Idefirix^® in transplantation in July 2026; the PAES trial was sponsored by Hansa Biopharma.

BRUSSELS, Oct. 23, 2026 (GLOBE NEWSWIRE) -- SERB Pharmaceuticals, a global specialty pharmaceutical company designed to address rare and urgent conditions, today announced results from the Post-Authorisation Efficacy Study (PAES) of Idefirix^® (imlifidase), a desensitisation treatment that allows kidney transplantation for highly sensitised adult kidney transplant patients who would otherwise be unlikely to receive a compatible organ from a deceased donor. The data were presented today by Professor Oriol Bestard, Vall d'Hebron University Hospital, Barcelona, in the High-Impact Clinical Trials oral abstract session at the American Society of Nephrology (ASN) Kidney Week 2026 in Denver, Colorado.¹

The European Medicines Agency (EMA) requested the PAES when it granted Idefirix^® conditional marketing authorisation in August 2020. These one-year results are intended to support conversion to full marketing authorisation for Idefirix^®.¹

Highly sensitised (HS) patients awaiting kidney transplantation with high levels of pre-formed human leukocyte antigen (HLA) antibodies face prolonged waiting times, increased waitlist mortality, and reduced transplantation rates.^2,3 This efficacy study helps demonstrate that Idefirix^® can rapidly cleave such antibodies, creating a window in which transplantation from an otherwise incompatible deceased donor can proceed.⁴

Study Population and Treatment:

• 50 highly sensitised patients who received a crossmatch-positive kidney offer from a deceased donor were transplanted following treatment with Idefirix^®.¹
  • All patients were considered unlikely to be transplanted under available kidney allocation systems, including prioritisation programmes for highly sensitised patients.¹
  • A majority (88%) had received at least one previous kidney transplant; the median time on dialysis was 9.1 years and the median calculated Panel Reactive Antibody (cPRA) was 99.98%.
    

Study Results:

• The primary objective of the study was met, with one-year graft failure-free survival of 90% (n=45).¹
  • Graft failure-free survival counts death with a functioning graft as an event; graft failure was defined as permanent return to dialysis for at least six weeks, retransplantation, transplantectomy or death.¹
  • Graft survival and patient survival at one year were 92% (n=46) and 98% (n=49), respectively.¹
• Based on local testing, all patients treated with Idefirix^® in the study converted to a negative crossmatch prior to transplantation.¹
• Mean estimated glomerular filtration rate (eGFR) at one year was 51.0 mL/min/1.73 m (95% CI 44.2–57.9).¹
• Idefirix^® was generally well tolerated.¹
  • No infusions were interrupted due to infusion reactions.¹
  • No new or additional safety signals were reported, and the overall safety profile was consistent with previous clinical trial experience.¹

“Highly sensitised patients often wait a long time for a compatible kidney, and many are unlikely to be transplanted under current allocation systems. In this multicentre European study, imlifidase allowed transplantation to proceed following crossmatch conversion, with one-year graft failure-free survival of 90%,” said Professor Oriol Bestard, Vall d'Hebron University Hospital, Barcelona, presenting author. “These findings provide further clinical data on outcomes following imlifidase-enabled transplantation in highly sensitised patients.”

“The PAES completes the post-authorisation study requested by the EMA and will form part of our application to convert Idefirix^® to a full marketing authorisation,” said Vignesh Rajah, Chief Medical Officer, SERB Pharmaceuticals. “We are grateful to the patients, investigators and transplant teams who made this study possible.”

SERB plans to submit an application to the EMA to convert the conditional marketing authorisation of Idefirix^® to a full marketing authorisation by the end of 2026.

The data were presented on 23 October 2026 from 11:15 to 11:30 a.m. MT in the High-Impact Clinical Trials oral abstract session (abstract FR-OR103) at ASN Kidney Week 2026, Bluebird Ballroom, Colorado Convention Center.¹ Topline results from the study were previously announced by Hansa Biopharma in May 2026. The PAES study was sponsored by Hansa Biopharma AB, from which SERB acquired the European and MENA rights to Idefirix^® in July 2026.

About the PAES Study

The European 20-HMedIdeS-19 Post-Authorisation Efficacy Study (PAES; NCT05369975) is a non-randomised, open-label study of imlifidase in highly sensitised adult kidney transplant patients with cPRA ≥95%) and a positive crossmatch against an available deceased donor, conducted at transplant centres across Europe (14 clinics in 7 countries). The first patient was enrolled in May 2022. The primary objective was graft failure-free survival at one year after transplantation, including patient death with a functioning graft; graft failure was defined as permanent return to dialysis for at least six weeks, retransplantation, transplantectomy or death. Secondary outcomes at one year included patient survival, graft survival, kidney function assessed by calculated eGFR (MDRD), delayed graft function, antibody-mediated rejection and safety. Patient retention exceeded 94%. Of 51 patients treated with imlifidase, 50 were transplanted; one patient was treated but not transplanted due to technical surgical issues and is included in the safety analysis only. The study also included two non-comparative reference cohorts: 63 non-sensitised patients transplanted with a compatible kidney at the same centres, and 100 less sensitised patients (cPRA <50%) from the Collaborative Transplant Study registry.

About Idefirix^® (imlifidase)

Idefirix^® is an antibody-cleaving enzyme originating from Streptococcus pyogenes that specifically targets and cleaves immunoglobulin G (IgG) antibodies and inhibits IgG-mediated immune response.⁴ It has a rapid onset of Action , cleaving IgG-antibodies and inhibiting their activity within hours after administration.

The use of Idefirix^® should be reserved for patients who are unlikely to be transplanted under the available kidney allocation system, including prioritisation programmes for highly sensitised patients.⁵ Idefirix^® was reviewed as part of the European Medicines Agency's (EMA) Priority Medicines (PRIME) programme.

The efficacy and safety of imlifidase as a pre-transplant treatment to reduce donor-specific IgG was studied in four Phase 2 open-label, single-arm, six-month clinical trials.^6,7,8,9

Full EU product information can be accessed via the Summary of Product Characteristics found here.

SERB Pharmaceuticals is the marketing authorisation holder for Idefirix^® in the European Union. Imlifidase is conditionally approved in the European Union, Norway, Liechtenstein and Iceland and the UK under the tradename Idefirix^® for the desensitisation treatment of highly sensitised adult kidney transplant patients with a positive crossmatch against an available deceased donor.

About SERB Pharmaceuticals

SERB is a fast-growing global specialty pharmaceutical company designed to address rare and urgent conditions by delivering life-saving medicines when time and complexity leave no room for failure. With a model that combines biotech agility and global pharma reliability, SERB operates end-to-end across 100+ countries, ensuring 70+ essential medicines for rare diseases, rare emergency medicine, and medical countermeasures reach patients and clinicians with urgency, wherever and whenever they are needed. Our growth is driven by selective acquisitions and geographic expansion, powered by teams who go the extra mile to keep critical medicines available worldwide.

Learn more at https://SERB.com.

Contact:

SERB Pharmaceuticals: Chris Sampson, VP of Communications

chris.sampson@serb.com; Tel: +44 (0)7773 251 178

Media Contact:

LifeSci Communications: Michael Fitzhugh

mfitzhugh@lifescicomms.com

References:

1. Bestard O, et al. PAES: Open-label post-authorization trial of 50 imlifidase crossmatch-positive deceased-donor kidney transplantations in Europe. Late-Breaking Clinical Trial, High-Impact Clinical Trials [FR-OR103]. In: American Society of Nephrology Kidney Week; October 22–25, 2026; Denver, CO.
2. Redfield RR, et al. The mode of sensitization and its influence on allograft outcomes in highly sensitized kidney transplant recipients. Nephrol Dial Transplant. 2016;31(10):1746-53. doi: 10.1093/ndt/gfw099.
3. Heidt S, et al. Highly Sensitized Patients are Well Served by Receiving a Compatible Organ Offer Based on Acceptable Mismatches. Front Immunol. 2021;12:687254. doi: 10.3389/fimmu.2021.687254.
4. Huang E, Maldonado AQ, Kjellman C, Jordan SC. Imlifidase for the treatment of anti-HLA antibody-mediated processes in kidney transplantation. Am J Transplant. 2022;22(3):691–697. doi: 10.1111/ajt.16828.
5. European Medicines Agency. Idefirix^® summary of product characteristics. Available at: https://www.ema.europa.eu/en/documents/product-information/idefirix-epar-product-information_en.pdf.
6. Jordan SC, et al. IgG Endopeptidase in Highly Sensitized Patients Undergoing Transplantation. N Engl J Med. 2017;377(5):442-453. doi: 10.1056/NEJMoa1612567.
7. Jordan SC, et al. Imlifidase Desensitization in Crossmatch-positive, Highly Sensitized Kidney Transplant Recipients: Results of an International Phase 2 Trial (Highdes). Transplantation. 2021;105(8):1808-1817. doi: 10.1097/TP.0000000000003496.
8. Winstedt L, et al. Complete Removal of Extracellular IgG Antibodies in a Randomized Dose-Escalation Phase I Study with the Bacterial Enzyme IdeS – A Novel Therapeutic Opportunity. PLoS One. 2015;10(7):e0132011. doi: 10.1371/journal.pone.0132011.
9. Lorant T, et al. Safety, immunogenicity, pharmacokinetics, and efficacy of degradation of anti-HLA antibodies by IdeS (imlifidase) in chronic kidney disease patients. Am J Transplant. 2018;18(11):2752-2762. doi: 10.1111/ajt.14733.